arch/s390/lib/string.c

   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/string.h>
  13 #include <linux/export.h>
  14
  15 /*
  16  * Helper functions to find the end of a string
  17  */
  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", "memory");
  25         return (char *) r0;
  26 }
  27
  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", "memory");
  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  */
  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  */
  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  */
  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  */
  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                 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  */
 117 char *strncpy(char *dest, const char *src, size_t n)
 118 {
 119         size_t len = __strnend(src, n) - src;
 120         memset(dest + len, 0, n - len);
 121         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  */
 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  */
 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                 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  */
 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         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  */
 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", "memory");
 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  */
 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 static inline int clcle(const char *s1, unsigned long l1,
 241                         const char *s2, unsigned long l2)
 242 {
 243         register unsigned long r2 asm("2") = (unsigned long) s1;
 244         register unsigned long r3 asm("3") = (unsigned long) l1;
 245         register unsigned long r4 asm("4") = (unsigned long) s2;
 246         register unsigned long r5 asm("5") = (unsigned long) l2;
 247         int cc;
 248
 249         asm volatile ("0: clcle %1,%3,0\n"
 250                       "   jo    0b\n"
 251                       "   ipm   %0\n"
 252                       "   srl   %0,28"
 253                       : "=&d" (cc), "+a" (r2), "+a" (r3),
 254                         "+a" (r4), "+a" (r5) : : "cc", "memory");
 255         return cc;
 256 }
 257
 258 /**
 259  * strstr - Find the first substring in a %NUL terminated string
 260  * @s1: The string to be searched
 261  * @s2: The string to search for
 262  */
 263 char * strstr(const char * s1,const char * s2)
 264 {
 265         int l1, l2;
 266
 267         l2 = __strend(s2) - s2;
 268         if (!l2)
 269                 return (char *) s1;
 270         l1 = __strend(s1) - s1;
 271         while (l1-- >= l2) {
 272                 int cc;
 273
 274                 cc = clcle(s1, l2, s2, l2);
 275                 if (!cc)
 276                         return (char *) s1;
 277                 s1++;
 278         }
 279         return NULL;
 280 }
 281 EXPORT_SYMBOL(strstr);
 282
 283 /**
 284  * memchr - Find a character in an area of memory.
 285  * @s: The memory area
 286  * @c: The byte to search for
 287  * @n: The size of the area.
 288  *
 289  * returns the address of the first occurrence of @c, or %NULL
 290  * if @c is not found
 291  */
 292 void *memchr(const void *s, int c, size_t n)
 293 {
 294         register int r0 asm("0") = (char) c;
 295         const void *ret = s + n;
 296
 297         asm volatile ("0: srst  %0,%1\n"
 298                       "   jo    0b\n"
 299                       "   jl    1f\n"
 300                       "   la    %0,0\n"
 301                       "1:"
 302                       : "+a" (ret), "+&a" (s) : "d" (r0) : "cc", "memory");
 303         return (void *) ret;
 304 }
 305 EXPORT_SYMBOL(memchr);
 306
 307 /**
 308  * memcmp - Compare two areas of memory
 309  * @cs: One area of memory
 310  * @ct: Another area of memory
 311  * @count: The size of the area.
 312  */
 313 int memcmp(const void *cs, const void *ct, size_t n)
 314 {
 315         int ret;
 316
 317         ret = clcle(cs, n, ct, n);
 318         if (ret)
 319                 ret = ret == 1 ? -1 : 1;
 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  */
 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", "memory");
 341         return (void *) ret;
 342 }
 343 EXPORT_SYMBOL(memscan);