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dnl IBM POWER mpn_sub_n -- Subtract two limb vectors of equal, non-zero
dnl length.
dnl Copyright 1992, 1994, 1995, 1996, 1999, 2000, 2001 Free Software
dnl Foundation, Inc.
dnl This file is part of the GNU MP Library.
dnl The GNU MP Library is free software; you can redistribute it and/or modify
dnl it under the terms of the GNU Lesser General Public License as published
dnl by the Free Software Foundation; either version 2.1 of the License, or (at
dnl your option) any later version.
dnl The GNU MP Library is distributed in the hope that it will be useful, but
dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
dnl License for more details.
dnl You should have received a copy of the GNU Lesser General Public License
dnl along with the GNU MP Library; see the file COPYING.LIB. If not, write to
dnl the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston,
dnl MA 02111-1307, USA.
dnl INPUT PARAMETERS
dnl res_ptr r3
dnl s1_ptr r4
dnl s2_ptr r5
dnl size r6
include(`../config.m4')
ASM_START()
PROLOGUE(mpn_sub_n)
andil. 10,6,1 C odd or even number of limbs?
l 8,0(4) C load least significant s1 limb
l 0,0(5) C load least significant s2 limb
cal 3,-4(3) C offset res_ptr, it's updated before it's used
sri 10,6,1 C count for unrolled loop
sf 7,0,8 C subtract least significant limbs, set cy
mtctr 10 C copy count into CTR
beq 0,Leven C branch if even C of limbs (C of limbs >= 2)
C We have an odd C of limbs. Add the first limbs separately.
cmpi 1,10,0 C is count for unrolled loop zero?
bc 4,6,L1 C bne cr1,L1 (misassembled by gas)
st 7,4(3)
sfe 3,0,0 C load !cy into ...
sfi 3,3,0 C ... return value register
br C return
C We added least significant limbs. Now reload the next limbs to enter loop.
L1: lu 8,4(4) C load s1 limb and update s1_ptr
lu 0,4(5) C load s2 limb and update s2_ptr
stu 7,4(3)
sfe 7,0,8 C subtract limbs, set cy
Leven: lu 9,4(4) C load s1 limb and update s1_ptr
lu 10,4(5) C load s2 limb and update s2_ptr
bdz Lend C If done, skip loop
Loop: lu 8,4(4) C load s1 limb and update s1_ptr
lu 0,4(5) C load s2 limb and update s2_ptr
sfe 11,10,9 C subtract previous limbs with cy, set cy
stu 7,4(3) C
lu 9,4(4) C load s1 limb and update s1_ptr
lu 10,4(5) C load s2 limb and update s2_ptr
sfe 7,0,8 C subtract previous limbs with cy, set cy
stu 11,4(3) C
bdn Loop C decrement CTR and loop back
Lend: sfe 11,10,9 C subtract limbs with cy, set cy
st 7,4(3) C
st 11,8(3) C
sfe 3,0,0 C load !cy into ...
sfi 3,3,0 C ... return value register
br
EPILOGUE(mpn_sub_n)
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