1 /*
2 * arch/s390/lib/string.c
3 * Optimized string functions
4 *
5 * S390 version
6 * Copyright (C) 2004 IBM Deutschland Entwicklung GmbH, IBM Corporation
7 * Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
8 */
9
10 #define IN_ARCH_STRING_C 1
11
12 #include <linux/types.h>
13 #include <linux/module.h>
14
15 /*
16 * Helper functions to find the end of a string
17 */
__strend(const char * s)18 static inline char *__strend(const char *s)
19 {
20 register unsigned long r0 asm("0") = 0;
21
22 asm volatile ("0: srst %0,%1\n"
23 " jo 0b"
24 : "+d" (r0), "+a" (s) : : "cc" );
25 return (char *) r0;
26 }
27
__strnend(const char * s,size_t n)28 static inline char *__strnend(const char *s, size_t n)
29 {
30 register unsigned long r0 asm("0") = 0;
31 const char *p = s + n;
32
33 asm volatile ("0: srst %0,%1\n"
34 " jo 0b"
35 : "+d" (p), "+a" (s) : "d" (r0) : "cc" );
36 return (char *) p;
37 }
38
39 /**
40 * strlen - Find the length of a string
41 * @s: The string to be sized
42 *
43 * returns the length of @s
44 */
strlen(const char * s)45 size_t strlen(const char *s)
46 {
47 return __strend(s) - s;
48 }
49 EXPORT_SYMBOL(strlen);
50
51 /**
52 * strnlen - Find the length of a length-limited string
53 * @s: The string to be sized
54 * @n: The maximum number of bytes to search
55 *
56 * returns the minimum of the length of @s and @n
57 */
strnlen(const char * s,size_t n)58 size_t strnlen(const char * s, size_t n)
59 {
60 return __strnend(s, n) - s;
61 }
62 EXPORT_SYMBOL(strnlen);
63
64 /**
65 * strcpy - Copy a %NUL terminated string
66 * @dest: Where to copy the string to
67 * @src: Where to copy the string from
68 *
69 * returns a pointer to @dest
70 */
strcpy(char * dest,const char * src)71 char *strcpy(char *dest, const char *src)
72 {
73 register int r0 asm("0") = 0;
74 char *ret = dest;
75
76 asm volatile ("0: mvst %0,%1\n"
77 " jo 0b"
78 : "+&a" (dest), "+&a" (src) : "d" (r0)
79 : "cc", "memory" );
80 return ret;
81 }
82 EXPORT_SYMBOL(strcpy);
83
84 /**
85 * strlcpy - Copy a %NUL terminated string into a sized buffer
86 * @dest: Where to copy the string to
87 * @src: Where to copy the string from
88 * @size: size of destination buffer
89 *
90 * Compatible with *BSD: the result is always a valid
91 * NUL-terminated string that fits in the buffer (unless,
92 * of course, the buffer size is zero). It does not pad
93 * out the result like strncpy() does.
94 */
strlcpy(char * dest,const char * src,size_t size)95 size_t strlcpy(char *dest, const char *src, size_t size)
96 {
97 size_t ret = __strend(src) - src;
98
99 if (size) {
100 size_t len = (ret >= size) ? size-1 : ret;
101 dest[len] = '\0';
102 __builtin_memcpy(dest, src, len);
103 }
104 return ret;
105 }
106 EXPORT_SYMBOL(strlcpy);
107
108 /**
109 * strncpy - Copy a length-limited, %NUL-terminated string
110 * @dest: Where to copy the string to
111 * @src: Where to copy the string from
112 * @n: The maximum number of bytes to copy
113 *
114 * The result is not %NUL-terminated if the source exceeds
115 * @n bytes.
