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[/] [openrisc/] [trunk/] [gnu-old/] [newlib-1.17.0/] [newlib/] [libc/] [machine/] [i960/] [strncat_ca.S] - Rev 148
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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 "sncat_ca.s"
#ifdef __PIC
.pic
#endif
#ifdef __PID
.pid
#endif
/*
* (c) copyright 1988,1993 Intel Corp., all rights reserved
*/
/*
procedure strncat (optimized assembler version for the CA)
dest_addr = strncat (dest_addr, src_addr, max_bytes)
append the null terminated string pointed to by src_addr to the null
terminated string pointed to by dest_addr. Return the original
dest_addr. If the source string is longer than max_bytes, then
append only max_bytes bytes, and tack on a null byte on the end
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, strncat
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 max_bytes
g3 src ptr (word aligned)
g4 dest ptr (word aligned)
g5 0xff -- byte extraction mask
Little endian:
g6 lsw of double word for extraction of 4 bytes
g7 msw of double word for extraction of 4 bytes
Big endian:
g6 msw of double word for extraction of 4 bytes
g7 lsw of double word for extraction of 4 bytes
g13 return address
g14 byte extracted.
*/
#if __i960_BIG_ENDIAN__
#define MSW g6
#define LSW g7
#else
#define LSW g6
#define MSW g7
#endif
.globl _strncat
.globl __strncat
.leafproc _strncat, __strncat
.align 2
_strncat:
#ifndef __PIC
lda Lrett,g14
#else
lda Lrett-(.+8)(ip),g14
#endif
__strncat:
notand g0,3,g4 # extract word addr of start of dest
lda (g14),g13 # preserve return address
cmpibge.f 0,g2,Lexit_code # Lexit if number of bytes to move is <= zero.
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
#else
shlo g14,LSW,LSW # get mask for bytes needed from first word
#endif
notor MSW,LSW,MSW # set unneeded bytes to all ones
lda 0xff,g5 # byte extraction mask
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
#if __i960_BIG_ENDIAN__
shro 24,LSW,g14 # extract byte
#else
and g5,LSW,g14 # extract byte
#endif
cmpo 0,g14 # branch if null is first byte of word
subo 4,g4,g4 # move dest word ptr to word with null
notand g1,3,g3 # extract word addr of start of src
bne.t Lsearch_for_null
Lcase_14:
cmpo g1,g3 # check alignment of source
ld (g3),LSW # fetch first word of source
shlo 3,g1,g14 # compute shift count
lda 4(g3),g3 # post-increment src addr
bne.f Lcase_4 # branch if source is unaligned
Lcase_1:
Lcase_1_wloop: # word copying loop
cmpi g2,4 # check for fewer than four bytes to move
lda (LSW),g1 # keep a copy of the src word
bl.f Lcase_1_cloop # branch if fewer than four bytes to copy
scanbyte 0,g1 # check for null byte in src word
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
subi 4,g2,g2 # decrease max_byte count by the 4 bytes moved
st g1,(g4) # store word in dest string
addo 4,g4,g4 # post-increment dest addr
b Lcase_1_wloop
Lcase_3_cloop:
Lcase_1_cloop: # character copying loop (max_bytes <= 3)
cmpdeci 0,g2,g2 # is max_bytes exhausted?
