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Diffstat (limited to 'newlib/libc/machine/i960/memchr.S')
| -rw-r--r-- | newlib/libc/machine/i960/memchr.S | 130 |
1 files changed, 130 insertions, 0 deletions
diff --git a/newlib/libc/machine/i960/memchr.S b/newlib/libc/machine/i960/memchr.S new file mode 100644 index 0000000..e9a4e42 --- /dev/null +++ b/newlib/libc/machine/i960/memchr.S @@ -0,0 +1,130 @@ +/******************************************************************************* + * + * 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 "memchr.s" +#ifdef __PIC + .pic +#endif +#ifdef __PID + .pid +#endif +/* + * (c) copyright 1988,1993 Intel Corp., all rights reserved + */ + +/* + procedure memchr (optimized assembler version for the 80960K series) + + src_addr = memchr (src_addr, char, max_bytes) + + searching from src_addr for a span of max_bytes bytes, return a + pointer to the first byte in the source array that contains the + indicated char. Return null if the char is not found. + + Undefined behavior will occur if the last byte of the source array + is in the last two words of the program's allocated memory space. + This is so because memchr fetches ahead. Disallowing the fetch + ahead would impose a severe performance penalty. + + Strategy: + + Fetch the source array by words and scanbyte the words for the + char until either a word with the byte is found or max_bytes is + exhausted. In the former case, move through the word to find the + matching byte and return its memory address. In the latter case, + return zero (null). + + 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 array, and + quit when the source byte pointer passes that. Refining, actually + I calculate the address of the fifth byte after the last byte of + the source array, because the source byte pointer is ahead of the + actual examination point due to fetch ahead. +*/ + + .globl _memchr + .globl __memchr + .leafproc _memchr, __memchr + .align 2 +_memchr: +#ifndef __PIC + lda Lrett,g14 +#else + lda Lrett-(.+8)(ip),g14 +#endif +__memchr: + + mov g14,g13 # preserve return address + lda 0xff,g7 # byte extraction mask + and g1,g7,g1 # make char an 8-bit ordinal + mov 0,g14 # conform to register linkage standard + cmpibge 0,g2,Lnot_found # do nothing if max_bytes <= 0 + addo 4,g0,g6 # post-increment src word pointer + addo g2,g6,g2 # compute ending address from start and len + ld (g0),g4 # fetch first word + shlo 8,g1,g3 # broadcast the char to four bytes + or g1,g3,g3 + shlo 16,g3,g5 + or g3,g5,g3 + +Lsearch_for_word_with_char: + mov g4,g5 # keep a copy of word + scanbyte g3,g5 # check for byte with char + ld (g6),g4 # fetch next word of src + bo Lsearch_for_char # branch if null found + addo 4,g6,g6 # post-increment src word pointer + cmpobge g2,g6,Lsearch_for_word_with_char # branch if max_bytes > 3 + +Lnot_found: + mov 0,g0 # char not found. Return null + bx (g13) # g0 = addr of char in src (or null); g14 = 0 +Lrett: + ret + +Lsearch_for_char: + cmpobe.f g6,g2,Lnot_found # quit if max_bytes exhausted + and g5,g7,g0 # extract byte + cmpo g1,g0 # is it char? + addo 1,g6,g6 # bump src byte ptr + shro 8,g5,g5 # shift word to position next byte + bne.t Lsearch_for_char + subo 5,g6,g0 # back up the byte pointer + bx (g13) + +/* end of memchr */ |