/*******************************************************************************
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/*******************************************************************************
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*
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*
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* Copyright (c) 1993 Intel Corporation
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* Copyright (c) 1993 Intel Corporation
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*
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*
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* Intel hereby grants you permission to copy, modify, and distribute this
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* Intel hereby grants you permission to copy, modify, and distribute this
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* software and its documentation. Intel grants this permission provided
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* software and its documentation. Intel grants this permission provided
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* that the above copyright notice appears in all copies and that both the
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* that the above copyright notice appears in all copies and that both the
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* copyright notice and this permission notice appear in supporting
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* copyright notice and this permission notice appear in supporting
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* documentation. In addition, Intel grants this permission provided that
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* documentation. In addition, Intel grants this permission provided that
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* you prominently mark as "not part of the original" any modifications
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* you prominently mark as "not part of the original" any modifications
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* made to this software or documentation, and that the name of Intel
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* made to this software or documentation, and that the name of Intel
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* Corporation not be used in advertising or publicity pertaining to
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* Corporation not be used in advertising or publicity pertaining to
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* distribution of the software or the documentation without specific,
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* distribution of the software or the documentation without specific,
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* written prior permission.
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* written prior permission.
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*
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*
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* Intel Corporation provides this AS IS, WITHOUT ANY WARRANTY, EXPRESS OR
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* Intel Corporation provides this AS IS, WITHOUT ANY WARRANTY, EXPRESS OR
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* IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY
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* IMPLIED, INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY
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* OR FITNESS FOR A PARTICULAR PURPOSE. Intel makes no guarantee or
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* OR FITNESS FOR A PARTICULAR PURPOSE. Intel makes no guarantee or
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* representations regarding the use of, or the results of the use of,
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* representations regarding the use of, or the results of the use of,
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* the software and documentation in terms of correctness, accuracy,
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* the software and documentation in terms of correctness, accuracy,
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* reliability, currentness, or otherwise; and you rely on the software,
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* reliability, currentness, or otherwise; and you rely on the software,
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* documentation and results solely at your own risk.
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* documentation and results solely at your own risk.
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*
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*
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* IN NO EVENT SHALL INTEL BE LIABLE FOR ANY LOSS OF USE, LOSS OF BUSINESS,
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* IN NO EVENT SHALL INTEL BE LIABLE FOR ANY LOSS OF USE, LOSS OF BUSINESS,
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* LOSS OF PROFITS, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES
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* LOSS OF PROFITS, INDIRECT, INCIDENTAL, SPECIAL OR CONSEQUENTIAL DAMAGES
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* OF ANY KIND. IN NO EVENT SHALL INTEL'S TOTAL LIABILITY EXCEED THE SUM
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* OF ANY KIND. IN NO EVENT SHALL INTEL'S TOTAL LIABILITY EXCEED THE SUM
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* PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER.
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* PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER.
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*
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*
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******************************************************************************/
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******************************************************************************/
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.file "memchr.s"
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.file "memchr.s"
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#ifdef __PIC
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#ifdef __PIC
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.pic
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.pic
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#endif
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#endif
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#ifdef __PID
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#ifdef __PID
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.pid
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.pid
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#endif
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#endif
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/*
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/*
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* (c) copyright 1988,1993 Intel Corp., all rights reserved
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* (c) copyright 1988,1993 Intel Corp., all rights reserved
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*/
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*/
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/*
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/*
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procedure memchr (optimized assembler version for the 80960K series)
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procedure memchr (optimized assembler version for the 80960K series)
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src_addr = memchr (src_addr, char, max_bytes)
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src_addr = memchr (src_addr, char, max_bytes)
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searching from src_addr for a span of max_bytes bytes, return a
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searching from src_addr for a span of max_bytes bytes, return a
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pointer to the first byte in the source array that contains the
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pointer to the first byte in the source array that contains the
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indicated char. Return null if the char is not found.
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indicated char. Return null if the char is not found.
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Undefined behavior will occur if the last byte of the source array
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Undefined behavior will occur if the last byte of the source array
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is in the last two words of the program's allocated memory space.
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is in the last two words of the program's allocated memory space.
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This is so because memchr fetches ahead. Disallowing the fetch
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This is so because memchr fetches ahead. Disallowing the fetch
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ahead would impose a severe performance penalty.
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ahead would impose a severe performance penalty.
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Strategy:
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Strategy:
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Fetch the source array by words and scanbyte the words for the
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Fetch the source array by words and scanbyte the words for the
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char until either a word with the byte is found or max_bytes is
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char until either a word with the byte is found or max_bytes is
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exhausted. In the former case, move through the word to find the
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exhausted. In the former case, move through the word to find the
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matching byte and return its memory address. In the latter case,
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matching byte and return its memory address. In the latter case,
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return zero (null).
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return zero (null).
