39 lines · cpp
1//===-- Implementation of wcsstr ------------------------------------------===//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-exception6//7//===----------------------------------------------------------------------===//8 9#include "src/wchar/wcsstr.h"10 11#include "hdr/types/size_t.h"12#include "hdr/types/wchar_t.h"13#include "src/__support/common.h"14#include "src/__support/macros/config.h"15#include "src/string/string_utils.h"16 17namespace LIBC_NAMESPACE_DECL {18 19LLVM_LIBC_FUNCTION(const wchar_t *, wcsstr,20 (const wchar_t *s1, const wchar_t *s2)) {21 size_t s1_len = internal::string_length(s1);22 size_t s2_len = internal::string_length(s2);23 if (s2_len == 0)24 return s1;25 if (s2_len > s1_len)26 return nullptr;27 for (size_t i = 0; i <= (s1_len - s2_len); ++i) {28 size_t j = 0;29 // j will increment until the characters don't match or end of string.30 for (; j < s2_len && s1[i + j] == s2[j]; ++j)31 ;32 if (j == s2_len)33 return (s1 + i);34 }35 return nullptr;36}37 38} // namespace LIBC_NAMESPACE_DECL39