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Source at commit 2604e7f9a98c27be50a0c3ff7503b6a5ea8f6cfe created 12 years 7 months ago. By Maarten ter Huurne, cpufreq_stats: Support runtime changes to frequency table | |
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1 | /* |
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 | * * Sat Feb 09 2002, Jason Thomas <jason@topic.com.au>, |
18 | * Matthew Hawkins <matt@mh.dropbear.id.au> |
19 | * - Kissed strtok() goodbye |
20 | */ |
21 | |
22 | #include <linux/types.h> |
23 | #include <linux/string.h> |
24 | #include <linux/ctype.h> |
25 | #include <linux/kernel.h> |
26 | #include <linux/export.h> |
27 | #include <linux/bug.h> |
28 | #include <linux/errno.h> |
29 | |
30 | #ifndef __HAVE_ARCH_STRNICMP |
31 | /** |
32 | * strnicmp - Case insensitive, length-limited string comparison |
33 | * @s1: One string |
34 | * @s2: The other string |
35 | * @len: the maximum number of characters to compare |
36 | */ |
37 | int strnicmp(const char *s1, const char *s2, size_t len) |
38 | { |
39 | /* Yes, Virginia, it had better be unsigned */ |
40 | unsigned char c1, c2; |
41 | |
42 | if (!len) |
43 | return 0; |
44 | |
45 | do { |
46 | c1 = *s1++; |
47 | c2 = *s2++; |
48 | if (!c1 || !c2) |
49 | break; |
50 | if (c1 == c2) |
51 | continue; |
52 | c1 = tolower(c1); |
53 | c2 = tolower(c2); |
54 | if (c1 != c2) |
55 | break; |
56 | } while (--len); |
57 | return (int)c1 - (int)c2; |
58 | } |
59 | EXPORT_SYMBOL(strnicmp); |
60 | #endif |
61 | |
62 | #ifndef __HAVE_ARCH_STRCASECMP |
63 | int strcasecmp(const char *s1, const char *s2) |
64 | { |
65 | int c1, c2; |
66 | |
67 | do { |
68 | c1 = tolower(*s1++); |
69 | c2 = tolower(*s2++); |
70 | } while (c1 == c2 && c1 != 0); |
71 | return c1 - c2; |
72 | } |
73 | EXPORT_SYMBOL(strcasecmp); |
74 | #endif |
75 | |
76 | #ifndef __HAVE_ARCH_STRNCASECMP |
77 | int strncasecmp(const char *s1, const char *s2, size_t n) |
78 | { |
79 | int c1, c2; |
80 | |
81 | do { |
82 | c1 = tolower(*s1++); |
83 | c2 = tolower(*s2++); |
84 | } while ((--n > 0) && c1 == c2 && c1 != 0); |
85 | return c1 - c2; |
86 | } |
87 | EXPORT_SYMBOL(strncasecmp); |
88 | #endif |
89 | |
90 | #ifndef __HAVE_ARCH_STRCPY |
91 | /** |
92 | * strcpy - Copy a %NUL terminated string |
93 | * @dest: Where to copy the string to |
94 | * @src: Where to copy the string from |
95 | */ |
96 | #undef strcpy |
97 | char *strcpy(char *dest, const char *src) |
98 | { |
99 | char *tmp = dest; |
100 | |
101 | while ((*dest++ = *src++) != '\0') |
102 | /* nothing */; |
103 | return tmp; |
104 | } |
105 | EXPORT_SYMBOL(strcpy); |
106 | #endif |
107 | |
108 | #ifndef __HAVE_ARCH_STRNCPY |
109 | /** |
110 | * strncpy - Copy a length-limited, %NUL-terminated string |
111 | * @dest: Where to copy the string to |
112 | * @src: Where to copy the string from |
113 | * @count: The maximum number of bytes to copy |
114 | * |
115 | * The result is not %NUL-terminated if the source exceeds |
116 | * @count bytes. |
117 | * |
118 | * In the case where the length of @src is less than that of |
119 | * count, the remainder of @dest will be padded with %NUL. |
120 | * |
121 | */ |
