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101 lines
3.1 KiB
ArmAsm
101 lines
3.1 KiB
ArmAsm
/* Copyright (C) 2000-2020 Free Software Foundation, Inc.
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Contributed by Richard Henderson <rth@tamu.edu>, 1996.
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EV67 optimized by Rick Gorton <rick.gorton@alpha-processor.com>.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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<https://www.gnu.org/licenses/>. */
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/* Return the address of a given character within a null-terminated
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string, or null if it is not found. */
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#include <sysdep.h>
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.arch ev6
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.set noreorder
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.set noat
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ENTRY(strchr)
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#ifdef PROF
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ldgp gp, 0(pv)
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lda AT, _mcount
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jsr AT, (AT), _mcount
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.prologue 1
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#else
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.prologue 0
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#endif
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ldq_u t0, 0(a0) # L : load first quadword Latency=3
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and a1, 0xff, t3 # E : 00000000000000ch
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insbl a1, 1, t5 # U : 000000000000ch00
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insbl a1, 7, a2 # U : ch00000000000000
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insbl t3, 6, a3 # U : 00ch000000000000
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or t5, t3, a1 # E : 000000000000chch
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andnot a0, 7, v0 # E : align our loop pointer
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lda t4, -1 # E : build garbage mask
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mskqh t4, a0, t4 # U : only want relevant part of first quad
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or a2, a3, a2 # E : chch000000000000
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inswl a1, 2, t5 # E : 00000000chch0000
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inswl a1, 4, a3 # E : 0000chch00000000
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or a1, a2, a1 # E : chch00000000chch
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or a3, t5, t5 # E : 0000chchchch0000
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cmpbge zero, t0, t2 # E : bits set iff byte == zero
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cmpbge zero, t4, t4 # E : bits set iff byte is garbage
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/* This quad is _very_ serialized. Lots of stalling happens */
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or t5, a1, a1 # E : chchchchchchchch
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xor t0, a1, t1 # E : make bytes == c zero
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cmpbge zero, t1, t3 # E : bits set iff byte == c
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or t2, t3, t0 # E : bits set iff char match or zero match
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andnot t0, t4, t0 # E : clear garbage bits
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cttz t0, a2 # U0 : speculative (in case we get a match)
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nop # E :
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bne t0, $found # U :
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/*
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* Yuk. This loop is going to stall like crazy waiting for the
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* data to be loaded. Not much can be done about it unless it's
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* unrolled multiple times, which is generally unsafe.
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*/
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$loop:
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ldq t0, 8(v0) # L : Latency=3
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addq v0, 8, v0 # E :
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xor t0, a1, t1 # E :
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cmpbge zero, t0, t2 # E : bits set iff byte == 0
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cmpbge zero, t1, t3 # E : bits set iff byte == c
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or t2, t3, t0 # E :
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cttz t3, a2 # U0 : speculative (in case we get a match)
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beq t0, $loop # U :
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$found:
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negq t0, t1 # E : clear all but least set bit
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and t0, t1, t0 # E :
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and t0, t3, t1 # E : bit set iff byte was the char
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addq v0, a2, v0 # E : Add in the bit number from above
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cmoveq t1, $31, v0 # E : Two mapping slots, latency = 2
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nop
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nop
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ret # L0 :
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END(strchr)
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weak_alias (strchr, index)
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libc_hidden_builtin_def (strchr)
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