Commit | Line | Data |
---|---|---|
b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
b520b85a AK |
2 | /* |
3 | * Most of the string-functions are rather heavily hand-optimized, | |
4 | * see especially strsep,strstr,str[c]spn. They should work, but are not | |
5 | * very easy to understand. Everything is done entirely within the register | |
6 | * set, making the functions fast and clean. String instructions have been | |
7 | * used through-out, making for "slightly" unclear code :-) | |
8 | * | |
9 | * AK: On P4 and K7 using non string instruction implementations might be faster | |
10 | * for large memory blocks. But most of them are unlikely to be used on large | |
11 | * strings. | |
12 | */ | |
13 | ||
14 | #include <linux/string.h> | |
e683014c | 15 | #include <linux/export.h> |
b520b85a AK |
16 | |
17 | #ifdef __HAVE_ARCH_STRCPY | |
8cf36d2b | 18 | char *strcpy(char *dest, const char *src) |
b520b85a AK |
19 | { |
20 | int d0, d1, d2; | |
8cf36d2b | 21 | asm volatile("1:\tlodsb\n\t" |
b520b85a AK |
22 | "stosb\n\t" |
23 | "testb %%al,%%al\n\t" | |
24 | "jne 1b" | |
25 | : "=&S" (d0), "=&D" (d1), "=&a" (d2) | |
3492cdf0 | 26 | : "0" (src), "1" (dest) : "memory"); |
b520b85a AK |
27 | return dest; |
28 | } | |
29 | EXPORT_SYMBOL(strcpy); | |
30 | #endif | |
31 | ||
32 | #ifdef __HAVE_ARCH_STRNCPY | |
8cf36d2b | 33 | char *strncpy(char *dest, const char *src, size_t count) |
b520b85a AK |
34 | { |
35 | int d0, d1, d2, d3; | |
8cf36d2b | 36 | asm volatile("1:\tdecl %2\n\t" |
b520b85a AK |
37 | "js 2f\n\t" |
38 | "lodsb\n\t" | |
39 | "stosb\n\t" | |
40 | "testb %%al,%%al\n\t" | |
41 | "jne 1b\n\t" | |
42 | "rep\n\t" | |
43 | "stosb\n" | |
44 | "2:" | |
45 | : "=&S" (d0), "=&D" (d1), "=&c" (d2), "=&a" (d3) | |
3492cdf0 | 46 | : "0" (src), "1" (dest), "2" (count) : "memory"); |
b520b85a AK |
47 | return dest; |
48 | } | |
49 | EXPORT_SYMBOL(strncpy); | |
50 | #endif | |
51 | ||
52 | #ifdef __HAVE_ARCH_STRCAT | |
8cf36d2b | 53 | char *strcat(char *dest, const char *src) |
b520b85a AK |
54 | { |
55 | int d0, d1, d2, d3; | |
8cf36d2b | 56 | asm volatile("repne\n\t" |
b520b85a AK |
57 | "scasb\n\t" |
58 | "decl %1\n" | |
59 | "1:\tlodsb\n\t" | |
60 | "stosb\n\t" | |
61 | "testb %%al,%%al\n\t" | |
62 | "jne 1b" | |
63 | : "=&S" (d0), "=&D" (d1), "=&a" (d2), "=&c" (d3) | |
3492cdf0 | 64 | : "0" (src), "1" (dest), "2" (0), "3" (0xffffffffu) : "memory"); |
b520b85a AK |
65 | return dest; |
66 | } | |
67 | EXPORT_SYMBOL(strcat); | |
68 | #endif | |
69 | ||
70 | #ifdef __HAVE_ARCH_STRNCAT | |
8cf36d2b | 71 | char *strncat(char *dest, const char *src, size_t count) |
b520b85a AK |
72 | { |
73 | int d0, d1, d2, d3; | |
8cf36d2b | 74 | asm volatile("repne\n\t" |
b520b85a AK |
75 | "scasb\n\t" |
76 | "decl %1\n\t" | |
77 | "movl %8,%3\n" | |
78 | "1:\tdecl %3\n\t" | |
79 | "js 2f\n\t" | |
80 | "lodsb\n\t" | |
81 | "stosb\n\t" | |
82 | "testb %%al,%%al\n\t" | |
83 | "jne 1b\n" | |
84 | "2:\txorl %2,%2\n\t" | |
85 | "stosb" | |
86 | : "=&S" (d0), "=&D" (d1), "=&a" (d2), "=&c" (d3) | |
8cf36d2b | 87 | : "0" (src), "1" (dest), "2" (0), "3" (0xffffffffu), "g" (count) |
b520b85a AK |
88 | : "memory"); |
89 | return dest; | |
90 | } | |
91 | EXPORT_SYMBOL(strncat); | |
92 | #endif | |
93 | ||
94 | #ifdef __HAVE_ARCH_STRCMP | |
8cf36d2b | 95 | int strcmp(const char *cs, const char *ct) |
b520b85a AK |
96 | { |
97 | int d0, d1; | |
98 | int res; | |
8cf36d2b | 99 | asm volatile("1:\tlodsb\n\t" |
b520b85a AK |
100 | "scasb\n\t" |
101 | "jne 2f\n\t" | |
102 | "testb %%al,%%al\n\t" | |
103 | "jne 1b\n\t" | |
104 | "xorl %%eax,%%eax\n\t" | |
105 | "jmp 3f\n" | |
106 | "2:\tsbbl %%eax,%%eax\n\t" | |
107 | "orb $1,%%al\n" | |
108 | "3:" | |
3492cdf0 PC |