122 | char *strncpy(char *dest, const char *src, size_t count) |
123 | { |
124 | char *tmp = dest; |
125 | |
126 | while (count) { |
127 | if ((*tmp = *src) != 0) |
128 | src++; |
129 | tmp++; |
130 | count--; |
131 | } |
132 | return dest; |
133 | } |
134 | EXPORT_SYMBOL(strncpy); |
135 | #endif |
136 | |
137 | #ifndef __HAVE_ARCH_STRLCPY |
138 | /** |
139 | * strlcpy - Copy a %NUL terminated string into a sized buffer |
140 | * @dest: Where to copy the string to |
141 | * @src: Where to copy the string from |
142 | * @size: size of destination buffer |
143 | * |
144 | * Compatible with *BSD: the result is always a valid |
145 | * NUL-terminated string that fits in the buffer (unless, |
146 | * of course, the buffer size is zero). It does not pad |
147 | * out the result like strncpy() does. |
148 | */ |
149 | size_t strlcpy(char *dest, const char *src, size_t size) |
150 | { |
151 | size_t ret = strlen(src); |
152 | |
153 | if (size) { |
154 | size_t len = (ret >= size) ? size - 1 : ret; |
155 | memcpy(dest, src, len); |
156 | dest[len] = '\0'; |
157 | } |
158 | return ret; |
159 | } |
160 | EXPORT_SYMBOL(strlcpy); |
161 | #endif |
162 | |
163 | #ifndef __HAVE_ARCH_STRCAT |
164 | /** |
165 | * strcat - Append one %NUL-terminated string to another |
166 | * @dest: The string to be appended to |
167 | * @src: The string to append to it |
168 | */ |
169 | #undef strcat |
170 | char *strcat(char *dest, const char *src) |
171 | { |
172 | char *tmp = dest; |
173 | |
174 | while (*dest) |
175 | dest++; |
176 | while ((*dest++ = *src++) != '\0') |
177 | ; |
178 | return tmp; |
179 | } |
180 | EXPORT_SYMBOL(strcat); |
181 | #endif |
182 | |
183 | #ifndef __HAVE_ARCH_STRNCAT |
184 | /** |
185 | * strncat - Append a length-limited, %NUL-terminated string to another |
186 | * @dest: The string to be appended to |
187 | * @src: The string to append to it |
188 | * @count: The maximum numbers of bytes to copy |
189 | * |
190 | * Note that in contrast to strncpy(), strncat() ensures the result is |
191 | * terminated. |
192 | */ |
193 | char *strncat(char *dest, const char *src, size_t count) |
194 | { |
195 | char *tmp = dest; |
196 | |
197 | if (count) { |
198 | while (*dest) |
199 | dest++; |
200 | while ((*dest++ = *src++) != 0) { |
201 | if (--count == 0) { |
202 | *dest = '\0'; |
203 | break; |
204 | } |
205 | } |
206 | } |
207 | return tmp; |
208 | } |
209 | EXPORT_SYMBOL(strncat); |
210 | #endif |
211 | |
212 | #ifndef __HAVE_ARCH_STRLCAT |
213 | /** |
214 | * strlcat - Append a length-limited, %NUL-terminated string to another |
215 | * @dest: The string to be appended to |
216 | * @src: The string to append to it |
217 | * @count: The size of the destination buffer. |
218 | */ |
219 | size_t strlcat(char *dest, const char *src, size_t count) |
220 | { |
221 | size_t dsize = strlen(dest); |
222 | size_t len = strlen(src); |
223 | size_t res = dsize + len; |
224 | |
225 | /* This would be a bug */ |
226 | BUG_ON(dsize >= count); |
227 | |
228 | dest += dsize; |
229 | count -= dsize; |
230 | if (len >= count) |
231 | len = count-1; |
232 | memcpy(dest, src, len); |
233 | dest[len] = 0; |
234 | return res; |
235 | } |
236 | EXPORT_SYMBOL(strlcat); |
