njs_vm_value_to_string(njs_vm_t *vm, njs_str_t *dst, njs_value_t *src)
{
    u_char       *start;
    size_t       size;
    njs_int_t    ret;
    njs_value_t  value, stack;

    if (njs_slow_path(src == NULL)) {
        return NJS_ERROR;
    }

    if (njs_is_error(src)) {
        if (njs_is_memory_error(vm, src)) {
            njs_string_get(&njs_string_memory_error, dst);
            return NJS_OK;
        }

        ret = njs_error_stack(vm, src, &stack);
        if (njs_slow_path(ret == NJS_ERROR)) {
            return ret;
        }

        if (ret == NJS_OK) {
            src = &stack;
        }
    }

    value = *src;

    ret = njs_value_to_string(vm, &value, &value);

    if (njs_fast_path(ret == NJS_OK)) {
        size = value.short_string.size;

        if (size != NJS_STRING_LONG) {
            start = njs_mp_alloc(vm->mem_pool, size);
            if (njs_slow_path(start == NULL)) {
                njs_memory_error(vm);
                return NJS_ERROR;
            }

            memcpy(start, value.short_string.start, size);

        } else {
            size = value.long_string.size;
            start = value.long_string.data->start;
        }

        dst->length = size;
        dst->start = start;
    }

    return ret;
}


njs_vm_prop_name(njs_vm_t *vm, njs_object_prop_t *prop, njs_str_t *dst)
{
    if (njs_slow_path(!njs_is_string(&prop->name))) {
        njs_type_error(vm, "property name is not a string");
        return NJS_ERROR;
    }

    njs_string_get(&prop->name, dst);

    return NJS_OK;
}

Fixed recursive async function calls.

Previously, PromiseCapability record was stored (function->context)
directly in function object during a function invocation.  This is
not correct, because PromiseCapability record should be linked to
current execution context.  As a result, function->context is
overwritten with consecutive recursive calls which results in
use-after-free.

This closes #451 issue on Github.


njs_vm_value_string_set(njs_vm_t *vm, njs_value_t *value, const u_char *start,
    uint32_t size)
{
    return njs_string_set(vm, value, start, size);
}


njs_vm_compile(njs_vm_t *vm, u_char **start, u_char *end)
{
    njs_int_t           ret;
    njs_str_t           ast;
    njs_chb_t           chain;
    njs_value_t         **global, **new;
    njs_lexer_t         lexer;
    njs_parser_t        parser;
    njs_vm_code_t       *code;
    njs_generator_t     generator;
    njs_parser_scope_t  *scope;

    njs_memzero(&parser, sizeof(njs_parser_t));

    parser.scope = vm->global_scope;

    if (parser.scope != NULL && vm->modules != NULL) {
        njs_module_reset(vm);
    }

    ret = njs_lexer_init(vm, &lexer, &vm->options.file, *start, end, 0);
    if (njs_slow_path(ret != NJS_OK)) {
        return NJS_ERROR;
    }

    parser.lexer = &lexer;

    ret = njs_parser(vm, &parser);
    if (njs_slow_path(ret != NJS_OK)) {
        return NJS_ERROR;
    }

    if (njs_slow_path(vm->options.ast)) {
        njs_chb_init(&chain, vm->mem_pool);
        ret = njs_parser_serialize_ast(parser.node, &chain);
        if (njs_slow_path(ret == NJS_ERROR)) {
            return ret;
        }

        if (njs_slow_path(njs_chb_join(&chain, &ast) != NJS_OK)) {
            return NJS_ERROR;
        }

        njs_print(ast.start, ast.length);

        njs_chb_destroy(&chain);
        njs_mp_free(vm->mem_pool, ast.start);
    }

    *start = lexer.start;
    scope = parser.scope;

    ret = njs_generator_init(&generator, 0, 0);
    if (njs_slow_path(ret != NJS_OK)) {
        njs_internal_error(vm, "njs_generator_init() failed");
        return NJS_ERROR;
    }

    code = njs_generate_scope(vm, &generator, scope, &njs_entry_main);
    if (njs_slow_path(code == NULL)) {
        if (!njs_is_error(&vm->retval)) {
            njs_internal_error(vm, "njs_generate_scope() failed");
        }

        return NJS_ERROR;
    }

    vm->global_scope = scope;

    if (scope->items > vm->global_items) {
        global = vm->levels[NJS_LEVEL_GLOBAL];

        new = njs_scope_make(vm, scope->items);
        if (njs_slow_path(new == NULL)) {
            return ret;
        }

        vm->levels[NJS_LEVEL_GLOBAL] = new;

        if (global != NULL) {
            while (vm->global_items != 0) {
                vm->global_items--;

                *new++ = *global++;
            }

            njs_mp_free(vm->mem_pool, global);
        }
    }

    /* globalThis and this */
    njs_scope_value_set(vm, njs_scope_global_this_index(), &vm->global_value);

    vm->start = generator.code_start;
    vm->variables_hash = &scope->variables;
    vm->global_items = scope->items;

    vm->levels[NJS_LEVEL_TEMP] = NULL;

    if (scope->temp != 0) {
        new = njs_scope_make(vm, scope->temp);
        if (njs_slow_path(new == NULL)) {
            return ret;
        }

        vm->levels[NJS_LEVEL_TEMP] = new;
    }

    if (vm->options.disassemble) {
        njs_disassembler(vm);
    }

    return NJS_OK;
}


njs_vm_function(njs_vm_t *vm, const njs_str_t *path)
{
    njs_int_t    ret;
    njs_value_t  retval;

    ret = njs_vm_value(vm, path, &retval);
    if (njs_slow_path(ret != NJS_OK || !njs_is_function(&retval))) {
        return NULL;
    }

    return njs_function(&retval);
}


njs_vmcode_interpreter(njs_vm_t *vm, u_char *pc, void *promise_cap,
    void *async_ctx)
{
    u_char                       *catch;
    double                       num, exponent;
    int32_t                      i32;
    uint32_t                     u32;
    njs_str_t                    string;
    njs_uint_t                   hint;
    njs_bool_t                   valid, lambda_call;
    njs_value_t                  *retval, *value1, *value2;
    njs_value_t                  *src, *s1, *s2, dst;
    njs_value_t                  *function, name;
    njs_value_t                  numeric1, numeric2, primitive1, primitive2;
    njs_frame_t                  *frame;
    njs_jump_off_t               ret;
    njs_vmcode_await_t           *await;
    njs_native_frame_t           *previous, *native;
    njs_property_next_t          *next;
    njs_vmcode_finally_t         *finally;
    njs_vmcode_generic_t         *vmcode;
    njs_vmcode_variable_t        *var;
    njs_vmcode_move_arg_t        *move_arg;
    njs_vmcode_prop_get_t        *get;
    njs_vmcode_prop_set_t        *set;
    njs_vmcode_operation_t       op;
    njs_vmcode_prop_next_t       *pnext;
    njs_vmcode_test_jump_t       *test_jump;
    njs_vmcode_equal_jump_t      *equal;
    njs_vmcode_try_return_t      *try_return;
    njs_vmcode_method_frame_t    *method_frame;
    njs_vmcode_function_copy_t   *fcopy;
    njs_vmcode_prop_accessor_t   *accessor;
    njs_vmcode_try_trampoline_t  *try_trampoline;
    njs_vmcode_function_frame_t  *function_frame;

next:

    for ( ;; ) {

        vmcode = (njs_vmcode_generic_t *) pc;

        /*
         * The first operand is passed as is in value2 to
         *   NJS_VMCODE_JUMP,
         *   NJS_VMCODE_IF_TRUE_JUMP,
         *   NJS_VMCODE_IF_FALSE_JUMP,
         *   NJS_VMCODE_FUNCTION_FRAME,
         *   NJS_VMCODE_FUNCTION_CALL,
         *   NJS_VMCODE_RETURN,
         *   NJS_VMCODE_TRY_START,
         *   NJS_VMCODE_TRY_CONTINUE,
         *   NJS_VMCODE_TRY_BREAK,
         *   NJS_VMCODE_TRY_END,
         *   NJS_VMCODE_CATCH,
         *   NJS_VMCODE_THROW,
         *   NJS_VMCODE_STOP.
         */
        value2 = (njs_value_t *) vmcode->operand1;
        value1 = NULL;

        switch (vmcode->code.operands) {

        case NJS_VMCODE_3OPERANDS:
            njs_vmcode_operand(vm, vmcode->operand3, value2);

            /* Fall through. */

        case NJS_VMCODE_2OPERANDS:
            njs_vmcode_operand(vm, vmcode->operand2, value1);
        }

        op = vmcode->code.operation;

        /*
         * On success an operation returns size of the bytecode,
         * a jump offset or zero after the call or return operations.
         * Jumps can return a negative offset.  Compilers can generate
         *    (ret < 0 && ret >= NJS_PREEMPT)
         * as a single unsigned comparision.
         */

        if (op > NJS_VMCODE_NORET) {

            if (op == NJS_VMCODE_MOVE) {
                njs_vmcode_operand(vm, vmcode->operand1, retval);
                *retval = *value1;

                pc += sizeof(njs_vmcode_move_t);
                goto next;
            }

            if (op == NJS_VMCODE_PROPERTY_GET) {
                get = (njs_vmcode_prop_get_t *) pc;
                njs_vmcode_operand(vm, get->value, retval);

                ret = njs_value_property(vm, value1, value2, retval);
                if (njs_slow_path(ret == NJS_ERROR)) {
                    goto error;
                }

                pc += sizeof(njs_vmcode_prop_get_t);
                goto next;
            }

            switch (op) {
            case NJS_VMCODE_INCREMENT:
            case NJS_VMCODE_POST_INCREMENT:
            case NJS_VMCODE_DECREMENT:
            case NJS_VMCODE_POST_DECREMENT:
                if (njs_slow_path(!njs_is_numeric(value2))) {
                    ret = njs_value_to_numeric(vm, value2, &numeric1);
                    if (njs_slow_path(ret != NJS_OK)) {
                        goto error;
                    }

                    num = njs_number(&numeric1);

                } else {
                    num = njs_number(value2);
                }

                njs_set_number(value1,
                           num + (1 - 2 * ((op - NJS_VMCODE_INCREMENT) >> 1)));

                njs_vmcode_operand(vm, vmcode->operand1, retval);

                if (op & 1) {
                    njs_set_number(retval, num);

                } else {
                    *retval = *value1;
                }

                pc += sizeof(njs_vmcode_3addr_t);
                goto next;

            case NJS_VMCODE_GLOBAL_GET:
                get = (njs_vmcode_prop_get_t *) pc;
                njs_vmcode_operand(vm, get->value, retval);

                ret = njs_value_property(vm, value1, value2, retval);
                if (njs_slow_path(ret == NJS_ERROR)) {
                    goto error;
                }

                pc += sizeof(njs_vmcode_prop_get_t);

                if (ret == NJS_OK) {
                    pc += sizeof(njs_vmcode_error_t);
                }

                goto next;

            /*
             * njs_vmcode_try_return() saves a return value to use it later by
             * njs_vmcode_finally(), and jumps to the nearest try_break block.
             */
            case NJS_VMCODE_TRY_RETURN:
                njs_vmcode_operand(vm, vmcode->operand1, retval);
                *retval = *value1;

                try_return = (njs_vmcode_try_return_t *) pc;
                pc += try_return->offset;
                goto next;

            case NJS_VMCODE_LESS:
            case NJS_VMCODE_GREATER:
            case NJS_VMCODE_LESS_OR_EQUAL:
            case NJS_VMCODE_GREATER_OR_EQUAL:
            case NJS_VMCODE_ADDITION:
                if (njs_slow_path(!njs_is_primitive(value1))) {
                    hint = (op == NJS_VMCODE_ADDITION) && njs_is_date(value1);
                    ret = njs_value_to_primitive(vm, &primitive1, value1, hint);
                    if (ret != NJS_OK) {
                        goto error;
                    }

                    value1 = &primitive1;
                }

                if (njs_slow_path(!njs_is_primitive(value2))) {
                    hint = (op == NJS_VMCODE_ADDITION) && njs_is_date(value2);
                    ret = njs_value_to_primitive(vm, &primitive2, value2, hint);
                    if (ret != NJS_OK) {
                        goto error;
                    }

                    value2 = &primitive2;
                }

                if (njs_slow_path(njs_is_symbol(value1)
                                  || njs_is_symbol(value2)))
                {
                    njs_symbol_conversion_failed(vm,
                        (op == NJS_VMCODE_ADDITION) &&
                        (njs_is_string(value1) || njs_is_string(value2)));

                    goto error;
                }

                njs_vmcode_operand(vm, vmcode->operand1, retval);

                if (op == NJS_VMCODE_ADDITION) {
                    if (njs_fast_path(njs_is_numeric(value1)
                                      && njs_is_numeric(value2)))
                    {
                        njs_set_number(retval, njs_number(value1)
                                               + njs_number(value2));
                        pc += sizeof(njs_vmcode_3addr_t);
                        goto next;
                    }

                    if (njs_is_string(value1)) {
                        s1 = value1;
                        s2 = &dst;
                        src = value2;

                    } else {
                        s1 = &dst;
                        s2 = value2;
                        src = value1;
                    }

                    ret = njs_primitive_value_to_string(vm, &dst, src);
                    if (njs_slow_path(ret != NJS_OK)) {
                        goto error;
                    }

                    ret = njs_string_concat(vm, s1, s2);
                    if (njs_slow_path(ret == NJS_ERROR)) {
                        goto error;
                    }

