string.c

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/*
 *    Optimized string functions
 *
 *  S390 version
 *    Copyright IBM Corp. 2004
 *    Author(s): Martin Schwidefsky ([email protected])
 */

#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;
}

size_t strlen(const char *s)
{
    return __strend(s) - s;
}
EXPORT_SYMBOL(strlen);

size_t strnlen(const char * s, size_t n)
{
    return __strnend(s, n) - s;
}
EXPORT_SYMBOL(strnlen);

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);

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';
        memcpy(dest, src, len);
    }
    return ret;
}
EXPORT_SYMBOL(strlcpy);

char *strncpy(char *dest, const char *src, size_t n)
{
    size_t len = __strnend(src, n) - src;
    memset(dest + len, 0, n - len);
    memcpy(dest, src, len);
    return dest;
}
EXPORT_SYMBOL(strncpy);

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);

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';
        memcpy(dest, src, len);
    }
    return res;
}
EXPORT_SYMBOL(strlcat);

char *strncat(char *dest, const char *src, size_t n)
{
    size_t len = __strnend(src, n) - src;
    char *p = __strend(dest);

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

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);

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);

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);

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);

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);

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);