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wdenkc6097192002-11-03 00:24:07 +00001/*
2 * linux/lib/string.c
3 *
4 * Copyright (C) 1991, 1992 Linus Torvalds
5 */
6
7/*
8 * stupid library routines.. The optimized versions should generally be found
9 * as inline code in <asm-xx/string.h>
10 *
11 * These are buggy as well..
12 *
13 * * Fri Jun 25 1999, Ingo Oeser <ioe@informatik.tu-chemnitz.de>
14 * - Added strsep() which will replace strtok() soon (because strsep() is
15 * reentrant and should be faster). Use only strsep() in new code, please.
16 */
17
Simon Glass96794a32018-11-06 15:21:38 -070018#include <config.h>
Marek BehĂșn46c3e292021-05-20 13:23:55 +020019#include <linux/compiler.h>
wdenkc6097192002-11-03 00:24:07 +000020#include <linux/types.h>
21#include <linux/string.h>
22#include <linux/ctype.h>
23#include <malloc.h>
24
wdenkc6097192002-11-03 00:24:07 +000025
wdenkc6097192002-11-03 00:24:07 +000026/**
Simon Glassb1f17bf2012-12-05 14:46:35 +000027 * strncasecmp - Case insensitive, length-limited string comparison
wdenkc6097192002-11-03 00:24:07 +000028 * @s1: One string
29 * @s2: The other string
30 * @len: the maximum number of characters to compare
31 */
Simon Glassb1f17bf2012-12-05 14:46:35 +000032int strncasecmp(const char *s1, const char *s2, size_t len)
wdenkc6097192002-11-03 00:24:07 +000033{
34 /* Yes, Virginia, it had better be unsigned */
35 unsigned char c1, c2;
36
37 c1 = 0; c2 = 0;
38 if (len) {
39 do {
40 c1 = *s1; c2 = *s2;
41 s1++; s2++;
42 if (!c1)
43 break;
44 if (!c2)
45 break;
46 if (c1 == c2)
47 continue;
48 c1 = tolower(c1);
49 c2 = tolower(c2);
50 if (c1 != c2)
51 break;
52 } while (--len);
53 }
54 return (int)c1 - (int)c2;
55}
Simon Glassb1f17bf2012-12-05 14:46:35 +000056
57/**
58 * strcasecmp - Case insensitive string comparison
59 * @s1: One string
60 * @s2: The other string
61 */
62int strcasecmp(const char *s1, const char *s2)
63{
64 return strncasecmp(s1, s2, -1U);
65}
wdenkc6097192002-11-03 00:24:07 +000066
67char * ___strtok;
68
69#ifndef __HAVE_ARCH_STRCPY
70/**
71 * strcpy - Copy a %NUL terminated string
72 * @dest: Where to copy the string to
73 * @src: Where to copy the string from
74 */
75char * strcpy(char * dest,const char *src)
76{
77 char *tmp = dest;
78
79 while ((*dest++ = *src++) != '\0')
80 /* nothing */;
81 return tmp;
82}
83#endif
84
85#ifndef __HAVE_ARCH_STRNCPY
86/**
87 * strncpy - Copy a length-limited, %NUL-terminated string
88 * @dest: Where to copy the string to
89 * @src: Where to copy the string from
90 * @count: The maximum number of bytes to copy
91 *
92 * Note that unlike userspace strncpy, this does not %NUL-pad the buffer.
93 * However, the result is not %NUL-terminated if the source exceeds
94 * @count bytes.
95 */
96char * strncpy(char * dest,const char *src,size_t count)
97{
98 char *tmp = dest;
99
100 while (count-- && (*dest++ = *src++) != '\0')
101 /* nothing */;
102
103 return tmp;
104}
105#endif
106
Masahiro Yamada80d9ef82014-11-20 21:20:32 +0900107#ifndef __HAVE_ARCH_STRLCPY
108/**
109 * strlcpy - Copy a C-string into a sized buffer
110 * @dest: Where to copy the string to
111 * @src: Where to copy the string from
112 * @size: size of destination buffer
113 *
114 * Compatible with *BSD: the result is always a valid
115 * NUL-terminated string that fits in the buffer (unless,
116 * of course, the buffer size is zero). It does not pad
117 * out the result like strncpy() does.
