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[/] [openrisc/] [trunk/] [gnu-src/] [newlib-1.17.0/] [newlib/] [libc/] [machine/] [i960/] [strcpy_ca.S] - Rev 194
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/*******************************************************************************
*
* 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 "strcp_ca.s"
#ifdef __PIC
.pic
#endif
#ifdef __PID
.pid
#endif
/*
* (c) copyright 1988,1993 Intel Corp., all rights reserved
*/
/*
procedure strcpy (optimized assembler version for the CA)
dest_addr = strcpy (dest_addr, src_addr)
copy the null terminated string pointed to by src_addr to
the string space pointed to by dest_addr. Return the original
dest_addr.
This routine will fail if the source and destination string
overlap (in particular, if the end of the source is overlapped
by the beginning of the destination). The behavior is undefined.
This is acceptable according to the draft C standard.
Undefined behavior will also occur if the end of the source string
(i.e. the terminating null byte) is in the last word of the program's
allocated memory space. This is so because, in several cases, strcpy
will fetch ahead one word. Disallowing the fetch ahead would impose
a severe performance penalty.
This program handles five cases:
1) both arguments start on a word boundary
2) neither are word aligned, but they are offset by the same amount
3) source is word aligned, destination is not
4) destination is word aligned, source is not
5) neither is word aligned, and they are offset by differing amounts
At the time of this writing, only g0 thru g7 and g13 are available
for use in this leafproc; other registers would have to be saved and
restored. These nine registers, plus tricky use of g14 are sufficient
to implement the routine. The registers are used as follows:
g0 original dest ptr; not modified, so that it may be returned.
g1 src ptr; shift count
g2 dest ptr; 4 bytes of src
g3 src ptr (word aligned)
g4 dest ptr (word aligned)
g5 0xff -- byte extraction mask
g6 lsw of double word for extraction of 4 bytes (little endian)
msw of double word for extraction of 4 bytes (big endian)
g7 msw of double word for extraction of 4 bytes (little endian)
lsw of double word for extraction of 4 bytes (big endian)
g13 return address
g14 byte extracted. When reaches null byte, which is zero, we will
be in conformance with register conventions, and can return to
the caller with a clear conscience.
procedure strcat
dest_addr = strcat (dest_addr, src_addr)
Appends the string pointed to by src_addr to the string pointed
to by dest_addr. The first character of the source string is
copied to the location initially occupied by the trailing null
byte of the destination string. Thereafter, characters are copied
from the source to the destination up thru the null byte that
trails the source string.
*/
#if __i960_BIG_ENDIAN__
#define MSW g6
#define LSW g7
#else
#define LSW g6
#define MSW g7
#endif
.globl _strcpy, _strcat
.globl __strcpy, __strcat
.leafproc _strcpy, __strcpy
.leafproc _strcat, __strcat
.align 2
_strcat:
#ifndef __PIC
lda Lrett,g14
#else
lda Lrett-(.+8)(ip),g14
#endif
__strcat:
notand g0,3,g4 # extract word addr of start of dest
lda (g14),g13 # preserve return address
and g0,3,LSW # extract byte offset of dest
ld (g4),MSW # fetch word containing at least first byte
shlo 3,LSW,g14 # get shift count for making mask for first word
subi 1,0,LSW # mask initially all ones
#if __i960_BIG_ENDIAN__
shro g14,LSW,LSW # get mask for bytes needed from first word
lda 0xff000000,g5 # byte extraction mask
#else
shlo g14,LSW,LSW # get mask for bytes needed from first word
lda 0xff,g5 # byte extraction mask
#endif
notor MSW,LSW,MSW # set unneeded bytes to all ones
Lsearch_for_word_with_null:
scanbyte 0,MSW # check for null byte
lda 4(g4),g4 # post-increment dest word pointer
mov MSW,LSW # keep a copy of current word
ld (g4),MSW # fetch next word of dest
bno.t Lsearch_for_word_with_null # branch if null not found yet
and g5,LSW,g14 # extract byte
cmpo 0,g14 # branch if null is first byte of word
subo 4,g4,g4 # move dest word ptr back to word with null
notand g1,3,g3 # extract word addr of start of src
