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
|
/*******************************************************************************
*
* Copyright (c) 1993 Intel Corporation
*
* Intel hereby grants you permission to copy, modify, and distribute this
* software and its documentation. Intel grants this permission provided
* that the above copyright notice appears in all copies and that both the
* copyright notice and this permission notice appear in supporting
* documentation. In addition, Intel grants this permission provided that
* you prominently mark as "not part of the original" any modifications
* made to this software or documentation, and that the name of Intel
* Corporation not be used in advertising or publicity pertaining to
* distribution of the software or the documentation without specific,
* written prior permission.
*
* Intel Corporation provides this AS IS, WITHOUT ANY WARRANTY, EXPRESS OR
* IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY
* OR FITNESS FOR A PARTICULAR PURPOSE. Intel makes no guarantee or
* representations regarding the use of, or the results of the use of,
* the software and documentation in terms of correctness, accuracy,
* reliability, currentness, or otherwise; and you rely on the software,
* documentation and results solely at your own risk.
*
* IN NO EVENT SHALL INTEL BE LIABLE FOR ANY LOSS OF USE, LOSS OF BUSINESS,
* LOSS OF PROFITS, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES
* OF ANY KIND. IN NO EVENT SHALL INTEL'S TOTAL LIABILITY EXCEED THE SUM
* PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER.
*
******************************************************************************/
.file "strcpy.s"
#ifdef __PIC
.pic
#endif
#ifdef __PID
.pid
#endif
/*
* (c) copyright 1988,1993 Intel Corp., all rights reserved
*/
/*
procedure strcpy (optimized assembler version for the 80960K series)
procedure strcat (optimized assembler version for the 80960K series)
dest_addr = strcpy (dest_addr, src_addr)
copy the null terminated string pointed to by src_addr to
the string space pointed to by dest_addr. Return the original
dest_addr.
This routine will fail if the source and destination string
overlap (in particular, if the end of the source is overlapped
by the beginning of the destination). The behavior is undefined.
This is acceptable according to the draft C standard.
Undefined behavior will also occur if the end of the source string
(i.e. the terminating null byte) is in the last two words of the
program's allocated memory space. This is so because strcpy fetches
ahead. Disallowing the fetch ahead would impose a severe performance
penalty.
Strategy:
Fetch the source string and store the destination string by words
until the null byte is encountered. When the word with the null
byte is reached, store it by bytes up through the null byte only.
Tactics:
1) Do NOT try to fetch and store the words in a word aligned manner
because, in my judgement, the performance degradation experienced due
to non-aligned accesses does NOT outweigh the time and complexity added
by the preamble and convoluted body that would be necessary to assure
alignment. This is supported by the intuition that most source and
destination strings will be word aligned to begin with.
procedure strcat
dest_addr = strcat (dest_addr, src_addr)
Appends the string pointed to by src_addr to the string pointed
to by dest_addr. The first character of the source string is
copied to the location initially occupied by the trailing null
byte of the destination string. Thereafter, characters are copied
from the source to the destination up thru the null byte that
trails the source string.
See the strcpy routine, above, for its caveats, as they apply here too.
Strategy:
Skip to the end (null byte) of the destination string, and then drop
into the strcpy code.
Tactics:
Skipping to the null byte is Ldone by reading the destination string
in long-words and scanbyte'ing them, then examining the bytes of the
word that contains the null byte, until the address of the null byte is
known. Then we drop into the strcpy routine. It is probable (approx.
three out of four times) that the destination string as strcpy sees
it will NOT be word aligned (i.e. that the null byte won't be the
last byte of a word). But it is not worth the complication to that
routine to force word aligned memory accesses to be gaurenteed.
*/
.globl _strcpy, _strcat
.globl __strcpy, __strcat
.leafproc _strcpy,__strcpy
.leafproc _strcat,__strcat
.align 2
_strcat:
#ifndef __PIC
lda Lrett,g14
#else
lda Lrett-(.+8)(ip),g14
#endif
__strcat:
mov g14,g13 # preserve return address
ldl (g0),g4 # fetch first two words
addo 8,g0,g2 # post-increment src word pointer
lda 0xff,g3 # byte extraction mask
Lsearch_for_word_with_null_byte:
scanbyte 0,g4 # check for null byte
mov g5,g7 # copy second word
bo.f Lsearch_for_null # branch if null found
scanbyte 0,g7 # check for null byte
ldl (g2),g4 # fetch next pair of word of src
addo 8,g2,g2 # post-increment src word pointer
bno Lsearch_for_word_with_null_byte # branch if null not found yet
subo 4,g2,g2 # back up the byte pointer
mov g7,g4 # move word with null to search word
Lsearch_for_null:
subo 9,g2,g5 # back up the byte pointer
Lsearch_for_null.a:
and g4,g3,g6 # extract byte
cmpo 0,g6 # is it null?
addo 1,g5,g5 # bump src byte ptr
shro 8,g4,g4 # shift word to position next byte
bne Lsearch_for_null.a
b Lend_of_dest_found
_strcpy:
#ifndef __PIC
lda Lrett,g14
#else
lda Lrett-(.+8)(ip),g14
#endif
__strcpy:
mov g0, g5
Lend_of_dest_found:
ld (g1), g2 # fetch first word of source
mov g14,g6 # preserve return address
lda 0xff, g3 # byte extraction mask = 0xff;
Lwloop: # word copying loop
addo 4, g1, g1 # post-increment source ptr
scanbyte 0, g2 # does source word contain null byte?
mov g2, g4 # save a copy of the source word
be Lcloop # branch if null present
ld (g1), g2 # pre-fetch next word of source
st g4, (g5) # store current word
addo 4, g5, g5 # post-increment dest ptr
b Lwloop
Lcloop: # character copying loop
and g3, g4, g14 # extract next char
shro 8, g4, g4 # position word for next byte extraction
cmpo 0, g14 # is it null?
stob g14, (g5) # store the byte
addo 1, g5, g5 # post-increment dest ptr
bne Lcloop # quit if null encountered
bx (g6) # g0 = dest string address; g14 = 0
Lrett:
ret
|
