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95 lines
2.9 KiB
ArmAsm
95 lines
2.9 KiB
ArmAsm
/* Copyright (C) 1996-2017 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Richard Henderson (rth@tamu.edu)
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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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<http://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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This is generally scheduled for the EV5 (got to look out for my own
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interests :-), but with EV4 needs in mind. There *should* be no more
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stalls for the EV4 than there are for the EV5.
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*/
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#include <sysdep.h>
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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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zapnot a1, 1, a1 # e0 : zero extend the search character
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ldq_u t0, 0(a0) # .. e1 : load first quadword
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sll a1, 8, t5 # e0 : replicate the search character
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andnot a0, 7, v0 # .. e1 : align our loop pointer
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or t5, a1, a1 # e0 :
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lda t4, -1 # .. e1 : build garbage mask
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sll a1, 16, t5 # e0 :
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cmpbge zero, t0, t2 # .. e1 : bits set iff byte == zero
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mskqh t4, a0, t4 # e0 :
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or t5, a1, a1 # .. e1 :
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sll a1, 32, t5 # e0 :
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cmpbge zero, t4, t4 # .. e1 : bits set iff byte is garbage
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or t5, a1, a1 # e0 :
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xor t0, a1, t1 # .. e1 : make bytes == c zero
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cmpbge zero, t1, t3 # e0 : bits set iff byte == c
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or t2, t3, t0 # e1 : bits set iff char match or zero match
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andnot t0, t4, t0 # e0 : clear garbage bits
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bne t0, $found # .. e1 (zdb)
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$loop: ldq t0, 8(v0) # e0 :
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addq v0, 8, v0 # .. e1 :
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nop # e0 :
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xor t0, a1, t1 # .. e1 (ev5 data stall)
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cmpbge zero, t0, t2 # e0 : bits set iff byte == 0
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cmpbge zero, t1, t3 # .. e1 : bits set iff byte == c
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or t2, t3, t0 # e0 :
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beq t0, $loop # .. e1 (zdb)
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$found: negq t0, t1 # e0 : clear all but least set bit
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and t0, t1, t0 # e1 (stall)
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and t0, t3, t1 # e0 : bit set iff byte was the char
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beq t1, $retnull # .. e1 (zdb)
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and t0, 0xf0, t2 # e0 : binary search for that set bit
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and t0, 0xcc, t3 # .. e1 :
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and t0, 0xaa, t4 # e0 :
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cmovne t2, 4, t2 # .. e1 :
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cmovne t3, 2, t3 # e0 :
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cmovne t4, 1, t4 # .. e1 :
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addq t2, t3, t2 # e0 :
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addq v0, t4, v0 # .. e1 :
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addq v0, t2, v0 # e0 :
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ret # .. e1 :
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$retnull:
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mov zero, v0 # e0 :
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ret # .. e1 :
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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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