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