237 | #endif |
238 | |
239 | #ifndef __HAVE_ARCH_STRCMP |
240 | /** |
241 | * strcmp - Compare two strings |
242 | * @cs: One string |
243 | * @ct: Another string |
244 | */ |
245 | #undef strcmp |
246 | int strcmp(const char *cs, const char *ct) |
247 | { |
248 | unsigned char c1, c2; |
249 | |
250 | while (1) { |
251 | c1 = *cs++; |
252 | c2 = *ct++; |
253 | if (c1 != c2) |
254 | return c1 < c2 ? -1 : 1; |
255 | if (!c1) |
256 | break; |
257 | } |
258 | return 0; |
259 | } |
260 | EXPORT_SYMBOL(strcmp); |
261 | #endif |
262 | |
263 | #ifndef __HAVE_ARCH_STRNCMP |
264 | /** |
265 | * strncmp - Compare two length-limited strings |
266 | * @cs: One string |
267 | * @ct: Another string |
268 | * @count: The maximum number of bytes to compare |
269 | */ |
270 | int strncmp(const char *cs, const char *ct, size_t count) |
271 | { |
272 | unsigned char c1, c2; |
273 | |
274 | while (count) { |
275 | c1 = *cs++; |
276 | c2 = *ct++; |
277 | if (c1 != c2) |
278 | return c1 < c2 ? -1 : 1; |
279 | if (!c1) |
280 | break; |
281 | count--; |
282 | } |
283 | return 0; |
284 | } |
285 | EXPORT_SYMBOL(strncmp); |
286 | #endif |
287 | |
288 | #ifndef __HAVE_ARCH_STRCHR |
289 | /** |
290 | * strchr - Find the first occurrence of a character in a string |
291 | * @s: The string to be searched |
292 | * @c: The character to search for |
293 | */ |
294 | char *strchr(const char *s, int c) |
295 | { |
296 | for (; *s != (char)c; ++s) |
297 | if (*s == '\0') |
298 | return NULL; |
299 | return (char *)s; |
300 | } |
301 | EXPORT_SYMBOL(strchr); |
302 | #endif |
303 | |
304 | #ifndef __HAVE_ARCH_STRRCHR |
305 | /** |
306 | * strrchr - Find the last occurrence of a character in a string |
307 | * @s: The string to be searched |
308 | * @c: The character to search for |
309 | */ |
310 | char *strrchr(const char *s, int c) |
311 | { |
312 | const char *p = s + strlen(s); |
313 | do { |
314 | if (*p == (char)c) |
315 | return (char *)p; |
316 | } while (--p >= s); |
317 | return NULL; |
318 | } |
319 | EXPORT_SYMBOL(strrchr); |
320 | #endif |
321 | |
322 | #ifndef __HAVE_ARCH_STRNCHR |
323 | /** |
324 | * strnchr - Find a character in a length limited string |
325 | * @s: The string to be searched |
326 | * @count: The number of characters to be searched |
327 | * @c: The character to search for |
328 | */ |
329 | char *strnchr(const char *s, size_t count, int c) |
330 | { |
331 | for (; count-- && *s != '\0'; ++s) |
332 | if (*s == (char)c) |
333 | return (char *)s; |
334 | return NULL; |
335 | } |
336 | EXPORT_SYMBOL(strnchr); |
337 | #endif |
338 | |
339 | /** |
340 | * skip_spaces - Removes leading whitespace from @str. |
341 | * @str: The string to be stripped. |
342 | * |
343 | * Returns a pointer to the first non-whitespace character in @str. |
344 | */ |
345 | char *skip_spaces(const char *str) |
346 | { |
347 | while (isspace(*str)) |
348 | ++str; |
349 | return (char *)str; |
350 | } |
351 | EXPORT_SYMBOL(skip_spaces); |
352 | |
353 | /** |
354 | * strim - Removes leading and trailing whitespace from @s. |
355 | * @s: The string to be stripped. |
356 | * |
357 | * Note that the first trailing whitespace is replaced with a %NUL-terminator |
