File: linux-asm-string.h

package info (click to toggle)
mknbi 1.4.4-14
  • links: PTS, VCS
  • area: main
  • in suites: buster, stretch
  • size: 996 kB
  • ctags: 1,659
  • sloc: ansic: 3,511; asm: 2,374; perl: 1,368; makefile: 217; sh: 72; pascal: 37
file content (287 lines) | stat: -rw-r--r-- 7,366 bytes parent folder | download | duplicates (6)
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
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
/*
 * Taken from Linux /usr/include/asm/string.h
 * All except memcpy, memmove, memset and memcmp removed.
 */

#ifndef	_I386_STRING_H_
#define _I386_STRING_H_

/*
 * This string-include defines all string functions as inline
 * functions. Use gcc. It also assumes ds=es=data space, this should be
 * normal. Most of the string-functions are rather heavily hand-optimized,
 * see especially strtok,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 :-)
 *
 *		NO Copyright (C) 1991, 1992 Linus Torvalds,
 *		consider these trivial functions to be PD.
 */

extern void *__memcpy(void * to, const void * from, size_t n);
extern void *__constant_memcpy(void * to, const void * from, size_t n);
extern void *memmove(void * dest,const void * src, size_t n);
extern void *__memset_generic(void * s, char c,size_t count);
extern void *__constant_c_memset(void * s, unsigned long c, size_t count);
extern void *__constant_c_and_count_memset(void * s, unsigned long pattern, size_t count);


extern inline void * __memcpy(void * to, const void * from, size_t n)
{
int d0, d1, d2;
__asm__ __volatile__(
	"cld\n\t"
	"rep ; movsl\n\t"
	"testb $2,%b4\n\t"
	"je 1f\n\t"
	"movsw\n"
	"1:\ttestb $1,%b4\n\t"
	"je 2f\n\t"
	"movsb\n"
	"2:"
	: "=&c" (d0), "=&D" (d1), "=&S" (d2)
	:"0" (n/4), "q" (n),"1" ((long) to),"2" ((long) from)
	: "memory");
return (to);
}

/*
 * This looks horribly ugly, but the compiler can optimize it totally,
 * as the count is constant.
 */
extern inline void * __constant_memcpy(void * to, const void * from, size_t n)
{
	switch (n) {
		case 0:
			return to;
		case 1:
			*(unsigned char *)to = *(const unsigned char *)from;
			return to;
		case 2:
			*(unsigned short *)to = *(const unsigned short *)from;
			return to;
		case 3:
			*(unsigned short *)to = *(const unsigned short *)from;
			*(2+(unsigned char *)to) = *(2+(const unsigned char *)from);
			return to;
		case 4:
			*(unsigned long *)to = *(const unsigned long *)from;
			return to;
		case 6:	/* for Ethernet addresses */
			*(unsigned long *)to = *(const unsigned long *)from;
			*(2+(unsigned short *)to) = *(2+(const unsigned short *)from);
			return to;
		case 8:
			*(unsigned long *)to = *(const unsigned long *)from;
			*(1+(unsigned long *)to) = *(1+(const unsigned long *)from);
			return to;
		case 12:
			*(unsigned long *)to = *(const unsigned long *)from;
			*(1+(unsigned long *)to) = *(1+(const unsigned long *)from);
			*(2+(unsigned long *)to) = *(2+(const unsigned long *)from);
			return to;
		case 16:
			*(unsigned long *)to = *(const unsigned long *)from;
			*(1+(unsigned long *)to) = *(1+(const unsigned long *)from);
			*(2+(unsigned long *)to) = *(2+(const unsigned long *)from);
			*(3+(unsigned long *)to) = *(3+(const unsigned long *)from);
			return to;
		case 20:
			*(unsigned long *)to = *(const unsigned long *)from;
			*(1+(unsigned long *)to) = *(1+(const unsigned long *)from);
			*(2+(unsigned long *)to) = *(2+(const unsigned long *)from);
			*(3+(unsigned long *)to) = *(3+(const unsigned long *)from);
			*(4+(unsigned long *)to) = *(4+(const unsigned long *)from);
			return to;
	}
#define COMMON(x) \
__asm__ __volatile__( \
	"cld\n\t" \
	"rep ; movsl" \
	x \
	: "=&c" (d0), "=&D" (d1), "=&S" (d2) \
	: "0" (n/4),"1" ((long) to),"2" ((long) from) \
	: "memory");
{
	int d0, d1, d2;
	switch (n % 4) {
		case 0: COMMON(""); return to;
		case 1: COMMON("\n\tmovsb"); return to;
		case 2: COMMON("\n\tmovsw"); return to;
		default: COMMON("\n\tmovsw\n\tmovsb"); return to;
	}
}

