source: trunk/libs/newlib/src/newlib/libc/machine/i960/memccpy.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: 4.7 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 "memccpy.s"
32#ifdef  __PIC
33        .pic
34#endif
35#ifdef  __PID
36        .pid
37#endif
38/*
39 * (c) copyright 1989,1993 Intel Corp., all rights reserved
40 */
41/*
42        procedure memccpy  (optimized assembler version for the 80960K series)
43
44        dest_addr = memccpy (dest_addr, src_addr, char, len)
45
46        copy len bytes pointed to by src_addr to the space pointed to by
47        dest_addr, stopping if char is copied.  If char is copied,
48        return address of byte after char in dest string;  else null.
49
50
51        Undefined behavior will occur if the end of the source array is in
52        the last two words of the program's allocated memory space.  This
53        is so because the routine fetches ahead.  Disallowing the fetch
54        ahead would impose a severe performance penalty.
55
56        Undefined behavior will also occur if the source and destination
57        strings overlap.
58
59        Strategy:
60
61        Fetch the source array by words and store them by words to the
62        destination array, until there are fewer than three bytes left
63        to copy.  Then, using the last word of the source (the one that
64        contains the remaining 0, 1, 2, or 3 bytes to be copied), store
65        a byte at a time until Ldone.
66
67        Tactics:
68
69        1) Do NOT try to fetch and store the words in a word aligned manner
70        because, in my judgement, the performance degradation experienced due
71        to non-aligned accesses does NOT outweigh the time and complexity added
72        by the preamble and convoluted body that would be necessary to assure
73        alignment.  This is supported by the intuition that most source and
74        destination arrays (even more true of most big source arrays) will
75        be word aligned to begin with.
76
77        2) Rather than decrementing len to zero,
78        I calculate the address of the byte after the last byte of the
79        destination array, and quit when the destination byte pointer passes
80        that. 
81
82*/
83
84        .globl _memccpy
85        .leafproc _memccpy, __memccpy
86        .align    2
87_memccpy:
88#ifndef __PIC
89        lda     Lrett,g14
90#else
91        lda     Lrett-(.+8)(ip),g14
92#endif
93__memccpy:
94        mov     g14, g13        # preserve return address
95        cmpibge 0,g3,Lexit_char_not_found
96
97        addo    g3,g1,g3        # compute beyond end of src
98        ld      (g1), g7        # fetch first word of source
99        lda     0xff,g5         # mask for char
100        and     g5,g2,g2        # extract only char
101        shlo    8,g2,g6
102        or      g2,g6,g6
103        shlo    16,g6,g4
104        or      g6,g4,g6        # word of char
105        b       Lwloop_b
106
107Lwloop_a:
108        ld      (g1), g7        # fetch ahead next word of source
109        st      g4, (g0)        # store word to dest
110        addo    4, g0, g0       # post-increment dest pointer
111Lwloop_b:                       # word copying loop
112        addo    4, g1, g1       # pre-increment src pointer
113        cmpo    g3, g1          # is len <= 3 ?
114        mov     g7, g4          # keep a copy of the current word
115        bl      Lcloop_setup    # quit word loop if less than 4 bytes
116        scanbyte g6, g7         # check for char
117        bno     Lwloop_a                # continue word loop if char not found.
118
119Lcloop_setup:
120        subo    4, g1, g1       # back down src pointer
121        cmpobe  g1, g3, Lexit_char_not_found
122
123Lcloop_a:                       # character copying loop (len < 3)
124        and     g5,g4,g7        # check the byte against char
125        cmpo    g7,g2
126        stob    g7,(g0)         # store the byte
127        addo    1, g0, g0
128        be      Lexit_char_found
129        addo    1,g1,g1
130        cmpo    g1,g3
131        shro    8,g4,g4         # position next byte
132        bne     Lcloop_a
133
134Lexit_char_not_found:
135        mov     0, g0
136Lexit_char_found:
137        lda     0,g14
138        bx      (g13)           # g0 = dest array address; g14 = 0
139Lrett: 
140        ret
141
142
143/* end of memccpy */
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