diff options
Diffstat (limited to 'newlib/libc/machine/i960/strncmp.S')
| -rw-r--r-- | newlib/libc/machine/i960/strncmp.S | 129 |
1 files changed, 129 insertions, 0 deletions
diff --git a/newlib/libc/machine/i960/strncmp.S b/newlib/libc/machine/i960/strncmp.S new file mode 100644 index 00000000000..030b75084af --- /dev/null +++ b/newlib/libc/machine/i960/strncmp.S @@ -0,0 +1,129 @@ +/******************************************************************************* + * + * 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 */ |