1//===-- Implementation of bsearch -----------------------------------------===//
2//
3// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4// See https://llvm.org/LICENSE.txt for license information.
5// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6//
7//===----------------------------------------------------------------------===//
8
9#include "src/stdlib/bsearch.h"
10#include "src/__support/common.h"
11#include "src/__support/macros/config.h"
12
13#include <stdint.h>
14
15namespace LIBC_NAMESPACE_DECL {
16
17LLVM_LIBC_FUNCTION(void *, bsearch,
18 (const void *key, const void *array, size_t array_size,
19 size_t elem_size,
20 int (*compare)(const void *, const void *))) {
21 if (key == nullptr || array == nullptr || array_size == 0 || elem_size == 0)
22 return nullptr;
23
24 while (array_size > 0) {
25 size_t mid = array_size / 2;
26 const void *elem =
27 reinterpret_cast<const uint8_t *>(array) + mid * elem_size;
28 int compare_result = compare(key, elem);
29 if (compare_result == 0)
30 return const_cast<void *>(elem);
31
32 if (compare_result < 0) {
33 // This means that key is less than the element at |mid|.
34 // So, in the next iteration, we only compare elements less
35 // than mid.
36 array_size = mid;
37 } else {
38 // |mid| is strictly less than |array_size|. So, the below
39 // decrement in |array_size| will not lead to a wrap around.
40 array_size -= (mid + 1);
41 array = reinterpret_cast<const uint8_t *>(elem) + elem_size;
42 }
43 }
44
45 return nullptr;
46}
47
48} // namespace LIBC_NAMESPACE_DECL
49

source code of libc/src/stdlib/bsearch.cpp