116 */
strncpy(char * dest,const char * src,size_t n)117 char *strncpy(char *dest, const char *src, size_t n)
118 {
119 size_t len = __strnend(src, n) - src;
120 __builtin_memset(dest + len, 0, n - len);
121 __builtin_memcpy(dest, src, len);
122 return dest;
123 }
124 EXPORT_SYMBOL(strncpy);
125
126 /**
127 * strcat - Append one %NUL-terminated string to another
128 * @dest: The string to be appended to
129 * @src: The string to append to it
130 *
131 * returns a pointer to @dest
132 */
strcat(char * dest,const char * src)133 char *strcat(char *dest, const char *src)
134 {
135 register int r0 asm("0") = 0;
136 unsigned long dummy;
137 char *ret = dest;
138
139 asm volatile ("0: srst %0,%1\n"
140 " jo 0b\n"
141 "1: mvst %0,%2\n"
142 " jo 1b"
143 : "=&a" (dummy), "+a" (dest), "+a" (src)
144 : "d" (r0), "0" (0UL) : "cc", "memory" );
145 return ret;
146 }
147 EXPORT_SYMBOL(strcat);
148
149 /**
150 * strlcat - Append a length-limited, %NUL-terminated string to another
151 * @dest: The string to be appended to
152 * @src: The string to append to it
153 * @n: The size of the destination buffer.
154 */
strlcat(char * dest,const char * src,size_t n)155 size_t strlcat(char *dest, const char *src, size_t n)
156 {
157 size_t dsize = __strend(dest) - dest;
158 size_t len = __strend(src) - src;
159 size_t res = dsize + len;
160
161 if (dsize < n) {
162 dest += dsize;
163 n -= dsize;
164 if (len >= n)
165 len = n - 1;
166 dest[len] = '\0';
167 __builtin_memcpy(dest, src, len);
168 }
169 return res;
170 }
171 EXPORT_SYMBOL(strlcat);
172
173 /**
174 * strncat - Append a length-limited, %NUL-terminated string to another
175 * @dest: The string to be appended to
176 * @src: The string to append to it
177 * @n: The maximum numbers of bytes to copy
178 *
179 * returns a pointer to @dest
180 *
181 * Note that in contrast to strncpy, strncat ensures the result is
182 * terminated.
183 */
strncat(char * dest,const char * src,size_t n)184 char *strncat(char *dest, const char *src, size_t n)
185 {
186 size_t len = __strnend(src, n) - src;
187 char *p = __strend(dest);
188
189 p[len] = '\0';
190 __builtin_memcpy(p, src, len);
191 return dest;
192 }
193 EXPORT_SYMBOL(strncat);
194
195 /**
196 * strcmp - Compare two strings
197 * @cs: One string
198 * @ct: Another string
199 *
200 * returns 0 if @cs and @ct are equal,
201 * < 0 if @cs is less than @ct
202 * > 0 if @cs is greater than @ct
203 */
strcmp(const char * cs,const char * ct)204 int strcmp(const char *cs, const char *ct)
205 {
206 register int r0 asm("0") = 0;
207 int ret = 0;
208
209 asm volatile ("0: clst %2,%3\n"
210 " jo 0b\n"
211 " je 1f\n"
212 " ic %0,0(%2)\n"
213 " ic %1,0(%3)\n"
214 " sr %0,%1\n"
215 "1:"
216 : "+d" (ret), "+d" (r0), "+a" (cs), "+a" (ct)
217 : : "cc" );
218 return ret;
219 }
220 EXPORT_SYMBOL(strcmp);
221
222 /**
223 * strrchr - Find the last occurrence of a character in a string
224 * @s: The string to be searched
225 * @c: The character to search for
226 */
strrchr(const char * s,int c)227 char * strrchr(const char * s, int c)
228 {
229 size_t len = __strend(s) - s;
230
231 if (len)
232 do {
233 if (s[len] == (char) c)
234 return (char *) s + len;
235 } while (--len > 0);
236 return NULL;
237 }
238 EXPORT_SYMBOL(strrchr);
239
240 /**
241 * strstr - Find the first substring in a %NUL terminated string
242 * @s1: The string to be searched
243 * @s2: The string to search for
244 */
strstr(const char * s1,const char * s2)245 char * strstr(const char * s1,const char * s2)
246 {
247 int l1, l2;
248
249 l2 = __strend(s2) - s2;
250 if (!l2)
251 return (char *) s1;
252 l1 = __strend(s1) - s1;
253 while (l1-- >= l2) {
254 register unsigned long r2 asm("2") = (unsigned long) s1;
255 register unsigned long r3 asm("3") = (unsigned long) l2;
256 register unsigned long r4 asm("4") = (unsigned long) s2;
257 register unsigned long r5 asm("5") = (unsigned long) l2;
258 int cc;
259
260 asm volatile ("0: clcle %1,%3,0\n"
261 " jo 0b\n"
262 " ipm %0\n"
263 " srl %0,28"
264 : "=&d" (cc), "+a" (r2), "+a" (r3),
265 "+a" (r4), "+a" (r5) : : "cc" );
266 if (!cc)
267 return (char *) s1;
268 s1++;
269 }
270 return NULL;
271 }
272 EXPORT_SYMBOL(strstr);
273
274 /**
275 * memchr - Find a character in an area of memory.
