Do some string library work

This commit is contained in:
Justine Tunney 2022-08-20 21:36:07 -07:00
parent 83d41e4588
commit 35203c0551
42 changed files with 1381 additions and 136 deletions

View file

@ -1,7 +1,7 @@
/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
vi: set net ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi
Copyright 2020 Justine Alexandra Roberts Tunney
Copyright 2021 Justine Alexandra Roberts Tunney
Permission to use, copy, modify, and/or distribute this software for
any purpose with or without fee is hereby granted, provided that the
@ -16,27 +16,28 @@
TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
PERFORMANCE OF THIS SOFTWARE.
*/
#include "libc/dce.h"
#include "libc/intrin/asan.internal.h"
#include "libc/str/str.h"
typedef wchar_t xmm_t __attribute__((__vector_size__(16), __aligned__(16)));
/**
* Searches for substring.
* Returns length of NUL-terminated wide string.
*
* @param haystack is the search area, as a NUL-terminated string
* @param needle is the desired substring, also NUL-terminated
* @return pointer to first substring within haystack, or NULL
* @param s is non-null NUL-terminated wide string pointer
* @return number of wide characters (excluding NUL)
* @asyncsignalsafe
* @see memmem()
*/
wchar_t *wcsstr(const wchar_t *haystack, const wchar_t *needle) {
size_t i;
for (;;) {
for (i = 0;;) {
if (!needle[i]) return (/*unconst*/ wchar_t *)haystack;
if (!haystack[i]) break;
if (needle[i] != haystack[i]) break;
++i;
}
if (!*haystack++) break;
}
return NULL;
noasan size_t wcslen(const wchar_t *s) {
size_t n;
xmm_t z = {0};
unsigned m, k = (uintptr_t)s & 15;
const xmm_t *p = (const xmm_t *)((uintptr_t)s & -16);
if (IsAsan()) __asan_verify(s, 4);
m = __builtin_ia32_pmovmskb128(*p == z) >> k << k;
while (!m) m = __builtin_ia32_pmovmskb128(*++p == z);
n = (const wchar_t *)p + (__builtin_ctzl(m) >> 2) - s;
if (IsAsan()) __asan_verify(s, n);
return n;
}