358 | * in the given string @s. Returns a pointer to the first non-whitespace |
359 | * character in @s. |
360 | */ |
361 | char *strim(char *s) |
362 | { |
363 | size_t size; |
364 | char *end; |
365 | |
366 | size = strlen(s); |
367 | if (!size) |
368 | return s; |
369 | |
370 | end = s + size - 1; |
371 | while (end >= s && isspace(*end)) |
372 | end--; |
373 | *(end + 1) = '\0'; |
374 | |
375 | return skip_spaces(s); |
376 | } |
377 | EXPORT_SYMBOL(strim); |
378 | |
379 | #ifndef __HAVE_ARCH_STRLEN |
380 | /** |
381 | * strlen - Find the length of a string |
382 | * @s: The string to be sized |
383 | */ |
384 | size_t strlen(const char *s) |
385 | { |
386 | const char *sc; |
387 | |
388 | for (sc = s; *sc != '\0'; ++sc) |
389 | /* nothing */; |
390 | return sc - s; |
391 | } |
392 | EXPORT_SYMBOL(strlen); |
393 | #endif |
394 | |
395 | #ifndef __HAVE_ARCH_STRNLEN |
396 | /** |
397 | * strnlen - Find the length of a length-limited string |
398 | * @s: The string to be sized |
399 | * @count: The maximum number of bytes to search |
400 | */ |
401 | size_t strnlen(const char *s, size_t count) |
402 | { |
403 | const char *sc; |
404 | |
405 | for (sc = s; count-- && *sc != '\0'; ++sc) |
406 | /* nothing */; |
407 | return sc - s; |
408 | } |
409 | EXPORT_SYMBOL(strnlen); |
410 | #endif |
411 | |
412 | #ifndef __HAVE_ARCH_STRSPN |
413 | /** |
414 | * strspn - Calculate the length of the initial substring of @s which only contain letters in @accept |
415 | * @s: The string to be searched |
416 | * @accept: The string to search for |
417 | */ |
418 | size_t strspn(const char *s, const char *accept) |
419 | { |
420 | const char *p; |
421 | const char *a; |
422 | size_t count = 0; |
423 | |
424 | for (p = s; *p != '\0'; ++p) { |
425 | for (a = accept; *a != '\0'; ++a) { |
426 | if (*p == *a) |
427 | break; |
428 | } |
429 | if (*a == '\0') |
430 | return count; |
431 | ++count; |
432 | } |
433 | return count; |
434 | } |
435 | |
436 | EXPORT_SYMBOL(strspn); |
437 | #endif |
438 | |
439 | #ifndef __HAVE_ARCH_STRCSPN |
440 | /** |
441 | * strcspn - Calculate the length of the initial substring of @s which does not contain letters in @reject |
442 | * @s: The string to be searched |
443 | * @reject: The string to avoid |
444 | */ |
445 | size_t strcspn(const char *s, const char *reject) |
446 | { |
447 | const char *p; |
448 | const char *r; |
449 | size_t count = 0; |
450 | |
451 | for (p = s; *p != '\0'; ++p) { |
452 | for (r = reject; *r != '\0'; ++r) { |
453 | if (*p == *r) |
454 | return count; |
455 | } |
456 | ++count; |
457 | } |
458 | return count; |
459 | } |
460 | EXPORT_SYMBOL(strcspn); |
461 | #endif |
462 | |
463 | #ifndef __HAVE_ARCH_STRPBRK |
464 | /** |
465 | * strpbrk - Find the first occurrence of a set of characters |
466 | * @cs: The string to be searched |
467 | * @ct: The characters to search for |
468 | */ |
469 | char *strpbrk(const char *cs, const char *ct) |
470 | { |
471 | const char *sc1, *sc2; |
472 | |
473 | for (sc1 = cs; *sc1 != '\0'; ++sc1) { |
474 | for (sc2 = ct; *sc2 != '\0'; ++sc2) { |
475 | if (*sc1 == *sc2) |
476 | return (char *)sc1; |
477 | } |
478 | } |
479 | return NULL; |
