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/* Copyright (C) 2000 Free Software Foundation, Inc.
This file is part of the GNU C Library.
Contributed by David Mosberger (davidm@cs.arizona.edu).
EV6 optimized by Rick Gorton <rick.gorton@alpha-processor.com>.
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. */
#include <sysdep.h>
.arch ev6
.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
# Hack -- if someone passes in (size_t)-1, hoping to just
# search til the end of the address space, we will overflow
# below when we find the address of the last byte. Given
# that we will never have a 56-bit address space, cropping
# the length is the easiest way to avoid trouble.
zap $18, 0x80, $5 # U : Bound length
beq $18, $not_found # U :
ldq_u $1, 0($16) # L : load first quadword Latency=3
and $17, 0xff, $17 # E : L L U U : 00000000000000ch
insbl $17, 1, $2 # U : 000000000000ch00
cmpult $18, 9, $4 # E : small (< 1 quad) string?
or $2, $17, $17 # E : 000000000000chch
lda $3, -1($31) # E : U L L U
sll $17, 16, $2 # U : 00000000chch0000
addq $16, $5, $5 # E : Max search address
or $2, $17, $17 # E : 00000000chchchch
sll $17, 32, $2 # U : U L L U : chchchch00000000
or $2, $17, $17 # E : chchchchchchchch
extql $1, $16, $7 # U : $7 is upper bits
beq $4, $first_quad # U :
ldq_u $6, -1($5) # L : L U U L : eight or less bytes to search Latency=3
extqh $6, $16, $6 # U : 2 cycle stall for $6
mov $16, $0 # E :
nop # E :
or $7, $6, $1 # E : L U L U $1 = quadword starting at $16
# Deal with the case where at most 8 bytes remain to be searched
# in $1. E.g.:
# $18 = 6
# $1 = ????c6c5c4c3c2c1
$last_quad:
negq $18, $6 # E :
xor $17, $1, $1 # E :
srl $3, $6, $6 # U : $6 = mask of $18 bits set
cmpbge $31, $1, $2 # E : L U L U
nop
nop
and $2, $6, $2 # E :
beq $2, $not_found # U : U L U L
$found_it:
#if defined(__alpha_fix__) && defined(__alpha_cix__)
/*
* Since we are guaranteed to have set one of the bits, we don't
* have to worry about coming back with a 0x40 out of cttz...
*/
cttz $2, $3 # U0 :
addq $0, $3, $0 # E : All done
nop # E :
ret # L0 : L U L U
#else
/*
* Slow and clunky. It can probably be improved.
* An exercise left for others.
*/
negq $2, $3 # E :
and $2, $3, $2 # E :
and $2, 0x0f, $1 # E :
addq $0, 4, $3 # E :
cmoveq $1, $3, $0 # E : Latency 2, extra map cycle
nop # E : keep with cmov
and $2, 0x33, $1 # E :
addq $0, 2, $3 # E : U L U L : 2 cycle stall on $0
cmoveq $1, $3, $0 # E : Latency 2, extra map cycle
nop # E : keep with cmov
and $2, 0x55, $1 # E :
addq $0, 1, $3 # E : U L U L : 2 cycle stall on $0
cmoveq $1, $3, $0 # E : Latency 2, extra map cycle
nop
nop
ret # L0 : L U L U
#endif
# Deal with the case where $18 > 8 bytes remain to be
# searched. $16 may not be aligned.
.align 4
$first_quad:
andnot $16, 0x7, $0 # E :
insqh $3, $16, $2 # U : $2 = 0000ffffffffffff ($16<0:2> ff)
xor $1, $17, $1 # E :
or $1, $2, $1 # E : U L U L $1 = ====ffffffffffff
cmpbge $31, $1, $2 # E :
bne $2, $found_it # U :
# At least one byte left to process.
ldq $1, 8($0) # L :
subq $5, 1, $18 # E : U L U L
addq $0, 8, $0 # E :
# Make $18 point to last quad to be accessed (the
# last quad may or may not be partial).
andnot $18, 0x7, $18 # E :
cmpult $0, $18, $2 # E :
beq $2, $final # U : U L U L
# At least two quads remain to be accessed.
subq $18, $0, $4 # E : $4 <- nr quads to be processed
and $4, 8, $4 # E : odd number of quads?
bne $4, $odd_quad_count # U :
# At least three quads remain to be accessed
mov $1, $4 # E : L U L U : move prefetched value to correct reg
.align 4
$unrolled_loop:
ldq $1, 8($0) # L : prefetch $1
xor $17, $4, $2 # E :
cmpbge $31, $2, $2 # E :
bne $2, $found_it # U : U L U L
addq $0, 8, $0 # E :
nop # E :
nop # E :
nop # E :
$odd_quad_count:
xor $17, $1, $2 # E :
ldq $4, 8($0) # L : prefetch $4
cmpbge $31, $2, $2 # E :
addq $0, 8, $6 # E :
bne $2, $found_it # U :
cmpult $6, $18, $6 # E :
addq $0, 8, $0 # E :
nop # E :
bne $6, $unrolled_loop # U :
mov $4, $1 # E : move prefetched value into $1
nop # E :
nop # E :
$final: subq $5, $0, $18 # E : $18 <- number of bytes left to do
nop # E :
nop # E :
bne $18, $last_quad # U :
$not_found:
mov $31, $0 # E :
nop # E :
nop # E :
ret # L0 :
END(__memchr)
weak_alias (__memchr, memchr)
#if !__BOUNDED_POINTERS__
weak_alias (__memchr, __ubp_memchr)
#endif
|
