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