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
|
/*******************************************************************************
*
* 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 "strle_ca.s"
#ifdef __PIC
.pic
#endif
#ifdef __PID
.pid
#endif
/*
* (c) copyright 1988,1993 Intel Corp., all rights reserved
*/
/*
procedure strlen (optimized assembler version for the CA)
src_addr = strlen (src_addr)
return the number of bytes that precede the null byte in the
string pointed to by src_addr.
Undefined behavior will occur if the end of the source string (i.e.
the terminating null byte) is in the last four words of the program's
allocated memory space. This is so because, in several cases, strlen
will fetch ahead several words. Disallowing the fetch ahead would
impose a severe performance penalty.
This program handles two cases:
1) the argument starts on a word boundary
2) the argument doesn't start on a word boundary
At the time of this writing, only g0 thru g7 and g13 are available
for use in this leafproc; other registers would have to be saved and
restored. These nine registers, plus tricky use of g14 are sufficient
to implement the routine. The registers are used as follows:
g0 original src ptr; upon return it is the byte count.
g1
g2 src ptr
g3 mask
g4 even word of the source string
g5 odd word of the source string
g6 copy of even word, shift count
g7 copy of odd word
g13 return address
g14 byte extracted.
*/
.globl _strlen
.globl __strlen
.leafproc _strlen, __strlen
.align 2
_strlen:
#ifndef __PIC
lda Lrett,g14
#else
lda Lrett-(.+8)(ip),g14
#endif
__strlen:
notand g0,3,g2 # extract word addr of start of src
lda (g14),g13 # preserve return address
and g0,3,g7 # extract byte offset of src
ld (g2),g5 # fetch word containing at least first byte
shlo 3,g7,g7 # get shift count for making mask for first word
lda 4(g2),g2 # post-increment src word pointer
subi 1,0,g3 # mask initially all ones
chkbit 2,g2 # are we on an even word boundary or an odd one?
#if __i960_BIG_ENDIAN__
shro g7,g3,g3 # get mask for bytes needed from first word
notor g5,g3,g7 # set unneeded bytes to all ones
lda 0xff000000,g3 # byte extraction mask
#else
shlo g7,g3,g3 # get mask for bytes needed from first word
notor g5,g3,g7 # set unneeded bytes to all ones
lda 0xff,g3 # byte extraction mask
#endif
bno.f Lodd_word # branch if first word is odd
mov g7,g4 # move first word to copy thereof
ld (g2),g5 # load odd word
lda 4(g2),g2 # post-increment src word pointer
Leven_word:
scanbyte 0,g4 # check for null byte
movl g4,g6 # copy both words
Lodd_word: # trickery! if we branch here, following branch
/* instruction will fall thru, as we want, */
/* effecting the load of g4 and g5 only. */
ldl (g2),g4 # fetch next pair of word of src
bo.f Lsearch_for_null # branch if null found
scanbyte 0,g7 # check for null byte
lda 8(g2),g2 # post-increment src word pointer
bno.t Leven_word # branch if null not found yet
subo 4,g2,g2 # back up the byte pointer
lda (g7),g6 # move odd word to search word
Lsearch_for_null:
subo 9,g2,g2 # back up the byte pointer
Lsearch_for_null.a:
and g6,g3,g14 # extract byte
cmpo 0,g14 # is it null?
lda 1(g2),g2 # bump src byte ptr
#if __i960_BIG_ENDIAN__
shlo 8,g6,g6 # shift word to position next byte
#else
shro 8,g6,g6 # shift word to position next byte
#endif
bne.t Lsearch_for_null.a
Lexit_code:
subo g0,g2,g0 # calculate string length
bx (g13) # g0 = addr of src; g14 = 0
Lrett:
ret
/* end of strlen */
|
