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
|
#ifndef ETHERBOOT_BITS_STRING_H
#define ETHERBOOT_BITS_STRING_H
/*
* Taken from Linux /usr/include/asm/string.h
* All except memcpy, memmove, memset and memcmp removed.
*
* Non-standard memswap() function added because it saves quite a bit
* of code (mbrown@fensystems.co.uk).
*/
/*
* 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.
*/
FILE_LICENCE ( PUBLIC_DOMAIN );
#define __HAVE_ARCH_MEMCPY
extern void * __memcpy ( void *dest, const void *src, size_t len );
#if 0
static inline __attribute__ (( always_inline )) void *
__memcpy ( void *dest, const void *src, size_t len ) {
int d0, d1, d2;
__asm__ __volatile__ ( "rep ; movsb"
: "=&c" ( d0 ), "=&S" ( d1 ), "=&D" ( d2 )
: "0" ( len ), "1" ( src ), "2" ( dest )
: "memory" );
return dest;
}
#endif
static inline __attribute__ (( always_inline )) void *
__constant_memcpy ( void *dest, const void *src, size_t len ) {
union {
uint32_t u32[2];
uint16_t u16[4];
uint8_t u8[8];
} __attribute__ (( __may_alias__ )) *dest_u = dest;
const union {
uint32_t u32[2];
uint16_t u16[4];
uint8_t u8[8];
} __attribute__ (( __may_alias__ )) *src_u = src;
const void *esi;
void *edi;
switch ( len ) {
case 0 : /* 0 bytes */
return dest;
/*
* Single-register moves; these are always better than a
* string operation. We can clobber an arbitrary two
* registers (data, source, dest can re-use source register)
* instead of being restricted to esi and edi. There's also a
* much greater potential for optimising with nearby code.
*
*/
case 1 : /* 4 bytes */
dest_u->u8[0] = src_u->u8[0];
return dest;
case 2 : /* 6 bytes */
dest_u->u16[0] = src_u->u16[0];
return dest;
case 4 : /* 4 bytes */
dest_u->u32[0] = src_u->u32[0];
return dest;
/*
* Double-register moves; these are probably still a win.
*
*/
case 3 : /* 12 bytes */
dest_u->u16[0] = src_u->u16[0];
dest_u->u8[2] = src_u->u8[2];
return dest;
case 5 : /* 10 bytes */
dest_u->u32[0] = src_u->u32[0];
dest_u->u8[4] = src_u->u8[4];
return dest;
case 6 : /* 12 bytes */
dest_u->u32[0] = src_u->u32[0];
dest_u->u16[2] = src_u->u16[2];
return dest;
case 8 : /* 10 bytes */
dest_u->u32[0] = src_u->u32[0];
dest_u->u32[1] = src_u->u32[1];
return dest;
}
/* Even if we have to load up esi and edi ready for a string
* operation, we can sometimes save space by using multiple
* single-byte "movs" operations instead of loading up ecx and
* using "rep movsb".
*
* "load ecx, rep movsb" is 7 bytes, plus an average of 1 byte
* to allow for saving/restoring ecx 50% of the time.
*
* "movsl" and "movsb" are 1 byte each, "movsw" is two bytes.
* (In 16-bit mode, "movsl" is 2 bytes and "movsw" is 1 byte,
* but "movsl" moves twice as much data, so it balances out).
*
* The cutoff point therefore occurs around 26 bytes; the byte
* requirements for each method are:
*
* len 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31
* #bytes (ecx) 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8
* #bytes (no ecx) 4 5 6 7 5 6 7 8 6 7 8 9 7 8 9 10
*/
esi = src;
edi = dest;
if ( len >= 26 )
return __memcpy ( dest, src, len );
if ( len >= 6*4 )
__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
if ( len >= 5*4 )
__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
if ( len >= 4*4 )
__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
if ( len >= 3*4 )
__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
if ( len >= 2*4 )
__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
if ( len >= 1*4 )
__asm__ __volatile__ ( "movsl" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
if ( ( len % 4 ) >= 2 )
__asm__ __volatile__ ( "movsw" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
if ( ( len % 2 ) >= 1 )
__asm__ __volatile__ ( "movsb" : "=&D" ( edi ), "=&S" ( esi )
: "0" ( edi ), "1" ( esi ) : "memory" );
return dest;
}
#define memcpy( dest, src, len ) \
( __builtin_constant_p ( (len) ) ? \
__constant_memcpy ( (dest), (src), (len) ) : \
__memcpy ( (dest), (src), (len) ) )
#define __HAVE_ARCH_MEMMOVE
static 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;
}
#define __HAVE_ARCH_MEMSET
static inline void * memset(void *s, int 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;
}
#define __HAVE_ARCH_MEMSWAP
static inline void * memswap(void *dest, void *src, size_t n)
{
int d0, d1, d2, d3;
__asm__ __volatile__(
"\n1:\t"
"movb (%%edi),%%al\n\t"
"xchgb (%%esi),%%al\n\t"
"incl %%esi\n\t"
"stosb\n\t"
"loop 1b"
: "=&c" (d0), "=&S" (d1), "=&D" (d2), "=&a" (d3)
: "0" (n), "1" (src), "2" (dest)
: "memory" );
return dest;
}
#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 /* ETHERBOOT_BITS_STRING_H */
|