Sean Andersond3358ec2021-03-11 00:15:41 -0500118 *
Matthias Schiffer61582872023-07-14 13:24:50 +0200119 * Return: strlen(src)
Masahiro Yamada80d9ef82014-11-20 21:20:32 +0900120 */
121size_t strlcpy(char *dest, const char *src, size_t size)
122{
Matthias Schiffer61582872023-07-14 13:24:50 +0200123 size_t ret = strlen(src);
Sean Andersond3358ec2021-03-11 00:15:41 -0500124
Matthias Schiffer61582872023-07-14 13:24:50 +0200125 if (size) {
126 size_t len = (ret >= size) ? size - 1 : ret;
Masahiro Yamada80d9ef82014-11-20 21:20:32 +0900127 memcpy(dest, src, len);
128 dest[len] = '\0';
129 }
Matthias Schiffer61582872023-07-14 13:24:50 +0200130 return ret;
Masahiro Yamada80d9ef82014-11-20 21:20:32 +0900131}
132#endif
133
wdenkc6097192002-11-03 00:24:07 +0000134#ifndef __HAVE_ARCH_STRCAT
135/**
136 * strcat - Append one %NUL-terminated string to another
137 * @dest: The string to be appended to
138 * @src: The string to append to it
139 */
140char * strcat(char * dest, const char * src)
141{
142 char *tmp = dest;
143
144 while (*dest)
145 dest++;
146 while ((*dest++ = *src++) != '\0')
147 ;
148
149 return tmp;
150}
151#endif
152
153#ifndef __HAVE_ARCH_STRNCAT
154/**
155 * strncat - Append a length-limited, %NUL-terminated string to another
156 * @dest: The string to be appended to
157 * @src: The string to append to it
158 * @count: The maximum numbers of bytes to copy
159 *
160 * Note that in contrast to strncpy, strncat ensures the result is
161 * terminated.
162 */
163char * strncat(char *dest, const char *src, size_t count)
164{
165 char *tmp = dest;
166
167 if (count) {
168 while (*dest)
169 dest++;
170 while ((*dest++ = *src++)) {
171 if (--count == 0) {
172 *dest = '\0';
173 break;
174 }
175 }
176 }
177
178 return tmp;
179}
180#endif
181
Sean Anderson9af869c2021-03-11 00:15:42 -0500182#ifndef __HAVE_ARCH_STRLCAT
183/**
184 * strlcat - Append a length-limited, %NUL-terminated string to another
185 * @dest: The string to be appended to
186 * @src: The string to append to it
187 * @size: The size of @dest
188 *
189 * Compatible with *BSD: the result is always a valid NUL-terminated string that
190 * fits in the buffer (unless, of course, the buffer size is zero). It does not
191 * write past @size like strncat() does.