109 | : "=a" (res), "=&S" (d0), "=&D" (d1) |
110 | : "1" (cs), "2" (ct) | |
111 | : "memory"); | |
b520b85a AK |
112 | return res; |
113 | } | |
114 | EXPORT_SYMBOL(strcmp); | |
115 | #endif | |
116 | ||
117 | #ifdef __HAVE_ARCH_STRNCMP | |
8cf36d2b | 118 | int strncmp(const char *cs, const char *ct, size_t count) |
b520b85a AK |
119 | { |
120 | int res; | |
121 | int d0, d1, d2; | |
8cf36d2b | 122 | asm volatile("1:\tdecl %3\n\t" |
b520b85a AK |
123 | "js 2f\n\t" |
124 | "lodsb\n\t" | |
125 | "scasb\n\t" | |
126 | "jne 3f\n\t" | |
127 | "testb %%al,%%al\n\t" | |
128 | "jne 1b\n" | |
129 | "2:\txorl %%eax,%%eax\n\t" | |
130 | "jmp 4f\n" | |
131 | "3:\tsbbl %%eax,%%eax\n\t" | |
132 | "orb $1,%%al\n" | |
133 | "4:" | |
3492cdf0 PC |
134 | : "=a" (res), "=&S" (d0), "=&D" (d1), "=&c" (d2) |
135 | : "1" (cs), "2" (ct), "3" (count) | |
136 | : "memory"); | |
b520b85a AK |
137 | return res; |
138 | } | |
139 | EXPORT_SYMBOL(strncmp); | |
140 | #endif | |
141 | ||
142 | #ifdef __HAVE_ARCH_STRCHR | |
8cf36d2b | 143 | char *strchr(const char *s, int c) |
b520b85a AK |
144 | { |
145 | int d0; | |
8cf36d2b PC |
146 | char *res; |
147 | asm volatile("movb %%al,%%ah\n" | |
b520b85a AK |
148 | "1:\tlodsb\n\t" |
149 | "cmpb %%ah,%%al\n\t" | |
150 | "je 2f\n\t" | |
151 | "testb %%al,%%al\n\t" | |
152 | "jne 1b\n\t" | |
153 | "movl $1,%1\n" | |
154 | "2:\tmovl %1,%0\n\t" | |
155 | "decl %0" | |
3492cdf0 PC |
156 | : "=a" (res), "=&S" (d0) |
157 | : "1" (s), "0" (c) | |
158 | : "memory"); | |
b520b85a AK |
159 | return res; |
160 | } | |
161 | EXPORT_SYMBOL(strchr); | |
162 | #endif | |
163 | ||
b520b85a | 164 | #ifdef __HAVE_ARCH_STRLEN |
8cf36d2b | 165 | size_t strlen(const char *s) |
b520b85a AK |
166 | { |
167 | int d0; | |
890890cb | 168 | size_t res; |
8cf36d2b | 169 | asm volatile("repne\n\t" |
890890cb | 170 | "scasb" |
3492cdf0 PC |
171 | : "=c" (res), "=&D" (d0) |
172 | : "1" (s), "a" (0), "0" (0xffffffffu) | |
173 | : "memory"); | |
890890cb | 174 | return ~res - 1; |
b520b85a AK |
175 | } |
176 | EXPORT_SYMBOL(strlen); | |
177 | #endif | |
178 | ||
179 | #ifdef __HAVE_ARCH_MEMCHR | |
8cf36d2b | 180 | void *memchr(const void *cs, int c, size_t count) |
b520b85a AK |
181 | { |
182 | int d0; | |
183 | void *res; | |
184 | if (!count) | |
185 | return NULL; | |
8cf36d2b | 186 | asm volatile("repne\n\t" |
b520b85a AK |
187 | "scasb\n\t" |
188 | "je 1f\n\t" | |
189 | "movl $1,%0\n" | |
190 | "1:\tdecl %0" | |
3492cdf0 PC |
191 | : "=D" (res), "=&c" (d0) |
192 | : "a" (c), "0" (cs), "1" (count) | |
193 | : "memory"); | |
b520b85a AK |
194 | return res; |
195 | } | |
196 | EXPORT_SYMBOL(memchr); | |
197 | #endif | |
198 | ||
199 | #ifdef __HAVE_ARCH_MEMSCAN | |
8cf36d2b | 200 | void *memscan(void *addr, int c, size_t size) |
b520b85a AK |
201 | { |
202 | if (!size) | |
203 | return addr; | |
204 | asm volatile("repnz; scasb\n\t" | |
205 | "jnz 1f\n\t" | |
206 | "dec %%edi\n" | |
207 | "1:" | |
208 | : "=D" (addr), "=c" (size) | |
209 | : "0" (addr), "1" (size), "a" (c) | |
210 | : "memory"); | |
211 | return addr; | |
212 | } | |
213 | EXPORT_SYMBOL(memscan); | |
214 | #endif | |
215 | ||
216 | #ifdef __HAVE_ARCH_STRNLEN | |
217 | size_t strnlen(const char *s, size_t count) | |
218 | { | |
219 | int d0; | |
220 | int res; | |
8cf36d2b | 221 | asm volatile("movl %2,%0\n\t" |
b520b85a AK |
222 | "jmp 2f\n" |
223 | "1:\tcmpb $0,(%0)\n\t" | |
224 | "je 3f\n\t" | |
225 | "incl %0\n" | |
226 | "2:\tdecl %1\n\t" | |
227 | "cmpl $-1,%1\n\t" | |
228 | "jne 1b\n" | |
229 | "3:\tsubl %2,%0" | |
3492cdf0 PC |
230 | : "=a" (res), "=&d" (d0) |
231 | : "c" (s), "1" (count) | |
232 | : "memory"); | |
b520b85a AK |
233 | return res; |
234 | } | |
235 | EXPORT_SYMBOL(strnlen); | |
236 | #endif |