source: trunk/libs/newlib/src/newlib/libc/machine/i960/strchr_ca.S @ 444

Last change on this file since 444 was 444, checked in by satin@…, 6 years ago

add newlib,libalmos-mkh, restructure shared_syscalls.h and mini-libc

File size: 5.1 KB
Line 
1/*******************************************************************************
2 *
3 * Copyright (c) 1993 Intel Corporation
4 *
5 * Intel hereby grants you permission to copy, modify, and distribute this
6 * software and its documentation.  Intel grants this permission provided
7 * that the above copyright notice appears in all copies and that both the
8 * copyright notice and this permission notice appear in supporting
9 * documentation.  In addition, Intel grants this permission provided that
10 * you prominently mark as "not part of the original" any modifications
11 * made to this software or documentation, and that the name of Intel
12 * Corporation not be used in advertising or publicity pertaining to
13 * distribution of the software or the documentation without specific,
14 * written prior permission.
15 *
16 * Intel Corporation provides this AS IS, WITHOUT ANY WARRANTY, EXPRESS OR
17 * IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY
18 * OR FITNESS FOR A PARTICULAR PURPOSE.  Intel makes no guarantee or
19 * representations regarding the use of, or the results of the use of,
20 * the software and documentation in terms of correctness, accuracy,
21 * reliability, currentness, or otherwise; and you rely on the software,
22 * documentation and results solely at your own risk.
23 *
24 * IN NO EVENT SHALL INTEL BE LIABLE FOR ANY LOSS OF USE, LOSS OF BUSINESS,
25 * LOSS OF PROFITS, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES
26 * OF ANY KIND.  IN NO EVENT SHALL INTEL'S TOTAL LIABILITY EXCEED THE SUM
27 * PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER.
28 *
29 ******************************************************************************/
30
31        .file "strch_ca.s"
32#ifdef  __PIC
33        .pic
34#endif
35#ifdef  __PID
36        .pid
37#endif
38/*
39 * (c) copyright 1988,1993 Intel Corp., all rights reserved
40 */
41
42/*
43        procedure strchr  (optimized assembler version for the CA)
44
45        src_addr = strchr (src_addr, char)
46
47        return a pointer to the first byte that contains the indicated
48        byte in the source string.  Return null if the byte is not found.
49
50        Undefined behavior will occur if the end of the source string (i.e.
51        the terminating null byte) is in the last two words of the program's
52        allocated memory space.  This is so because, in several cases, strchr
53        will fetch ahead.  Disallowing the fetch ahead would impose a severe
54        performance penalty.
55
56        This program handles two cases:
57
58        1) the argument starts on a word boundary
59        2) the argument doesn't start on a word boundary
60
61        At the time of this writing, only g0 thru g7 and g13 are available
62        for use in this leafproc;  other registers would have to be saved and
63        restored.  These nine registers, plus tricky use of g14 are sufficient
64        to implement the routine.  The registers are used as follows:
65
66        g0  src ptr;  upon return it is a pointer to the matching byte, or null
67        g1  char to seek
68        g2  mask to avoid unimportant bytes in first word
69        g3  char to seek, broadcast to all four bytes
70        g4  word of the source string
71        g5  copy of the word
72        g6  extracted character
73        g7  byte extraction mask
74        g13 return address
75        g14
76*/
77
78        .globl  _strchr
79        .globl  __strchr
80        .leafproc       _strchr, __strchr
81        .align  2
82_strchr:
83#ifndef __PIC
84        lda     Lrett,g14
85#else
86        lda     Lrett-(.+8)(ip),g14
87#endif
88__strchr:
89
90        lda     0xff,g7         # byte extraction mask
91        and     g1,g7,g1        # make char an 8-bit ordinal
92        shlo    8,g1,g2         # broadcast the char to four bytes
93        or      g1,g2,g2
94        shlo    16,g2,g4
95        cmpo    g1,g7           # is char being sought 0xff?
96        or      g4,g2,g3
97         lda    (g14),g13       # preserve return address
98        notand  g0,3,g5         # extract word addr of start of src
99         lda    0,g14           # conform to register linkage standard
100        and     g0,3,g6         # extract byte offset of src
101         ld     (g5),g4         # fetch word containing at least first byte
102        shlo    3,g6,g6         # get shift count for making mask for first word
103         lda    4(g5),g0        # post-increment src word pointer
104        subi    1,0,g5          # mask initially all ones
105#if __i960_BIG_ENDIAN__
106        shro    g6,g5,g5        # get mask for bytes needed from first word
107#else
108        shlo    g6,g5,g5        # get mask for bytes needed from first word
109#endif
110        notor   g4,g5,g4        # set unneeded bytes to all ones
111         be.f   Lsearch_for_0xff        # branch if seeking 0xff
112
113Lsearch_for_word_with_char_or_null:
114        scanbyte g3,g4          # check for byte with char
115         lda    (g4),g5         # copy word
116        ld      (g0),g4         # fetch next word of src
117         bo.f   Lsearch_for_char        # branch if null found
118        scanbyte 0,g5           # check for null byte
119         lda    4(g0),g0        # post-increment src word pointer
120        bno.t   Lsearch_for_word_with_char_or_null      # branch if not null
121
122Lnot_found:
123        mov     0,g0            # char not found.  Return null
124Lexit_code:
125        bx      (g13)           # g0 = addr of char in src (or null);  g14 = 0
126Lrett:
127        ret
128
129Lsearch_for_char:
130        subo    5,g0,g0         # back up the byte pointer
131Lsearch_for_char.a:
132#if __i960_BIG_ENDIAN__
133        rotate  8,g5,g5         # shift word to position next byte
134#endif
135        and     g5,g7,g6        # extract byte
136        cmpo    g1,g6           # is it char?
137         lda    1(g0),g0        # bump src byte ptr
138#if ! __i960_BIG_ENDIAN__
139        shro    8,g5,g5         # shift word to position next byte
140#endif
141         be.f   Lexit_code
142        cmpobne.t 0,g6,Lsearch_for_char.a       # quit if null comes before char
143        b       Lnot_found
144
145Lsearch_for_0xff:
146        lda     0xf0f0f0f0,g2   # make first comparison mask for char=-1 case.
147        or      g5,g2,g2
148        and     g4,g2,g4        # make unimportant bytes of first word 0x0f
149         b      Lsearch_for_word_with_char_or_null
150
151/* end of strchr */
152
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