Logo Search packages:      
Sourcecode: linux version File versions

string.c

/*
 *  arch/s390/lib/string.c
 *    Optimized string functions
 *
 *  S390 version
 *    Copyright (C) 2004 IBM Deutschland Entwicklung GmbH, IBM Corporation
 *    Author(s): Martin Schwidefsky (schwidefsky@de.ibm.com)
 */

#define IN_ARCH_STRING_C 1

#include <linux/types.h>
#include <linux/module.h>

/*
 * Helper functions to find the end of a string
 */
static inline char *__strend(const char *s)
{
      register unsigned long r0 asm("0") = 0;

      asm volatile ("0: srst  %0,%1\n"
                  "   jo    0b"
                  : "+d" (r0), "+a" (s) :  : "cc" );
      return (char *) r0;
}

static inline char *__strnend(const char *s, size_t n)
{
      register unsigned long r0 asm("0") = 0;
      const char *p = s + n;

      asm volatile ("0: srst  %0,%1\n"
                  "   jo    0b"
                  : "+d" (p), "+a" (s) : "d" (r0) : "cc" );
      return (char *) p;
}

/**
 * strlen - Find the length of a string
 * @s: The string to be sized
 *
 * returns the length of @s
 */
size_t strlen(const char *s)
{
      return __strend(s) - s;
}
EXPORT_SYMBOL(strlen);

/**
 * strnlen - Find the length of a length-limited string
 * @s: The string to be sized
 * @n: The maximum number of bytes to search
 *
 * returns the minimum of the length of @s and @n
 */
size_t strnlen(const char * s, size_t n)
{
      return __strnend(s, n) - s;
}
EXPORT_SYMBOL(strnlen);

/**
 * strcpy - Copy a %NUL terminated string
 * @dest: Where to copy the string to
 * @src: Where to copy the string from
 *
 * returns a pointer to @dest
 */
char *strcpy(char *dest, const char *src)
{
      register int r0 asm("0") = 0;
      char *ret = dest;

      asm volatile ("0: mvst  %0,%1\n"
                  "   jo    0b"
                  : "+&a" (dest), "+&a" (src) : "d" (r0)
                  : "cc", "memory" );
      return ret;
}
EXPORT_SYMBOL(strcpy);

/**
 * strlcpy - Copy a %NUL terminated string into a sized buffer
 * @dest: Where to copy the string to
 * @src: Where to copy the string from
 * @size: size of destination buffer
 *
 * Compatible with *BSD: the result is always a valid
 * NUL-terminated string that fits in the buffer (unless,
 * of course, the buffer size is zero). It does not pad
 * out the result like strncpy() does.
 */
size_t strlcpy(char *dest, const char *src, size_t size)
{
      size_t ret = __strend(src) - src;

      if (size) {
            size_t len = (ret >= size) ? size-1 : ret;
            dest[len] = '\0';
            __builtin_memcpy(dest, src, len);
      }
      return ret;
}
EXPORT_SYMBOL(strlcpy);

/**
 * strncpy - Copy a length-limited, %NUL-terminated string
 * @dest: Where to copy the string to
 * @src: Where to copy the string from
 * @n: The maximum number of bytes to copy
 *
 * The result is not %NUL-terminated if the source exceeds
 * @n bytes.
 */
char *strncpy(char *dest, const char *src, size_t n)
{
      size_t len = __strnend(src, n) - src;
      __builtin_memset(dest + len, 0, n - len);
      __builtin_memcpy(dest, src, len);
      return dest;
}
EXPORT_SYMBOL(strncpy);

/**
 * strcat - Append one %NUL-terminated string to another
 * @dest: The string to be appended to
 * @src: The string to append to it
 *
 * returns a pointer to @dest
 */
char *strcat(char *dest, const char *src)
{
      register int r0 asm("0") = 0;
      unsigned long dummy;
      char *ret = dest;

      asm volatile ("0: srst  %0,%1\n"
                  "   jo    0b\n"
                  "1: mvst  %0,%2\n"
                  "   jo    1b"
                  : "=&a" (dummy), "+a" (dest), "+a" (src)
                  : "d" (r0), "0" (0UL) : "cc", "memory" );
      return ret;
}
EXPORT_SYMBOL(strcat);

/**
 * strlcat - Append a length-limited, %NUL-terminated string to another
 * @dest: The string to be appended to
 * @src: The string to append to it
 * @n: The size of the destination buffer.
 */
size_t strlcat(char *dest, const char *src, size_t n)
{
      size_t dsize = __strend(dest) - dest;
      size_t len = __strend(src) - src;
      size_t res = dsize + len;

      if (dsize < n) {
            dest += dsize;
            n -= dsize;
            if (len >= n)
                  len = n - 1;
            dest[len] = '\0';
            __builtin_memcpy(dest, src, len);
      }
      return res;
}
EXPORT_SYMBOL(strlcat);

/**
 * strncat - Append a length-limited, %NUL-terminated string to another
 * @dest: The string to be appended to
 * @src: The string to append to it
 * @n: The maximum numbers of bytes to copy
 *
 * returns a pointer to @dest
 *
 * Note that in contrast to strncpy, strncat ensures the result is
 * terminated.
 */
char *strncat(char *dest, const char *src, size_t n)
{
      size_t len = __strnend(src, n) - src;
      char *p = __strend(dest);

      p[len] = '\0';
      __builtin_memcpy(p, src, len);
      return dest;
}
EXPORT_SYMBOL(strncat);

