97 lines
2.4 KiB
ArmAsm
97 lines
2.4 KiB
ArmAsm
/* SPDX-License-Identifier: GPL-2.0 */
|
|
/*
|
|
* arch/alpha/lib/ev67-strncat.S
|
|
* 21264 version contributed by Rick Gorton <rick.gorton@api-networks.com>
|
|
*
|
|
* Append no more than COUNT characters from the null-terminated string SRC
|
|
* to the null-terminated string DST. Always null-terminate the new DST.
|
|
*
|
|
* This differs slightly from the semantics in libc in that we never write
|
|
* past count, whereas libc may write to count+1. This follows the generic
|
|
* implementation in lib/string.c and is, IMHO, more sensible.
|
|
*
|
|
* Much of the information about 21264 scheduling/coding comes from:
|
|
* Compiler Writer's Guide for the Alpha 21264
|
|
* abbreviated as 'CWG' in other comments here
|
|
* ftp.digital.com/pub/Digital/info/semiconductor/literature/dsc-library.html
|
|
* Scheduling notation:
|
|
* E - either cluster
|
|
* U - upper subcluster; U0 - subcluster U0; U1 - subcluster U1
|
|
* L - lower subcluster; L0 - subcluster L0; L1 - subcluster L1
|
|
* Try not to change the actual algorithm if possible for consistency.
|
|
*/
|
|
|
|
#include <asm/export.h>
|
|
.text
|
|
|
|
.align 4
|
|
.globl strncat
|
|
.ent strncat
|
|
strncat:
|
|
.frame $30, 0, $26
|
|
.prologue 0
|
|
|
|
mov $16, $0 # set up return value
|
|
beq $18, $zerocount # U :
|
|
/* Find the end of the string. */
|
|
ldq_u $1, 0($16) # L : load first quadword ($16 may be misaligned)
|
|
lda $2, -1($31) # E :
|
|
|
|
insqh $2, $0, $2 # U :
|
|
andnot $16, 7, $16 # E :
|
|
nop # E :
|
|
or $2, $1, $1 # E :
|
|
|
|
nop # E :
|
|
nop # E :
|
|
cmpbge $31, $1, $2 # E : bits set iff byte == 0
|
|
bne $2, $found # U :
|
|
|
|
$loop: ldq $1, 8($16) # L :
|
|
addq $16, 8, $16 # E :
|
|
cmpbge $31, $1, $2 # E :
|
|
beq $2, $loop # U :
|
|
|
|
$found: cttz $2, $3 # U0 :
|
|
addq $16, $3, $16 # E :
|
|
nop # E :
|
|
bsr $23, __stxncpy # L0 :/* Now do the append. */
|
|
|
|
/* Worry about the null termination. */
|
|
|
|
zapnot $1, $27, $2 # U : was last byte a null?
|
|
cmplt $27, $24, $5 # E : did we fill the buffer completely?
|
|
bne $2, 0f # U :
|
|
ret # L0 :
|
|
|
|
0: or $5, $18, $2 # E :
|
|
nop
|
|
bne $2, 2f # U :
|
|
and $24, 0x80, $3 # E : no zero next byte
|
|
|
|
nop # E :
|
|
bne $3, 1f # U :
|
|
/* Here there are bytes left in the current word. Clear one. */
|
|
addq $24, $24, $24 # E : end-of-count bit <<= 1
|
|
nop # E :
|
|
|
|
2: zap $1, $24, $1 # U :
|
|
nop # E :
|
|
stq_u $1, 0($16) # L :
|
|
ret # L0 :
|
|
|
|
1: /* Here we must clear the first byte of the next DST word */
|
|
stb $31, 8($16) # L :
|
|
nop # E :
|
|
nop # E :
|
|
ret # L0 :
|
|
|
|
$zerocount:
|
|
nop # E :
|
|
nop # E :
|
|
nop # E :
|
|
ret # L0 :
|
|
|
|
.end strncat
|
|
EXPORT_SYMBOL(strncat)
|