#undef COMMON
}

#define __HAVE_ARCH_MEMCPY
#define memcpy(t, f, n) \
(__builtin_constant_p(n) ? \
 __constant_memcpy((t),(f),(n)) : \
 __memcpy((t),(f),(n)))

#define __HAVE_ARCH_MEMMOVE
extern inline void * memmove(void * dest,const void * src, size_t n)
{
int d0, d1, d2;
if (dest<src)
__asm__ __volatile__(
	"cld\n\t"
	"rep\n\t"
	"movsb"
	: "=&c" (d0), "=&S" (d1), "=&D" (d2)
	:"0" (n),"1" (src),"2" (dest)
	: "memory");
else
__asm__ __volatile__(
	"std\n\t"
	"rep\n\t"
	"movsb\n\t"
	"cld"
	: "=&c" (d0), "=&S" (d1), "=&D" (d2)
	:"0" (n),
	 "1" (n-1+(const char *)src),
	 "2" (n-1+(char *)dest)
	:"memory");
return dest;
}

extern inline void * __memset_generic(void * s, char c,size_t count)
{
int d0, d1;
__asm__ __volatile__(
	"cld\n\t"
	"rep\n\t"
	"stosb"
	: "=&c" (d0), "=&D" (d1)
	:"a" (c),"1" (s),"0" (count)
	:"memory");
return s;
}

/* we might want to write optimized versions of these later */
#define __constant_count_memset(s,c,count) __memset_generic((s),(c),(count))

/*
 * memset(x,0,y) is a reasonably common thing to do, so we want to fill
 * things 32 bits at a time even when we don't know the size of the
 * area at compile-time..
 */
extern inline void * __constant_c_memset(void * s, unsigned long c, size_t count)
{
int d0, d1;
__asm__ __volatile__(
	"cld\n\t"
	"rep ; stosl\n\t"
	"testb $2,%b3\n\t"
	"je 1f\n\t"
	"stosw\n"
	"1:\ttestb $1,%b3\n\t"
	"je 2f\n\t"
	"stosb\n"
	"2:"
	: "=&c" (d0), "=&D" (d1)
	:"a" (c), "q" (count), "0" (count/4), "1" ((long) s)
	:"memory");
return (s);
}

/*
 * This looks horribly ugly, but the compiler can optimize it totally,
 * as we by now know that both pattern and count is constant..
 */
extern inline void * __constant_c_and_count_memset(void * s, unsigned long pattern, size_t count)
{
	switch (count) {
		case 0:
			return s;
		case 1:
			*(unsigned char *)s = pattern;
			return s;
		case 2:
			*(unsigned short *)s = pattern;
			return s;
		case 3:
			*(unsigned short *)s = pattern;
			*(2+(unsigned char *)s) = pattern;
			return s;
		case 4:
			*(unsigned long *)s = pattern;
			return s;
	}
#define COMMON(x) \
__asm__  __volatile__("cld\n\t" \
	"rep ; stosl" \
	x \
	: "=&c" (d0), "=&D" (d1) \
	: "a" (pattern),"0" (count/4),"1" ((long) s) \
	: "memory")
{
	int d0, d1;
	switch (count % 4) {
		case 0: COMMON(""); return s;
		case 1: COMMON("\n\tstosb"); return s;
		case 2: COMMON("\n\tstosw"); return s;
		default: COMMON("\n\tstosw\n\tstosb"); return s;
	}
}

#undef COMMON
}

#define __constant_c_x_memset(s, c, count) \
(__builtin_constant_p(count) ? \
 __constant_c_and_count_memset((s),(c),(count)) : \
 __constant_c_memset((s),(c),(count)))

#define __memset(s, c, count) \
(__builtin_constant_p(count) ? \
 __constant_count_memset((s),(c),(count)) : \
 __memset_generic((s),(c),(count)))

#define __HAVE_ARCH_MEMSET
#define memset(s, c, count) \
(__builtin_constant_p(c) ? \
 __constant_c_x_memset((s),(c),(count)) : \
 __memset((s),(c),(count)))

#define __HAVE_ARCH_STRNCMP
static inline int strncmp(const char * cs,const char * ct,size_t count)
{
register 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));
return __res;
}

#define __HAVE_ARCH_STRLEN
static inline size_t strlen(const char * s)
{
int d0;
register 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" (0xffffffff));
return __res;
}

#endif