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96 lines
2.6 KiB
ArmAsm
96 lines
2.6 KiB
ArmAsm
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/* Optimized version of the standard memset() function.
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This file is part of the GNU C Library.
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Copyright (C) 2000 Free Software Foundation, Inc.
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Contributed by Dan Pop <Dan.Pop@cern.ch>.
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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 Library General Public License as
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published by the Free Software Foundation; either version 2 of the
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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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Library General Public License for more details.
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You should have received a copy of the GNU Library General Public
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License along with the GNU C Library; see the file COPYING.LIB. If not,
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write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
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Boston, MA 02111-1307, USA. */
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/* Return: dest
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Inputs:
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in0: dest
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in1: value
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in2: count
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The algorithm is fairly straightforward: set byte by byte until we
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we get to a word aligned address, then set word by word as much as
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possible; the remaining few bytes are set one by one. */
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#include <sysdep.h>
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#undef ret
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#define dest in0
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#define byteval in1
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#define cnt in2
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#define save_pfs loc0
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#define ptr1 loc1
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#define ptr2 loc2
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#define tmp loc3
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#define loopcnt loc4
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#define save_lc loc5
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#define wordval loc6
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ENTRY(memset)
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alloc save_pfs = ar.pfs, 3, 7, 0, 0
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mov save_lc = ar.lc
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mov ret0 = dest
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and tmp = 7, dest
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cmp.eq p6, p0 = cnt, r0
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(p6) br.cond.spnt .restore_and_exit ;;
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mov ptr1 = dest
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sub loopcnt = 8, tmp
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cmp.gt p6, p0 = 16, cnt
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(p6) br.cond.spnt .set_few;;
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cmp.eq p6, p0 = tmp, r0
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(p6) br.cond.sptk .dest_aligned
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sub cnt = cnt, loopcnt
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adds loopcnt = -1, loopcnt;;
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mov ar.lc = loopcnt;;
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.l1:
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st1 [ptr1] = byteval, 1
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br.cloop.dptk .l1 ;;
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.dest_aligned:
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adds ptr2 = 8, ptr1
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mux1 wordval = byteval, @brcst
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shr.u loopcnt = cnt, 4 ;; // loopcnt = cnt / 16
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cmp.eq p6, p0 = loopcnt, r0
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(p6) br.cond.spnt .one_more
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and cnt = 0xf, cnt // compute the remaining cnt
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adds loopcnt = -1, loopcnt;;
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mov ar.lc = loopcnt;;
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.l2:
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st8 [ptr1] = wordval, 16
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st8 [ptr2] = wordval, 16
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br.cloop.dptk .l2
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cmp.le p6, p0 = 8, cnt ;;
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.one_more:
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(p6) st8 [ptr1] = wordval, 8
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(p6) adds cnt = -8, cnt ;;
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cmp.eq p6, p0 = cnt, r0
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(p6) br.cond.spnt .restore_and_exit
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.set_few:
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adds loopcnt = -1, cnt;;
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mov ar.lc = loopcnt;;
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.l3:
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st1 [ptr1] = byteval, 1
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br.cloop.dptk .l3 ;;
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.restore_and_exit:
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mov ar.lc = save_lc
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mov ar.pfs = save_pfs
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br.ret.sptk.many b0
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END(memset)
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