1 // SPDX-License-Identifier: GPL-2.0
2 #include <linux/string.h>
3 #include <linux/export.h>
4
5 char *strstr(const char *cs, const char *ct)
6 {
7 int d0, d1;
8 register 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), "1" (0xffffffff), "2" (cs), "g" (ct)
30 : "dx", "di");
31 return __res;
32 }
33 EXPORT_SYMBOL(strstr);
34
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