lda (g4),g2 # set dest byte ptr to 1st byte of word w/ null
be.f Lcase_14
Lsearch_for_null:
#if __i960_BIG_ENDIAN__
shro 8,g5,g5 # move mask down to next byte
#else
shlo 8,g5,g5 # move mask up to next byte
#endif
lda 1(g2),g2 # move dest byte ptr to next byte
and g5,LSW,g14 # extract byte
cmpobne.t 0,g14,Lsearch_for_null # branch if null is not yet found
lda 0xff,g5 # byte extraction mask
b Lcase_235.a
_strcpy:
#ifndef __PIC
lda Lrett,g14
#else
lda Lrett-(.+8)(ip),g14
#endif
__strcpy:
notand g0,3,g4 # extract word addr of start of dest
lda (g14),g13 # preserve return address
cmpo g0,g4 # check alignment of dest
lda 0xff,g5 # load mask for byte extraction
notand g1,3,g3 # extract word addr of start of src
bne.f Lcase_235 # branch if dest is NOT word aligned
Lcase_14:
cmpo g3,g1 # check alignment of src
ld (g3),LSW # fetch word containing at least first byte
shlo 3,g1,g1 # compute shift count
lda 4(g3),g3 # advance src word addr
#if __i960_BIG_ENDIAN__
lda 0xff,g5 # byte extraction mask
#endif
bne.f Lcase_4 # branch if src is NOT word aligned
Lcase_1: # src and dest are word aligned
subo 4,g4,g4 # store is pre-incrementing; back up dest addr
Lcase_1_wloop: # word copying loop
scanbyte 0,LSW # check for null byte in src word
lda (LSW),g2 # keep a copy of the src word
addo 4,g4,g4 # pre-increment dest addr
ld (g3),LSW # pre-fetch next word of src
addo 4,g3,g3 # post-increment src addr
bo.f Lcase_1_cloop # branch if word contains null byte
st g2,(g4) # store word in dest string
b Lcase_1_wloop
Lcase_3_cloop:
Lcase_1_cloop: # character copying loop
#if __i960_BIG_ENDIAN__
rotate 8,g2,g2 # move next byte into position for extraction
and g5,g2,g14 # extract next char
#else
and g5,g2,g14 # extract next char
shro 8,g2,g2 # move next byte into position for extraction
#endif
cmpo 0,g14 # check for null byte
stob g14,(g4) # store the byte in dest
lda 1(g4),g4 # post-increment dest byte addr
bne.t Lcase_1_cloop # branch if null not reached
Lexit_code:
bx (g13) # g0 = addr of dest; g14 = 0
Lrett:
ret
Lcase_3: # src is word aligned; dest is not
addo 4,g4,g4 # move dest word ptr to first word boundary
mov LSW,MSW # make copy of first word of src
lda 0,g1 # initialize shift count to zero
Lcase_25:
Lcase_3_cloop_at_start: # character copying loop for start of dest str
#if __i960_BIG_ENDIAN__
rotate 8,MSW,MSW # move next byte into position for extraction
and g5,MSW,g14 # extract next char
#else
and g5,MSW,g14 # extract next char
shro 8,MSW,MSW # move next byte into position for extraction
#endif
cmpo 0,g14 # check for null byte
stob g14,(g2) # store the byte in dest
lda 1(g2),g2 # post-increment dest ptr
be.f Lexit_code # branch if null byte reached
cmpo g2,g4 # have we reached word boundary in dest?
lda 8(g1),g1 # augment the shift counter
bne.t Lcase_3_cloop_at_start
Lcase_4:
ld (g3),MSW # fetch msw of operand for double shift
#if __i960_BIG_ENDIAN__
subo g1,0,g1 # Adjust shift count for big endian.
#endif
Lcase_3_wloop:
eshro g1,g6,g2 # extract 4 bytes of src
lda 4(g3),g3 # post-increment src word addr
scanbyte 0,g2 # check for null byte
lda (MSW),LSW # move msw to lsw
ld (g3),MSW # pre-fetch msw of operand for double shift
bo.f Lcase_3_cloop # branch if word contains null byte
st g2,(g4) # store 4 bytes to dest
addo 4,g4,g4 # post-increment dest ptr
b Lcase_3_wloop
Lcase_235:
lda (g0),g2 # copy dest ptr
Lcase_235.a:
cmpo g3,g1 # check alignment of src
ld (g3),LSW # fetch word containing at least first byte
and 3,g1,g14 # compute shift count
lda 4(g3),g3 # advance src word addr
shlo 3,g14,g1
be.t Lcase_3 # branch if dest is word aligned
or g4,g14,g14 # is src earlier in word, later, or sync w/ dst
ld (g3),MSW # pre-fetch second half
cmpo g2,g14 # < indicates first word of dest has more bytes
lda 4(g4),g4 # move dest word addr to first word boundary
/* than first word of source. */
#if __i960_BIG_ENDIAN__
subo g1,0,g14 # Adjust shift count for big endian.
eshro g14,g6,g14 # extract four bytes
bge.f 1f
#else
eshro g1,g6,g14 # extract four bytes
bg.f 1f
#endif
mov MSW,LSW
lda 4(g3),g3 # move src word addr to second word boundary
1:
mov g14,MSW
b Lcase_25
/* end of strcpy */
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