                    *retval = vm->retval;

                    pc += ret;
                    goto next;
                }

                if ((uint8_t) (op - NJS_VMCODE_GREATER) < 2) {
                    /* NJS_VMCODE_GREATER, NJS_VMCODE_LESS_OR_EQUAL */
                    src = value1;
                    value1 = value2;
                    value2 = src;
                }

                ret = njs_primitive_values_compare(vm, value1, value2);

                if (op < NJS_VMCODE_LESS_OR_EQUAL) {
                    ret = ret > 0;

                } else {
                    ret = ret == 0;
                }

                njs_set_boolean(retval, ret);

                pc += sizeof(njs_vmcode_3addr_t);
                goto next;

            case NJS_VMCODE_EQUAL:
            case NJS_VMCODE_NOT_EQUAL:
                ret = njs_values_equal(vm, value1, value2);
                if (njs_slow_path(ret < 0)) {
                    goto error;
                }

                ret ^= op - NJS_VMCODE_EQUAL;

                njs_vmcode_operand(vm, vmcode->operand1, retval);
                njs_set_boolean(retval, ret);

                pc += sizeof(njs_vmcode_3addr_t);
                goto next;

            case NJS_VMCODE_SUBSTRACTION:
            case NJS_VMCODE_MULTIPLICATION:
            case NJS_VMCODE_EXPONENTIATION:
            case NJS_VMCODE_DIVISION:
            case NJS_VMCODE_REMAINDER:
            case NJS_VMCODE_BITWISE_AND:
            case NJS_VMCODE_BITWISE_OR:
            case NJS_VMCODE_BITWISE_XOR:
            case NJS_VMCODE_LEFT_SHIFT:
            case NJS_VMCODE_RIGHT_SHIFT:
            case NJS_VMCODE_UNSIGNED_RIGHT_SHIFT:
                if (njs_slow_path(!njs_is_numeric(value1))) {
                    ret = njs_value_to_numeric(vm, value1, &numeric1);
                    if (njs_slow_path(ret != NJS_OK)) {
                        goto error;
                    }

                    value1 = &numeric1;
                }

                if (njs_slow_path(!njs_is_numeric(value2))) {
                    ret = njs_value_to_numeric(vm, value2, &numeric2);
                    if (njs_slow_path(ret != NJS_OK)) {
                        goto error;
                    }

                    value2 = &numeric2;
                }

                num = njs_number(value1);

                njs_vmcode_operand(vm, vmcode->operand1, retval);
                pc += sizeof(njs_vmcode_3addr_t);

                switch (op) {
                case NJS_VMCODE_SUBSTRACTION:
                    num -= njs_number(value2);
                    break;

                case NJS_VMCODE_MULTIPLICATION:
                    num *= njs_number(value2);
                    break;

                case NJS_VMCODE_EXPONENTIATION:
                    exponent = njs_number(value2);

                    /*
                     * According to ES7:
                     *  1. If exponent is NaN, the result should be NaN;
                     *  2. The result of +/-1 ** +/-Infinity should be NaN.
                     */
                    valid = njs_expect(1, fabs(num) != 1
                                          || (!isnan(exponent)
                                              && !isinf(exponent)));

                    num = valid ? pow(num, exponent) : NAN;
                    break;

                case NJS_VMCODE_DIVISION:
                    num /= njs_number(value2);
                    break;

                case NJS_VMCODE_REMAINDER:
                    num = fmod(num, njs_number(value2));
                    break;

                case NJS_VMCODE_BITWISE_AND:
                case NJS_VMCODE_BITWISE_OR:
                case NJS_VMCODE_BITWISE_XOR:
                    i32 = njs_number_to_int32(njs_number(value2));

                    switch (op) {
                    case NJS_VMCODE_BITWISE_AND:
                        i32 &= njs_number_to_int32(num);
                        break;

                    case NJS_VMCODE_BITWISE_OR:
                        i32 |= njs_number_to_int32(num);
                        break;

                    case NJS_VMCODE_BITWISE_XOR:
                        i32 ^= njs_number_to_int32(num);
                        break;
                    }

                    njs_set_int32(retval, i32);
                    goto next;

                default:
                    u32 = njs_number_to_uint32(njs_number(value2)) & 0x1f;

                    switch (op) {
                    case NJS_VMCODE_LEFT_SHIFT:
                    case NJS_VMCODE_RIGHT_SHIFT:
                        i32 = njs_number_to_int32(num);

                        if (op == NJS_VMCODE_LEFT_SHIFT) {
                            /* Shifting of negative numbers is undefined. */
                            i32 = (uint32_t) i32 << u32;
                        } else {
                            i32 >>= u32;
                        }

                        njs_set_int32(retval, i32);
                        break;

                    default: /* NJS_VMCODE_UNSIGNED_RIGHT_SHIFT */
                        njs_set_uint32(retval,
                                       njs_number_to_uint32(num) >> u32);
                    }

                    goto next;
                }

                njs_set_number(retval, num);
                goto next;

            case NJS_VMCODE_OBJECT_COPY:
                ret = njs_vmcode_object_copy(vm, value1, value2);
                break;

            case NJS_VMCODE_TEMPLATE_LITERAL:
                ret = njs_vmcode_template_literal(vm, value1, value2);
                break;

            case NJS_VMCODE_PROPERTY_IN:
                ret = njs_vmcode_property_in(vm, value1, value2);
                break;

            case NJS_VMCODE_PROPERTY_DELETE:
                ret = njs_value_property_delete(vm, value1, value2, NULL);
                if (njs_fast_path(ret != NJS_ERROR)) {
                    vm->retval = njs_value_true;

                    ret = sizeof(njs_vmcode_3addr_t);
                }

                break;

            case NJS_VMCODE_PROPERTY_FOREACH:
                ret = njs_vmcode_property_foreach(vm, value1, value2, pc);
                break;

            case NJS_VMCODE_STRICT_EQUAL:
            case NJS_VMCODE_STRICT_NOT_EQUAL:
                ret = njs_values_strict_equal(value1, value2);

                ret ^= op - NJS_VMCODE_STRICT_EQUAL;

                njs_vmcode_operand(vm, vmcode->operand1, retval);
                njs_set_boolean(retval, ret);

                pc += sizeof(njs_vmcode_3addr_t);
                goto next;

            case NJS_VMCODE_TEST_IF_TRUE:
            case NJS_VMCODE_TEST_IF_FALSE:
            case NJS_VMCODE_COALESCE:
                if (op == NJS_VMCODE_COALESCE) {
                    ret = !njs_is_null_or_undefined(value1);

                } else {
                    ret = njs_is_true(value1);
                    ret ^= op - NJS_VMCODE_TEST_IF_TRUE;
                }

                if (ret) {
                    test_jump = (njs_vmcode_test_jump_t *) pc;
                    ret = test_jump->offset;

                } else {
                    ret = sizeof(njs_vmcode_3addr_t);
                }

                njs_vmcode_operand(vm, vmcode->operand1, retval);
                *retval = *value1;

                pc += ret;
                goto next;

            case NJS_VMCODE_UNARY_PLUS:
            case NJS_VMCODE_UNARY_NEGATION:
            case NJS_VMCODE_BITWISE_NOT:
                if (njs_slow_path(!njs_is_numeric(value1))) {
                    ret = njs_value_to_numeric(vm, value1, &numeric1);
                    if (njs_slow_path(ret != NJS_OK)) {
                        goto error;
                    }

                    value1 = &numeric1;
                }

                num = njs_number(value1);
                njs_vmcode_operand(vm, vmcode->operand1, retval);

                switch (op) {
                case NJS_VMCODE_UNARY_NEGATION:
                    num = -num;

                    /* Fall through. */
                case NJS_VMCODE_UNARY_PLUS:
                    njs_set_number(retval, num);
                    break;

                case NJS_VMCODE_BITWISE_NOT:
                    njs_set_int32(retval, ~njs_number_to_uint32(num));
                }

                pc += sizeof(njs_vmcode_2addr_t);
                goto next;

            case NJS_VMCODE_LOGICAL_NOT:
                njs_vmcode_operand(vm, vmcode->operand1, retval);
                njs_set_boolean(retval, !njs_is_true(value1));

                pc += sizeof(njs_vmcode_2addr_t);
                goto next;

            case NJS_VMCODE_OBJECT:
                ret = njs_vmcode_object(vm);
                break;

            case NJS_VMCODE_ARRAY:
                ret = njs_vmcode_array(vm, pc);
                break;

            case NJS_VMCODE_FUNCTION:
                ret = njs_vmcode_function(vm, pc);
                break;

            case NJS_VMCODE_REGEXP:
                ret = njs_vmcode_regexp(vm, pc);
                break;

            case NJS_VMCODE_INSTANCE_OF:
                ret = njs_vmcode_instance_of(vm, value1, value2);
                break;

            case NJS_VMCODE_TYPEOF:
                ret = njs_vmcode_typeof(vm, value1, value2);
                break;

            case NJS_VMCODE_VOID:
                njs_set_undefined(&vm->retval);

                ret = sizeof(njs_vmcode_2addr_t);
                break;

            case NJS_VMCODE_DELETE:
                njs_release(vm, value1);
                vm->retval = njs_value_true;

                ret = sizeof(njs_vmcode_2addr_t);
                break;

            case NJS_VMCODE_DEBUGGER:
                ret = njs_vmcode_debugger(vm);
                break;

            default:
                njs_internal_error(vm, "%d has retval", op);
                goto error;
            }

            if (njs_slow_path(ret < 0 && ret >= NJS_PREEMPT)) {
                break;
            }

            njs_vmcode_operand(vm, vmcode->operand1, retval);
            njs_release(vm, retval);
            *retval = vm->retval;

        } else {

            switch (op) {
            case NJS_VMCODE_MOVE_ARG:
                move_arg = (njs_vmcode_move_arg_t *) pc;
                native = vm->top_frame;

                hint = move_arg->dst;

                value1 = &native->arguments_offset[hint];
                njs_vmcode_operand(vm, move_arg->src, value2);

                *value1 = *value2;

                ret = sizeof(njs_vmcode_move_arg_t);
                break;

            case NJS_VMCODE_STOP:
                njs_vmcode_operand(vm, (njs_index_t) value2, value2);
                vm->retval = *value2;

                return NJS_OK;

            case NJS_VMCODE_JUMP:
                ret = (njs_jump_off_t) value2;
                break;

            case NJS_VMCODE_PROPERTY_SET:
                set = (njs_vmcode_prop_set_t *) pc;
                njs_vmcode_operand(vm, set->value, retval);

                ret = njs_value_property_set(vm, value1, value2, retval);
                if (njs_slow_path(ret == NJS_ERROR)) {
                    goto error;
                }

                ret = sizeof(njs_vmcode_prop_set_t);
                break;

            case NJS_VMCODE_PROPERTY_ACCESSOR:
                accessor = (njs_vmcode_prop_accessor_t *) pc;
                njs_vmcode_operand(vm, accessor->value, function);

                ret = njs_value_to_key(vm, &name, value2);
                if (njs_slow_path(ret != NJS_OK)) {
                    njs_internal_error(vm, "failed conversion of type \"%s\" "
                                       "to string while property define",
                                       njs_type_string(value2->type));
                    goto error;
                }

                ret = njs_object_prop_define(vm, value1, &name, function,
                                             accessor->type);
                if (njs_slow_path(ret != NJS_OK)) {
                    return NJS_ERROR;
                }

                ret = sizeof(njs_vmcode_prop_accessor_t);
                break;

            case NJS_VMCODE_IF_TRUE_JUMP:
            case NJS_VMCODE_IF_FALSE_JUMP:
                ret = njs_is_true(value1);

                ret ^= op - NJS_VMCODE_IF_TRUE_JUMP;

                ret = ret ? (njs_jump_off_t) value2
                          : (njs_jump_off_t) sizeof(njs_vmcode_cond_jump_t);

                break;

            case NJS_VMCODE_IF_EQUAL_JUMP:
                if (njs_values_strict_equal(value1, value2)) {
                    equal = (njs_vmcode_equal_jump_t *) pc;
                    ret = equal->offset;

                } else {
                    ret = sizeof(njs_vmcode_3addr_t);
                }

                break;

            case NJS_VMCODE_PROPERTY_INIT:
                set = (njs_vmcode_prop_set_t *) pc;
                njs_vmcode_operand(vm, set->value, retval);
                ret = njs_vmcode_property_init(vm, value1, value2, retval);
                if (njs_slow_path(ret == NJS_ERROR)) {
                    goto error;
                }

                break;

            case NJS_VMCODE_RETURN:
                njs_vmcode_operand(vm, (njs_index_t) value2, value2);
                return njs_vmcode_return(vm, NULL, value2);

            case NJS_VMCODE_FUNCTION_COPY:
                fcopy = (njs_vmcode_function_copy_t *) pc;
                ret = njs_vmcode_function_copy(vm, fcopy->function,
                                               fcopy->retval);
                break;

            case NJS_VMCODE_FUNCTION_FRAME:
                function_frame = (njs_vmcode_function_frame_t *) pc;