Matthias Schiffer61582872023-07-14 13:24:50 +0200192 *
193 * Return: min(strlen(dest), size) + strlen(src)
Sean Anderson9af869c2021-03-11 00:15:42 -0500194 */
195size_t strlcat(char *dest, const char *src, size_t size)
196{
197 size_t len = strnlen(dest, size);
198
199 return len + strlcpy(dest + len, src, size - len);
200}
201#endif
202
wdenkc6097192002-11-03 00:24:07 +0000203#ifndef __HAVE_ARCH_STRCMP
204/**
205 * strcmp - Compare two strings
206 * @cs: One string
207 * @ct: Another string
208 */
Rasmus Villemoesfb633622022-10-05 11:09:25 +0200209int strcmp(const char *cs, const char *ct)
wdenkc6097192002-11-03 00:24:07 +0000210{
Rasmus Villemoesfb633622022-10-05 11:09:25 +0200211 int ret;
wdenkc6097192002-11-03 00:24:07 +0000212
213 while (1) {
Rasmus Villemoesfb633622022-10-05 11:09:25 +0200214 unsigned char a = *cs++;
215 unsigned char b = *ct++;
216
217 ret = a - b;
218 if (ret || !b)
wdenkc6097192002-11-03 00:24:07 +0000219 break;
220 }
221
Rasmus Villemoesfb633622022-10-05 11:09:25 +0200222 return ret;
wdenkc6097192002-11-03 00:24:07 +0000223}
224#endif
225
226#ifndef __HAVE_ARCH_STRNCMP
227/**
228 * strncmp - Compare two length-limited strings
229 * @cs: One string
230 * @ct: Another string
231 * @count: The maximum number of bytes to compare
232 */
Rasmus Villemoesfb633622022-10-05 11:09:25 +0200233int strncmp(const char *cs, const char *ct, size_t count)
wdenkc6097192002-11-03 00:24:07 +0000234{
Rasmus Villemoesfb633622022-10-05 11:09:25 +0200235 int ret = 0;
wdenkc6097192002-11-03 00:24:07 +0000236
Rasmus Villemoesfb633622022-10-05 11:09:25 +0200237 while (count--) {
238 unsigned char a = *cs++;
239 unsigned char b = *ct++;
240
241 ret = a - b;
242 if (ret || !b)
wdenkc6097192002-11-03 00:24:07 +0000243 break;
wdenkc6097192002-11-03 00:24:07 +0000244 }
245
Rasmus Villemoesfb633622022-10-05 11:09:25 +0200246 return ret;
wdenkc6097192002-11-03 00:24:07 +0000247}
248#endif
249
250#ifndef __HAVE_ARCH_STRCHR
251/**
252 * strchr - Find the first occurrence of a character in a string
253 * @s: The string to be searched
254 * @c: The character to search for
255 */
256char * strchr(const char * s, int c)
257{
258 for(; *s != (char) c; ++s)
259 if (*s == '\0')
260 return NULL;
261 return (char *) s;
262}
263#endif
264
Simon Glass6b45ba42017-05-18 20:09:28 -0600265const char *strchrnul(const char *s, int c)
266{
267 for (; *s != (char)c; ++s)
268 if (*s == '\0')
269 break;
270 return s;
271}
272
wdenkc6097192002-11-03 00:24:07 +0000273#ifndef __HAVE_ARCH_STRRCHR
274/**
275 * strrchr - Find the last occurrence of a character in a string
276 * @s: The string to be searched
277 * @c: The character to search for
278 */
279char * strrchr(const char * s, int c)
280{
281 const char *p = s + strlen(s);
282 do {
wdenk8bde7f72003-06-27 21:31:46 +0000283 if (*p == (char)c)
284 return (char *)p;
wdenkc6097192002-11-03 00:24:07 +0000285 } while (--p >= s);
286 return NULL;
287}
288#endif
289
290#ifndef __HAVE_ARCH_STRLEN
291/**
292 * strlen - Find the length of a string
293 * @s: The string to be sized
294 */
295size_t strlen(const char * s)
296{
297 const char *sc;
298
299 for (sc = s; *sc != '\0'; ++sc)
300 /* nothing */;
301 return sc - s;
302}
303#endif
304
305#ifndef __HAVE_ARCH_STRNLEN
306/**
307 * strnlen - Find the length of a length-limited string
308 * @s: The string to be sized
309 * @count: The maximum number of bytes to search
310 */
311size_t strnlen(const char * s, size_t count)
312{
313 const char *sc;
