167 lines
4.1 KiB
ArmAsm
167 lines
4.1 KiB
ArmAsm
/* Copyright (C) 1996 Free Software Foundation, Inc.
|
|
This file is part of the GNU C Library.
|
|
Contributed by David Mosberger (davidm@cs.arizona.edu).
|
|
|
|
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., 59 Temple Place - Suite 330,
|
|
Boston, MA 02111-1307, USA. */
|
|
|
|
/* Finds characters in a memory area. Optimized for the Alpha
|
|
architecture:
|
|
|
|
- memory accessed as aligned quadwords only
|
|
- uses cmpbge to compare 8 bytes in parallel
|
|
- does binary search to find 0 byte in last
|
|
quadword (HAKMEM needed 12 instructions to
|
|
do this instead of the 9 instructions that
|
|
binary search needs).
|
|
|
|
For correctness consider that:
|
|
|
|
- only minimum number of quadwords may be accessed
|
|
- the third argument is an unsigned long
|
|
*/
|
|
|
|
#include <sysdep.h>
|
|
|
|
.set noreorder
|
|
.set noat
|
|
|
|
ENTRY(memchr)
|
|
#ifdef PROF
|
|
ldgp gp, 0(pv)
|
|
lda AT, _mcount
|
|
jsr AT, (AT), _mcount
|
|
.prologue 1
|
|
#else
|
|
.prologue 0
|
|
#endif
|
|
|
|
beq a2, $not_found
|
|
ldq_u t0, 0(a0) # load first quadword (a0 may be misaligned)
|
|
addq a0, a2, t4
|
|
and a1, 0xff, a1 # a1 = 00000000000000ch
|
|
sll a1, 8, t1 # t1 = 000000000000ch00
|
|
cmpult a2, 9, t3
|
|
or t1, a1, a1 # a1 = 000000000000chch
|
|
sll a1, 16, t1 # t1 = 00000000chch0000
|
|
lda t2, -1(zero)
|
|
or t1, a1, a1 # a1 = 00000000chchchch
|
|
sll a1, 32, t1 # t1 = chchchch00000000
|
|
extql t0, a0, t6
|
|
or t1, a1, a1 # a1 = chchchchchchchch
|
|
|
|
beq t3, $first_quad
|
|
|
|
ldq_u t5, -1(t4)
|
|
extqh t5, a0, t5
|
|
mov a0, v0
|
|
or t6, t5, t0 # t0 = quadword starting at a0
|
|
|
|
#
|
|
# Deal with the case where at most 8 bytes remain to be searched
|
|
# in t0. E.g.:
|
|
# a2 = 6
|
|
# t0 = ????c6c5c4c3c2c1
|
|
$last_quad:
|
|
negq a2, t5
|
|
srl t2, t5, t5 # t5 = mask of a2 bits set
|
|
xor a1, t0, t0
|
|
cmpbge zero, t0, t1
|
|
and t1, t5, t1
|
|
beq t1, $not_found
|
|
|
|
$found_it:
|
|
# now, determine which byte matched:
|
|
negq t1, t2
|
|
and t1, t2, t1
|
|
|
|
and t1, 0x0f, t0
|
|
addq v0, 4, t2
|
|
cmoveq t0, t2, v0
|
|
|
|
and t1, 0x33, t0
|
|
addq v0, 2, t2
|
|
cmoveq t0, t2, v0
|
|
|
|
and t1, 0x55, t0
|
|
addq v0, 1, t2
|
|
cmoveq t0, t2, v0
|
|
|
|
$done: ret
|
|
|
|
|
|
#
|
|
# Deal with the case where a2 > 8 bytes remain to be
|
|
# searched. a0 may not be aligned.
|
|
#
|
|
$first_quad:
|
|
andnot a0, 0x7, v0
|
|
insqh t2, a0, t1 # t1 = 0000ffffffffffff (a0<0:2> ff bytes)
|
|
xor t0, a1, t0
|
|
or t0, t1, t0 # t0 = ====ffffffffffff
|
|
cmpbge zero, t0, t1
|
|
bne t1, $found_it
|
|
|
|
/* at least one byte left to process */
|
|
|
|
ldq t0, 8(v0)
|
|
addq v0, 8, v0
|
|
/*
|
|
* Make a2 point to last quad to be accessed (the
|
|
* last quad may or may not be partial).
|
|
*/
|
|
subq t4, 1, a2
|
|
andnot a2, 0x7, a2
|
|
cmpult v0, a2, t1
|
|
beq t1, $final
|
|
|
|
/* at least two quads remain to be accessed */
|
|
|
|
subq a2, v0, t3 # t3 <- number of quads to be processed in loop
|
|
and t3, 8, t3 # odd number of quads?
|
|
bne t3, $odd_quad_count
|
|
|
|
/* at least three quads remain to be accessed */
|
|
|
|
mov t0, t3 # move prefetched value into correct register
|
|
|
|
.align 3
|
|
$unrolled_loop:
|
|
ldq t0, 8(v0) # prefetch t0
|
|
xor a1, t3, t1
|
|
cmpbge zero, t1, t1
|
|
bne t1, $found_it
|
|
|
|
addq v0, 8, v0
|
|
$odd_quad_count:
|
|
xor a1, t0, t1
|
|
ldq t3, 8(v0) # prefetch t3
|
|
cmpbge zero, t1, t1
|
|
bne t1, $found_it
|
|
|
|
addq v0, 8, v0
|
|
cmpult v0, a2, t5
|
|
bne t5, $unrolled_loop
|
|
|
|
mov t3, t0 # move prefetched value into t0
|
|
$final: subq t4, v0, a2 # a2 <- number of bytes left to do
|
|
bne a2, $last_quad
|
|
|
|
$not_found:
|
|
mov zero, v0
|
|
ret
|
|
|
|
END(memchr)
|