                /* TODO: external object instead of void this. */

                ret = njs_function_frame_create(vm, value1,
                                                &njs_value_undefined,
                                                (uintptr_t) value2,
                                                function_frame->ctor);

                if (njs_slow_path(ret != NJS_OK)) {
                    goto error;
                }

                ret = sizeof(njs_vmcode_function_frame_t);
                break;

            case NJS_VMCODE_METHOD_FRAME:
                method_frame = (njs_vmcode_method_frame_t *) pc;

                ret = njs_value_property(vm, value1, value2, &dst);
                if (njs_slow_path(ret == NJS_ERROR)) {
                    goto error;
                }

                if (njs_slow_path(!njs_is_function(&dst))) {
                    ret = njs_value_to_key(vm, value2, value2);
                    if (njs_slow_path(ret != NJS_OK)) {
                        return NJS_ERROR;
                    }

                    njs_key_string_get(vm, value2, &string);
                    njs_type_error(vm,
                               "(intermediate value)[\"%V\"] is not a function",
                               &string);
                    goto error;
                }

                ret = njs_function_frame_create(vm, &dst, value1,
                                                method_frame->nargs,
                                                method_frame->ctor);

                if (njs_slow_path(ret != NJS_OK)) {
                    goto error;
                }

                ret = sizeof(njs_vmcode_method_frame_t);
                break;

            case NJS_VMCODE_FUNCTION_CALL:
                vm->active_frame->native.pc = pc;

                njs_vmcode_operand(vm, (njs_index_t) value2, value2);

                ret = njs_function_frame_invoke(vm, value2);
                if (njs_slow_path(ret == NJS_ERROR)) {
                    goto error;
                }

                ret = sizeof(njs_vmcode_function_call_t);
                break;

            case NJS_VMCODE_PROPERTY_NEXT:
                pnext = (njs_vmcode_prop_next_t *) pc;
                retval = njs_scope_value(vm, pnext->retval);

                next = value2->data.u.next;

                if (next->index < next->array->length) {
                    *retval = next->array->start[next->index++];

                    ret = pnext->offset;
                    break;
                }

                njs_mp_free(vm->mem_pool, next);

                ret = sizeof(njs_vmcode_prop_next_t);
                break;

            case NJS_VMCODE_ARGUMENTS:
                ret = njs_vmcode_arguments(vm, pc);
                if (njs_slow_path(ret == NJS_ERROR)) {
                    goto error;
                }

                break;

            case NJS_VMCODE_PROTO_INIT:
                set = (njs_vmcode_prop_set_t *) pc;
                njs_vmcode_operand(vm, set->value, retval);
                ret = njs_vmcode_proto_init(vm, value1, value2, retval);
                if (njs_slow_path(ret == NJS_ERROR)) {
                    goto error;
                }

                break;

            case NJS_VMCODE_AWAIT:
                await = (njs_vmcode_await_t *) pc;
                return njs_vmcode_await(vm, await, promise_cap, async_ctx);

            case NJS_VMCODE_TRY_START:
                ret = njs_vmcode_try_start(vm, value1, value2, pc);
                if (njs_slow_path(ret == NJS_ERROR)) {
                    goto error;
                }

                break;

            case NJS_VMCODE_THROW:
                njs_vmcode_operand(vm, (njs_index_t) value2, value2);
                vm->retval = *value2;
                goto error;

            case NJS_VMCODE_TRY_BREAK:
                try_trampoline = (njs_vmcode_try_trampoline_t *) pc;
                value1 = njs_scope_value(vm, try_trampoline->exit_value);

                ret = njs_vmcode_try_break(vm, value1, value2);
                break;

            case NJS_VMCODE_TRY_CONTINUE:
                try_trampoline = (njs_vmcode_try_trampoline_t *) pc;
                value1 = njs_scope_value(vm, try_trampoline->exit_value);

                ret = njs_vmcode_try_continue(vm, value1, value2);
                break;

            case NJS_VMCODE_TRY_END:
                ret = njs_vmcode_try_end(vm, value1, value2);
                break;

            /*
             * njs_vmcode_catch() is set on the start of a "catch" block to
             * store exception and to remove a "try" block if there is no
             * "finally" block or to update a catch address to the start of
             * a "finally" block.
             * njs_vmcode_catch() is set on the start of a "finally" block
             * to store uncaught exception and to remove a "try" block.
             */
            case NJS_VMCODE_CATCH:
                *value1 = vm->retval;

                if ((njs_jump_off_t) value2 == sizeof(njs_vmcode_catch_t)) {
                    ret = njs_vmcode_try_end(vm, value1, value2);

                } else {
                    frame = (njs_frame_t *) vm->top_frame;
                    frame->exception.catch = pc + (njs_jump_off_t) value2;
                    ret = sizeof(njs_vmcode_catch_t);
                }

                break;

            case NJS_VMCODE_FINALLY:
                finally = (njs_vmcode_finally_t *) pc;
                value1 = njs_scope_value(vm, finally->exit_value);

                ret = njs_vmcode_finally(vm, value1, value2, pc);

                switch (ret) {
                case NJS_OK:
                    return NJS_OK;
                case NJS_ERROR:
                    goto error;
                }

                break;

            case NJS_VMCODE_LET:
                var = (njs_vmcode_variable_t *) pc;
                value1 = njs_scope_value(vm, var->dst);

                if (njs_is_valid(value1)) {
                    value1 = njs_mp_alloc(vm->mem_pool, sizeof(njs_value_t));
                    if (njs_slow_path(value1 == NULL)) {
                        return NJS_ERROR;
                    }

                    njs_scope_value_set(vm, var->dst, value1);
                }

                njs_set_undefined(value1);

                ret = sizeof(njs_vmcode_variable_t);
                break;

            case NJS_VMCODE_LET_UPDATE:
                var = (njs_vmcode_variable_t *) pc;
                value2 = njs_scope_value(vm, var->dst);

                value1 = njs_mp_alloc(vm->mem_pool, sizeof(njs_value_t));
                if (njs_slow_path(value1 == NULL)) {
                    return NJS_ERROR;
                }

                *value1 = *value2;

                njs_scope_value_set(vm, var->dst, value1);

                ret = sizeof(njs_vmcode_variable_t);
                break;

            case NJS_VMCODE_INITIALIZATION_TEST:
                var = (njs_vmcode_variable_t *) pc;
                value1 = njs_scope_value(vm, var->dst);

                if (njs_is_valid(value1)) {
                    ret = sizeof(njs_vmcode_variable_t);
                    break;
                }

                /* Fall through. */

            case NJS_VMCODE_NOT_INITIALIZED:
                njs_reference_error(vm, "cannot access variable "
                                        "before initialization");
                goto error;

            case NJS_VMCODE_ERROR:
                njs_vmcode_error(vm, pc);
                goto error;

            case NJS_VMCODE_ASSIGNMENT_ERROR:
                njs_type_error(vm, "assignment to constant variable");
                goto error;

            default:
                njs_internal_error(vm, "%d has NO retval", op);
                goto error;
            }
        }

        pc += ret;
    }

error:

    if (njs_is_error(&vm->retval)) {
        vm->active_frame->native.pc = pc;
        (void) njs_error_stack_attach(vm, &vm->retval);
    }

    for ( ;; ) {
        native = vm->top_frame;

        if (!native->native) {
            frame = (njs_frame_t *) native;
            catch = frame->exception.catch;

            if (catch != NULL) {
                pc = catch;

                goto next;
            }
        }

        previous = native->previous;
        if (previous == NULL) {
            break;
        }

        lambda_call = (native == &vm->active_frame->native);

        njs_vm_scopes_restore(vm, native, previous);

        if (native->size != 0) {
            vm->stack_size -= native->size;
            njs_mp_free(vm->mem_pool, native);
        }

        if (lambda_call) {
            break;
        }
    }

    return NJS_ERROR;
}


njs_vm_create(njs_vm_opt_t *options)
{
    njs_mp_t      *mp;
    njs_vm_t      *vm;
    njs_int_t     ret;
    njs_uint_t    i;
    njs_module_t  **addons;

    mp = njs_mp_fast_create(2 * njs_pagesize(), 128, 512, 16);
    if (njs_slow_path(mp == NULL)) {
        return NULL;
    }

    vm = njs_mp_zalign(mp, sizeof(njs_value_t), sizeof(njs_vm_t));
    if (njs_slow_path(vm == NULL)) {
        return NULL;
    }

    vm->mem_pool = mp;

    ret = njs_regexp_init(vm);
    if (njs_slow_path(ret != NJS_OK)) {
        return NULL;
    }

    njs_lvlhsh_init(&vm->values_hash);

    vm->options = *options;

    if (options->shared != NULL) {
        vm->shared = options->shared;

    } else {
        ret = njs_builtin_objects_create(vm);
        if (njs_slow_path(ret != NJS_OK)) {
            return NULL;
        }
    }

    vm->external = options->external;

    vm->trace.level = NJS_LEVEL_TRACE;
    vm->trace.size = 2048;
    vm->trace.data = vm;

    njs_set_undefined(&vm->retval);

    if (options->init) {
        ret = njs_vm_init(vm);
        if (njs_slow_path(ret != NJS_OK)) {
            return NULL;
        }
    }

    for (i = 0; njs_modules[i] != NULL; i++) {
        ret = njs_modules[i]->init(vm);
        if (njs_slow_path(ret != NJS_OK)) {
            return NULL;
        }
    }

    if (options->addons != NULL) {
        addons = options->addons;
        for (i = 0; addons[i] != NULL; i++) {
            ret = addons[i]->init(vm);
            if (njs_slow_path(ret != NJS_OK)) {
                return NULL;
            }
        }
    }

    vm->symbol_generator = NJS_SYMBOL_KNOWN_MAX;

    if (njs_scope_undefined_index(vm, 0) == NJS_INDEX_ERROR) {
        return NULL;
    }

    return vm;
}


njs_vm_value(njs_vm_t *vm, const njs_str_t *path, njs_value_t *retval)
{
    u_char       *start, *p, *end;
    size_t       size;
    njs_int_t    ret;
    njs_value_t  value, key;

    start = path->start;
    end = start + path->length;

    njs_set_object(&value, &vm->global_object);

    for ( ;; ) {
        p = njs_strlchr(start, end, '.');

        size = ((p != NULL) ? p : end) - start;
        if (njs_slow_path(size == 0)) {
            njs_type_error(vm, "empty path element");
            return NJS_ERROR;
        }

        ret = njs_string_set(vm, &key, start, size);
        if (njs_slow_path(ret != NJS_OK)) {
            return NJS_ERROR;
        }

        ret = njs_value_property(vm, &value, &key, njs_value_arg(retval));
        if (njs_slow_path(ret != NJS_OK)) {
            return ret;
        }

        if (p == NULL) {
            break;
        }

        start = p + 1;
        value = *retval;
    }

    return NJS_OK;
}


njs_vm_invoke(njs_vm_t *vm, njs_function_t *function, const njs_value_t *args,
    njs_uint_t nargs, njs_value_t *retval)
{
    njs_int_t  ret;

    ret = njs_function_frame(vm, function, &njs_value_undefined, args, nargs,
                             0);
    if (njs_slow_path(ret != NJS_OK)) {
        return ret;
    }

    return njs_function_frame_invoke(vm, retval);
}


njs_vm_call(njs_vm_t *vm, njs_function_t *function, const njs_value_t *args,
    njs_uint_t nargs)
{
    return njs_vm_invoke(vm, function, args, nargs, &vm->retval);
}


njs_vm_object_keys(njs_vm_t *vm, njs_value_t *value, njs_value_t *retval)
{
    njs_array_t  *keys;

    keys = njs_value_own_enumerate(vm, value, NJS_ENUM_KEYS,
                                   NJS_ENUM_STRING, 0);
    if (njs_slow_path(keys == NULL)) {
        return NULL;
    }

    njs_set_array(retval, keys);

    return retval;
}


njs_lvlhsh_free(void *data, void *p, size_t size)
{
    njs_mp_free(data, p);
}


njs_vm_add_path(njs_vm_t *vm, const njs_str_t *path)
{
    njs_str_t  *item;

    if (vm->paths == NULL) {
        vm->paths = njs_arr_create(vm->mem_pool, 4, sizeof(njs_str_t));
        if (njs_slow_path(vm->paths == NULL)) {
            return NJS_ERROR;
        }
    }

    item = njs_arr_add(vm->paths);
    if (njs_slow_path(item == NULL)) {
        return NJS_ERROR;
    }

    *item = *path;

    return NJS_OK;
}


njs_vm_value_string_alloc(njs_vm_t *vm, njs_value_t *value, uint32_t size)
{
    return njs_string_alloc(vm, value, size, 0);
}


njs_vm_scopes_restore(njs_vm_t *vm, njs_native_frame_t *native,
    njs_native_frame_t *previous)
{
    njs_frame_t  *frame;

    vm->top_frame = previous;

    if (native->function->native) {
        return;
    }

    frame = (njs_frame_t *) native;
    frame = frame->previous_active_frame;
    vm->active_frame = frame;
}


njs_vm_array_prop(njs_vm_t *vm, njs_value_t *value, int64_t index,
    njs_opaque_value_t *retval)
{
    njs_int_t    ret;
    njs_array_t  *array;

    if (njs_slow_path(!njs_is_object(value))) {
        njs_type_error(vm, "njs_vm_array_prop() argument is not object");
        return NULL;
    }

    if (njs_fast_path(njs_is_fast_array(value))) {
        array = njs_array(value);

        if (index >= 0 && index < array->length) {
            return &array->start[index];
        }

        return NULL;
    }

    ret = njs_value_property_i64(vm, value, index, njs_value_arg(retval));
    if (njs_slow_path(ret != NJS_OK)) {
        return NULL;
    }

    return njs_value_arg(retval);
}


njs_vm_prop_magic32(njs_object_prop_t *prop)
{
    return prop->value.data.magic32;
}


njs_vm_array_length(njs_vm_t *vm, njs_value_t *value, int64_t *length)
{
    if (njs_fast_path(njs_is_array(value))) {
        *length = njs_array(value)->length;
    }

    return njs_object_length(vm, value, length);
}


njs_vm_array_start(njs_vm_t *vm, njs_value_t *value)
{
    if (njs_slow_path(!njs_is_fast_array(value))) {
        njs_type_error(vm, "njs_vm_array_start() argument is not a fast array");
        return NULL;
    }

    return njs_array(value)->start;
}


njs_vm_value_to_bytes(njs_vm_t *vm, njs_str_t *dst, njs_value_t *src)
{
    u_char              *start;
    size_t              size, length, offset;
    njs_int_t           ret;
    njs_value_t         value;
    njs_typed_array_t   *array;
    njs_array_buffer_t  *buffer;

    if (njs_slow_path(src == NULL)) {
        return NJS_ERROR;
    }

    ret = NJS_OK;
    value = *src;

    switch (value.type) {
    case NJS_TYPED_ARRAY:
    case NJS_DATA_VIEW:
    case NJS_ARRAY_BUFFER:

        if (value.type != NJS_ARRAY_BUFFER) {
            array = njs_typed_array(&value);
            buffer = njs_typed_array_buffer(array);
            offset = array->offset;
            length = array->byte_length;