314
315 for (sc = s; count-- && *sc != '\0'; ++sc)
316 /* nothing */;
317 return sc - s;
318}
319#endif
320
Simon Glassa7d00212017-05-18 20:09:29 -0600321#ifndef __HAVE_ARCH_STRCSPN
322/**
323 * strcspn - Calculate the length of the initial substring of @s which does
324 * not contain letters in @reject
325 * @s: The string to be searched
326 * @reject: The string to avoid
327 */
328size_t strcspn(const char *s, const char *reject)
329{
330 const char *p;
331 const char *r;
332 size_t count = 0;
333
334 for (p = s; *p != '\0'; ++p) {
335 for (r = reject; *r != '\0'; ++r) {
336 if (*p == *r)
337 return count;
338 }
339 ++count;
340 }
341 return count;
342}
343#endif
344
wdenkc6097192002-11-03 00:24:07 +0000345#ifndef __HAVE_ARCH_STRDUP
346char * strdup(const char *s)
347{
348 char *new;
349
350 if ((s == NULL) ||
351 ((new = malloc (strlen(s) + 1)) == NULL) ) {
352 return NULL;
353 }
354
355 strcpy (new, s);
356 return new;
357}
wdenkc6097192002-11-03 00:24:07 +0000358
Thierry Reding0c4e2652019-04-15 11:32:14 +0200359char * strndup(const char *s, size_t n)
360{
361 size_t len;
362 char *new;
363
364 if (s == NULL)
365 return NULL;
366
367 len = strlen(s);
368
369 if (n < len)
370 len = n;
371
372 new = malloc(len + 1);
373 if (new == NULL)
374 return NULL;
375
376 strncpy(new, s, len);
377 new[len] = '\0';
378
379 return new;
380}
Simon Glass1ea1c7d2020-02-03 07:36:00 -0700381#endif
Thierry Reding0c4e2652019-04-15 11:32:14 +0200382
wdenkc6097192002-11-03 00:24:07 +0000383#ifndef __HAVE_ARCH_STRSPN
384/**
385 * strspn - Calculate the length of the initial substring of @s which only
Wolfgang Denk53677ef2008-05-20 16:00:29 +0200386 * contain letters in @accept
wdenkc6097192002-11-03 00:24:07 +0000387 * @s: The string to be searched
388 * @accept: The string to search for
389 */
390size_t strspn(const char *s, const char *accept)
391{
392 const char *p;
393 const char *a;
394 size_t count = 0;
395
396 for (p = s; *p != '\0'; ++p) {
397 for (a = accept; *a != '\0'; ++a) {
398 if (*p == *a)
399 break;
400 }
401 if (*a == '\0')
402 return count;
403 ++count;
404 }
405
406 return count;
407}
408#endif
409
410#ifndef __HAVE_ARCH_STRPBRK
411/**
412 * strpbrk - Find the first occurrence of a set of characters
413 * @cs: The string to be searched
414 * @ct: The characters to search for
415 */
416char * strpbrk(const char * cs,const char * ct)
417{
418 const char *sc1,*sc2;
419
420 for( sc1 = cs; *sc1 != '\0'; ++sc1) {
421 for( sc2 = ct; *sc2 != '\0'; ++sc2) {
422 if (*sc1 == *sc2)
423 return (char *) sc1;
424 }
425 }
426 return NULL;
427}
428#endif
429
430#ifndef __HAVE_ARCH_STRTOK
431/**
432 * strtok - Split a string into tokens
433 * @s: The string to be searched
434 * @ct: The characters to search for
435 *
436 * WARNING: strtok is deprecated, use strsep instead.
437 */
438char * strtok(char * s,const char * ct)
439{
440 char *sbegin, *send;
441
442 sbegin = s ? s : ___strtok;
443 if (!sbegin) {
444 return NULL;
445 }
446 sbegin += strspn(sbegin,ct);
447 if (*sbegin == '\0') {
448 ___strtok = NULL;
449 return( NULL );
450 }
451 send = strpbrk( sbegin, ct);
452 if (send && *send != '\0')
453 *send++ = '\0';
454 ___strtok = send;
455 return (sbegin);
456}
457#endif
458
459#ifndef __HAVE_ARCH_STRSEP
460/**
461 * strsep - Split a string into tokens
462 * @s: The string to be searched
463 * @ct: The characters to search for
464 *
465 * strsep() updates @s to point after the token, ready for the next call.
