LXR linux/arch/x86/lib/strstr

   1// SPDX-License-Identifier: GPL-2.0
   2#include <linux/string.h>
   3#include <linux/export.h>
   4
   5char *strstr(const char *cs, const char *ct)
   6{
   7int     d0, d1;
   8register char *__res;
   9__asm__ __volatile__(
  10        "movl %6,%%edi\n\t"
  11        "repne\n\t"
  12        "scasb\n\t"
  13        "notl %%ecx\n\t"
  14        "decl %%ecx\n\t"        /* NOTE! This also sets Z if searchstring='' */
  15        "movl %%ecx,%%edx\n"
  16        "1:\tmovl %6,%%edi\n\t"
  17        "movl %%esi,%%eax\n\t"
  18        "movl %%edx,%%ecx\n\t"
  19        "repe\n\t"
  20        "cmpsb\n\t"
  21        "je 2f\n\t"             /* also works for empty string, see above */
  22        "xchgl %%eax,%%esi\n\t"
  23        "incl %%esi\n\t"
  24        "cmpb $0,-1(%%eax)\n\t"
  25        "jne 1b\n\t"
  26        "xorl %%eax,%%eax\n\t"
  27        "2:"
  28        : "=a" (__res), "=&c" (d0), "=&S" (d1)
  29        : "0" (0), "1" (0xffffffff), "2" (cs), "g" (ct)
  30        : "dx", "di");
  31return __res;
  32}
  33EXPORT_SYMBOL(strstr);
  34