        } else {
            buffer = njs_array_buffer(&value);
            offset = 0;
            length = buffer->size;
        }

        if (njs_slow_path(njs_is_detached_buffer(buffer))) {
            njs_type_error(vm, "detached buffer");
            return NJS_ERROR;
        }

        dst->start = &buffer->u.u8[offset];
        dst->length = length;
        break;

    default:
        ret = njs_value_to_string(vm, &value, &value);
        if (njs_slow_path(ret != NJS_OK)) {
            return NJS_ERROR;
        }

        size = value.short_string.size;

        if (size != NJS_STRING_LONG) {
            start = njs_mp_alloc(vm->mem_pool, size);
            if (njs_slow_path(start == NULL)) {
                njs_memory_error(vm);
                return NJS_ERROR;
            }

            memcpy(start, value.short_string.start, size);

        } else {
            size = value.long_string.size;
            start = value.long_string.data->start;
        }

        dst->length = size;
        dst->start = start;
    }

    return ret;
}


njs_vm_memory_pool(njs_vm_t *vm)
{
    return vm->mem_pool;
}


njs_async_function_frame_invoke(njs_vm_t *vm, njs_value_t *retval)
{
    njs_int_t                 ret;
    njs_value_t               ctor;
    njs_native_frame_t        *frame;
    njs_promise_capability_t  *capability;

    frame = vm->top_frame;
    frame->retval = retval;

    njs_set_function(&ctor, &vm->constructors[NJS_OBJ_TYPE_PROMISE]);

    capability = njs_promise_new_capability(vm, &ctor);
    if (njs_slow_path(capability == NULL)) {
        return NJS_ERROR;
    }

    ret = njs_function_lambda_call(vm, capability, NULL);

    if (ret == NJS_OK) {
        ret = njs_function_call(vm, njs_function(&capability->resolve),
                                &njs_value_undefined, retval, 1, &vm->retval);

    } else if (ret == NJS_AGAIN) {
        ret = NJS_OK;

    } else if (ret == NJS_ERROR) {
        if (njs_is_memory_error(vm, &vm->retval)) {
            return NJS_ERROR;
        }

        ret = njs_function_call(vm, njs_function(&capability->reject),
                                &njs_value_undefined, &vm->retval, 1,
                                &vm->retval);
    }

    *retval = capability->promise;

    return ret;
}


njs_vm_array_alloc(njs_vm_t *vm, njs_value_t *retval, uint32_t spare)
{
    njs_array_t  *array;

    array = njs_array_alloc(vm, 1, 0, spare);

    if (njs_slow_path(array == NULL)) {
        return NJS_ERROR;
    }

    njs_set_array(retval, array);

    return NJS_OK;
}


njs_vm_retval_dump(njs_vm_t *vm, njs_str_t *dst, njs_uint_t indent)
{
    if (vm->top_frame == NULL) {
        /* An exception was thrown during compilation. */

        njs_vm_init(vm);
    }

    return njs_vm_value_dump(vm, dst, &vm->retval, 0, 1);
}


njs_vm_retval_set(njs_vm_t *vm, const njs_value_t *value)
{
    vm->retval = *value;
}


njs_vm_start(njs_vm_t *vm)
{
    njs_int_t  ret;

    ret = njs_module_load(vm);
    if (njs_slow_path(ret != NJS_OK)) {
        return ret;
    }

    ret = njs_vmcode_interpreter(vm, vm->start, NULL, NULL);

    return (ret == NJS_ERROR) ? NJS_ERROR : NJS_OK;
}


njs_vm_del_event(njs_vm_t *vm, njs_vm_event_t vm_event)
{
    njs_event_t  *event;

    event = (njs_event_t *) vm_event;

    njs_del_event(vm, event, NJS_EVENT_RELEASE | NJS_EVENT_DELETE);
}


njs_vm_value_error_set(njs_vm_t *vm, njs_value_t *value, const char *fmt, ...)
{
    va_list  args;
    u_char   buf[NJS_MAX_ERROR_STR], *p;

    p = buf;

    if (fmt != NULL) {
        va_start(args, fmt);
        p = njs_vsprintf(buf, buf + sizeof(buf), fmt, args);
        va_end(args);
    }

    njs_error_new(vm, value, NJS_OBJ_TYPE_ERROR, buf, p - buf);
}


njs_vm_opt_init(njs_vm_opt_t *options)
{
    njs_memzero(options, sizeof(njs_vm_opt_t));
}


njs_vm_value_array_buffer_set(njs_vm_t *vm, njs_value_t *value,
    const u_char *start, uint32_t size)
{
    njs_array_buffer_t  *array;

    array = njs_array_buffer_alloc(vm, 0, 0);
    if (njs_slow_path(array == NULL)) {
        return NJS_ERROR;
    }

    array->u.data = (u_char *) start;
    array->size = size;

    njs_set_array_buffer(value, array);

    return NJS_OK;
}


njs_vm_value_string_copy(njs_vm_t *vm, njs_str_t *retval,
    njs_value_t *value, uintptr_t *next)
{
    uintptr_t    n;
    njs_array_t  *array;

    switch (value->type) {

    case NJS_STRING:
        if (*next != 0) {
            return NJS_DECLINED;
        }

        *next = 1;
        break;

    case NJS_ARRAY:
        array = njs_array(value);

        do {
            n = (*next)++;

            if (n == array->length) {
                return NJS_DECLINED;
            }

            value = &array->start[n];

        } while (!njs_is_valid(value));

        break;

    default:
        return NJS_ERROR;
    }

    return njs_vm_value_to_string(vm, retval, value);
}


njs_vm_post_event(njs_vm_t *vm, njs_vm_event_t vm_event,
    const njs_value_t *args, njs_uint_t nargs)
{
    njs_event_t  *event;

    event = (njs_event_t *) vm_event;

    if (nargs != 0 && !event->posted) {
        event->nargs = nargs;
        event->args = njs_mp_alloc(vm->mem_pool, sizeof(njs_value_t) * nargs);
        if (njs_slow_path(event->args == NULL)) {
            return NJS_ERROR;
        }

        memcpy(event->args, args, sizeof(njs_value_t) * nargs);
    }

    if (!event->posted) {
        event->posted = 1;
        njs_queue_insert_tail(&vm->posted_events, &event->link);
    }

    return NJS_OK;
}


njs_vm_handle_events(njs_vm_t *vm)
{
    njs_int_t         ret;
    njs_str_t         str;
    njs_value_t       string;
    njs_event_t       *ev;
    njs_queue_t       *promise_events, *posted_events;
    njs_queue_link_t  *link;

    promise_events = &vm->promise_events;
    posted_events = &vm->posted_events;

    do {
        for ( ;; ) {
            link = njs_queue_first(promise_events);

            if (link == njs_queue_tail(promise_events)) {
                break;
            }

            ev = njs_queue_link_data(link, njs_event_t, link);

            njs_queue_remove(&ev->link);

            ret = njs_vm_call(vm, ev->function, ev->args, ev->nargs);
            if (njs_slow_path(ret == NJS_ERROR)) {
                return ret;
            }
        }

        if (njs_vm_unhandled_rejection(vm)) {
            ret = njs_value_to_string(vm, &string,
                                      &vm->promise_reason->start[0]);
            if (njs_slow_path(ret != NJS_OK)) {
                return ret;
            }

            njs_string_get(&string, &str);
            njs_vm_error(vm, "unhandled promise rejection: %V", &str);

            njs_mp_free(vm->mem_pool, vm->promise_reason);
            vm->promise_reason = NULL;

            return NJS_ERROR;
        }

        for ( ;; ) {
            link = njs_queue_first(posted_events);

            if (link == njs_queue_tail(posted_events)) {
                break;
            }

            ev = njs_queue_link_data(link, njs_event_t, link);

            if (ev->once) {
                njs_del_event(vm, ev, NJS_EVENT_RELEASE | NJS_EVENT_DELETE);

            } else {
                ev->posted = 0;
                njs_queue_remove(&ev->link);
            }

            ret = njs_vm_call(vm, ev->function, ev->args, ev->nargs);

            if (ret == NJS_ERROR) {
                return ret;
            }
        }

    } while (!njs_queue_is_empty(promise_events));

    return njs_vm_pending(vm) ? NJS_AGAIN : NJS_OK;
}


njs_await_rejected(njs_vm_t *vm, njs_value_t *args, njs_uint_t nargs,
    njs_index_t unused)
{
    njs_value_t      *value;
    njs_async_ctx_t  *ctx;

    ctx = vm->top_frame->function->context;

    value = njs_arg(args, nargs, 1);

    if (ctx->await->native.pc == ctx->pc) {
        (void) njs_function_call(vm, njs_function(&ctx->capability->reject),
                                 &njs_value_undefined, value, 1, &vm->retval);

        njs_async_context_free(vm, ctx);

        return NJS_ERROR;
    }

    ctx->pc = ctx->await->native.pc;

    return njs_await_fulfilled(vm, args, nargs, unused);
}


njs_vm_object_prop(njs_vm_t *vm, njs_value_t *value, const njs_str_t *prop,
    njs_opaque_value_t *retval)
{
    njs_int_t    ret;
    njs_value_t  key;

    if (njs_slow_path(!njs_is_object(value))) {
        njs_type_error(vm, "njs_vm_object_prop() argument is not object");
        return NULL;
    }

    ret = njs_vm_value_string_set(vm, &key, prop->start, prop->length);
    if (njs_slow_path(ret != NJS_OK)) {
        return NULL;
    }

    ret = njs_value_property(vm, value, &key, njs_value_arg(retval));
    if (njs_slow_path(ret != NJS_OK)) {
        return NULL;
    }

    return njs_value_arg(retval);
}


njs_await_fulfilled(njs_vm_t *vm, njs_value_t *args, njs_uint_t nargs,
    njs_index_t unused)
{
    njs_int_t           ret;
    njs_value_t         **cur_local, **cur_closures, **cur_temp, *value;
    njs_frame_t         *frame, *async_frame;
    njs_async_ctx_t     *ctx;
    njs_native_frame_t  *top, *async;

    ctx = vm->top_frame->function->context;

    value = njs_arg(args, nargs, 1);
    if (njs_is_error(value)) {
        goto failed;
    }

    async_frame = ctx->await;
    async = &async_frame->native;
    async->previous = vm->top_frame;

    cur_local = vm->levels[NJS_LEVEL_LOCAL];
    cur_closures = vm->levels[NJS_LEVEL_CLOSURE];
    cur_temp = vm->levels[NJS_LEVEL_TEMP];
    top = vm->top_frame;
    frame = vm->active_frame;

    vm->levels[NJS_LEVEL_LOCAL] = async->local;
    vm->levels[NJS_LEVEL_CLOSURE] = njs_function_closures(async->function);
    vm->levels[NJS_LEVEL_TEMP] = async->temp;

    vm->top_frame = async;
    vm->active_frame = async_frame;

    *njs_scope_value(vm, ctx->index) = *value;
    vm->retval = *value;

    vm->top_frame->retval = &vm->retval;

    ret = njs_vmcode_interpreter(vm, ctx->pc, ctx->capability, ctx);

    vm->levels[NJS_LEVEL_LOCAL] = cur_local;
    vm->levels[NJS_LEVEL_CLOSURE] = cur_closures;
    vm->levels[NJS_LEVEL_TEMP] = cur_temp;

    vm->top_frame = top;
    vm->active_frame = frame;

    if (ret == NJS_OK) {
        ret = njs_function_call(vm, njs_function(&ctx->capability->resolve),
                            &njs_value_undefined, &vm->retval, 1, &vm->retval);

        njs_async_context_free(vm, ctx);

    } else if (ret == NJS_AGAIN) {
        ret = NJS_OK;

    } else if (ret == NJS_ERROR) {
        if (njs_is_memory_error(vm, &vm->retval)) {
            return NJS_ERROR;
        }

        value = &vm->retval;

        goto failed;
    }

    return ret;

failed:

