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 */
17static 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
27static 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 */
44size_t strlen(const char *s)
45{
46	return __strend(s) - s;
47}
48EXPORT_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 */
57size_t strnlen(const char * s, size_t n)
58{
59	return __strnend(s, n) - s;
60}
61EXPORT_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 */
70char *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}
81EXPORT_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 */
94size_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}
105EXPORT_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 */
116char *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}
123EXPORT_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 */
132char *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}
146EXPORT_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 */
154size_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}
170EXPORT_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 */
183char *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}
192EXPORT_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 */
203int 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}
219EXPORT_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 */
226char * 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}
237EXPORT_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 */
244char * 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}
271EXPORT_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 */
282void *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}
295EXPORT_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 */
303int 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}
321EXPORT_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 */
332void *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}
342EXPORT_SYMBOL(memscan);
343