480 | } |
481 | EXPORT_SYMBOL(strpbrk); |
482 | #endif |
483 | |
484 | #ifndef __HAVE_ARCH_STRSEP |
485 | /** |
486 | * strsep - Split a string into tokens |
487 | * @s: The string to be searched |
488 | * @ct: The characters to search for |
489 | * |
490 | * strsep() updates @s to point after the token, ready for the next call. |
491 | * |
492 | * It returns empty tokens, too, behaving exactly like the libc function |
493 | * of that name. In fact, it was stolen from glibc2 and de-fancy-fied. |
494 | * Same semantics, slimmer shape. ;) |
495 | */ |
496 | char *strsep(char **s, const char *ct) |
497 | { |
498 | char *sbegin = *s; |
499 | char *end; |
500 | |
501 | if (sbegin == NULL) |
502 | return NULL; |
503 | |
504 | end = strpbrk(sbegin, ct); |
505 | if (end) |
506 | *end++ = '\0'; |
507 | *s = end; |
508 | return sbegin; |
509 | } |
510 | EXPORT_SYMBOL(strsep); |
511 | #endif |
512 | |
513 | /** |
514 | * sysfs_streq - return true if strings are equal, modulo trailing newline |
515 | * @s1: one string |
516 | * @s2: another string |
517 | * |
518 | * This routine returns true iff two strings are equal, treating both |
519 | * NUL and newline-then-NUL as equivalent string terminations. It's |
520 | * geared for use with sysfs input strings, which generally terminate |
521 | * with newlines but are compared against values without newlines. |
522 | */ |
523 | bool sysfs_streq(const char *s1, const char *s2) |
524 | { |
525 | while (*s1 && *s1 == *s2) { |
526 | s1++; |
527 | s2++; |
528 | } |
529 | |
530 | if (*s1 == *s2) |
531 | return true; |
532 | if (!*s1 && *s2 == '\n' && !s2[1]) |
533 | return true; |
534 | if (*s1 == '\n' && !s1[1] && !*s2) |
535 | return true; |
536 | return false; |
537 | } |
538 | EXPORT_SYMBOL(sysfs_streq); |
539 | |
540 | /** |
541 | * strtobool - convert common user inputs into boolean values |
542 | * @s: input string |
543 | * @res: result |
544 | * |
545 | * This routine returns 0 iff the first character is one of 'Yy1Nn0'. |
546 | * Otherwise it will return -EINVAL. Value pointed to by res is |
547 | * updated upon finding a match. |
548 | */ |
549 | int strtobool(const char *s, bool *res) |
550 | { |
551 | switch (s[0]) { |
552 | case 'y': |
553 | case 'Y': |
554 | case '1': |
555 | *res = true; |
556 | break; |
557 | case 'n': |
558 | case 'N': |
559 | case '0': |
560 | *res = false; |
561 | break; |
562 | default: |
563 | return -EINVAL; |
564 | } |
565 | return 0; |
566 | } |
567 | EXPORT_SYMBOL(strtobool); |
568 | |
569 | #ifndef __HAVE_ARCH_MEMSET |
570 | /** |
571 | * memset - Fill a region of memory with the given value |
572 | * @s: Pointer to the start of the area. |
573 | * @c: The byte to fill the area with |
574 | * @count: The size of the area. |
575 | * |
576 | * Do not use memset() to access IO space, use memset_io() instead. |
577 | */ |
578 | void *memset(void *s, int c, size_t count) |
579 | { |
580 | char *xs = s; |
581 | |
582 | while (count--) |
583 | *xs++ = c; |
584 | return s; |
585 | } |
586 | EXPORT_SYMBOL(memset); |
587 | #endif |
588 | |
589 | #ifndef __HAVE_ARCH_MEMCPY |
590 | /** |
591 | * memcpy - Copy one area of memory to another |