    (void) njs_function_call(vm, njs_function(&ctx->capability->reject),
                             &njs_value_undefined, value, 1, &vm->retval);

    njs_async_context_free(vm, ctx);

    return NJS_ERROR;
}


njs_vm_object_alloc(njs_vm_t *vm, njs_value_t *retval, ...)
{
    va_list             args;
    njs_int_t           ret;
    njs_value_t         *name, *value;
    njs_object_t        *object;
    njs_object_prop_t   *prop;
    njs_lvlhsh_query_t  lhq;

    object = njs_object_alloc(vm);
    if (njs_slow_path(object == NULL)) {
        return NJS_ERROR;
    }

    ret = NJS_ERROR;

    va_start(args, retval);

    for ( ;; ) {
        name = va_arg(args, njs_value_t *);
        if (name == NULL) {
            break;
        }

        value = va_arg(args, njs_value_t *);
        if (value == NULL) {
            njs_type_error(vm, "missed value for a key");
            goto done;
        }

        if (njs_slow_path(!njs_is_string(name))) {
            njs_type_error(vm, "prop name is not a string");
            goto done;
        }

        lhq.replace = 0;
        lhq.pool = vm->mem_pool;
        lhq.proto = &njs_object_hash_proto;

        njs_string_get(name, &lhq.key);
        lhq.key_hash = njs_djb_hash(lhq.key.start, lhq.key.length);

        prop = njs_object_prop_alloc(vm, name, value, 1);
        if (njs_slow_path(prop == NULL)) {
            goto done;
        }

        lhq.value = prop;

        ret = njs_lvlhsh_insert(&object->hash, &lhq);
        if (njs_slow_path(ret != NJS_OK)) {
            njs_internal_error(vm, NULL);
            goto done;
        }
    }

    ret = NJS_OK;

    njs_set_object(retval, object);

done:

    va_end(args);

    return ret;
}


njs_vm_bind(njs_vm_t *vm, const njs_str_t *var_name, const njs_value_t *value,
    njs_bool_t shared)
{
    njs_int_t           ret;
    njs_object_t        *global;
    njs_lvlhsh_t        *hash;
    njs_object_prop_t   *prop;
    njs_lvlhsh_query_t  lhq;

    prop = njs_object_prop_alloc(vm, &njs_value_undefined, value, 1);
    if (njs_slow_path(prop == NULL)) {
        return NJS_ERROR;
    }

    ret = njs_string_new(vm, &prop->name, var_name->start, var_name->length, 0);
    if (njs_slow_path(ret != NJS_OK)) {
        return NJS_ERROR;
    }

    lhq.value = prop;
    lhq.key = *var_name;
    lhq.key_hash = njs_djb_hash(lhq.key.start, lhq.key.length);
    lhq.replace = 1;
    lhq.pool = vm->mem_pool;
    lhq.proto = &njs_object_hash_proto;

    global = &vm->global_object;
    hash = shared ? &global->shared_hash : &global->hash;

    ret = njs_lvlhsh_insert(hash, &lhq);
    if (njs_slow_path(ret != NJS_OK)) {
        njs_internal_error(vm, "lvlhsh insert failed");
        return ret;
    }

    return NJS_OK;
}


const uECC_word_t *uECC_curve_b(uECC_Curve curve) {
    return curve->b;
}

Fix for #168


uECC_VLI_API void uECC_vli_rshift1(uECC_word_t *vli, wordcount_t num_words) {
    uECC_word_t *end = vli;
    uECC_word_t carry = 0;

    vli += num_words;
    while (vli-- > end) {
        uECC_word_t temp = *vli;
        *vli = (temp >> 1) | carry;
        carry = temp << (uECC_WORD_BITS - 1);
    }
}

Fix for #168


unsigned uECC_curve_num_n_bits(uECC_Curve curve) {
    return curve->num_n_bits;
}

Fix for #168


uECC_VLI_API void uECC_vli_modSquare_fast(uECC_word_t *result,
                                          const uECC_word_t *left,
                                          uECC_Curve curve) {
    uECC_vli_modMult_fast(result, left, left, curve);
}

Fix for #168


uECC_VLI_API void uECC_vli_mult(uECC_word_t *result,
                                const uECC_word_t *left,
                                const uECC_word_t *right,
                                wordcount_t num_words) {
    uECC_word_t r0 = 0;
    uECC_word_t r1 = 0;
    uECC_word_t r2 = 0;
    wordcount_t i, k;

    /* Compute each digit of result in sequence, maintaining the carries. */
    for (k = 0; k < num_words; ++k) {
        for (i = 0; i <= k; ++i) {
            muladd(left[i], right[k - i], &r0, &r1, &r2);
        }
        result[k] = r0;
        r0 = r1;
        r1 = r2;
        r2 = 0;
    }
    for (k = num_words; k < num_words * 2 - 1; ++k) {
        for (i = (k + 1) - num_words; i < num_words; ++i) {
            muladd(left[i], right[k - i], &r0, &r1, &r2);
        }
        result[k] = r0;
        r0 = r1;
        r1 = r2;
        r2 = 0;
    }
    result[num_words * 2 - 1] = r0;
}

Fix for #168


const uECC_word_t *uECC_curve_p(uECC_Curve curve) {
    return curve->p;
}

Fix for #168


static uECC_word_t EccPoint_compute_public_key(uECC_word_t *result,
                                               uECC_word_t *private_key,
                                               uECC_Curve curve) {
    uECC_word_t tmp1[uECC_MAX_WORDS];
    uECC_word_t tmp2[uECC_MAX_WORDS];
    uECC_word_t *p2[2] = {tmp1, tmp2};
    uECC_word_t carry;

    /* Regularize the bitcount for the private key so that attackers cannot use a side channel
       attack to learn the number of leading zeros. */
    carry = regularize_k(private_key, tmp1, tmp2, curve);

    EccPoint_mult(result, curve->G, p2[!carry], 0, curve->num_n_bits + 1, curve);

    if (EccPoint_isZero(result, curve)) {
        return 0;
    }
    return 1;
}

Fix for #168


int uECC_compute_public_key(const uint8_t *private_key, uint8_t *public_key, uECC_Curve curve) {
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
    uECC_word_t *_private = (uECC_word_t *)private_key;
    uECC_word_t *_public = (uECC_word_t *)public_key;
#else
    uECC_word_t _private[uECC_MAX_WORDS];
    uECC_word_t _public[uECC_MAX_WORDS * 2];
#endif

#if uECC_VLI_NATIVE_LITTLE_ENDIAN == 0
    uECC_vli_bytesToNative(_private, private_key, BITS_TO_BYTES(curve->num_n_bits));
#endif

    /* Make sure the private key is in the range [1, n-1]. */
    if (uECC_vli_isZero(_private, BITS_TO_WORDS(curve->num_n_bits))) {
        return 0;
    }

    if (uECC_vli_cmp(curve->n, _private, BITS_TO_WORDS(curve->num_n_bits)) != 1) {
        return 0;
    }

    /* Compute public key. */
    if (!EccPoint_compute_public_key(_public, _private, curve)) {
        return 0;
    }

#if uECC_VLI_NATIVE_LITTLE_ENDIAN == 0
    uECC_vli_nativeToBytes(public_key, curve->num_bytes, _public);
    uECC_vli_nativeToBytes(
        public_key + curve->num_bytes, curve->num_bytes, _public + curve->num_words);
#endif
    return 1;
}

Fix for #168


int uECC_curve_private_key_size(uECC_Curve curve) {
    return BITS_TO_BYTES(curve->num_n_bits);
}

Fix for #168


int uECC_make_key(uint8_t *public_key,
                  uint8_t *private_key,
                  uECC_Curve curve) {
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
    uECC_word_t *_private = (uECC_word_t *)private_key;
    uECC_word_t *_public = (uECC_word_t *)public_key;
#else
    uECC_word_t _private[uECC_MAX_WORDS];
    uECC_word_t _public[uECC_MAX_WORDS * 2];
#endif
    uECC_word_t tries;

    for (tries = 0; tries < uECC_RNG_MAX_TRIES; ++tries) {
        if (!uECC_generate_random_int(_private, curve->n, BITS_TO_WORDS(curve->num_n_bits))) {
            return 0;
        }

        if (EccPoint_compute_public_key(_public, _private, curve)) {
#if uECC_VLI_NATIVE_LITTLE_ENDIAN == 0
            uECC_vli_nativeToBytes(private_key, BITS_TO_BYTES(curve->num_n_bits), _private);
            uECC_vli_nativeToBytes(public_key, curve->num_bytes, _public);
            uECC_vli_nativeToBytes(
                public_key + curve->num_bytes, curve->num_bytes, _public + curve->num_words);
#endif
            return 1;
        }
    }
    return 0;
}

Fix for #168


static void HMAC_update(const uECC_HashContext *hash_context,
                        const uint8_t *message,
                        unsigned message_size) {
    hash_context->update_hash(hash_context, message, message_size);
}

Fix for #168


static void apply_z(uECC_word_t * X1,
                    uECC_word_t * Y1,
                    const uECC_word_t * const Z,
                    uECC_Curve curve) {
    uECC_word_t t1[uECC_MAX_WORDS];

    uECC_vli_modSquare_fast(t1, Z, curve);    /* z^2 */
    uECC_vli_modMult_fast(X1, X1, t1, curve); /* x1 * z^2 */
    uECC_vli_modMult_fast(t1, t1, Z, curve);  /* z^3 */
    uECC_vli_modMult_fast(Y1, Y1, t1, curve); /* y1 * z^3 */
}

Fix for #168


void uECC_decompress(const uint8_t *compressed, uint8_t *public_key, uECC_Curve curve) {
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
    uECC_word_t *point = (uECC_word_t *)public_key;
#else
    uECC_word_t point[uECC_MAX_WORDS * 2];
#endif
    uECC_word_t *y = point + curve->num_words;
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
    bcopy(public_key, compressed+1, curve->num_bytes);
#else
    uECC_vli_bytesToNative(point, compressed + 1, curve->num_bytes);
#endif
    curve->x_side(y, point, curve);
    curve->mod_sqrt(y, curve);

    if ((y[0] & 0x01) != (compressed[0] & 0x01)) {
        uECC_vli_sub(y, curve->p, y, curve->num_words);
    }

#if uECC_VLI_NATIVE_LITTLE_ENDIAN == 0
    uECC_vli_nativeToBytes(public_key, curve->num_bytes, point);
    uECC_vli_nativeToBytes(public_key + curve->num_bytes, curve->num_bytes, y);
#endif
}

Fix for #168


uECC_VLI_API void uECC_vli_square(uECC_word_t *result,
                                  const uECC_word_t *left,
                                  wordcount_t num_words) {
    uECC_word_t r0 = 0;
    uECC_word_t r1 = 0;
    uECC_word_t r2 = 0;

    wordcount_t i, k;

    for (k = 0; k < num_words * 2 - 1; ++k) {
        uECC_word_t min = (k < num_words ? 0 : (k + 1) - num_words);
        for (i = min; i <= k && i <= k - i; ++i) {
            if (i < k-i) {
                mul2add(left[i], left[k - i], &r0, &r1, &r2);
            } else {
                muladd(left[i], left[k - i], &r0, &r1, &r2);
            }
        }
        result[k] = r0;
        r0 = r1;
        r1 = r2;
        r2 = 0;
    }

    result[num_words * 2 - 1] = r0;
}

Fix for #168


static void bcopy(uint8_t *dst,
                  const uint8_t *src,
                  unsigned num_bytes) {
    while (0 != num_bytes) {
        num_bytes--;
        dst[num_bytes] = src[num_bytes];
    }
}

Fix for #168


unsigned uECC_curve_num_bytes(uECC_Curve curve) {
    return curve->num_bytes;
}

Fix for #168


uECC_VLI_API void uECC_vli_nativeToBytes(uint8_t *bytes,
                                         int num_bytes,
                                         const uint8_t *native) {
    wordcount_t i;
    for (i = 0; i < num_bytes; ++i) {
        bytes[i] = native[(num_bytes - 1) - i];
    }
}

Fix for #168


uECC_VLI_API void uECC_vli_bytesToNative(uECC_word_t *native,
                                         const uint8_t *bytes,
                                         int num_bytes) {
    wordcount_t i;
    uECC_vli_clear(native, (num_bytes + (uECC_WORD_SIZE - 1)) / uECC_WORD_SIZE);
    for (i = 0; i < num_bytes; ++i) {
        unsigned b = num_bytes - 1 - i;
        native[b / uECC_WORD_SIZE] |=
            (uECC_word_t)bytes[i] << (8 * (b % uECC_WORD_SIZE));
    }
}

Fix for #168


static void bits2int(uECC_word_t *native,
                     const uint8_t *bits,
                     unsigned bits_size,
                     uECC_Curve curve) {
    unsigned num_n_bytes = BITS_TO_BYTES(curve->num_n_bits);
    unsigned num_n_words = BITS_TO_WORDS(curve->num_n_bits);
    int shift;
    uECC_word_t carry;
    uECC_word_t *ptr;

    if (bits_size > num_n_bytes) {
        bits_size = num_n_bytes;
    }

    uECC_vli_clear(native, num_n_words);
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
    bcopy((uint8_t *) native, bits, bits_size);
#else
    uECC_vli_bytesToNative(native, bits, bits_size);
#endif
    if (bits_size * 8 <= (unsigned)curve->num_n_bits) {
        return;
    }
    shift = bits_size * 8 - curve->num_n_bits;
    carry = 0;
    ptr = native + num_n_words;
    while (ptr-- > native) {
        uECC_word_t temp = *ptr;
        *ptr = (temp >> shift) | carry;
        carry = temp << (uECC_WORD_BITS - shift);
    }

