/******************************************************************************* * * 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 "memcm_ca.s" #ifdef __PIC .pic #endif #ifdef __PID .pid #endif /* * (c) copyright 1988,1992,1993 Intel Corp., all rights reserved */ /* procedure memcmp (optimized assembler version for the CA) result = memcmp (src1_addr, src2_addr, max_bytes) compare the byte array pointed to by src1_addr to the byte array pointed to by src2_addr. Return 0 iff the arrays are equal, -1 if src1_addr is lexicly less than src2_addr, and 1 if it is lexicly greater. Do not compare more than max_bytes bytes. Undefined behavior will occur if the end of either source array is in the last word of the program's allocated memory space. This is so because, in several cases, memcmp will fetch ahead one word. Disallowing the fetch ahead would impose a severe performance penalty. This program handles five cases: 1) both arguments start on a word boundary 2) neither are word aligned, but they are offset by the same amount 3) source1 is word aligned, source2 is not 4) source2 is word aligned, source1 is not 5) neither is word aligned, and they are offset by differing amounts At the time of this writing, only g0 thru g7 and g14 are available for use in this leafproc; other registers would have to be saved and restored. These nine registers are sufficient to implement the routine. The registers are used as follows: g0 original src1 ptr; extracted word; return result g1 src2 ptr; byt extraction mask g2 maximum number of bytes to compare g3 src2 word ptr Little endian g4 lsw of src1 g5 msw of src1 g6 src2 word g7 src1 word ptr Big endian g4 msw of src1 g5 lsw of src1 g6 src1 word ptr g7 src2 word g13 return address g14 shift count */ #if __i960_BIG_ENDIAN__ #define MSW g4 #define LSW g5 #define SRC1 g6 #define SRC2 g7 #else #define LSW g4 #define MSW g5 #define SRC2 g6 #define SRC1 g7 #endif .globl _memcmp .globl __memcmp .leafproc _memcmp, __memcmp .align 2 _memcmp: #ifndef __PIC lda Lrett,g14 #else lda Lrett-(.+8)(ip),g14 #endif __memcmp: Lrestart: #if __i960_BIG_ENDIAN__ subo 1,g0,SRC1 notand SRC1,3,SRC1 # extract word addr of start of src1 #else notand g0,3,SRC1 # extract word addr of start of src1 #endif lda (g14),g13 # preserve return address cmpibge.f 0,g2,Lequal_exit # return equality if number bytes 0 notand g1,3,g3 # extract word addr of start of src2 ld (SRC1),LSW # fetch word with at least first byte of src1 cmpo g3,g1 # check alignment of src2 ld 4(SRC1),MSW # fetch second word of src1 shlo 3,g0,g14 # compute shift count for src1 #if __i960_BIG_ENDIAN__ subo g14,0,g14 # adjust shift count for big endian. #endif ld (g3),SRC2 # fetch word with at least first byte of src2 eshro g14,g4,LSW # extract word of src1 lda 8(SRC1),SRC1 # advance src1 word addr bne.f Lsrc2_unaligned # branch if src2 is NOT word aligned mov LSW,g0 # at least src2 is word aligned lda 0xff,g1 Lwloop: # word comparing loop cmpo SRC2,g0 # compare src1 and src2 words lda 4(g3),g3 # pre-increment src2 addr mov MSW,LSW # move msw of src1 to lsw ld (SRC1),MSW # pre-fetch next msw of src1 subi 4,g2,g2 # decrement maximum byte count bne.f Lcloop # branch if src1 and src2 unequal cmpi 0,g2 ld (g3),SRC2 # pre-fetch next word of src2 eshro g14,g4,g0 # extract word of src1 lda 4(SRC1),SRC1 # post-increment src1 addr bl.t Lwloop # branch if max_bytes not reached yet b Lequal_exit # strings were equal up through max_bytes Lcloop_setup: # setup for coming from Lsrc2_unaligned mov LSW,g0 # restore extracted src1 word subo 4,g2,g2 # make up for later re-incrementing lda 0xff,g1 # byte extraction mask Lcloop: # character comparing loop #if __i960_BIG_ENDIAN__ rotate 24,g1,g1 # shift mask for next byte #endif and SRC2,g1,g3 # extract next char of src2 and g0,g1,LSW # extract next char of src1 cmpobne.f LSW,g3,.diff # check for equality #if ! __i960_BIG_ENDIAN__ shlo 8,g1,g1 # shift mask for next byte #endif subi 1,g2,g2 # decrement character counter b Lcloop # branch if null not reached Lequal_exit: # words are equal up thru null byte mov 0,g14 # conform to register conventions lda 0,g0 # return zero, indicating equality bx (g13) # return Lrett: ret .diff: addo 4,g2,g2 # to make up for extra decrement in loop lda 0,g14 bl Lless_than_exit Lgreater_than_exit: cmpibge.f 0,g2,Lequal_exit # branch if difference is beyond max_bytes mov 1,g0 bx (g13) # g0 = 1 (src1 > src2) Lless_than_exit: cmpibge.f 0,g2,Lequal_exit # branch if difference is beyond max_bytes subi 1,0,g0 bx (g13) # g0 = -1 (src1 < src2) Lsrc2_unaligned: notor g1,3,g14 # first step in computing new src1 ptr ld 4(g3),SRC1 # fetch second word of src2 shlo 3,g1,MSW # compute shift count for src2 #if __i960_BIG_ENDIAN__ subo MSW,0,MSW #endif eshro MSW,g6,SRC2 # extract word of src2 cmpo LSW,SRC2 # compare src1 and src2 words lda 4(g3),g1 # set new src2 ptr bne.f Lcloop_setup # first four bytes differ subo g14,g0,g0 # second (final) step in computing new src1 ptr addi g14,g2,g2 # compute new max_bytes too lda (g13),g14 # prepare return pointer for Lrestart b Lrestart # continue with both string fetches shifted