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