592 | * @dest: Where to copy to |
593 | * @src: Where to copy from |
594 | * @count: The size of the area. |
595 | * |
596 | * You should not use this function to access IO space, use memcpy_toio() |
597 | * or memcpy_fromio() instead. |
598 | */ |
599 | void *memcpy(void *dest, const void *src, size_t count) |
600 | { |
601 | char *tmp = dest; |
602 | const char *s = src; |
603 | |
604 | while (count--) |
605 | *tmp++ = *s++; |
606 | return dest; |
607 | } |
608 | EXPORT_SYMBOL(memcpy); |
609 | #endif |
610 | |
611 | #ifndef __HAVE_ARCH_MEMMOVE |
612 | /** |
613 | * memmove - Copy one area of memory to another |
614 | * @dest: Where to copy to |
615 | * @src: Where to copy from |
616 | * @count: The size of the area. |
617 | * |
618 | * Unlike memcpy(), memmove() copes with overlapping areas. |
619 | */ |
620 | void *memmove(void *dest, const void *src, size_t count) |
621 | { |
622 | char *tmp; |
623 | const char *s; |
624 | |
625 | if (dest <= src) { |
626 | tmp = dest; |
627 | s = src; |
628 | while (count--) |
629 | *tmp++ = *s++; |
630 | } else { |
631 | tmp = dest; |
632 | tmp += count; |
633 | s = src; |
634 | s += count; |
635 | while (count--) |
636 | *--tmp = *--s; |
637 | } |
638 | return dest; |
639 | } |
640 | EXPORT_SYMBOL(memmove); |
641 | #endif |
642 | |
643 | #ifndef __HAVE_ARCH_MEMCMP |
644 | /** |
645 | * memcmp - Compare two areas of memory |
646 | * @cs: One area of memory |
647 | * @ct: Another area of memory |
648 | * @count: The size of the area. |
649 | */ |
650 | #undef memcmp |
651 | int memcmp(const void *cs, const void *ct, size_t count) |
652 | { |
653 | const unsigned char *su1, *su2; |
654 | int res = 0; |
655 | |
656 | for (su1 = cs, su2 = ct; 0 < count; ++su1, ++su2, count--) |
657 | if ((res = *su1 - *su2) != 0) |
658 | break; |
659 | return res; |
660 | } |
661 | EXPORT_SYMBOL(memcmp); |
662 | #endif |
663 | |
664 | #ifndef __HAVE_ARCH_MEMSCAN |
665 | /** |
666 | * memscan - Find a character in an area of memory. |
667 | * @addr: The memory area |
668 | * @c: The byte to search for |
669 | * @size: The size of the area. |
670 | * |
671 | * returns the address of the first occurrence of @c, or 1 byte past |
672 | * the area if @c is not found |
673 | */ |
674 | void *memscan(void *addr, int c, size_t size) |
675 | { |
676 | unsigned char *p = addr; |
677 | |
678 | while (size) { |
679 | if (*p == c) |
680 | return (void *)p; |
681 | p++; |
682 | size--; |
683 | } |
684 | return (void *)p; |
685 | } |
686 | EXPORT_SYMBOL(memscan); |
687 | #endif |
688 | |
689 | #ifndef __HAVE_ARCH_STRSTR |
690 | /** |
691 | * strstr - Find the first substring in a %NUL terminated string |
692 | * @s1: The string to be searched |
693 | * @s2: The string to search for |
694 | */ |
695 | char *strstr(const char *s1, const char *s2) |
696 | { |
697 | size_t l1, l2; |
698 | |
699 | l2 = strlen(s2); |
700 | if (!l2) |
701 | return (char *)s1; |
702 | l1 = strlen(s1); |
703 | while (l1 >= l2) { |
704 | l1--; |
705 | if (!memcmp(s1, s2, l2)) |
706 | return (char *)s1; |
707 | s1++; |
708 | } |
709 | return NULL; |
710 | } |
711 | EXPORT_SYMBOL(strstr); |
712 | #endif |
713 | |
714 | #ifndef __HAVE_ARCH_STRNSTR |
