aboutsummaryrefslogtreecommitdiff
path: root/arch/i386/lib/string.c
blob: 2c773fefa3ddad023fb16e21e90209b2cbeb507b (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
/*
 * Most of the string-functions are rather heavily hand-optimized,
 * see especially strsep,strstr,str[c]spn. They should work, but are not
 * very easy to understand. Everything is done entirely within the register
 * set, making the functions fast and clean. String instructions have been
 * used through-out, making for "slightly" unclear code :-)
 *
 * AK: On P4 and K7 using non string instruction implementations might be faster
 * for large memory blocks. But most of them are unlikely to be used on large
 * strings.
 */

#include <linux/string.h>
#include <linux/module.h>

#ifdef __HAVE_ARCH_STRCPY
char *strcpy(char * dest,const char *src)
{
	int d0, d1, d2;
	asm volatile( "1:\tlodsb\n\t"
		"stosb\n\t"
		"testb %%al,%%al\n\t"
		"jne 1b"
		: "=&S" (d0), "=&D" (d1), "=&a" (d2)
		:"0" (src),"1" (dest) : "memory");
	return dest;
}
EXPORT_SYMBOL(strcpy);
#endif

#ifdef __HAVE_ARCH_STRNCPY
char *strncpy(char * dest,const char *src,size_t count)
{
	int d0, d1, d2, d3;
	asm volatile( "1:\tdecl %2\n\t"
		"js 2f\n\t"
		"lodsb\n\t"
		"stosb\n\t"
		"testb %%al,%%al\n\t"
		"jne 1b\n\t"
		"rep\n\t"
		"stosb\n"
		"2:"
		: "=&S" (d0), "=&D" (d1), "=&c" (d2), "=&a" (d3)
		:"0" (src),"1" (dest),"2" (count) : "memory");
	return dest;
}
EXPORT_SYMBOL(strncpy);
#endif

#ifdef __HAVE_ARCH_STRCAT
char *strcat(char * dest,const char * src)
{
	int d0, d1, d2, d3;
	asm volatile( "repne\n\t"
		"scasb\n\t"
		"decl %1\n"
		"1:\tlodsb\n\t"
		"stosb\n\t"
		"testb %%al,%%al\n\t"
		"jne 1b"
		: "=&S" (d0), "=&D" (d1), "=&a" (d2), "=&c" (d3)
		: "0" (src), "1" (dest), "2" (0), "3" (0xffffffffu): "memory");
	return dest;
}
EXPORT_SYMBOL(strcat);
#endif

#ifdef __HAVE_ARCH_STRNCAT
char *strncat(char * dest,const char * src,size_t count)
{
	int d0, d1, d2, d3;
	asm volatile( "repne\n\t"
		"scasb\n\t"
		"decl %1\n\t"
		"movl %8,%3\n"
		"1:\tdecl %3\n\t"
		"js 2f\n\t"
		"lodsb\n\t"
		"stosb\n\t"
		"testb %%al,%%al\n\t"
		"jne 1b\n"
		"2:\txorl %2,%2\n\t"
		"stosb"
		: "=&S" (d0), "=&D" (d1), "=&a" (d2), "=&c" (d3)
		: "0" (src),"1" (dest),"2" (0),"3" (0xffffffffu), "g" (count)
		: "memory");
	return dest;
}
EXPORT_SYMBOL(strncat);
#endif

#ifdef __HAVE_ARCH_STRCMP
int strcmp(const char * cs,const char * ct)
{
	int d0, d1;
	int res;
	asm volatile( "1:\tlodsb\n\t"
		"scasb\n\t"
		"jne 2f\n\t"
		"testb %%al,%%al\n\t"
		"jne 1b\n\t"
		"xorl %%eax,%%eax\n\t"
		"jmp 3f\n"
		"2:\tsbbl %%eax,%%eax\n\t"
		"orb $1,%%al\n"
		"3:"
		:"=a" (res), "=&S" (d0), "=&D" (d1)
		:"1" (cs),"2" (ct)
		:"memory");
	return res;
}
EXPORT_SYMBOL(strcmp);
#endif

