78 lines
2.7 KiB
NASM
78 lines
2.7 KiB
NASM
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dnl IBM POWER mpn_sub_n -- Subtract two limb vectors of equal, non-zero
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dnl length.
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dnl Copyright 1992, 1994, 1995, 1996, 1999, 2000, 2001, 2005 Free Software
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dnl Foundation, Inc.
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dnl This file is part of the GNU MP Library.
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dnl The GNU MP Library is free software; you can redistribute it and/or modify
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dnl it under the terms of the GNU Lesser General Public License as published
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dnl by the Free Software Foundation; either version 2.1 of the License, or (at
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dnl your option) any later version.
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dnl The GNU MP Library is distributed in the hope that it will be useful, but
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dnl WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
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dnl or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
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dnl License for more details.
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dnl You should have received a copy of the GNU Lesser General Public License
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dnl along with the GNU MP Library; see the file COPYING.LIB. If not, write
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dnl to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor,
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dnl Boston, MA 02110-1301, USA.
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dnl INPUT PARAMETERS
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dnl res_ptr r3
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dnl s1_ptr r4
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dnl s2_ptr r5
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dnl size r6
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include(`../config.m4')
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ASM_START()
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PROLOGUE(mpn_sub_n)
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andil. 10,6,1 C odd or even number of limbs?
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l 8,0(4) C load least significant s1 limb
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l 0,0(5) C load least significant s2 limb
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cal 3,-4(3) C offset res_ptr, it's updated before it's used
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sri 10,6,1 C count for unrolled loop
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sf 7,0,8 C subtract least significant limbs, set cy
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mtctr 10 C copy count into CTR
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beq 0,Leven C branch if even # of limbs (# of limbs >= 2)
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C We have an odd # of limbs. Add the first limbs separately.
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cmpi 1,10,0 C is count for unrolled loop zero?
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bc 4,6,L1 C bne cr1,L1 (misassembled by gas)
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st 7,4(3)
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sfe 3,0,0 C load !cy into ...
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sfi 3,3,0 C ... return value register
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br C return
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C We added least significant limbs. Now reload the next limbs to enter loop.
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L1: lu 8,4(4) C load s1 limb and update s1_ptr
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lu 0,4(5) C load s2 limb and update s2_ptr
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stu 7,4(3)
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sfe 7,0,8 C subtract limbs, set cy
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Leven: lu 9,4(4) C load s1 limb and update s1_ptr
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lu 10,4(5) C load s2 limb and update s2_ptr
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bdz Lend C If done, skip loop
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Loop: lu 8,4(4) C load s1 limb and update s1_ptr
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lu 0,4(5) C load s2 limb and update s2_ptr
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sfe 11,10,9 C subtract previous limbs with cy, set cy
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stu 7,4(3) C
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lu 9,4(4) C load s1 limb and update s1_ptr
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lu 10,4(5) C load s2 limb and update s2_ptr
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sfe 7,0,8 C subtract previous limbs with cy, set cy
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stu 11,4(3) C
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bdn Loop C decrement CTR and loop back
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Lend: sfe 11,10,9 C subtract limbs with cy, set cy
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st 7,4(3) C
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st 11,8(3) C
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sfe 3,0,0 C load !cy into ...
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sfi 3,3,0 C ... return value register
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br
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EPILOGUE(mpn_sub_n)
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