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285 lines
9.7 KiB
ArmAsm
285 lines
9.7 KiB
ArmAsm
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/*******************************************************************************
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*
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* Copyright (c) 1993 Intel Corporation
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*
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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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* 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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* 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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* 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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* distribution of the software or the documentation without specific,
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* written prior permission.
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*
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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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* 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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* 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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* documentation and results solely at your own risk.
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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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* 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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* PAID TO INTEL FOR THE PRODUCT LICENSED HEREUNDER.
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*
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******************************************************************************/
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.file "strcp_ca.s"
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#ifdef __PIC
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.pic
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#endif
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#ifdef __PID
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.pid
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#endif
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/*
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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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procedure strcpy (optimized assembler version for the CA)
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dest_addr = strcpy (dest_addr, src_addr)
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copy the null terminated string pointed to by src_addr to
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the string space pointed to by dest_addr. Return the original
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dest_addr.
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This routine will fail if the source and destination string
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overlap (in particular, if the end of the source is overlapped
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by the beginning of the destination). The behavior is undefined.
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This is acceptable according to the draft C standard.
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Undefined behavior will also occur if the end of the source string
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(i.e. the terminating null byte) is in the last word of the program's
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allocated memory space. This is so because, in several cases, strcpy
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will fetch ahead one word. Disallowing the fetch ahead would impose
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a severe performance penalty.
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This program handles five cases:
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1) both arguments start on a word boundary
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2) neither are word aligned, but they are offset by the same amount
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3) source is word aligned, destination is not
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4) destination is word aligned, source is not
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5) neither is word aligned, and they are offset by differing amounts
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At the time of this writing, only g0 thru g7 and g13 are available
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for use in this leafproc; other registers would have to be saved and
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restored. These nine registers, plus tricky use of g14 are sufficient
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to implement the routine. The registers are used as follows:
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g0 original dest ptr; not modified, so that it may be returned.
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g1 src ptr; shift count
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g2 dest ptr; 4 bytes of src
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g3 src ptr (word aligned)
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g4 dest ptr (word aligned)
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g5 0xff -- byte extraction mask
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g6 lsw of double word for extraction of 4 bytes (little endian)
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msw of double word for extraction of 4 bytes (big endian)
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g7 msw of double word for extraction of 4 bytes (little endian)
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lsw of double word for extraction of 4 bytes (big endian)
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g13 return address
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g14 byte extracted. When reaches null byte, which is zero, we will
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be in conformance with register conventions, and can return to
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the caller with a clear conscience.
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procedure strcat
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dest_addr = strcat (dest_addr, src_addr)
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Appends the string pointed to by src_addr to the string pointed
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to by dest_addr. The first character of the source string is
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copied to the location initially occupied by the trailing null
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byte of the destination string. Thereafter, characters are copied
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from the source to the destination up thru the null byte that
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trails the source string.
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*/
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#if __i960_BIG_ENDIAN__
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#define MSW g6
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#define LSW g7
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#else
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#define LSW g6
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#define MSW g7
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#endif
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.globl _strcpy, _strcat
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.globl __strcpy, __strcat
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.leafproc _strcpy, __strcpy
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.leafproc _strcat, __strcat
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.align 2
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_strcat:
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#ifndef __PIC
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lda Lrett,g14
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#else
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lda Lrett-(.+8)(ip),g14
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#endif
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__strcat:
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notand g0,3,g4 # extract word addr of start of dest
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lda (g14),g13 # preserve return address
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and g0,3,LSW # extract byte offset of dest
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ld (g4),MSW # fetch word containing at least first byte
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shlo 3,LSW,g14 # get shift count for making mask for first word
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subi 1,0,LSW # mask initially all ones
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#if __i960_BIG_ENDIAN__
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shro g14,LSW,LSW # get mask for bytes needed from first word
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lda 0xff000000,g5 # byte extraction mask
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#else
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shlo g14,LSW,LSW # get mask for bytes needed from first word
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lda 0xff,g5 # byte extraction mask
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#endif
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notor MSW,LSW,MSW # set unneeded bytes to all ones
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Lsearch_for_word_with_null:
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scanbyte 0,MSW # check for null byte
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lda 4(g4),g4 # post-increment dest word pointer
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mov MSW,LSW # keep a copy of current word
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ld (g4),MSW # fetch next word of dest
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bno.t Lsearch_for_word_with_null # branch if null not found yet
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and g5,LSW,g14 # extract byte
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cmpo 0,g14 # branch if null is first byte of word
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subo 4,g4,g4 # move dest word ptr back to word with null
