1 // SPDX-License-Identifier: GPL-2.0
3  * Most of the string-functions are rather heavily hand-optimized,
7  * used through-out, making for "slightly" unclear code :-)
22 	asm volatile("1:\tlodsb\n\t"  in strcpy()
23 		"stosb\n\t"  in strcpy()
24 		"testb %%al,%%al\n\t"  in strcpy()
25 		"jne 1b"  in strcpy()
27 		: "0" (src), "1" (dest) : "memory");  in strcpy()
37 	asm volatile("1:\tdecl %2\n\t"  in strncpy()
38 		"js 2f\n\t"  in strncpy()
39 		"lodsb\n\t"  in strncpy()
40 		"stosb\n\t"  in strncpy()
41 		"testb %%al,%%al\n\t"  in strncpy()
42 		"jne 1b\n\t"  in strncpy()
43 		"rep\n\t"  in strncpy()
44 		"stosb\n"  in strncpy()
47 		: "0" (src), "1" (dest), "2" (count) : "memory");  in strncpy()
57 	asm volatile("repne\n\t"  in strcat()
58 		"scasb\n\t"  in strcat()
59 		"decl %1\n"  in strcat()
60 		"1:\tlodsb\n\t"  in strcat()
61 		"stosb\n\t"  in strcat()
62 		"testb %%al,%%al\n\t"  in strcat()
63 		"jne 1b"  in strcat()
65 		: "0" (src), "1" (dest), "2" (0), "3" (0xffffffffu) : "memory");  in strcat()
75 	asm volatile("repne\n\t"  in strncat()
76 		"scasb\n\t"  in strncat()
77 		"decl %1\n\t"  in strncat()
78 		"movl %8,%3\n"  in strncat()
79 		"1:\tdecl %3\n\t"  in strncat()
80 		"js 2f\n\t"  in strncat()
81 		"lodsb\n\t"  in strncat()
82 		"stosb\n\t"  in strncat()
83 		"testb %%al,%%al\n\t"  in strncat()
84 		"jne 1b\n"  in strncat()
85 		"2:\txorl %2,%2\n\t"  in strncat()
88 		: "0" (src), "1" (dest), "2" (0), "3" (0xffffffffu), "g" (count)  in strncat()
100 	asm volatile("1:\tlodsb\n\t"  in strcmp()
101 		"scasb\n\t"  in strcmp()
102 		"jne 2f\n\t"  in strcmp()
103 		"testb %%al,%%al\n\t"  in strcmp()
104 		"jne 1b\n\t"  in strcmp()
105 		"xorl %%eax,%%eax\n\t"  in strcmp()
106 		"jmp 3f\n"  in strcmp()
107 		"2:\tsbbl %%eax,%%eax\n\t"  in strcmp()
108 		"orb $1,%%al\n"  in strcmp()
111 		: "1" (cs), "2" (ct)  in strcmp()
123 	asm volatile("1:\tdecl %3\n\t"  in strncmp()
124 		"js 2f\n\t"  in strncmp()
125 		"lodsb\n\t"  in strncmp()
126 		"scasb\n\t"  in strncmp()
127 		"jne 3f\n\t"  in strncmp()
128 		"testb %%al,%%al\n\t"  in strncmp()
129 		"jne 1b\n"  in strncmp()
130 		"2:\txorl %%eax,%%eax\n\t"  in strncmp()
131 		"jmp 4f\n"  in strncmp()
132 		"3:\tsbbl %%eax,%%eax\n\t"  in strncmp()
133 		"orb $1,%%al\n"  in strncmp()
136 		: "1" (cs), "2" (ct), "3" (count)  in strncmp()
148 	asm volatile("movb %%al,%%ah\n"  in strchr()
149 		"1:\tlodsb\n\t"  in strchr()
150 		"cmpb %%ah,%%al\n\t"  in strchr()
151 		"je 2f\n\t"  in strchr()
152 		"testb %%al,%%al\n\t"  in strchr()
153 		"jne 1b\n\t"  in strchr()
154 		"movl $1,%1\n"  in strchr()
155 		"2:\tmovl %1,%0\n\t"  in strchr()
158 		: "1" (s), "0" (c)  in strchr()
170 	asm volatile("repne\n\t"  in strlen()
173 		: "1" (s), "a" (0), "0" (0xffffffffu)  in strlen()
175 	return ~res - 1;  in strlen()
187 	asm volatile("repne\n\t"  in memchr()
188 		"scasb\n\t"  in memchr()
189 		"je 1f\n\t"  in memchr()
190 		"movl $1,%0\n"  in memchr()
191 		"1:\tdecl %0"  in memchr()
193 		: "a" (c), "0" (cs), "1" (count)  in memchr()
205 	asm volatile("repnz; scasb\n\t"  in memscan()
206 	    "jnz 1f\n\t"  in memscan()
207 	    "dec %%edi\n"  in memscan()
208 	    "1:"  in memscan()
210 	    : "0" (addr), "1" (size), "a" (c)  in memscan()
222 	asm volatile("movl %2,%0\n\t"  in strnlen()
223 		"jmp 2f\n"  in strnlen()
224 		"1:\tcmpb $0,(%0)\n\t"  in strnlen()
225 		"je 3f\n\t"  in strnlen()
226 		"incl %0\n"  in strnlen()
227 		"2:\tdecl %1\n\t"  in strnlen()
228 		"cmpl $-1,%1\n\t"  in strnlen()
229 		"jne 1b\n"  in strnlen()
232 		: "c" (s), "1" (count)  in strnlen()