715 | /** |
716 | * strnstr - Find the first substring in a length-limited string |
717 | * @s1: The string to be searched |
718 | * @s2: The string to search for |
719 | * @len: the maximum number of characters to search |
720 | */ |
721 | char *strnstr(const char *s1, const char *s2, size_t len) |
722 | { |
723 | size_t l2; |
724 | |
725 | l2 = strlen(s2); |
726 | if (!l2) |
727 | return (char *)s1; |
728 | while (len >= l2) { |
729 | len--; |
730 | if (!memcmp(s1, s2, l2)) |
731 | return (char *)s1; |
732 | s1++; |
733 | } |
734 | return NULL; |
735 | } |
736 | EXPORT_SYMBOL(strnstr); |
737 | #endif |
738 | |
739 | #ifndef __HAVE_ARCH_MEMCHR |
740 | /** |
741 | * memchr - Find a character in an area of memory. |
742 | * @s: The memory area |
743 | * @c: The byte to search for |
744 | * @n: The size of the area. |
745 | * |
746 | * returns the address of the first occurrence of @c, or %NULL |
747 | * if @c is not found |
748 | */ |
749 | void *memchr(const void *s, int c, size_t n) |
750 | { |
751 | const unsigned char *p = s; |
752 | while (n-- != 0) { |
753 | if ((unsigned char)c == *p++) { |
754 | return (void *)(p - 1); |
755 | } |
756 | } |
757 | return NULL; |
758 | } |
759 | EXPORT_SYMBOL(memchr); |
760 | #endif |
761 | |
762 | static void *check_bytes8(const u8 *start, u8 value, unsigned int bytes) |
763 | { |
764 | while (bytes) { |
765 | if (*start != value) |
766 | return (void *)start; |
767 | start++; |
768 | bytes--; |
769 | } |
770 | return NULL; |
771 | } |
772 | |
773 | /** |
774 | * memchr_inv - Find an unmatching character in an area of memory. |
775 | * @start: The memory area |
776 | * @c: Find a character other than c |
777 | * @bytes: The size of the area. |
778 | * |
779 | * returns the address of the first character other than @c, or %NULL |
780 | * if the whole buffer contains just @c. |
781 | */ |
782 | void *memchr_inv(const void *start, int c, size_t bytes) |
783 | { |
784 | u8 value = c; |
785 | u64 value64; |
786 | unsigned int words, prefix; |
787 | |
788 | if (bytes <= 16) |
789 | return check_bytes8(start, value, bytes); |
790 | |
791 | value64 = value; |
792 | #if defined(ARCH_HAS_FAST_MULTIPLIER) && BITS_PER_LONG == 64 |
793 | value64 *= 0x0101010101010101; |
794 | #elif defined(ARCH_HAS_FAST_MULTIPLIER) |
795 | value64 *= 0x01010101; |
796 | value64 |= value64 << 32; |
797 | #else |
798 | value64 |= value64 << 8; |
799 | value64 |= value64 << 16; |
800 | value64 |= value64 << 32; |
801 | #endif |
802 | |
803 | prefix = (unsigned long)start % 8; |
804 | if (prefix) { |
805 | u8 *r; |
806 | |
807 | prefix = 8 - prefix; |
808 | r = check_bytes8(start, value, prefix); |
809 | if (r) |
810 | return r; |
811 | start += prefix; |
812 | bytes -= prefix; |
813 | } |
814 | |
815 | words = bytes / 8; |
816 | |
817 | while (words) { |
818 | if (*(u64 *)start != value64) |
819 | return check_bytes8(start, value, 8); |
820 | start += 8; |
821 | words--; |
822 | } |
823 | |
824 | return check_bytes8(start, value, bytes % 8); |
825 | } |
826 | EXPORT_SYMBOL(memchr_inv); |
827 |
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v2.6.34-rc5
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