    /* Reduce mod curve_n */
    if (uECC_vli_cmp_unsafe(curve->n, native, num_n_words) != 1) {
        uECC_vli_sub(native, native, curve->n, num_n_words);
    }
}

Fix for #168


int uECC_sign_deterministic(const uint8_t *private_key,
                            const uint8_t *message_hash,
                            unsigned hash_size,
                            const uECC_HashContext *hash_context,
                            uint8_t *signature,
                            uECC_Curve curve) {
    uint8_t *K = hash_context->tmp;
    uint8_t *V = K + hash_context->result_size;
    wordcount_t num_bytes = curve->num_bytes;
    wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
    bitcount_t num_n_bits = curve->num_n_bits;
    uECC_word_t tries;
    unsigned i;
    for (i = 0; i < hash_context->result_size; ++i) {
        V[i] = 0x01;
        K[i] = 0;
    }

    /* K = HMAC_K(V || 0x00 || int2octets(x) || h(m)) */
    HMAC_init(hash_context, K);
    V[hash_context->result_size] = 0x00;
    HMAC_update(hash_context, V, hash_context->result_size + 1);
    HMAC_update(hash_context, private_key, num_bytes);
    HMAC_update(hash_context, message_hash, hash_size);
    HMAC_finish(hash_context, K, K);

    update_V(hash_context, K, V);

    /* K = HMAC_K(V || 0x01 || int2octets(x) || h(m)) */
    HMAC_init(hash_context, K);
    V[hash_context->result_size] = 0x01;
    HMAC_update(hash_context, V, hash_context->result_size + 1);
    HMAC_update(hash_context, private_key, num_bytes);
    HMAC_update(hash_context, message_hash, hash_size);
    HMAC_finish(hash_context, K, K);

    update_V(hash_context, K, V);

    for (tries = 0; tries < uECC_RNG_MAX_TRIES; ++tries) {
        uECC_word_t T[uECC_MAX_WORDS];
        uint8_t *T_ptr = (uint8_t *)T;
        wordcount_t T_bytes = 0;
        for (;;) {
            update_V(hash_context, K, V);
            for (i = 0; i < hash_context->result_size; ++i) {
                T_ptr[T_bytes++] = V[i];
                if (T_bytes >= num_n_words * uECC_WORD_SIZE) {
                    goto filled;
                }
            }
        }
    filled:
        if ((bitcount_t)num_n_words * uECC_WORD_SIZE * 8 > num_n_bits) {
            uECC_word_t mask = (uECC_word_t)-1;
            T[num_n_words - 1] &=
                mask >> ((bitcount_t)(num_n_words * uECC_WORD_SIZE * 8 - num_n_bits));
        }

        if (uECC_sign_with_k(private_key, message_hash, hash_size, T, signature, curve)) {
            return 1;
        }

        /* K = HMAC_K(V || 0x00) */
        HMAC_init(hash_context, K);
        V[hash_context->result_size] = 0x00;
        HMAC_update(hash_context, V, hash_context->result_size + 1);
        HMAC_finish(hash_context, K, K);

        update_V(hash_context, K, V);
    }
    return 0;
}

Fix for #168


uECC_RNG_Function uECC_get_rng(void) {
    return g_rng_function;
}

Fix for #168


static void XYcZ_initial_double(uECC_word_t * X1,
                                uECC_word_t * Y1,
                                uECC_word_t * X2,
                                uECC_word_t * Y2,
                                const uECC_word_t * const initial_Z,
                                uECC_Curve curve) {
    uECC_word_t z[uECC_MAX_WORDS];
    wordcount_t num_words = curve->num_words;
    if (initial_Z) {
        uECC_vli_set(z, initial_Z, num_words);
    } else {
        uECC_vli_clear(z, num_words);
        z[0] = 1;
    }

    uECC_vli_set(X2, X1, num_words);
    uECC_vli_set(Y2, Y1, num_words);

    apply_z(X1, Y1, z, curve);
    curve->double_jacobian(X1, Y1, z, curve);
    apply_z(X2, Y2, z, curve);
}

Fix for #168


void uECC_vli_mod_sqrt(uECC_word_t *a, uECC_Curve curve) {
    curve->mod_sqrt(a, curve);
}

Fix for #168


static void update_V(const uECC_HashContext *hash_context, uint8_t *K, uint8_t *V) {
    HMAC_init(hash_context, K);
    HMAC_update(hash_context, V, hash_context->result_size);
    HMAC_finish(hash_context, K, V);
}

Fix for #168


static void XYcZ_add(uECC_word_t * X1,
                     uECC_word_t * Y1,
                     uECC_word_t * X2,
                     uECC_word_t * Y2,
                     uECC_Curve curve) {
    /* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */
    uECC_word_t t5[uECC_MAX_WORDS];
    wordcount_t num_words = curve->num_words;

    uECC_vli_modSub(t5, X2, X1, curve->p, num_words); /* t5 = x2 - x1 */
    uECC_vli_modSquare_fast(t5, t5, curve);                  /* t5 = (x2 - x1)^2 = A */
    uECC_vli_modMult_fast(X1, X1, t5, curve);                /* t1 = x1*A = B */
    uECC_vli_modMult_fast(X2, X2, t5, curve);                /* t3 = x2*A = C */
    uECC_vli_modSub(Y2, Y2, Y1, curve->p, num_words); /* t4 = y2 - y1 */
    uECC_vli_modSquare_fast(t5, Y2, curve);                  /* t5 = (y2 - y1)^2 = D */

    uECC_vli_modSub(t5, t5, X1, curve->p, num_words); /* t5 = D - B */
    uECC_vli_modSub(t5, t5, X2, curve->p, num_words); /* t5 = D - B - C = x3 */
    uECC_vli_modSub(X2, X2, X1, curve->p, num_words); /* t3 = C - B */
    uECC_vli_modMult_fast(Y1, Y1, X2, curve);                /* t2 = y1*(C - B) */
    uECC_vli_modSub(X2, X1, t5, curve->p, num_words); /* t3 = B - x3 */
    uECC_vli_modMult_fast(Y2, Y2, X2, curve);                /* t4 = (y2 - y1)*(B - x3) */
    uECC_vli_modSub(Y2, Y2, Y1, curve->p, num_words); /* t4 = y3 */

    uECC_vli_set(X2, t5, num_words);
}

Fix for #168


void uECC_vli_mmod_fast(uECC_word_t *result, uECC_word_t *product, uECC_Curve curve) {
#if (uECC_OPTIMIZATION_LEVEL > 0)
    curve->mmod_fast(result, product);
#else
    uECC_vli_mmod(result, product, curve->p, curve->num_words);
#endif
}

Fix for #168


uECC_VLI_API void uECC_vli_mmod(uECC_word_t *result,
                                uECC_word_t *product,
                                const uECC_word_t *mod,
                                wordcount_t num_words) {
    uECC_word_t mod_multiple[2 * uECC_MAX_WORDS];
    uECC_word_t tmp[2 * uECC_MAX_WORDS];
    uECC_word_t *v[2] = {tmp, product};
    uECC_word_t index;

    /* Shift mod so its highest set bit is at the maximum position. */
    bitcount_t shift = (num_words * 2 * uECC_WORD_BITS) - uECC_vli_numBits(mod, num_words);
    wordcount_t word_shift = shift / uECC_WORD_BITS;
    wordcount_t bit_shift = shift % uECC_WORD_BITS;
    uECC_word_t carry = 0;
    uECC_vli_clear(mod_multiple, word_shift);
    if (bit_shift > 0) {
        for(index = 0; index < (uECC_word_t)num_words; ++index) {
            mod_multiple[word_shift + index] = (mod[index] << bit_shift) | carry;
            carry = mod[index] >> (uECC_WORD_BITS - bit_shift);
        }
    } else {
        uECC_vli_set(mod_multiple + word_shift, mod, num_words);
    }

    for (index = 1; shift >= 0; --shift) {
        uECC_word_t borrow = 0;
        wordcount_t i;
        for (i = 0; i < num_words * 2; ++i) {
            uECC_word_t diff = v[index][i] - mod_multiple[i] - borrow;
            if (diff != v[index][i]) {
                borrow = (diff > v[index][i]);
            }
            v[1 - index][i] = diff;
        }
        index = !(index ^ borrow); /* Swap the index if there was no borrow */
        uECC_vli_rshift1(mod_multiple, num_words);
        mod_multiple[num_words - 1] |= mod_multiple[num_words] << (uECC_WORD_BITS - 1);
        uECC_vli_rshift1(mod_multiple + num_words, num_words);
    }
    uECC_vli_set(result, v[index], num_words);
}

Fix for #168


uECC_VLI_API void uECC_vli_square(uECC_word_t *result,
                                  const uECC_word_t *left,
                                  wordcount_t num_words) {
    uECC_vli_mult(result, left, left, num_words);
}

Fix for #168


static void XYcZ_addC(uECC_word_t * X1,
                      uECC_word_t * Y1,
                      uECC_word_t * X2,
                      uECC_word_t * Y2,
                      uECC_Curve curve) {
    /* t1 = X1, t2 = Y1, t3 = X2, t4 = Y2 */
    uECC_word_t t5[uECC_MAX_WORDS];
    uECC_word_t t6[uECC_MAX_WORDS];
    uECC_word_t t7[uECC_MAX_WORDS];
    wordcount_t num_words = curve->num_words;

    uECC_vli_modSub(t5, X2, X1, curve->p, num_words); /* t5 = x2 - x1 */
    uECC_vli_modSquare_fast(t5, t5, curve);                  /* t5 = (x2 - x1)^2 = A */
    uECC_vli_modMult_fast(X1, X1, t5, curve);                /* t1 = x1*A = B */
    uECC_vli_modMult_fast(X2, X2, t5, curve);                /* t3 = x2*A = C */
    uECC_vli_modAdd(t5, Y2, Y1, curve->p, num_words); /* t5 = y2 + y1 */
    uECC_vli_modSub(Y2, Y2, Y1, curve->p, num_words); /* t4 = y2 - y1 */

    uECC_vli_modSub(t6, X2, X1, curve->p, num_words); /* t6 = C - B */
    uECC_vli_modMult_fast(Y1, Y1, t6, curve);                /* t2 = y1 * (C - B) = E */
    uECC_vli_modAdd(t6, X1, X2, curve->p, num_words); /* t6 = B + C */
    uECC_vli_modSquare_fast(X2, Y2, curve);                  /* t3 = (y2 - y1)^2 = D */
    uECC_vli_modSub(X2, X2, t6, curve->p, num_words); /* t3 = D - (B + C) = x3 */

    uECC_vli_modSub(t7, X1, X2, curve->p, num_words); /* t7 = B - x3 */
    uECC_vli_modMult_fast(Y2, Y2, t7, curve);                /* t4 = (y2 - y1)*(B - x3) */
    uECC_vli_modSub(Y2, Y2, Y1, curve->p, num_words); /* t4 = (y2 - y1)*(B - x3) - E = y3 */

    uECC_vli_modSquare_fast(t7, t5, curve);                  /* t7 = (y2 + y1)^2 = F */
    uECC_vli_modSub(t7, t7, t6, curve->p, num_words); /* t7 = F - (B + C) = x3' */
    uECC_vli_modSub(t6, t7, X1, curve->p, num_words); /* t6 = x3' - B */
    uECC_vli_modMult_fast(t6, t6, t5, curve);                /* t6 = (y2+y1)*(x3' - B) */
    uECC_vli_modSub(Y1, t6, Y1, curve->p, num_words); /* t2 = (y2+y1)*(x3' - B) - E = y3' */

    uECC_vli_set(X1, t7, num_words);
}

Fix for #168


static void EccPoint_mult(uECC_word_t * result,
                          const uECC_word_t * point,
                          const uECC_word_t * scalar,
                          const uECC_word_t * initial_Z,
                          bitcount_t num_bits,
                          uECC_Curve curve) {
    /* R0 and R1 */
    uECC_word_t Rx[2][uECC_MAX_WORDS];
    uECC_word_t Ry[2][uECC_MAX_WORDS];
    uECC_word_t z[uECC_MAX_WORDS];
    bitcount_t i;
    uECC_word_t nb;
    wordcount_t num_words = curve->num_words;

    uECC_vli_set(Rx[1], point, num_words);
    uECC_vli_set(Ry[1], point + num_words, num_words);

    XYcZ_initial_double(Rx[1], Ry[1], Rx[0], Ry[0], initial_Z, curve);

    for (i = num_bits - 2; i > 0; --i) {
        nb = !uECC_vli_testBit(scalar, i);
        XYcZ_addC(Rx[1 - nb], Ry[1 - nb], Rx[nb], Ry[nb], curve);
        XYcZ_add(Rx[nb], Ry[nb], Rx[1 - nb], Ry[1 - nb], curve);
    }

    nb = !uECC_vli_testBit(scalar, 0);
    XYcZ_addC(Rx[1 - nb], Ry[1 - nb], Rx[nb], Ry[nb], curve);

    /* Find final 1/Z value. */
    uECC_vli_modSub(z, Rx[1], Rx[0], curve->p, num_words); /* X1 - X0 */
    uECC_vli_modMult_fast(z, z, Ry[1 - nb], curve);               /* Yb * (X1 - X0) */
    uECC_vli_modMult_fast(z, z, point, curve);                    /* xP * Yb * (X1 - X0) */
    uECC_vli_modInv(z, z, curve->p, num_words);            /* 1 / (xP * Yb * (X1 - X0)) */
    /* yP / (xP * Yb * (X1 - X0)) */
    uECC_vli_modMult_fast(z, z, point + num_words, curve);
    uECC_vli_modMult_fast(z, z, Rx[1 - nb], curve); /* Xb * yP / (xP * Yb * (X1 - X0)) */
    /* End 1/Z calculation */

