mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-30 00:31:08 +00:00
111 lines
3.1 KiB
ArmAsm
111 lines
3.1 KiB
ArmAsm
/* Copyright (C) 1996, 1997, 1998 Free Software Foundation, Inc.
|
|
Contributed by Richard Henderson (rth@tamu.edu)
|
|
This file is part of the GNU C Library.
|
|
|
|
The GNU C Library is free software; you can redistribute it and/or
|
|
modify it under the terms of the GNU Lesser General Public
|
|
License as published by the Free Software Foundation; either
|
|
version 2.1 of the License, or (at your option) any later version.
|
|
|
|
The GNU C Library is distributed in the hope that it will be useful,
|
|
but WITHOUT ANY WARRANTY; without even the implied warranty of
|
|
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
|
|
Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public
|
|
License along with the GNU C Library. If not, see
|
|
<http://www.gnu.org/licenses/>. */
|
|
|
|
/* Fill a block of memory with zeros. Optimized for the Alpha architecture:
|
|
|
|
- memory accessed as aligned quadwords only
|
|
- destination memory not read unless needed for good cache behaviour
|
|
- basic blocks arranged to optimize branch prediction for full-quadword
|
|
aligned memory blocks.
|
|
- partial head and tail quadwords constructed with byte-mask instructions
|
|
|
|
This is generally scheduled for the EV5 (got to look out for my own
|
|
interests :-), but with EV4 needs in mind. There *should* be no more
|
|
stalls for the EV4 than there are for the EV5.
|
|
*/
|
|
|
|
|
|
#include <sysdep.h>
|
|
|
|
.set noat
|
|
.set noreorder
|
|
|
|
.text
|
|
.type __bzero, @function
|
|
.globl __bzero
|
|
.usepv __bzero, USEPV_PROF
|
|
|
|
cfi_startproc
|
|
|
|
/* On entry to this basic block:
|
|
t3 == loop counter
|
|
t4 == bytes in partial final word
|
|
a0 == possibly misaligned destination pointer */
|
|
|
|
.align 3
|
|
bzero_loop:
|
|
beq t3, $tail #
|
|
blbc t3, 0f # skip single store if count even
|
|
|
|
stq_u zero, 0(a0) # e0 : store one word
|
|
subq t3, 1, t3 # .. e1 :
|
|
addq a0, 8, a0 # e0 :
|
|
beq t3, $tail # .. e1 :
|
|
|
|
0: stq_u zero, 0(a0) # e0 : store two words
|
|
subq t3, 2, t3 # .. e1 :
|
|
stq_u zero, 8(a0) # e0 :
|
|
addq a0, 16, a0 # .. e1 :
|
|
bne t3, 0b # e1 :
|
|
|
|
$tail: bne t4, 1f # is there a tail to do?
|
|
ret # no
|
|
|
|
1: ldq_u t0, 0(a0) # yes, load original data
|
|
mskqh t0, t4, t0 #
|
|
stq_u t0, 0(a0) #
|
|
ret #
|
|
|
|
__bzero:
|
|
#ifdef PROF
|
|
ldgp gp, 0(pv)
|
|
lda AT, _mcount
|
|
jsr AT, (AT), _mcount
|
|
#endif
|
|
|
|
mov a0, v0 # e0 : move return value in place
|
|
beq a1, $done # .. e1 : early exit for zero-length store
|
|
and a0, 7, t1 # e0 :
|
|
addq a1, t1, a1 # e1 : add dest misalignment to count
|
|
srl a1, 3, t3 # e0 : loop = count >> 3
|
|
and a1, 7, t4 # .. e1 : find number of bytes in tail
|
|
unop # :
|
|
beq t1, bzero_loop # e1 : aligned head, jump right in
|
|
|
|
ldq_u t0, 0(a0) # e0 : load original data to mask into
|
|
cmpult a1, 8, t2 # .. e1 : is this a sub-word set?
|
|
bne t2, $oneq # e1 :
|
|
|
|
mskql t0, a0, t0 # e0 : we span words. finish this partial
|
|
subq t3, 1, t3 # e0 :
|
|
addq a0, 8, a0 # .. e1 :
|
|
stq_u t0, -8(a0) # e0 :
|
|
br bzero_loop # .. e1 :
|
|
|
|
.align 3
|
|
$oneq:
|
|
mskql t0, a0, t2 # e0 :
|
|
mskqh t0, a1, t3 # e0 :
|
|
or t2, t3, t0 # e1 :
|
|
stq_u t0, 0(a0) # e0 :
|
|
|
|
$done: ret
|
|
|
|
cfi_endproc
|
|
weak_alias (__bzero, bzero)
|