1*4882a593Smuzhiyun // SPDX-License-Identifier: GPL-2.0
2*4882a593Smuzhiyun #include <linux/string.h>
3*4882a593Smuzhiyun #include <linux/export.h>
4*4882a593Smuzhiyun
strstr(const char * cs,const char * ct)5*4882a593Smuzhiyun char *strstr(const char *cs, const char *ct)
6*4882a593Smuzhiyun {
7*4882a593Smuzhiyun int d0, d1;
8*4882a593Smuzhiyun register char *__res;
9*4882a593Smuzhiyun __asm__ __volatile__(
10*4882a593Smuzhiyun "movl %6,%%edi\n\t"
11*4882a593Smuzhiyun "repne\n\t"
12*4882a593Smuzhiyun "scasb\n\t"
13*4882a593Smuzhiyun "notl %%ecx\n\t"
14*4882a593Smuzhiyun "decl %%ecx\n\t" /* NOTE! This also sets Z if searchstring='' */
15*4882a593Smuzhiyun "movl %%ecx,%%edx\n"
16*4882a593Smuzhiyun "1:\tmovl %6,%%edi\n\t"
17*4882a593Smuzhiyun "movl %%esi,%%eax\n\t"
18*4882a593Smuzhiyun "movl %%edx,%%ecx\n\t"
19*4882a593Smuzhiyun "repe\n\t"
20*4882a593Smuzhiyun "cmpsb\n\t"
21*4882a593Smuzhiyun "je 2f\n\t" /* also works for empty string, see above */
22*4882a593Smuzhiyun "xchgl %%eax,%%esi\n\t"
23*4882a593Smuzhiyun "incl %%esi\n\t"
24*4882a593Smuzhiyun "cmpb $0,-1(%%eax)\n\t"
25*4882a593Smuzhiyun "jne 1b\n\t"
26*4882a593Smuzhiyun "xorl %%eax,%%eax\n\t"
27*4882a593Smuzhiyun "2:"
28*4882a593Smuzhiyun : "=a" (__res), "=&c" (d0), "=&S" (d1)
29*4882a593Smuzhiyun : "0" (0), "1" (0xffffffff), "2" (cs), "g" (ct)
30*4882a593Smuzhiyun : "dx", "di");
31*4882a593Smuzhiyun return __res;
32*4882a593Smuzhiyun }
33*4882a593Smuzhiyun EXPORT_SYMBOL(strstr);
34