466 *
467 * It returns empty tokens, too, behaving exactly like the libc function
468 * of that name. In fact, it was stolen from glibc2 and de-fancy-fied.
469 * Same semantics, slimmer shape. ;)
470 */
471char * strsep(char **s, const char *ct)
472{
473 char *sbegin = *s, *end;
474
475 if (sbegin == NULL)
476 return NULL;
477
478 end = strpbrk(sbegin, ct);
479 if (end)
480 *end++ = '\0';
481 *s = end;
482
483 return sbegin;
484}
485#endif
486
wdenkc3f9d492004-03-14 00:59:59 +0000487#ifndef __HAVE_ARCH_STRSWAB
488/**
489 * strswab - swap adjacent even and odd bytes in %NUL-terminated string
490 * s: address of the string
491 *
492 * returns the address of the swapped string or NULL on error. If
493 * string length is odd, last byte is untouched.
494 */
495char *strswab(const char *s)
496{
Wolfgang Denk389db1f2005-09-25 16:15:17 +0200497 char *p, *q;
wdenkc3f9d492004-03-14 00:59:59 +0000498
499 if ((NULL == s) || ('\0' == *s)) {
500 return (NULL);
501 }
502
Wolfgang Denke5e98ed2005-10-04 23:38:07 +0200503 for (p=(char *)s, q=p+1; (*p != '\0') && (*q != '\0'); p+=2, q+=2) {
wdenkc3f9d492004-03-14 00:59:59 +0000504 char tmp;
Wolfgang Denk389db1f2005-09-25 16:15:17 +0200505
506 tmp = *p;
507 *p = *q;
508 *q = tmp;
wdenkc3f9d492004-03-14 00:59:59 +0000509 }
510
511 return (char *) s;
512}
513#endif
514
wdenkc6097192002-11-03 00:24:07 +0000515#ifndef __HAVE_ARCH_MEMSET
516/**
517 * memset - Fill a region of memory with the given value
518 * @s: Pointer to the start of the area.
519 * @c: The byte to fill the area with
520 * @count: The size of the area.
521 *
522 * Do not use memset() to access IO space, use memset_io() instead.
523 */
Marek BehĂșn46c3e292021-05-20 13:23:55 +0200524__used void * memset(void * s,int c,size_t count)
wdenkc6097192002-11-03 00:24:07 +0000525{
Alessandro Rubinie3ea9482009-10-10 11:51:16 +0200526 unsigned long *sl = (unsigned long *) s;
Alessandro Rubinie3ea9482009-10-10 11:51:16 +0200527 char *s8;
Simon Glassab4458b2017-04-02 09:50:28 -0600528
529#if !CONFIG_IS_ENABLED(TINY_MEMSET)
530 unsigned long cl = 0;
Alessandro Rubinie3ea9482009-10-10 11:51:16 +0200531 int i;
wdenkc6097192002-11-03 00:24:07 +0000532
Alessandro Rubinie3ea9482009-10-10 11:51:16 +0200533 /* do it one word at a time (32 bits or 64 bits) while possible */
534 if ( ((ulong)s & (sizeof(*sl) - 1)) == 0) {
535 for (i = 0; i < sizeof(*sl); i++) {
536 cl <<= 8;
537 cl |= c & 0xff;
538 }
539 while (count >= sizeof(*sl)) {
540 *sl++ = cl;
541 count -= sizeof(*sl);
542 }
543 }
Simon Glassab4458b2017-04-02 09:50:28 -0600544#endif /* fill 8 bits at a time */
Alessandro Rubinie3ea9482009-10-10 11:51:16 +0200545 s8 = (char *)sl;
wdenkc6097192002-11-03 00:24:07 +0000546 while (count--)
Alessandro Rubinie3ea9482009-10-10 11:51:16 +0200547 *s8++ = c;
wdenkc6097192002-11-03 00:24:07 +0000548
549 return s;
550}
551#endif
552
wdenkc6097192002-11-03 00:24:07 +0000553#ifndef __HAVE_ARCH_MEMCPY
554/**
555 * memcpy - Copy one area of memory to another
556 * @dest: Where to copy to
557 * @src: Where to copy from
558 * @count: The size of the area.