    XYcZ_add(Rx[nb], Ry[nb], Rx[1 - nb], Ry[1 - nb], curve);
    apply_z(Rx[0], Ry[0], z, curve);

    uECC_vli_set(result, Rx[0], num_words);
    uECC_vli_set(result + num_words, Ry[0], num_words);
}

Fix for #168


uECC_VLI_API uECC_word_t uECC_vli_testBit(const uECC_word_t *vli, bitcount_t bit) {
    return (vli[bit >> uECC_WORD_BITS_SHIFT] & ((uECC_word_t)1 << (bit & uECC_WORD_BITS_MASK)));
}

Fix for #168


uECC_VLI_API void uECC_vli_modSub(uECC_word_t *result,
                                  const uECC_word_t *left,
                                  const uECC_word_t *right,
                                  const uECC_word_t *mod,
                                  wordcount_t num_words) {
    uECC_word_t l_borrow = uECC_vli_sub(result, left, right, num_words);
    if (l_borrow) {
        /* In this case, result == -diff == (max int) - diff. Since -x % d == d - x,
           we can get the correct result from result + mod (with overflow). */
        uECC_vli_add(result, result, mod, num_words);
    }
}

Fix for #168


static cmpresult_t uECC_vli_cmp_unsafe(const uECC_word_t *left,
                                       const uECC_word_t *right,
                                       wordcount_t num_words) {
    wordcount_t i;
    for (i = num_words - 1; i >= 0; --i) {
        if (left[i] > right[i]) {
            return 1;
        } else if (left[i] < right[i]) {
            return -1;
        }
    }
    return 0;
}

Fix for #168


uECC_VLI_API void uECC_vli_set(uECC_word_t *dest, const uECC_word_t *src, wordcount_t num_words) {
    wordcount_t i;
    for (i = 0; i < num_words; ++i) {
        dest[i] = src[i];
    }
}

Fix for #168


uECC_VLI_API uECC_word_t uECC_vli_add(uECC_word_t *result,
                                      const uECC_word_t *left,
                                      const uECC_word_t *right,
                                      wordcount_t num_words) {
    uECC_word_t carry = 0;
    wordcount_t i;
    for (i = 0; i < num_words; ++i) {
        uECC_word_t sum = left[i] + right[i] + carry;
        if (sum != left[i]) {
            carry = (sum < left[i]);
        }
        result[i] = sum;
    }
    return carry;
}

Fix for #168


static void vli_modInv_update(uECC_word_t *uv,
                              const uECC_word_t *mod,
                              wordcount_t num_words) {
    uECC_word_t carry = 0;
    if (!EVEN(uv)) {
        carry = uECC_vli_add(uv, uv, mod, num_words);
    }
    uECC_vli_rshift1(uv, num_words);
    if (carry) {
        uv[num_words - 1] |= HIGH_BIT_SET;
    }
}

Fix for #168


static uECC_word_t regularize_k(const uECC_word_t * const k,
                                uECC_word_t *k0,
                                uECC_word_t *k1,
                                uECC_Curve curve) {
    wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
    bitcount_t num_n_bits = curve->num_n_bits;
    uECC_word_t carry = uECC_vli_add(k0, k, curve->n, num_n_words) ||
        (num_n_bits < ((bitcount_t)num_n_words * uECC_WORD_SIZE * 8) &&
         uECC_vli_testBit(k0, num_n_bits));
    uECC_vli_add(k1, k0, curve->n, num_n_words);
    return carry;
}

Fix for #168


int uECC_shared_secret(const uint8_t *public_key,
                       const uint8_t *private_key,
                       uint8_t *secret,
                       uECC_Curve curve) {
    uECC_word_t _public[uECC_MAX_WORDS * 2];
    uECC_word_t _private[uECC_MAX_WORDS];

    uECC_word_t tmp[uECC_MAX_WORDS];
    uECC_word_t *p2[2] = {_private, tmp};
    uECC_word_t *initial_Z = 0;
    uECC_word_t carry;
    wordcount_t num_words = curve->num_words;
    wordcount_t num_bytes = curve->num_bytes;

#if uECC_VLI_NATIVE_LITTLE_ENDIAN
    bcopy((uint8_t *) _private, private_key, num_bytes);
    bcopy((uint8_t *) _public, public_key, num_bytes*2);
#else
    uECC_vli_bytesToNative(_private, private_key, BITS_TO_BYTES(curve->num_n_bits));
    uECC_vli_bytesToNative(_public, public_key, num_bytes);
    uECC_vli_bytesToNative(_public + num_words, public_key + num_bytes, num_bytes);
#endif

    /* Regularize the bitcount for the private key so that attackers cannot use a side channel
       attack to learn the number of leading zeros. */
    carry = regularize_k(_private, _private, tmp, curve);

    /* If an RNG function was specified, try to get a random initial Z value to improve
       protection against side-channel attacks. */
    if (g_rng_function) {
        if (!uECC_generate_random_int(p2[carry], curve->p, num_words)) {
            return 0;
        }
        initial_Z = p2[carry];
    }

    EccPoint_mult(_public, _public, p2[!carry], initial_Z, curve->num_n_bits + 1, curve);
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
    bcopy((uint8_t *) secret, (uint8_t *) _public, num_bytes);
#else
    uECC_vli_nativeToBytes(secret, num_bytes, _public);
#endif
    return !EccPoint_isZero(_public, curve);
}

Fix for #168


uECC_VLI_API uECC_word_t uECC_vli_isZero(const uECC_word_t *vli, wordcount_t num_words) {
    uECC_word_t bits = 0;
    wordcount_t i;
    for (i = 0; i < num_words; ++i) {
        bits |= vli[i];
    }
    return (bits == 0);
}

Fix for #168


unsigned uECC_curve_num_words(uECC_Curve curve) {
    return curve->num_words;
}

Fix for #168


unsigned uECC_curve_num_bits(uECC_Curve curve) {
    return curve->num_bytes * 8;
}

Fix for #168


uECC_VLI_API bitcount_t uECC_vli_numBits(const uECC_word_t *vli, const wordcount_t max_words) {
    uECC_word_t i;
    uECC_word_t digit;

    wordcount_t num_digits = vli_numDigits(vli, max_words);
    if (num_digits == 0) {
        return 0;
    }

    digit = vli[num_digits - 1];
    for (i = 0; digit; ++i) {
        digit >>= 1;
    }

    return (((bitcount_t)(num_digits - 1) << uECC_WORD_BITS_SHIFT) + i);
}

Fix for #168


uECC_VLI_API int uECC_generate_random_int(uECC_word_t *random,
                                          const uECC_word_t *top,
                                          wordcount_t num_words) {
    uECC_word_t mask = (uECC_word_t)-1;
    uECC_word_t tries;
    bitcount_t num_bits = uECC_vli_numBits(top, num_words);

    if (!g_rng_function) {
        return 0;
    }

    for (tries = 0; tries < uECC_RNG_MAX_TRIES; ++tries) {
        if (!g_rng_function((uint8_t *)random, num_words * uECC_WORD_SIZE)) {
            return 0;
	    }
        random[num_words - 1] &= mask >> ((bitcount_t)(num_words * uECC_WORD_SIZE * 8 - num_bits));
        if (!uECC_vli_isZero(random, num_words) &&
		        uECC_vli_cmp(top, random, num_words) == 1) {
            return 1;
        }
    }
    return 0;
}

Fix for #168


static bitcount_t smax(bitcount_t a, bitcount_t b) {
    return (a > b ? a : b);
}

Fix for #168


static wordcount_t vli_numDigits(const uECC_word_t *vli, const wordcount_t max_words) {
    wordcount_t i;
    /* Search from the end until we find a non-zero digit.
       We do it in reverse because we expect that most digits will be nonzero. */
    for (i = max_words - 1; i >= 0 && vli[i] == 0; --i) {
    }

    return (i + 1);
}

Fix for #168


uECC_VLI_API uECC_word_t uECC_vli_equal(const uECC_word_t *left,
                                        const uECC_word_t *right,
                                        wordcount_t num_words) {
    uECC_word_t diff = 0;
    wordcount_t i;
    for (i = num_words - 1; i >= 0; --i) {
        diff |= (left[i] ^ right[i]);
    }
    return (diff == 0);
}

Fix for #168


uECC_VLI_API void uECC_vli_modSquare(uECC_word_t *result,
                                     const uECC_word_t *left,
                                     const uECC_word_t *mod,
                                     wordcount_t num_words) {
    uECC_word_t product[2 * uECC_MAX_WORDS];
    uECC_vli_square(product, left, num_words);
    uECC_vli_mmod(result, product, mod, num_words);
}

Fix for #168


const uECC_word_t *uECC_curve_G(uECC_Curve curve) {
    return curve->G;
}

Fix for #168


Fix for #168


uECC_VLI_API void uECC_vli_modSquare(uECC_word_t *result,
                                     const uECC_word_t *left,
                                     const uECC_word_t *mod,
                                     wordcount_t num_words) {
    uECC_vli_modMult(result, left, left, mod, num_words);
}

Fix for #168


int uECC_sign(const uint8_t *private_key,
              const uint8_t *message_hash,
              unsigned hash_size,
              uint8_t *signature,
              uECC_Curve curve) {
    uECC_word_t k[uECC_MAX_WORDS];
    uECC_word_t tries;

    for (tries = 0; tries < uECC_RNG_MAX_TRIES; ++tries) {
        if (!uECC_generate_random_int(k, curve->n, BITS_TO_WORDS(curve->num_n_bits))) {
            return 0;
        }

        if (uECC_sign_with_k(private_key, message_hash, hash_size, k, signature, curve)) {
            return 1;
        }
    }
    return 0;
}

Fix for #168


static void HMAC_init(const uECC_HashContext *hash_context, const uint8_t *K) {
    uint8_t *pad = hash_context->tmp + 2 * hash_context->result_size;
    unsigned i;
    for (i = 0; i < hash_context->result_size; ++i)
        pad[i] = K[i] ^ 0x36;
    for (; i < hash_context->block_size; ++i)
        pad[i] = 0x36;

    hash_context->init_hash(hash_context);
    hash_context->update_hash(hash_context, pad, hash_context->block_size);
}

Fix for #168


int uECC_curve_public_key_size(uECC_Curve curve) {
    return 2 * curve->num_bytes;
}

Fix for #168


unsigned uECC_curve_num_n_bytes(uECC_Curve curve) {
    return BITS_TO_BYTES(curve->num_n_bits);
}

Fix for #168


uECC_VLI_API void uECC_vli_modAdd(uECC_word_t *result,
                                  const uECC_word_t *left,
                                  const uECC_word_t *right,
                                  const uECC_word_t *mod,
                                  wordcount_t num_words) {
    uECC_word_t carry = uECC_vli_add(result, left, right, num_words);
    if (carry || uECC_vli_cmp_unsafe(mod, result, num_words) != 1) {
        /* result > mod (result = mod + remainder), so subtract mod to get remainder. */
        uECC_vli_sub(result, result, mod, num_words);
    }
}

Fix for #168


const uECC_word_t *uECC_curve_n(uECC_Curve curve) {
    return curve->n;
}

Fix for #168


void uECC_set_rng(uECC_RNG_Function rng_function) {
    g_rng_function = rng_function;
}

Fix for #168


uECC_VLI_API void uECC_vli_modSquare_fast(uECC_word_t *result,
                                          const uECC_word_t *left,
                                          uECC_Curve curve) {
    uECC_word_t product[2 * uECC_MAX_WORDS];
    uECC_vli_square(product, left, curve->num_words);
#if (uECC_OPTIMIZATION_LEVEL > 0)
    curve->mmod_fast(result, product);
#else
    uECC_vli_mmod(result, product, curve->p, curve->num_words);
#endif
}

Fix for #168


uECC_VLI_API void uECC_vli_modInv(uECC_word_t *result,
                                  const uECC_word_t *input,
                                  const uECC_word_t *mod,
                                  wordcount_t num_words) {
    uECC_word_t a[uECC_MAX_WORDS], b[uECC_MAX_WORDS], u[uECC_MAX_WORDS], v[uECC_MAX_WORDS];
    cmpresult_t cmpResult;

    if (uECC_vli_isZero(input, num_words)) {
        uECC_vli_clear(result, num_words);
        return;
    }

    uECC_vli_set(a, input, num_words);
    uECC_vli_set(b, mod, num_words);
    uECC_vli_clear(u, num_words);
    u[0] = 1;
    uECC_vli_clear(v, num_words);
    while ((cmpResult = uECC_vli_cmp_unsafe(a, b, num_words)) != 0) {
        if (EVEN(a)) {
            uECC_vli_rshift1(a, num_words);
            vli_modInv_update(u, mod, num_words);
        } else if (EVEN(b)) {
            uECC_vli_rshift1(b, num_words);
            vli_modInv_update(v, mod, num_words);
        } else if (cmpResult > 0) {
            uECC_vli_sub(a, a, b, num_words);
            uECC_vli_rshift1(a, num_words);
            if (uECC_vli_cmp_unsafe(u, v, num_words) < 0) {
                uECC_vli_add(u, u, mod, num_words);
            }
            uECC_vli_sub(u, u, v, num_words);
            vli_modInv_update(u, mod, num_words);
        } else {
            uECC_vli_sub(b, b, a, num_words);
            uECC_vli_rshift1(b, num_words);
            if (uECC_vli_cmp_unsafe(v, u, num_words) < 0) {
                uECC_vli_add(v, v, mod, num_words);
            }
            uECC_vli_sub(v, v, u, num_words);
            vli_modInv_update(v, mod, num_words);
        }
    }
    uECC_vli_set(result, u, num_words);
}

