source: trunk/libs/newlib/src/newlib/libc/machine/i960/memchr_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: 5.2 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 "memchr_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 memchr  (optimized assembler version for the CA)     
44
45        src_addr = memchr (src_addr, char, max_bytes)
46
47        searching from src_addr for max_bytes bytes, return a pointer to the
48        first byte that contains the indicated byte in the source string. 
49        Return null if the byte is not found.
50
51        Undefined behavior will occur if the end of the source string (i.e.
52        the terminating null byte) is in the last two words of the program's
53        allocated memory space.  This is so because, in several cases, memchr
54        will fetch ahead.  Disallowing the fetch ahead would impose a severe
55        performance penalty.
56
57        This program handles two cases:
58
59        1) the argument starts on a word boundary
60        2) the argument doesn't start on a word boundary
61
62        At the time of this writing, only g0 thru g7 and g13 are available
63        for use in this leafproc;  other registers would have to be saved and
64        restored.  These nine registers, plus tricky use of g14 are sufficient
65        to implement the routine.  The registers are used as follows:
66
67        g0  src ptr;  upon return it is a pointer to the matching byte, or null
68        g1  char to seek
69        g2  maximum number of bytes to check
70        g3  char to seek, broadcast to all four bytes
71        g4  word of the source string
72        g5  copy of the word
73        g6  mask to avoid unimportant bytes in first word
74        g7  byte extraction mask
75        g13 return address
76        g14
77*/
78
79        .globl  _memchr
80        .globl  __memchr
81        .leafproc       _memchr, __memchr
82        .align  2
83_memchr:
84#ifndef __PIC
85        lda     Lrett,g14
86#else
87        lda     Lrett-(.+8)(ip),g14
88#endif
89__memchr:
90
91        mov     g14,g13         # preserve return address
92         lda    0xff,g7         # byte extraction mask
93        and     g1,g7,g1        # make char an 8-bit ordinal
94         lda    0,g14           # conform to register linkage standard
95        cmpibge.f 0,g2,Lnot_found       # do nothing if max_bytes <= 0
96        addo    g0,g2,g2        # compute ending address from start and len
97        and     g0,3,g6         # extract byte offset of src
98        notand  g0,3,g0         # extract word addr of start of src
99        shlo    8,g1,g3         # broadcast the char to four bytes
100         ld     (g0),g4         # fetch word containing at least first byte
101        or      g1,g3,g3
102        shlo    16,g3,g5
103        cmpo    g1,g7           # is char being sought 0xff?
104        or      g5,g3,g3
105        shlo    3,g6,g6         # get shift count for making mask for first word
106        subi    1,0,g5          # mask initially all ones
107#if __i960_BIG_ENDIAN__
108        shro    g6,g5,g5        # get mask for bytes needed from first word
109#else
110        shlo    g6,g5,g5        # get mask for bytes needed from first word
111#endif
112        notor   g4,g5,g4        # set unneeded bytes to all ones
113         be.f   Lsearch_for_0xff        # branch if seeking 0xff
114
115Lsearch_for_word_with_char:
116        scanbyte g3,g4          # check for byte with char
117         lda    4(g0),g0        # pre-increment src word pointer
118        mov     g4,g5           # keep a copy of word
119        ld      (g0),g4         # fetch next word of src
120         bo.f   Lsearch_for_char        # branch if null found
121        cmpoble.t g0,g2,Lsearch_for_word_with_char      # branch if not null
122
123Lnot_found:
124        mov     0,g0            # char not found.  Return null
125Lexit_code:
126        bx      (g13)           # g0 = addr of char in src (or null);  g14 = 0
127Lrett:
128        ret
129
130Lsearch_for_char:
131        subo    4,g0,g0         # back up the byte pointer
132Lsearch_for_char.a:
133        cmpobe.f g0,g2,Lnot_found       # quit if max_bytes exhausted
134#if __i960_BIG_ENDIAN__
135        rotate  8,g5,g5         # shift word to position next byte
136#endif
137        and     g5,g7,g6        # extract byte
138        cmpo    g1,g6           # is it char?
139         lda    1(g0),g0        # bump src byte ptr
140#if ! __i960_BIG_ENDIAN__
141        shro    8,g5,g5         # shift word to position next byte
142#endif
143         bne.t  Lsearch_for_char.a
144        subo    1,g0,g0         # back up the byte pointer
145         b      Lexit_code
146
147Lsearch_for_0xff:
148        lda     0xf0f0f0f0,g6   # make first comparison mask for char=-1 case.
149        or      g6,g5,g6
150        and     g4,g6,g4        # make unimportant bytes of first word 0x0f
151         b      Lsearch_for_word_with_char
152
153/* end of memchr */
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