559 *
560 * You should not use this function to access IO space, use memcpy_toio()
561 * or memcpy_fromio() instead.
562 */
Marek BehĂșn46c3e292021-05-20 13:23:55 +0200563__used void * memcpy(void *dest, const void *src, size_t count)
wdenkc6097192002-11-03 00:24:07 +0000564{
Alessandro Rubiniecd830b2009-10-10 11:51:05 +0200565 unsigned long *dl = (unsigned long *)dest, *sl = (unsigned long *)src;
566 char *d8, *s8;
wdenkc6097192002-11-03 00:24:07 +0000567
Matthias Weisserb038db82011-05-22 23:03:55 +0000568 if (src == dest)
569 return dest;
570
Alessandro Rubiniecd830b2009-10-10 11:51:05 +0200571 /* while all data is aligned (common case), copy a word at a time */
572 if ( (((ulong)dest | (ulong)src) & (sizeof(*dl) - 1)) == 0) {
573 while (count >= sizeof(*dl)) {
574 *dl++ = *sl++;
575 count -= sizeof(*dl);
576 }
577 }
578 /* copy the reset one byte at a time */
579 d8 = (char *)dl;
580 s8 = (char *)sl;
wdenkc6097192002-11-03 00:24:07 +0000581 while (count--)
Alessandro Rubiniecd830b2009-10-10 11:51:05 +0200582 *d8++ = *s8++;
wdenkc6097192002-11-03 00:24:07 +0000583
584 return dest;
585}
586#endif
587
588#ifndef __HAVE_ARCH_MEMMOVE
589/**
590 * memmove - Copy one area of memory to another
591 * @dest: Where to copy to
592 * @src: Where to copy from
593 * @count: The size of the area.
594 *
595 * Unlike memcpy(), memmove() copes with overlapping areas.
596 */
Marek BehĂșn46c3e292021-05-20 13:23:55 +0200597__used void * memmove(void * dest,const void *src,size_t count)
wdenkc6097192002-11-03 00:24:07 +0000598{
599 char *tmp, *s;
600
Patrick Delaunay976a68a2020-12-11 14:59:23 +0100601 if (dest <= src || (src + count) <= dest) {
602 /*
603 * Use the fast memcpy implementation (ARCH optimized or lib/string.c) when it is possible:
604 * - when dest is before src (assuming that memcpy is doing forward-copying)
605 * - when destination don't overlap the source buffer (src + count <= dest)
606 *
607 * WARNING: the first optimisation cause an issue, when __HAVE_ARCH_MEMCPY is defined,
608 * __HAVE_ARCH_MEMMOVE is not defined and if the memcpy ARCH-specific
609 * implementation is not doing a forward-copying.
610 *
611 * No issue today because memcpy is doing a forward-copying in lib/string.c and for ARM32
612 * architecture; no other arches use __HAVE_ARCH_MEMCPY without __HAVE_ARCH_MEMMOVE.
613 */
Simon Glasscb0eae82017-04-05 16:23:31 -0600614 memcpy(dest, src, count);
615 } else {
wdenkc6097192002-11-03 00:24:07 +0000616 tmp = (char *) dest + count;
617 s = (char *) src + count;
618 while (count--)
619 *--tmp = *--s;
620 }
621
622 return dest;
623}
624#endif
625
626#ifndef __HAVE_ARCH_MEMCMP
627/**
628 * memcmp - Compare two areas of memory
629 * @cs: One area of memory
630 * @ct: Another area of memory
631 * @count: The size of the area.
632 */
Marek BehĂșn46c3e292021-05-20 13:23:55 +0200633__used int memcmp(const void * cs,const void * ct,size_t count)
wdenkc6097192002-11-03 00:24:07 +0000634{
635 const unsigned char *su1, *su2;
636 int res = 0;
637
638 for( su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--)
639 if ((res = *su1 - *su2) != 0)
640 break;
641 return res;
642}
643#endif
644
645#ifndef __HAVE_ARCH_MEMSCAN
646/**
647 * memscan - Find a character in an area of memory.
