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91 lines
2.3 KiB
ArmAsm
91 lines
2.3 KiB
ArmAsm
/* Copyright (C) 1996-2024 Free Software Foundation, Inc.
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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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/* Finds the first bit set in an integer. Optimized for the Alpha
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architecture. */
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#include <sysdep.h>
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.set noreorder
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.set noat
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ENTRY(__ffs)
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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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zap $16, 0xF0, $16
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br $ffsl..ng
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#else
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.prologue 0
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zap $16, 0xF0, $16
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# FALLTHRU
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#endif
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END(__ffs)
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.align 4
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ENTRY(ffsl)
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#ifdef PROF
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ldgp gp, 0(pv)
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lda AT, _mcount
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jsr AT, (AT), _mcount
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.prologue 1
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$ffsl..ng:
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#else
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.prologue 0
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#endif
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not $16, $1 # e0 :
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ldi $2, -1 # .. e1 :
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cmpbge $1, $2, $3 # e0 : bit N == 1 for byte N == 0
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clr $0 # .. e1 :
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addq $3, 1, $4 # e0 :
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bic $4, $3, $3 # e1 : bit N == 1 for first byte N != 0
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and $3, 0xF0, $4 # e0 :
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and $3, 0xCC, $5 # .. e1 :
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and $3, 0xAA, $6 # e0 :
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cmovne $4, 4, $0 # .. e1 :
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cmovne $5, 2, $5 # e0 :
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cmovne $6, 1, $6 # .. e1 :
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addl $0, $5, $0 # e0 :
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addl $0, $6, $0 # e1 : $0 == N
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extbl $16, $0, $1 # e0 : $1 == byte N
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ldi $2, 1 # .. e1 :
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negq $1, $3 # e0 :
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and $3, $1, $3 # e1 : bit N == least bit set of byte N
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and $3, 0xF0, $4 # e0 :
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and $3, 0xCC, $5 # .. e1 :
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and $3, 0xAA, $6 # e0 :
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cmovne $4, 5, $2 # .. e1 :
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cmovne $5, 2, $5 # e0 :
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cmovne $6, 1, $6 # .. e1 :
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s8addl $0, $2, $0 # e0 : mult byte ofs by 8 and sum
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addl $5, $6, $5 # .. e1 :
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addl $0, $5, $0 # e0 :
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nop # .. e1 :
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cmoveq $16, 0, $0 # e0 : trap input == 0 case.
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ret # .. e1 : 18
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END(ffsl)
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weak_alias (__ffs, ffs)
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libc_hidden_def (__ffs)
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libc_hidden_builtin_def (ffs)
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weak_extern (ffsl)
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weak_alias (ffsl, ffsll)
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