diff options
Diffstat (limited to 'newlib/libc/machine/i960/strncmp_ca.S')
| -rw-r--r-- | newlib/libc/machine/i960/strncmp_ca.S | 253 |
1 files changed, 253 insertions, 0 deletions
diff --git a/newlib/libc/machine/i960/strncmp_ca.S b/newlib/libc/machine/i960/strncmp_ca.S new file mode 100644 index 0000000..0b1a8ff --- /dev/null +++ b/newlib/libc/machine/i960/strncmp_ca.S @@ -0,0 +1,253 @@ +/******************************************************************************* + * + * 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) |