#if __i960_BIG_ENDIAN__
rotate 8,g1,g1 # move next byte into position for extraction
#endif
and g5,g1,g14 # extract next char
be.f Lstore_null # if max_bytes is exhausted, store null and quit
cmpo 0,g14 # check for null byte
stob g14,(g4) # store the byte in dest
#if ! __i960_BIG_ENDIAN__
shro 8,g1,g1 # move next byte into position for extraction
#endif
lda 1(g4),g4 # post-increment dest byte addr
bne.t Lcase_1_cloop # branch if null not reached
bx (g13) # Lexit (g14 == 0)
Lstore_null:
mov 0,g14 # store null, and set g14 to zero
stob g14,(g4)
bx (g13)
Lsearch_for_null:
#if __i960_BIG_ENDIAN__
shlo 8,LSW,LSW # check next byte
shro 24,LSW,g14
#else
shlo 8,g5,g5 # move mask up to next byte
and g5,LSW,g14 # extract byte
#endif
lda 1(g4),g4 # move dest byte ptr to next byte
cmpobne.t 0,g14,Lsearch_for_null # branch if null is not yet found
Lcase_235:
cmpo g1,g3 # check alignment of src
ld (g3),LSW # pre-fetch word with start of src
and 3,g1,g1 # compute shift count
lda 0xff,g5 # load mask for byte extraction
shlo 3,g1,g14
lda 4(g3),g3 # post-increment src word counter
be.t Lcase_3 # branch if src is word aligned
and g4,3,MSW # extract byte offset for dest string
cmpo MSW,g1 # < indicates first word of dest has more bytes
/* than first word of source. */
ld (g3),MSW # fetch second word of src
#if __i960_BIG_ENDIAN__
subo g14,0,g14 # adjust shift count for big endian
#endif
eshro g14,g6,g5 # extract four bytes
#if __i960_BIG_ENDIAN__
bge.f 1f
#else
bg.f 1f
#endif
mov MSW,LSW
lda 4(g3),g3 # move src word addr to second word boundary
1:
mov g5,MSW
lda 0xff,g5
b Lcase_25
Lcase_3: # src is word aligned; dest is not
mov LSW,MSW # make copy of first word of src
lda 32,g14 # initialize shift count to zero (mod 32)
Lcase_25:
Lcase_3_cloop_at_start: # character copying loop for start of dest str
cmpdeci 0,g2,g2 # is max_bytes exhausted?
#if __i960_BIG_ENDIAN__
shro 24,MSW,g5 # extract next char
#else
and g5,MSW,g5 # extract next char
#endif
be.f Lstore_null # Lexit if max_bytes is exhausted
cmpo 0,g5 # check for null byte
stob g5,(g4) # store the byte in dest
addo 1,g4,g4 # post-increment dest ptr
lda 0xff,g5 # re-initialize byte extraction mask
notand g4,3,g1 # extract word address
be.t Lexit_code # Lexit if null byte reached
cmpo g1,g4 # have we reached word boundary in dest yet?
#if __i960_BIG_ENDIAN__
lda -8(g14),g14 # augment the shift counter
rotate 8,MSW,MSW # move next byte into position for extraction
#else
lda 8(g14),g14 # augment the shift counter
shro 8,MSW,MSW # move next byte into position for extraction
#endif
bne.t Lcase_3_cloop_at_start # branch if reached word boundary?
#if __i960_BIG_ENDIAN__
cmpo 0,g14
ld (g3),MSW # fetch msw of operand for double shift
bne Lcase_3_wloop # branch if src is still unaligned.
Lcase_3_wloop2:
cmpi g2,4 # less than four bytes to move?
mov LSW,g1 # extract 4 bytes of src
lda 4(g3),g3 # post-increment src word addr
bl.f Lcase_3_cloop # branch if < four bytes left to move
scanbyte 0,g1 # check for null byte
mov 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
subi 4,g2,g2 # decrease max_byte count by the 4 bytes moved
st g1,(g4) # store 4 bytes to dest
addo 4,g4,g4 # post-increment dest ptr
b Lcase_3_wloop2
Lcase_4:
subo g14,0,g14 # adjust shift count for big endian
#else
Lcase_4:
#endif
ld (g3),MSW # fetch msw of operand for double shift
Lcase_3_wloop:
cmpi g2,4 # less than four bytes to move?
eshro g14,g6,g1 # extract 4 bytes of src
lda 4(g3),g3 # post-increment src word addr
bl.f Lcase_3_cloop # branch if < four bytes left to move
scanbyte 0,g1 # check for null byte
mov 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
subi 4,g2,g2 # decrease max_byte count by the 4 bytes moved
st g1,(g4) # store 4 bytes to dest
addo 4,g4,g4 # post-increment dest ptr
b Lcase_3_wloop
Lexit_code:
mov 0,g14 # conform to register conventions
bx (g13) # g0 = addr of dest; g14 = 0
Lrett:
ret
/* end of strncat */
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