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Diffstat (limited to 'newlib/libc/machine/i960/memcmp.S')
| -rw-r--r-- | newlib/libc/machine/i960/memcmp.S | 128 |
1 files changed, 128 insertions, 0 deletions
diff --git a/newlib/libc/machine/i960/memcmp.S b/newlib/libc/machine/i960/memcmp.S new file mode 100644 index 00000000000..709eb2bdbb8 --- /dev/null +++ b/newlib/libc/machine/i960/memcmp.S @@ -0,0 +1,128 @@ +/******************************************************************************* + * + * 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 "memcmp.s" +#ifdef __PIC + .pic +#endif +#ifdef __PID + .pid +#endif +/* + * (c) copyright 1988,1993 Intel Corp., all rights reserved + */ +/* + procedure memcmp (optimized assembler version for the 80960K series) + + 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 iff + src1_addr is lexicographically less than src2_addr, and 1 iff it is + lexicographically greater. Do not compare more than max_bytes bytes. + + Undefined behavior will occur if the end of either source array + is in the last two words of the program's allocated memory space. + This is so because memcmp fetches ahead. Disallowing the fetch ahead + would impose a severe performance penalty. + + Strategy: + + Fetch the source strings by words and compare the words until either + a differing word is found or max_bytes is exhausted. In the former + case, move through the words to find the differing byte and return + plus or minus one, appropriately. In the latter case, return zero + (equality). + + 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 that would be necessary to assure alignment. This + is supported by the intuition that most source arrays (even more + true of most big source arrays) will be word aligned to begin with. + + 2) Rather than decrementing max_bytes to zero, I calculate the + address of the byte after the last byte of the source_1 array, and + quit when the source byte pointer passes that. +*/ + + .globl _memcmp + .globl __memcmp + .leafproc _memcmp,__memcmp + .align 2 + +_memcmp: +#ifndef __PIC + lda .Lrett,g14 +#else + lda .Lrett-(.+8)(ip),g14 +#endif +__memcmp: + mov g14,g13 # preserve return address + ldconst 0,g14 # conform to register conventions + cmpibge 0,g2,Lequal_exit # quit if max_bytes <= 0 + addo g0,g2,g2 # calculate byte addr of byte after last in src1 + +.Lwloop: + cmpo g0,g2 + ld (g0), g5 # fetch word of source_1 + bge Lequal_exit # quit (equal) if max_bytes exhausted + ld (g1), g3 # fetch word of source_2 + addo 4,g0,g0 # post-increment source_1 byte ptr + addo 4,g1,g1 # post-increment source_2 byte ptr + cmpobe g5,g3,.Lwloop # branch if source words are equal + + ldconst 0xff,g4 # byte extraction mask + subo 4,g0,g0 # back up src1 pointer + +.Lcloop: and g4,g5,g7 # extract and compare individual bytes + and g4,g3,g6 + cmpobne g7,g6,.diff # branch if they are different + shlo 8,g4,g4 # position mask for next extraction + addo 1,g0,g0 + cmpobl g0,g2,.Lcloop # quit if max_bytes is exhausted + +Lequal_exit: + mov 0,g0 + bx (g13) +.Lrett: + ret + +.diff: bl .neg # arrays differ at current byte. + /* return 1 or -1 appropriately */ + mov 1,g0 + bx (g13) +.neg: subi 1,0,g0 +.Lexit: + bx (g13) + +/* end or memcmp */ |