Fix for #168


unsigned uECC_curve_num_n_words(uECC_Curve curve) {
    return BITS_TO_WORDS(curve->num_n_bits);
}

Fix for #168


uECC_VLI_API void uECC_vli_modMult(uECC_word_t *result,
                                   const uECC_word_t *left,
                                   const uECC_word_t *right,
                                   const uECC_word_t *mod,
                                   wordcount_t num_words) {
    uECC_word_t product[2 * uECC_MAX_WORDS];
    uECC_vli_mult(product, left, right, num_words);
    uECC_vli_mmod(result, product, mod, num_words);
}

Fix for #168


int uECC_valid_public_key(const uint8_t *public_key, uECC_Curve curve) {
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
    uECC_word_t *_public = (uECC_word_t *)public_key;
#else
    uECC_word_t _public[uECC_MAX_WORDS * 2];
#endif

#if uECC_VLI_NATIVE_LITTLE_ENDIAN == 0
    uECC_vli_bytesToNative(_public, public_key, curve->num_bytes);
    uECC_vli_bytesToNative(
        _public + curve->num_words, public_key + curve->num_bytes, curve->num_bytes);
#endif
    return uECC_valid_point(_public, curve);
}

Fix for #168


uECC_VLI_API void uECC_vli_bytesToNative(uint8_t *native,
                                         const uint8_t *bytes,
                                         int num_bytes) {
    uECC_vli_nativeToBytes(native, num_bytes, bytes);
}

Fix for #168


uECC_VLI_API uECC_word_t uECC_vli_sub(uECC_word_t *result,
                                      const uECC_word_t *left,
                                      const uECC_word_t *right,
                                      wordcount_t num_words) {
    uECC_word_t borrow = 0;
    wordcount_t i;
    for (i = 0; i < num_words; ++i) {
        uECC_word_t diff = left[i] - right[i] - borrow;
        if (diff != left[i]) {
            borrow = (diff > left[i]);
        }
        result[i] = diff;
    }
    return borrow;
}

Fix for #168


uECC_VLI_API void uECC_vli_nativeToBytes(uint8_t *bytes,
                                         int num_bytes,
                                         const uECC_word_t *native) {
    wordcount_t i;
    for (i = 0; i < num_bytes; ++i) {
        unsigned b = num_bytes - 1 - i;
        bytes[i] = native[b / uECC_WORD_SIZE] >> (8 * (b % uECC_WORD_SIZE));
    }
}

Fix for #168


static int uECC_sign_with_k(const uint8_t *private_key,
                            const uint8_t *message_hash,
                            unsigned hash_size,
                            uECC_word_t *k,
                            uint8_t *signature,
                            uECC_Curve curve) {

    uECC_word_t tmp[uECC_MAX_WORDS];
    uECC_word_t s[uECC_MAX_WORDS];
    uECC_word_t *k2[2] = {tmp, s};
    uECC_word_t *initial_Z = 0;
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
    uECC_word_t *p = (uECC_word_t *)signature;
#else
    uECC_word_t p[uECC_MAX_WORDS * 2];
#endif
    uECC_word_t carry;
    wordcount_t num_words = curve->num_words;
    wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);
    bitcount_t num_n_bits = curve->num_n_bits;

    /* Make sure 0 < k < curve_n */
    if (uECC_vli_isZero(k, num_words) || uECC_vli_cmp(curve->n, k, num_n_words) != 1) {
        return 0;
    }

    carry = regularize_k(k, tmp, s, curve);
    /* If an RNG function was specified, try to get a random initial Z value to improve
       protection against side-channel attacks. */
    if (g_rng_function) {
        if (!uECC_generate_random_int(k2[carry], curve->p, num_words)) {
            return 0;
        }
        initial_Z = k2[carry];
    }
    EccPoint_mult(p, curve->G, k2[!carry], initial_Z, num_n_bits + 1, curve);
    if (uECC_vli_isZero(p, num_words)) {
        return 0;
    }

    /* If an RNG function was specified, get a random number
       to prevent side channel analysis of k. */
    if (!g_rng_function) {
        uECC_vli_clear(tmp, num_n_words);
        tmp[0] = 1;
    } else if (!uECC_generate_random_int(tmp, curve->n, num_n_words)) {
        return 0;
    }

    /* Prevent side channel analysis of uECC_vli_modInv() to determine
       bits of k / the private key by premultiplying by a random number */
    uECC_vli_modMult(k, k, tmp, curve->n, num_n_words); /* k' = rand * k */
    uECC_vli_modInv(k, k, curve->n, num_n_words);       /* k = 1 / k' */
    uECC_vli_modMult(k, k, tmp, curve->n, num_n_words); /* k = 1 / k */

#if uECC_VLI_NATIVE_LITTLE_ENDIAN == 0
    uECC_vli_nativeToBytes(signature, curve->num_bytes, p); /* store r */
#endif

#if uECC_VLI_NATIVE_LITTLE_ENDIAN
    bcopy((uint8_t *) tmp, private_key, BITS_TO_BYTES(curve->num_n_bits));
#else
    uECC_vli_bytesToNative(tmp, private_key, BITS_TO_BYTES(curve->num_n_bits)); /* tmp = d */
#endif

    s[num_n_words - 1] = 0;
    uECC_vli_set(s, p, num_words);
    uECC_vli_modMult(s, tmp, s, curve->n, num_n_words); /* s = r*d */

    bits2int(tmp, message_hash, hash_size, curve);
    uECC_vli_modAdd(s, tmp, s, curve->n, num_n_words); /* s = e + r*d */
    uECC_vli_modMult(s, s, k, curve->n, num_n_words);  /* s = (e + r*d) / k */
    if (uECC_vli_numBits(s, num_n_words) > (bitcount_t)curve->num_bytes * 8) {
        return 0;
    }
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
    bcopy((uint8_t *) signature + curve->num_bytes, (uint8_t *) s, curve->num_bytes);
#else
    uECC_vli_nativeToBytes(signature + curve->num_bytes, curve->num_bytes, s);
#endif
    return 1;
}

Fix for #168


uECC_VLI_API void uECC_vli_clear(uECC_word_t *vli, wordcount_t num_words) {
    wordcount_t i;
    for (i = 0; i < num_words; ++i) {
        vli[i] = 0;
    }
}

Fix for #168


int uECC_verify(const uint8_t *public_key,
                const uint8_t *message_hash,
                unsigned hash_size,
                const uint8_t *signature,
                uECC_Curve curve) {
    uECC_word_t u1[uECC_MAX_WORDS], u2[uECC_MAX_WORDS];
    uECC_word_t z[uECC_MAX_WORDS];
    uECC_word_t sum[uECC_MAX_WORDS * 2];
    uECC_word_t rx[uECC_MAX_WORDS];
    uECC_word_t ry[uECC_MAX_WORDS];
    uECC_word_t tx[uECC_MAX_WORDS];
    uECC_word_t ty[uECC_MAX_WORDS];
    uECC_word_t tz[uECC_MAX_WORDS];
    const uECC_word_t *points[4];
    const uECC_word_t *point;
    bitcount_t num_bits;
    bitcount_t i;
#if uECC_VLI_NATIVE_LITTLE_ENDIAN
    uECC_word_t *_public = (uECC_word_t *)public_key;
#else
    uECC_word_t _public[uECC_MAX_WORDS * 2];
#endif
    uECC_word_t r[uECC_MAX_WORDS], s[uECC_MAX_WORDS];
    wordcount_t num_words = curve->num_words;
    wordcount_t num_n_words = BITS_TO_WORDS(curve->num_n_bits);

    rx[num_n_words - 1] = 0;
    r[num_n_words - 1] = 0;
    s[num_n_words - 1] = 0;

#if uECC_VLI_NATIVE_LITTLE_ENDIAN
    bcopy((uint8_t *) r, signature, curve->num_bytes);
    bcopy((uint8_t *) s, signature + curve->num_bytes, curve->num_bytes);
#else
    uECC_vli_bytesToNative(_public, public_key, curve->num_bytes);
    uECC_vli_bytesToNative(
        _public + num_words, public_key + curve->num_bytes, curve->num_bytes);
    uECC_vli_bytesToNative(r, signature, curve->num_bytes);
    uECC_vli_bytesToNative(s, signature + curve->num_bytes, curve->num_bytes);
#endif

    /* r, s must not be 0. */
    if (uECC_vli_isZero(r, num_words) || uECC_vli_isZero(s, num_words)) {
        return 0;
    }

    /* r, s must be < n. */
    if (uECC_vli_cmp_unsafe(curve->n, r, num_n_words) != 1 ||
            uECC_vli_cmp_unsafe(curve->n, s, num_n_words) != 1) {
        return 0;
    }

    /* Calculate u1 and u2. */
    uECC_vli_modInv(z, s, curve->n, num_n_words); /* z = 1/s */
    u1[num_n_words - 1] = 0;
    bits2int(u1, message_hash, hash_size, curve);
    uECC_vli_modMult(u1, u1, z, curve->n, num_n_words); /* u1 = e/s */
    uECC_vli_modMult(u2, r, z, curve->n, num_n_words); /* u2 = r/s */

    /* Calculate sum = G + Q. */
    uECC_vli_set(sum, _public, num_words);
    uECC_vli_set(sum + num_words, _public + num_words, num_words);
    uECC_vli_set(tx, curve->G, num_words);
    uECC_vli_set(ty, curve->G + num_words, num_words);
    uECC_vli_modSub(z, sum, tx, curve->p, num_words); /* z = x2 - x1 */
    XYcZ_add(tx, ty, sum, sum + num_words, curve);
    uECC_vli_modInv(z, z, curve->p, num_words); /* z = 1/z */
    apply_z(sum, sum + num_words, z, curve);

    /* Use Shamir's trick to calculate u1*G + u2*Q */
    points[0] = 0;
    points[1] = curve->G;
    points[2] = _public;
    points[3] = sum;
    num_bits = smax(uECC_vli_numBits(u1, num_n_words),
                    uECC_vli_numBits(u2, num_n_words));

    point = points[(!!uECC_vli_testBit(u1, num_bits - 1)) |
                   ((!!uECC_vli_testBit(u2, num_bits - 1)) << 1)];
    uECC_vli_set(rx, point, num_words);
    uECC_vli_set(ry, point + num_words, num_words);
    uECC_vli_clear(z, num_words);
    z[0] = 1;

    for (i = num_bits - 2; i >= 0; --i) {
        uECC_word_t index;
        curve->double_jacobian(rx, ry, z, curve);

        index = (!!uECC_vli_testBit(u1, i)) | ((!!uECC_vli_testBit(u2, i)) << 1);
        point = points[index];
        if (point) {
            uECC_vli_set(tx, point, num_words);
            uECC_vli_set(ty, point + num_words, num_words);
            apply_z(tx, ty, z, curve);
            uECC_vli_modSub(tz, rx, tx, curve->p, num_words); /* Z = x2 - x1 */
            XYcZ_add(tx, ty, rx, ry, curve);
            uECC_vli_modMult_fast(z, z, tz, curve);
        }
    }

    uECC_vli_modInv(z, z, curve->p, num_words); /* Z = 1/Z */
    apply_z(rx, ry, z, curve);

    /* v = x1 (mod n) */
    if (uECC_vli_cmp_unsafe(curve->n, rx, num_n_words) != 1) {
        uECC_vli_sub(rx, rx, curve->n, num_n_words);
    }

    /* Accept only if v == r. */
    return (int)(uECC_vli_equal(rx, r, num_words));
}

Fix for #168


uECC_VLI_API int uECC_valid_point(const uECC_word_t *point, uECC_Curve curve) {
    uECC_word_t tmp1[uECC_MAX_WORDS];
    uECC_word_t tmp2[uECC_MAX_WORDS];
    wordcount_t num_words = curve->num_words;

    /* The point at infinity is invalid. */
    if (EccPoint_isZero(point, curve)) {
        return 0;
    }

    /* x and y must be smaller than p. */
    if (uECC_vli_cmp_unsafe(curve->p, point, num_words) != 1 ||
            uECC_vli_cmp_unsafe(curve->p, point + num_words, num_words) != 1) {
        return 0;
    }

    uECC_vli_modSquare_fast(tmp1, point + num_words, curve);
    curve->x_side(tmp2, point, curve); /* tmp2 = x^3 + ax + b */

    /* Make sure that y^2 == x^3 + ax + b */
    return (int)(uECC_vli_equal(tmp1, tmp2, num_words));
}

Fix for #168


static void HMAC_finish(const uECC_HashContext *hash_context,
                        const uint8_t *K,
                        uint8_t *result) {
    uint8_t *pad = hash_context->tmp + 2 * hash_context->result_size;
    unsigned i;
    for (i = 0; i < hash_context->result_size; ++i)
        pad[i] = K[i] ^ 0x5c;
    for (; i < hash_context->block_size; ++i)
        pad[i] = 0x5c;

    hash_context->finish_hash(hash_context, result);

    hash_context->init_hash(hash_context);
    hash_context->update_hash(hash_context, pad, hash_context->block_size);
    hash_context->update_hash(hash_context, result, hash_context->result_size);
    hash_context->finish_hash(hash_context, result);
}

Fix for #168