276 * @s: The memory area
277 * @c: The byte to search for
278 * @n: The size of the area.
279 *
280 * returns the address of the first occurrence of @c, or %NULL
281 * if @c is not found
282 */
memchr(const void * s,int c,size_t n)283 void *memchr(const void *s, int c, size_t n)
284 {
285 register int r0 asm("0") = (char) c;
286 const void *ret = s + n;
287
288 asm volatile ("0: srst %0,%1\n"
289 " jo 0b\n"
290 " jl 1f\n"
291 " la %0,0\n"
292 "1:"
293 : "+a" (ret), "+&a" (s) : "d" (r0) : "cc" );
294 return (void *) ret;
295 }
296 EXPORT_SYMBOL(memchr);
297
298 /**
299 * memcmp - Compare two areas of memory
300 * @cs: One area of memory
301 * @ct: Another area of memory
302 * @count: The size of the area.
303 */
memcmp(const void * cs,const void * ct,size_t n)304 int memcmp(const void *cs, const void *ct, size_t n)
305 {
306 register unsigned long r2 asm("2") = (unsigned long) cs;
307 register unsigned long r3 asm("3") = (unsigned long) n;
308 register unsigned long r4 asm("4") = (unsigned long) ct;
309 register unsigned long r5 asm("5") = (unsigned long) n;
310 int ret;
311
312 asm volatile ("0: clcle %1,%3,0\n"
313 " jo 0b\n"
314 " ipm %0\n"
315 " srl %0,28"
316 : "=&d" (ret), "+a" (r2), "+a" (r3), "+a" (r4), "+a" (r5)
317 : : "cc" );
318 if (ret)
319 ret = *(char *) r2 - *(char *) r4;
320 return ret;
321 }
322 EXPORT_SYMBOL(memcmp);
323
324 /**
325 * memscan - Find a character in an area of memory.
326 * @s: The memory area
327 * @c: The byte to search for
328 * @n: The size of the area.
329 *
330 * returns the address of the first occurrence of @c, or 1 byte past
331 * the area if @c is not found
332 */
memscan(void * s,int c,size_t n)333 void *memscan(void *s, int c, size_t n)
334 {
335 register int r0 asm("0") = (char) c;
336 const void *ret = s + n;
337
338 asm volatile ("0: srst %0,%1\n"
339 " jo 0b\n"
340 : "+a" (ret), "+&a" (s) : "d" (r0) : "cc" );
341 return (void *) ret;
342 }
343 EXPORT_SYMBOL(memscan);
344
345 /**
346 * memcpy - Copy one area of memory to another
347 * @dest: Where to copy to
348 * @src: Where to copy from
349 * @n: The size of the area.
350 *
351 * returns a pointer to @dest
352 */
memcpy(void * dest,const void * src,size_t n)353 void *memcpy(void *dest, const void *src, size_t n)
354 {
355 return __builtin_memcpy(dest, src, n);
356 }
357 EXPORT_SYMBOL(memcpy);
358
359 /**
360 * memset - Fill a region of memory with the given value
361 * @s: Pointer to the start of the area.
362 * @c: The byte to fill the area with
363 * @n: The size of the area.
364 *
365 * returns a pointer to @s
366 */
memset(void * s,int c,size_t n)367 void *memset(void *s, int c, size_t n)
368 {
369 char *xs;
370
371 if (c == 0)
372 return __builtin_memset(s, 0, n);
373
374 xs = (char *) s;
375 if (n > 0)
376 do {
377 *xs++ = c;
378 } while (--n > 0);
379 return s;
380 }
381 EXPORT_SYMBOL(memset);
382