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glibc/ports/sysdeps/alpha/alphaev67/strchr.S
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/* Copyright (C) 2000, 2003 Free Software Foundation, Inc. | |
Contributed by Richard Henderson <rth@tamu.edu>, 1996. | |
EV67 optimized by Rick Gorton <rick.gorton@alpha-processor.com>. | |
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/>. */ | |
/* Return the address of a given character within a null-terminated | |
string, or null if it is not found. */ | |
#include <sysdep.h> | |
.arch ev6 | |
.set noreorder | |
.set noat | |
ENTRY(strchr) | |
#ifdef PROF | |
ldgp gp, 0(pv) | |
lda AT, _mcount | |
jsr AT, (AT), _mcount | |
.prologue 1 | |
#else | |
.prologue 0 | |
#endif | |
ldq_u t0, 0(a0) # L : load first quadword Latency=3 | |
and a1, 0xff, t3 # E : 00000000000000ch | |
insbl a1, 1, t5 # U : 000000000000ch00 | |
insbl a1, 7, a2 # U : ch00000000000000 | |
insbl t3, 6, a3 # U : 00ch000000000000 | |
or t5, t3, a1 # E : 000000000000chch | |
andnot a0, 7, v0 # E : align our loop pointer | |
lda t4, -1 # E : build garbage mask | |
mskqh t4, a0, t4 # U : only want relevant part of first quad | |
or a2, a3, a2 # E : chch000000000000 | |
inswl a1, 2, t5 # E : 00000000chch0000 | |
inswl a1, 4, a3 # E : 0000chch00000000 | |
or a1, a2, a1 # E : chch00000000chch | |
or a3, t5, t5 # E : 0000chchchch0000 | |
cmpbge zero, t0, t2 # E : bits set iff byte == zero | |
cmpbge zero, t4, t4 # E : bits set iff byte is garbage | |
/* This quad is _very_ serialized. Lots of stalling happens */ | |
or t5, a1, a1 # E : chchchchchchchch | |
xor t0, a1, t1 # E : make bytes == c zero | |
cmpbge zero, t1, t3 # E : bits set iff byte == c | |
or t2, t3, t0 # E : bits set iff char match or zero match | |
andnot t0, t4, t0 # E : clear garbage bits | |
cttz t0, a2 # U0 : speculative (in case we get a match) | |
nop # E : | |
bne t0, $found # U : | |
/* | |
* Yuk. This loop is going to stall like crazy waiting for the | |
* data to be loaded. Not much can be done about it unless it's | |
* unrolled multiple times, which is generally unsafe. | |
*/ | |
$loop: | |
ldq t0, 8(v0) # L : Latency=3 | |
addq v0, 8, v0 # E : | |
xor t0, a1, t1 # E : | |
cmpbge zero, t0, t2 # E : bits set iff byte == 0 | |
cmpbge zero, t1, t3 # E : bits set iff byte == c | |
or t2, t3, t0 # E : | |
cttz t3, a2 # U0 : speculative (in case we get a match) | |
beq t0, $loop # U : | |
$found: | |
negq t0, t1 # E : clear all but least set bit | |
and t0, t1, t0 # E : | |
and t0, t3, t1 # E : bit set iff byte was the char | |
addq v0, a2, v0 # E : Add in the bit number from above | |
cmoveq t1, $31, v0 # E : Two mapping slots, latency = 2 | |
nop | |
nop | |
ret # L0 : | |
END(strchr) | |
weak_alias (strchr, index) | |
libc_hidden_builtin_def (strchr) |