/**
 * strcmp - Compare two strings
 * @cs: One string
 * @ct: Another string
 *
 * returns   0 if @cs and @ct are equal,
 *         < 0 if @cs is less than @ct
 *         > 0 if @cs is greater than @ct
 */
int strcmp(const char *cs, const char *ct)
{
      register int r0 asm("0") = 0;
      int ret = 0;

      asm volatile ("0: clst %2,%3\n"
                  "   jo   0b\n"
                  "   je   1f\n"
                  "   ic   %0,0(%2)\n"
                  "   ic   %1,0(%3)\n"
                  "   sr   %0,%1\n"
                  "1:"
                  : "+d" (ret), "+d" (r0), "+a" (cs), "+a" (ct)
                  : : "cc" );
      return ret;
}
EXPORT_SYMBOL(strcmp);

/**
 * strrchr - Find the last occurrence of a character in a string
 * @s: The string to be searched
 * @c: The character to search for
 */
char * strrchr(const char * s, int c)
{
       size_t len = __strend(s) - s;

       if (len)
             do {
                   if (s[len] == (char) c)
                         return (char *) s + len;
             } while (--len > 0);
       return NULL;
}
EXPORT_SYMBOL(strrchr);

/**
 * strstr - Find the first substring in a %NUL terminated string
 * @s1: The string to be searched
 * @s2: The string to search for
 */
char * strstr(const char * s1,const char * s2)
{
      int l1, l2;

      l2 = __strend(s2) - s2;
      if (!l2)
            return (char *) s1;
      l1 = __strend(s1) - s1;
      while (l1-- >= l2) {
            register unsigned long r2 asm("2") = (unsigned long) s1;
            register unsigned long r3 asm("3") = (unsigned long) l2;
            register unsigned long r4 asm("4") = (unsigned long) s2;
            register unsigned long r5 asm("5") = (unsigned long) l2;
            int cc;

            asm volatile ("0: clcle %1,%3,0\n"
                        "   jo    0b\n"
                        "   ipm   %0\n"
                        "   srl   %0,28"
                        : "=&d" (cc), "+a" (r2), "+a" (r3),
                          "+a" (r4), "+a" (r5) : : "cc" );
            if (!cc)
                  return (char *) s1;
            s1++;
      }
      return NULL;
}
EXPORT_SYMBOL(strstr);

/**
 * memchr - Find a character in an area of memory.
 * @s: The memory area
 * @c: The byte to search for
 * @n: The size of the area.
 *
 * returns the address of the first occurrence of @c, or %NULL
 * if @c is not found
 */
void *memchr(const void *s, int c, size_t n)
{
      register int r0 asm("0") = (char) c;
      const void *ret = s + n;

      asm volatile ("0: srst  %0,%1\n"
                  "   jo    0b\n"
                  "   jl      1f\n"
                  "   la    %0,0\n"
                  "1:"
                  : "+a" (ret), "+&a" (s) : "d" (r0) : "cc" );
      return (void *) ret;
}
EXPORT_SYMBOL(memchr);

/**
 * memcmp - Compare two areas of memory
 * @cs: One area of memory
 * @ct: Another area of memory
 * @count: The size of the area.
 */
int memcmp(const void *cs, const void *ct, size_t n)
{
      register unsigned long r2 asm("2") = (unsigned long) cs;
      register unsigned long r3 asm("3") = (unsigned long) n;
      register unsigned long r4 asm("4") = (unsigned long) ct;
      register unsigned long r5 asm("5") = (unsigned long) n;
      int ret;

      asm volatile ("0: clcle %1,%3,0\n"
                  "   jo    0b\n"
                  "   ipm   %0\n"
                  "   srl   %0,28"
                  : "=&d" (ret), "+a" (r2), "+a" (r3), "+a" (r4), "+a" (r5)
                  : : "cc" );
      if (ret)
            ret = *(char *) r2 - *(char *) r4;
      return ret;
}
EXPORT_SYMBOL(memcmp);

/**
 * memscan - Find a character in an area of memory.
 * @s: The memory area
 * @c: The byte to search for
 * @n: The size of the area.
 *
 * returns the address of the first occurrence of @c, or 1 byte past
 * the area if @c is not found
 */
void *memscan(void *s, int c, size_t n)
{
      register int r0 asm("0") = (char) c;
      const void *ret = s + n;

      asm volatile ("0: srst  %0,%1\n"
                  "   jo    0b\n"
                  : "+a" (ret), "+&a" (s) : "d" (r0) : "cc" );
      return (void *) ret;
}
EXPORT_SYMBOL(memscan);

/**
 * memcpy - Copy one area of memory to another
 * @dest: Where to copy to
 * @src: Where to copy from
 * @n: The size of the area.
 *
 * returns a pointer to @dest
 */
void *memcpy(void *dest, const void *src, size_t n)
{
      return __builtin_memcpy(dest, src, n);
}
EXPORT_SYMBOL(memcpy);

/**
 * memset - Fill a region of memory with the given value
 * @s: Pointer to the start of the area.
 * @c: The byte to fill the area with
 * @n: The size of the area.
 *
 * returns a pointer to @s
 */
void *memset(void *s, int c, size_t n)
{
      char *xs;

      if (c == 0)
            return __builtin_memset(s, 0, n);

      xs = (char *) s;
      if (n > 0)
            do {
                  *xs++ = c;
            } while (--n > 0);
      return s;
}
EXPORT_SYMBOL(memset);

Generated by  Doxygen 1.6.0   Back to index