#ifdef __HAVE_ARCH_STRNCMP
int strncmp(const char * cs,const char * ct,size_t count)
{
	int res;
	int d0, d1, d2;
	asm volatile( "1:\tdecl %3\n\t"
		"js 2f\n\t"
		"lodsb\n\t"
		"scasb\n\t"
		"jne 3f\n\t"
		"testb %%al,%%al\n\t"
		"jne 1b\n"
		"2:\txorl %%eax,%%eax\n\t"
		"jmp 4f\n"
		"3:\tsbbl %%eax,%%eax\n\t"
		"orb $1,%%al\n"
		"4:"
		:"=a" (res), "=&S" (d0), "=&D" (d1), "=&c" (d2)
		:"1" (cs),"2" (ct),"3" (count)
		:"memory");
	return res;
}
EXPORT_SYMBOL(strncmp);
#endif

#ifdef __HAVE_ARCH_STRCHR
char *strchr(const char * s, int c)
{
	int d0;
	char * res;
	asm volatile( "movb %%al,%%ah\n"
		"1:\tlodsb\n\t"
		"cmpb %%ah,%%al\n\t"
		"je 2f\n\t"
		"testb %%al,%%al\n\t"
		"jne 1b\n\t"
		"movl $1,%1\n"
		"2:\tmovl %1,%0\n\t"
		"decl %0"
		:"=a" (res), "=&S" (d0)
		:"1" (s),"0" (c)
		:"memory");
	return res;
}
EXPORT_SYMBOL(strchr);
#endif

#ifdef __HAVE_ARCH_STRRCHR
char *strrchr(const char * s, int c)
{
	int d0, d1;
	char * res;
	asm volatile( "movb %%al,%%ah\n"
		"1:\tlodsb\n\t"
		"cmpb %%ah,%%al\n\t"
		"jne 2f\n\t"
		"leal -1(%%esi),%0\n"
		"2:\ttestb %%al,%%al\n\t"
		"jne 1b"
		:"=g" (res), "=&S" (d0), "=&a" (d1)
		:"0" (0),"1" (s),"2" (c)
		:"memory");
	return res;
}
EXPORT_SYMBOL(strrchr);
#endif

#ifdef __HAVE_ARCH_STRLEN
size_t strlen(const char * s)
{
	int d0;
	int res;
	asm volatile( "repne\n\t"
		"scasb\n\t"
		"notl %0\n\t"
		"decl %0"
		:"=c" (res), "=&D" (d0)
		:"1" (s),"a" (0), "0" (0xffffffffu)
		:"memory");
	return res;
}
EXPORT_SYMBOL(strlen);
#endif

#ifdef __HAVE_ARCH_MEMCHR
void *memchr(const void *cs,int c,size_t count)
{
	int d0;
	void *res;
	if (!count)
		return NULL;
	asm volatile( "repne\n\t"
		"scasb\n\t"
		"je 1f\n\t"
		"movl $1,%0\n"
		"1:\tdecl %0"
		:"=D" (res), "=&c" (d0)
		:"a" (c),"0" (cs),"1" (count)
		:"memory");
	return res;
}
EXPORT_SYMBOL(memchr);
#endif

#ifdef __HAVE_ARCH_MEMSCAN
void *memscan(void * addr, int c, size_t size)
{
	if (!size)
		return addr;
	asm volatile("repnz; scasb\n\t"
	    "jnz 1f\n\t"
	    "dec %%edi\n"
	    "1:"
	    : "=D" (addr), "=c" (size)
	    : "0" (addr), "1" (size), "a" (c)
	    : "memory");
	return addr;
}
EXPORT_SYMBOL(memscan);
#endif

#ifdef __HAVE_ARCH_STRNLEN
size_t strnlen(const char *s, size_t count)
{
	int d0;
	int res;
	asm volatile( "movl %2,%0\n\t"
		"jmp 2f\n"
		"1:\tcmpb $0,(%0)\n\t"
		"je 3f\n\t"
		"incl %0\n"
		"2:\tdecl %1\n\t"
		"cmpl $-1,%1\n\t"
		"jne 1b\n"
		"3:\tsubl %2,%0"
		:"=a" (res), "=&d" (d0)
		:"c" (s),"1" (count)
		:"memory");
	return res;
}
EXPORT_SYMBOL(strnlen);
#endif