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Tactics:
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Tactics:
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1) Do NOT try to fetch the words in a word aligned manner because,
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1) Do NOT try to fetch the words in a word aligned manner because,
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in my judgement, the performance degradation experienced due to
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in my judgement, the performance degradation experienced due to
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non-aligned accesses does NOT outweigh the time and complexity added
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non-aligned accesses does NOT outweigh the time and complexity added
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by the preamble that would be necessary to assure alignment. This
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by the preamble that would be necessary to assure alignment. This
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is supported by the intuition that most source arrays (even more
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is supported by the intuition that most source arrays (even more
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true of most big source arrays) will be word aligned to begin with.
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true of most big source arrays) will be word aligned to begin with.
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2) Rather than decrementing max_bytes to zero, I calculate the
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2) Rather than decrementing max_bytes to zero, I calculate the
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address of the byte after the last byte of the source array, and
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address of the byte after the last byte of the source array, and
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quit when the source byte pointer passes that. Refining, actually
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quit when the source byte pointer passes that. Refining, actually
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I calculate the address of the fifth byte after the last byte of
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I calculate the address of the fifth byte after the last byte of
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the source array, because the source byte pointer is ahead of the
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the source array, because the source byte pointer is ahead of the
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actual examination point due to fetch ahead.
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actual examination point due to fetch ahead.
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*/
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*/
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.globl _memchr
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.globl _memchr
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.globl __memchr
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.globl __memchr
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.leafproc _memchr, __memchr
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.leafproc _memchr, __memchr
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.align 2
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.align 2
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_memchr:
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_memchr:
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#ifndef __PIC
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#ifndef __PIC
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lda Lrett,g14
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lda Lrett,g14
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#else
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#else
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lda Lrett-(.+8)(ip),g14
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lda Lrett-(.+8)(ip),g14
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#endif
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#endif
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__memchr:
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__memchr:
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mov g14,g13 # preserve return address
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mov g14,g13 # preserve return address
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lda 0xff,g7 # byte extraction mask
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lda 0xff,g7 # byte extraction mask
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and g1,g7,g1 # make char an 8-bit ordinal
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and g1,g7,g1 # make char an 8-bit ordinal
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mov 0,g14 # conform to register linkage standard
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mov 0,g14 # conform to register linkage standard
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cmpibge 0,g2,Lnot_found # do nothing if max_bytes <= 0
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cmpibge 0,g2,Lnot_found # do nothing if max_bytes <= 0
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addo 4,g0,g6 # post-increment src word pointer
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addo 4,g0,g6 # post-increment src word pointer
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addo g2,g6,g2 # compute ending address from start and len
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addo g2,g6,g2 # compute ending address from start and len
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ld (g0),g4 # fetch first word
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ld (g0),g4 # fetch first word
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shlo 8,g1,g3 # broadcast the char to four bytes
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shlo 8,g1,g3 # broadcast the char to four bytes
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or g1,g3,g3
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or g1,g3,g3
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shlo 16,g3,g5
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shlo 16,g3,g5
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or g3,g5,g3
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or g3,g5,g3
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Lsearch_for_word_with_char:
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Lsearch_for_word_with_char:
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mov g4,g5 # keep a copy of word
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mov g4,g5 # keep a copy of word
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scanbyte g3,g5 # check for byte with char
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scanbyte g3,g5 # check for byte with char
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ld (g6),g4 # fetch next word of src
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ld (g6),g4 # fetch next word of src
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bo Lsearch_for_char # branch if null found
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bo Lsearch_for_char # branch if null found
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addo 4,g6,g6 # post-increment src word pointer
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addo 4,g6,g6 # post-increment src word pointer
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cmpobge g2,g6,Lsearch_for_word_with_char # branch if max_bytes > 3
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cmpobge g2,g6,Lsearch_for_word_with_char # branch if max_bytes > 3
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Lnot_found:
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Lnot_found:
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mov 0,g0 # char not found. Return null
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mov 0,g0 # char not found. Return null
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bx (g13) # g0 = addr of char in src (or null); g14 = 0
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bx (g13) # g0 = addr of char in src (or null); g14 = 0
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Lrett:
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Lrett:
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ret
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ret
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Lsearch_for_char:
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Lsearch_for_char:
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cmpobe.f g6,g2,Lnot_found # quit if max_bytes exhausted
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cmpobe.f g6,g2,Lnot_found # quit if max_bytes exhausted
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and g5,g7,g0 # extract byte
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and g5,g7,g0 # extract byte
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cmpo g1,g0 # is it char?
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cmpo g1,g0 # is it char?
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addo 1,g6,g6 # bump src byte ptr
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addo 1,g6,g6 # bump src byte ptr
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shro 8,g5,g5 # shift word to position next byte
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shro 8,g5,g5 # shift word to position next byte
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bne.t Lsearch_for_char
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bne.t Lsearch_for_char
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subo 5,g6,g0 # back up the byte pointer
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subo 5,g6,g0 # back up the byte pointer
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bx (g13)
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bx (g13)
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/* end of memchr */
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/* end of memchr */
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