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notand g1,3,g3 # extract word addr of start of src
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lda (g4),g2 # set dest byte ptr to 1st byte of word w/ null
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be.f Lcase_14
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Lsearch_for_null:
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#if __i960_BIG_ENDIAN__
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shro 8,g5,g5 # move mask down to next byte
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#else
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shlo 8,g5,g5 # move mask up to next byte
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#endif
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lda 1(g2),g2 # move dest byte ptr to next byte
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and g5,LSW,g14 # extract byte
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cmpobne.t 0,g14,Lsearch_for_null # branch if null is not yet found
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lda 0xff,g5 # byte extraction mask
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b Lcase_235.a
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_strcpy:
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#ifndef __PIC
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lda Lrett,g14
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#else
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lda Lrett-(.+8)(ip),g14
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#endif
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__strcpy:
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notand g0,3,g4 # extract word addr of start of dest
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lda (g14),g13 # preserve return address
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cmpo g0,g4 # check alignment of dest
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lda 0xff,g5 # load mask for byte extraction
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notand g1,3,g3 # extract word addr of start of src
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bne.f Lcase_235 # branch if dest is NOT word aligned
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Lcase_14:
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cmpo g3,g1 # check alignment of src
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ld (g3),LSW # fetch word containing at least first byte
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shlo 3,g1,g1 # compute shift count
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lda 4(g3),g3 # advance src word addr
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#if __i960_BIG_ENDIAN__
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lda 0xff,g5 # byte extraction mask
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#endif
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bne.f Lcase_4 # branch if src is NOT word aligned
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Lcase_1: # src and dest are word aligned
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subo 4,g4,g4 # store is pre-incrementing; back up dest addr
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Lcase_1_wloop: # word copying loop
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scanbyte 0,LSW # check for null byte in src word
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lda (LSW),g2 # keep a copy of the src word
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addo 4,g4,g4 # pre-increment dest addr
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ld (g3),LSW # pre-fetch next word of src
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addo 4,g3,g3 # post-increment src addr
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bo.f Lcase_1_cloop # branch if word contains null byte
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st g2,(g4) # store word in dest string
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b Lcase_1_wloop
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Lcase_3_cloop:
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Lcase_1_cloop: # character copying loop
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#if __i960_BIG_ENDIAN__
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rotate 8,g2,g2 # move next byte into position for extraction
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and g5,g2,g14 # extract next char
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#else
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and g5,g2,g14 # extract next char
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shro 8,g2,g2 # move next byte into position for extraction
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#endif
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cmpo 0,g14 # check for null byte
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stob g14,(g4) # store the byte in dest
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lda 1(g4),g4 # post-increment dest byte addr
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bne.t Lcase_1_cloop # branch if null not reached
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Lexit_code:
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bx (g13) # g0 = addr of dest; g14 = 0
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Lrett:
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ret
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Lcase_3: # src is word aligned; dest is not
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addo 4,g4,g4 # move dest word ptr to first word boundary
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mov LSW,MSW # make copy of first word of src
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lda 0,g1 # initialize shift count to zero
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Lcase_25:
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Lcase_3_cloop_at_start: # character copying loop for start of dest str
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#if __i960_BIG_ENDIAN__
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rotate 8,MSW,MSW # move next byte into position for extraction
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and g5,MSW,g14 # extract next char
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#else
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and g5,MSW,g14 # extract next char
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shro 8,MSW,MSW # move next byte into position for extraction
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#endif
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cmpo 0,g14 # check for null byte
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stob g14,(g2) # store the byte in dest
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lda 1(g2),g2 # post-increment dest ptr
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be.f Lexit_code # branch if null byte reached
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cmpo g2,g4 # have we reached word boundary in dest?
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lda 8(g1),g1 # augment the shift counter
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bne.t Lcase_3_cloop_at_start
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Lcase_4:
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ld (g3),MSW # fetch msw of operand for double shift
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#if __i960_BIG_ENDIAN__
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subo g1,0,g1 # Adjust shift count for big endian.
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#endif
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Lcase_3_wloop:
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eshro g1,g6,g2 # extract 4 bytes of src
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lda 4(g3),g3 # post-increment src word addr
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scanbyte 0,g2 # check for null byte
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lda (MSW),LSW # move msw to lsw
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ld (g3),MSW # pre-fetch msw of operand for double shift
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bo.f Lcase_3_cloop # branch if word contains null byte
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st g2,(g4) # store 4 bytes to dest
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addo 4,g4,g4 # post-increment dest ptr
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b Lcase_3_wloop
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Lcase_235:
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lda (g0),g2 # copy dest ptr
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Lcase_235.a:
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cmpo g3,g1 # check alignment of src
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ld (g3),LSW # fetch word containing at least first byte
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and 3,g1,g14 # compute shift count
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lda 4(g3),g3 # advance src word addr
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shlo 3,g14,g1
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be.t Lcase_3 # branch if dest is word aligned
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or g4,g14,g14 # is src earlier in word, later, or sync w/ dst
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ld (g3),MSW # pre-fetch second half
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cmpo g2,g14 # < indicates first word of dest has more bytes
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lda 4(g4),g4 # move dest word addr to first word boundary
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/* than first word of source. */
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#if __i960_BIG_ENDIAN__
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subo g1,0,g14 # Adjust shift count for big endian.
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eshro g14,g6,g14 # extract four bytes
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bge.f 1f
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#else
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eshro g1,g6,g14 # extract four bytes
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bg.f 1f
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#endif
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mov MSW,LSW
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lda 4(g3),g3 # move src word addr to second word boundary
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1:
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mov g14,MSW
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b Lcase_25
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/* end of strcpy */
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