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/*******************************************************************************
*
* 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 "memccpy.s"
#ifdef __PIC
.pic
#endif
#ifdef __PID
.pid
#endif
/*
* (c) copyright 1989,1993 Intel Corp., all rights reserved
*/
/*
procedure memccpy (optimized assembler version for the 80960K series)
dest_addr = memccpy (dest_addr, src_addr, char, len)
copy len bytes pointed to by src_addr to the space pointed to by
dest_addr, stopping if char is copied. If char is copied,
return address of byte after char in dest string; else null.
Undefined behavior will occur if the end of the source array is in
the last two words of the program's allocated memory space. This
is so because the routine fetches ahead. Disallowing the fetch
ahead would impose a severe performance penalty.
Undefined behavior will also occur if the source and destination
strings overlap.
Strategy:
Fetch the source array by words and store them by words to the
destination array, until there are fewer than three bytes left
to copy. Then, using the last word of the source (the one that
contains the remaining 0, 1, 2, or 3 bytes to be copied), store
a byte at a time until Ldone.
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 arrays (even more true of most big source arrays) will
be word aligned to begin with.
2) Rather than decrementing len to zero,
I calculate the address of the byte after the last byte of the
destination array, and quit when the destination byte pointer passes
that.
*/
.globl _memccpy
.leafproc _memccpy, __memccpy
.align 2
_memccpy:
#ifndef __PIC
lda Lrett,g14
#else
lda Lrett-(.+8)(ip),g14
#endif
__memccpy:
mov g14, g13 # preserve return address
cmpibge 0,g3,Lexit_char_not_found
addo g3,g1,g3 # compute beyond end of src
ld (g1), g7 # fetch first word of source
lda 0xff,g5 # mask for char
and g5,g2,g2 # extract only char
shlo 8,g2,g6
or g2,g6,g6
shlo 16,g6,g4
or g6,g4,g6 # word of char
b Lwloop_b
Lwloop_a:
ld (g1), g7 # fetch ahead next word of source
st g4, (g0) # store word to dest
addo 4, g0, g0 # post-increment dest pointer
Lwloop_b: # word copying loop
addo 4, g1, g1 # pre-increment src pointer
cmpo g3, g1 # is len <= 3 ?
mov g7, g4 # keep a copy of the current word
bl Lcloop_setup # quit word loop if less than 4 bytes
scanbyte g6, g7 # check for char
bno Lwloop_a # continue word loop if char not found.
Lcloop_setup:
subo 4, g1, g1 # back down src pointer
cmpobe g1, g3, Lexit_char_not_found
Lcloop_a: # character copying loop (len < 3)
and g5,g4,g7 # check the byte against char
cmpo g7,g2
stob g7,(g0) # store the byte
addo 1, g0, g0
be Lexit_char_found
addo 1,g1,g1
cmpo g1,g3
shro 8,g4,g4 # position next byte
bne Lcloop_a
Lexit_char_not_found:
mov 0, g0
Lexit_char_found:
lda 0,g14
bx (g13) # g0 = dest array address; g14 = 0
Lrett:
ret
/* end of memccpy */
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