mirror of
https://github.com/autc04/Retro68.git
synced 2024-12-01 11:52:47 +00:00
130 lines
4.5 KiB
ArmAsm
130 lines
4.5 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 "strncmp.s"
|
|
#ifdef __PIC
|
|
.pic
|
|
#endif
|
|
#ifdef __PID
|
|
.pid
|
|
#endif
|
|
/*
|
|
* (c) copyright 1988,1993 Intel Corp., all rights reserved
|
|
*/
|
|
/*
|
|
procedure strncmp (optimized assembler version for the 80960K Series)
|
|
|
|
result = strncmp (src1_addr, src2_addr, max_bytes)
|
|
|
|
compare the null terminated string pointed to by src1_addr to
|
|
the string pointed to by src2_addr. Return 0 iff the strings
|
|
are equal, -1 if src1_addr is lexicographically less than src2_addr,
|
|
and 1 if it is lexicographically greater. Do not compare more than
|
|
max_bytes bytes.
|
|
|
|
Undefined behavior will occur if the end of either 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 strncmp
|
|
will fetch ahead. Disallowing the fetch ahead would impose
|
|
a severe performance penalty.
|
|
|
|
Strategy:
|
|
|
|
Fetch and compare the strings by words and go to a character
|
|
comparison loop as soon as a pair of words differ. If the
|
|
words are equal up through either the exhaustion of max_bytes
|
|
or the presence of the null byte, return 0 (equality). Otherwise,
|
|
the character comparator will return -1 or 1 for inequality, or
|
|
0 if the differing byte is after the null byte or after the
|
|
exhaustion of max_bytes.
|
|
|
|
Tactics:
|
|
|
|
1) Do NOT try to fetch 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.
|
|
*/
|
|
|
|
.globl _strncmp
|
|
.globl __strncmp
|
|
.leafproc _strncmp,__strncmp
|
|
.align 2
|
|
|
|
_strncmp:
|
|
#ifndef __PIC
|
|
lda .Lrett,g14
|
|
#else
|
|
lda .Lrett-(.+8)(ip),g14
|
|
#endif
|
|
__strncmp:
|
|
mov g14,g13
|
|
ldconst 0,g14
|
|
cmpibge 0,g2,Lequal_exit # Lexit early if max_bytes <= 0
|
|
addo g2,g0,g2
|
|
.Lwloop:
|
|
cmpo g0,g2 # are max_bytes exhausted?
|
|
ld (g0), g5 # fetch word of source_1
|
|
bge Lequal_exit # Lexit (equality) if max_bytes exhausted
|
|
ld (g1), g3 # fetch word of source_2
|
|
addo 4,g0,g0 # post-increment source_1 ptr
|
|
scanbyte 0,g5 # is a null byte present?
|
|
addo 4,g1,g1 # post-increment source_1 ptr
|
|
be .Lcloop.a # perform char comparator if null byte found
|
|
cmpobe g5,g3,.Lwloop # perform char comparator if words are unequal
|
|
|
|
.Lcloop.a: subo 4,g0,g0 # adjust max_byte counter
|
|
ldconst 0xff,g4 # byte extraction mask
|
|
|
|
.Lcloop: and g4,g5,g7 # compare individual bytes
|
|
and g4,g3,g6
|
|
cmpobne g7,g6,.diff # if different, return -1 or 1
|
|
cmpo 0,g6 # they are equal. are they null?
|
|
shlo 8,g4,g4 # position mask to extract next byte
|
|
be Lequal_exit # if they are null, Lexit (equality)
|
|
addo 1,g0,g0 # is max_bytes exhausted?
|
|
cmpobl g0,g2,.Lcloop # if not, loop. if so, Lexit (equality)
|
|
|
|
Lequal_exit:
|
|
mov 0,g0
|
|
bx (g13)
|
|
.Lrett:
|
|
ret
|
|
.diff: bl .neg
|
|
mov 1,g0
|
|
bx (g13)
|
|
|
|
.neg: subi 1,0,g0
|
|
.Lexit:
|
|
bx (g13)
|
|
|
|
/* end of strncmp */
|