648 * @addr: The memory area
649 * @c: The byte to search for
650 * @size: The size of the area.
651 *
652 * returns the address of the first occurrence of @c, or 1 byte past
653 * the area if @c is not found
654 */
655void * memscan(void * addr, int c, size_t size)
656{
657 unsigned char * p = (unsigned char *) addr;
658
659 while (size) {
660 if (*p == c)
661 return (void *) p;
662 p++;
663 size--;
664 }
wdenk8bde7f72003-06-27 21:31:46 +0000665 return (void *) p;
wdenkc6097192002-11-03 00:24:07 +0000666}
667#endif
668
Simon Glass930c8872021-09-25 07:03:06 -0600669char *memdup(const void *src, size_t len)
670{
671 char *p;
672
673 p = malloc(len);
674 if (!p)
675 return NULL;
676
677 memcpy(p, src, len);
678
679 return p;
680}
681
wdenkc6097192002-11-03 00:24:07 +0000682#ifndef __HAVE_ARCH_STRSTR
683/**
684 * strstr - Find the first substring in a %NUL terminated string
685 * @s1: The string to be searched
686 * @s2: The string to search for
687 */
688char * strstr(const char * s1,const char * s2)
689{
690 int l1, l2;
691
692 l2 = strlen(s2);
693 if (!l2)
694 return (char *) s1;
695 l1 = strlen(s1);
696 while (l1 >= l2) {
697 l1--;
698 if (!memcmp(s1,s2,l2))
699 return (char *) s1;
700 s1++;
701 }
702 return NULL;
703}
704#endif
705
706#ifndef __HAVE_ARCH_MEMCHR
707/**
708 * memchr - Find a character in an area of memory.
709 * @s: The memory area
710 * @c: The byte to search for
711 * @n: The size of the area.
712 *
713 * returns the address of the first occurrence of @c, or %NULL
714 * if @c is not found
715 */
716void *memchr(const void *s, int c, size_t n)
717{
718 const unsigned char *p = s;
719 while (n-- != 0) {
wdenk8bde7f72003-06-27 21:31:46 +0000720 if ((unsigned char)c == *p++) {
wdenkc6097192002-11-03 00:24:07 +0000721 return (void *)(p-1);
722 }
723 }
724 return NULL;
725}
726
727#endif
Sergey Lapindfe64e22013-01-14 03:46:50 +0000728#ifndef __HAVE_ARCH_MEMCHR_INV
729static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes)
730{
731 while (bytes) {
732 if (*start != value)
733 return (void *)start;
734 start++;
735 bytes--;
736 }
737 return NULL;
738}
739/**
740 * memchr_inv - Find an unmatching character in an area of memory.
741 * @start: The memory area
742 * @c: Find a character other than c
743 * @bytes: The size of the area.
744 *
745 * returns the address of the first character other than @c, or %NULL
746 * if the whole buffer contains just @c.
747 */
748void *memchr_inv(const void *start, int c, size_t bytes)
749{
750 u8 value = c;
751 u64 value64;
752 unsigned int words, prefix;
753
754 if (bytes <= 16)
755 return check_bytes8(start, value, bytes);
756
757 value64 = value;
758 value64 |= value64 << 8;
759 value64 |= value64 << 16;
760 value64 |= value64 << 32;
761
762 prefix = (unsigned long)start % 8;
763 if (prefix) {
764 u8 *r;
765
766 prefix = 8 - prefix;
767 r = check_bytes8(start, value, prefix);
768 if (r)
769 return r;
770 start += prefix;
771 bytes -= prefix;
772 }
773
774 words = bytes / 8;
775
776 while (words) {
777 if (*(u64 *)start != value64)
778 return check_bytes8(start, value, 8);
779 start += 8;
780 words--;
781 }
782
783 return check_bytes8(start, value, bytes % 8);
784}
785#endif