/******************************************************************************* * * 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 "sncmp_ca.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 CA) result = strncmp (src1_addr, src2_addr, max_bytes) compare the null terminated string pointed to by src1_addr to the string space pointed to by src2_addr. Return 0 iff the strings 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 string (i.e. the terminating null byte) is in the last word of the program's allocated memory space. This is so because, in several cases, strncmp 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; 0xff -- byte 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 _strncmp .globl __strncmp .leafproc _strncmp, __strncmp .align 2 _strncmp: #ifndef __PIC lda Lrett,g14 #else lda Lrett-(.+8)(ip),g14 #endif __strncmp: Lrestart: notand g0,3,SRC1 # extract word addr of start of src1 lda (g14),g13 # preserve return address cmpibge.f 0,g2,Lequal_exit # return equality if number of bytes to /* compare is none. */ #if __i960_BIG_ENDIAN__ cmpo g0,SRC1 # check alignment of src1 #endif ld (SRC1),LSW # fetch word with at least first byte of src1 notand g1,3,g3 # extract word addr of start of src2 ld 4(SRC1),MSW # fetch second word of src1 #if __i960_BIG_ENDIAN__ bne Lsrc1_unaligned # branch if src1 is unaligned cmpo g3,g1 # check alignment of src2 ld (g3),SRC2 # fetch word with at least first byte of src2 shlo 3,g0,g14 # compute shift count for src1 subo g14,0,g14 # adjust shift count for big endian lda 8(SRC1),SRC1 # advance src1 word addr bne.f Lsrc2_unaligned # branch if src2 is NOT word aligned /* src2 is word aligned */ mov LSW,g0 Lwloop2: # word comparing loop cmpo SRC2,g0 # compare src1 and src2 words lda 0xff000000,g1 # byte extraction mask mov MSW,LSW # move msw of src1 to lsw ld (SRC1),MSW # pre-fetch next msw of src1 addo 4,SRC1,SRC1 # post-increment src1 addr lda 4(g3),g3 # pre-increment src2 addr bne.f Lcloop # branch if src1 and src2 unequal scanbyte 0,g0 # check for null byte in src1 word ld (g3),SRC2 # pre-fetch next word of src2 mov LSW,g0 # extract word of src1 subi 4,g2,g2 # decrement maximum byte count bo.f Lequal_exit # branch if null byte encountered cmpibl.t 0,g2,Lwloop2 # branch if max_bytes not reached yet b Lequal_exit # strings were equal up through max_bytes Lsrc1_unaligned: #endif cmpo g3,g1 # check alignment of src2 ld (g3),SRC2 # fetch word with at least first byte of src2 shlo 3,g0,g14 # compute shift count for src1 #if __i960_BIG_ENDIAN__ subo g14,0,g14 # adjust shift count for big endian #endif 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 /* at least src2 is word aligned */ mov LSW,g0 Lwloop: # word comparing loop cmpo SRC2,g0 # compare src1 and src2 words #if __i960_BIG_ENDIAN__ lda 0xff000000,g1 # byte extraction mask #else lda 0xff,g1 # byte extraction mask #endif mov MSW,LSW # move msw of src1 to lsw ld (SRC1),MSW # pre-fetch next msw of src1 addo 4,SRC1,SRC1 # post-increment src1 addr lda 4(g3),g3 # pre-increment src2 addr bne.f Lcloop # branch if src1 and src2 unequal scanbyte 0,g0 # check for null byte in src1 word ld (g3),SRC2 # pre-fetch next word of src2 eshro g14,g4,g0 # extract word of src1 subi 4,g2,g2 # decrement maximum byte count bo.f Lequal_exit # branch if null byte encountered cmpibl.t 0,g2,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 #if __i960_BIG_ENDIAN__ lda 0xff000000,g1 # byte extraction mask #else lda 0xff,g1 # byte extraction mask #endif Lcloop: # character comparing loop 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 cmpo 0,LSW # check for null byte #if __i960_BIG_ENDIAN__ shro 8,g1,g1 # shift mask for next byte #else shlo 8,g1,g1 # shift mask for next byte #endif subi 1,g2,g2 # decrement character counter bne.t Lcloop # branch if null not reached /* words are equal up thru null byte */ Lequal_exit: mov 0,g14 # conform to register conventions lda 0,g0 # return zero, indicating equality bx (g13) # return Lrett: ret .diff: mov 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 # adjust shift count for big endian #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 scanbyte 0,LSW # check for null byte 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 bno.t Lrestart # if null byte not encountered, continue /* with both string fetches shifted such that*/ /* src2 is now word aligned.*/ mov 0,g14 # conform to register conventions. lda 0,g0 # return indicator of equality. bx (g13)