mirror of
https://github.com/autc04/Retro68.git
synced 2024-11-24 07:31:32 +00:00
154 lines
5.2 KiB
ArmAsm
154 lines
5.2 KiB
ArmAsm
/*******************************************************************************
|
|
*
|
|
* 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 "memchr_ca.s"
|
|
#ifdef __PIC
|
|
.pic
|
|
#endif
|
|
#ifdef __PID
|
|
.pid
|
|
#endif
|
|
/*
|
|
* (c) copyright 1988,1993 Intel Corp., all rights reserved
|
|
*/
|
|
|
|
/*
|
|
procedure memchr (optimized assembler version for the CA)
|
|
|
|
src_addr = memchr (src_addr, char, max_bytes)
|
|
|
|
searching from src_addr for max_bytes bytes, return a pointer to the
|
|
first byte that contains the indicated byte in the source string.
|
|
Return null if the byte is not found.
|
|
|
|
Undefined behavior will occur if the end of the source string (i.e.
|
|
the terminating null byte) is in the last two words of the program's
|
|
allocated memory space. This is so because, in several cases, memchr
|
|
will fetch ahead. 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 src ptr; upon return it is a pointer to the matching byte, or null
|
|
g1 char to seek
|
|
g2 maximum number of bytes to check
|
|
g3 char to seek, broadcast to all four bytes
|
|
g4 word of the source string
|
|
g5 copy of the word
|
|
g6 mask to avoid unimportant bytes in first word
|
|
g7 byte extraction mask
|
|
g13 return address
|
|
g14
|
|
*/
|
|
|
|
.globl _memchr
|
|
.globl __memchr
|
|
.leafproc _memchr, __memchr
|
|
.align 2
|
|
_memchr:
|
|
#ifndef __PIC
|
|
lda Lrett,g14
|
|
#else
|
|
lda Lrett-(.+8)(ip),g14
|
|
#endif
|
|
__memchr:
|
|
|
|
mov g14,g13 # preserve return address
|
|
lda 0xff,g7 # byte extraction mask
|
|
and g1,g7,g1 # make char an 8-bit ordinal
|
|
lda 0,g14 # conform to register linkage standard
|
|
cmpibge.f 0,g2,Lnot_found # do nothing if max_bytes <= 0
|
|
addo g0,g2,g2 # compute ending address from start and len
|
|
and g0,3,g6 # extract byte offset of src
|
|
notand g0,3,g0 # extract word addr of start of src
|
|
shlo 8,g1,g3 # broadcast the char to four bytes
|
|
ld (g0),g4 # fetch word containing at least first byte
|
|
or g1,g3,g3
|
|
shlo 16,g3,g5
|
|
cmpo g1,g7 # is char being sought 0xff?
|
|
or g5,g3,g3
|
|
shlo 3,g6,g6 # get shift count for making mask for first word
|
|
subi 1,0,g5 # mask initially all ones
|
|
#if __i960_BIG_ENDIAN__
|
|
shro g6,g5,g5 # get mask for bytes needed from first word
|
|
#else
|
|
shlo g6,g5,g5 # get mask for bytes needed from first word
|
|
#endif
|
|
notor g4,g5,g4 # set unneeded bytes to all ones
|
|
be.f Lsearch_for_0xff # branch if seeking 0xff
|
|
|
|
Lsearch_for_word_with_char:
|
|
scanbyte g3,g4 # check for byte with char
|
|
lda 4(g0),g0 # pre-increment src word pointer
|
|
mov g4,g5 # keep a copy of word
|
|
ld (g0),g4 # fetch next word of src
|
|
bo.f Lsearch_for_char # branch if null found
|
|
cmpoble.t g0,g2,Lsearch_for_word_with_char # branch if not null
|
|
|
|
Lnot_found:
|
|
mov 0,g0 # char not found. Return null
|
|
Lexit_code:
|
|
bx (g13) # g0 = addr of char in src (or null); g14 = 0
|
|
Lrett:
|
|
ret
|
|
|
|
Lsearch_for_char:
|
|
subo 4,g0,g0 # back up the byte pointer
|
|
Lsearch_for_char.a:
|
|
cmpobe.f g0,g2,Lnot_found # quit if max_bytes exhausted
|
|
#if __i960_BIG_ENDIAN__
|
|
rotate 8,g5,g5 # shift word to position next byte
|
|
#endif
|
|
and g5,g7,g6 # extract byte
|
|
cmpo g1,g6 # is it char?
|
|
lda 1(g0),g0 # bump src byte ptr
|
|
#if ! __i960_BIG_ENDIAN__
|
|
shro 8,g5,g5 # shift word to position next byte
|
|
#endif
|
|
bne.t Lsearch_for_char.a
|
|
subo 1,g0,g0 # back up the byte pointer
|
|
b Lexit_code
|
|
|
|
Lsearch_for_0xff:
|
|
lda 0xf0f0f0f0,g6 # make first comparison mask for char=-1 case.
|
|
or g6,g5,g6
|
|
and g4,g6,g4 # make unimportant bytes of first word 0x0f
|
|
b Lsearch_for_word_with_char
|
|
|
|
/* end of memchr */
|