mirror of
https://sourceware.org/git/glibc.git
synced 2024-11-15 09:30:06 +00:00
131 lines
3.8 KiB
ArmAsm
131 lines
3.8 KiB
ArmAsm
/* Copyright (C) 1996 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 Library General Public License as
|
|
published by the Free Software Foundation; either version 2 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
|
|
Library General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Library General Public
|
|
License along with the GNU C Library; see the file COPYING.LIB. If
|
|
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
|
|
Cambridge, MA 02139, USA. */
|
|
|
|
/* Fill a block of memory with a character. 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
|
|
|
|
/* There is a problem with either gdb (as of 4.16) or gas (as of 2.7) that
|
|
doesn't like putting the entry point for a procedure somewhere in the
|
|
middle of the procedure descriptor. Work around this by putting the main
|
|
loop in its own procedure descriptor. */
|
|
|
|
/* On entry to this basic block:
|
|
t3 == loop counter
|
|
t4 == bytes in partial final word
|
|
a0 == possibly misaligned destination pointer
|
|
a1 == replicated source character */
|
|
|
|
.ent memset_loop
|
|
.align 3
|
|
memset_loop:
|
|
.frame sp, 0, ra, 0
|
|
.prologue 0
|
|
|
|
beq t3, $tail
|
|
blbc t3, 0f # skip single store if count even
|
|
|
|
stq_u a1, 0(a0) # e0 : store one word
|
|
subq t3, 1, t3 # .. e1 :
|
|
addq a0, 8, a0 # e0 :
|
|
beq t3, $tail # .. e1 :
|
|
|
|
0: stq_u a1, 0(a0) # e0 : store two words
|
|
subq t3, 2, t3 # .. e1 :
|
|
stq_u a1, 8(a0) # e0 :
|
|
addq a0, 16, a0 # .. e1 :
|
|
bne t3, 0b # e1 :
|
|
|
|
$tail: bne t4, 1f # is there a tail to do?
|
|
ret # no
|
|
|
|
.align 3
|
|
1: ldq_u t0, 0(a0) # e1 : yes, load original data
|
|
mskql a1, t4, t1 # .. e0 :
|
|
mskqh t0, t4, t0 # e0 :
|
|
or t0, t1, t0 # e1 (stall)
|
|
stq_u t0, 0(a0) # e0 :
|
|
ret # .. e1 :
|
|
|
|
.end memset_loop
|
|
|
|
ENTRY(memset)
|
|
.prologue 0
|
|
|
|
zapnot a1, 1, a1 # e0 : zero extend input character
|
|
mov a0, v0 # .. e1 : move return value in place
|
|
sll a1, 8, t0 # e0 : begin replicating the char
|
|
beq a2, $done # .. e1 : early exit for zero-length store
|
|
or t0, a1, a1 # e0 :
|
|
and a0, 7, t1 # .. e1 : dest misalignment
|
|
sll a1, 16, t0 # e0 :
|
|
addq a2, t1, a2 # .. e1 : add dest misalignment to count
|
|
or t0, a1, a1 # e0 :
|
|
srl a2, 3, t3 # .. e1 : loop = count >> 3
|
|
sll a1, 32, t0 # e0 :
|
|
and a2, 7, t4 # .. e1 : find number of bytes in tail
|
|
or t0, a1, a1 # e0 : character replication done
|
|
|
|
beq t1, memset_loop # .. e1 : aligned head, jump right in
|
|
|
|
ldq_u t0, 0(a0) # e1 : load original data to mask into
|
|
mskqh a1, a0, t1 # .. e0 :
|
|
|
|
cmpult a2, 8, t2 # e0 : is this a sub-word set?
|
|
bne t2, $oneq # .. e1 (zdb)
|
|
|
|
mskql t0, a0, t0 # e0 : we span words. finish this partial
|
|
subq t3, 1, t3 # .. e1 :
|
|
addq a0, 8, a0 # e0 :
|
|
or t0, t1, t0 # .. e1 :
|
|
stq_u t0, -8(a0) # e0 :
|
|
br memset_loop # .. e1 :
|
|
|
|
.align 3
|
|
$oneq:
|
|
mskql t1, a2, t1 # e0 : entire operation within one word
|
|
mskql t0, a0, t2 # e0 :
|
|
mskqh t0, a2, t3 # e0 :
|
|
or t1, t2, t0 # .. e1 :
|
|
or t0, t3, t0 # e1 :
|
|
stq_u t0, 0(a0) # e0 (stall)
|
|
|
|
$done: ret
|
|
|
|
END(memset)
|