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# Alpha __mpn_sub_n -- Subtract two limb vectors of the same length > 0 and
# store difference in a third limb vector.
# Copyright (C) 1995-2021 Free Software Foundation, Inc.
# This file is part of the GNU MP Library.
# The GNU MP Library is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License as published by
# the Free Software Foundation; either version 2.1 of the License, or (at your
# option) any later version.
# The GNU MP Library is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
# or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
# License for more details.
# You should have received a copy of the GNU Lesser General Public License
# along with the GNU MP Library. If not, see <https://www.gnu.org/licenses/>.
# INPUT PARAMETERS
# res_ptr $16
# s1_ptr $17
# s2_ptr $18
# size $19
.set noreorder
.set noat
.text
.align 3
.globl __mpn_sub_n
.ent __mpn_sub_n
__mpn_sub_n:
.frame $30,0,$26,0
or $31,$31,$25 # clear cy
subq $19,4,$19 # decr loop cnt
blt $19,.Lend2 # if less than 4 limbs, goto 2nd loop
# Start software pipeline for 1st loop
ldq $0,0($18)
ldq $1,8($18)
ldq $4,0($17)
ldq $5,8($17)
addq $17,32,$17 # update s1_ptr
ldq $2,16($18)
subq $4,$0,$20 # 1st main sub
ldq $3,24($18)
subq $19,4,$19 # decr loop cnt
ldq $6,-16($17)
cmpult $4,$20,$25 # compute cy from last sub
ldq $7,-8($17)
addq $1,$25,$28 # cy add
addq $18,32,$18 # update s2_ptr
subq $5,$28,$21 # 2nd main sub
cmpult $28,$25,$8 # compute cy from last add
blt $19,.Lend1 # if less than 4 limbs remain, jump
# 1st loop handles groups of 4 limbs in a software pipeline
.align 4
.Loop: cmpult $5,$21,$25 # compute cy from last add
ldq $0,0($18)
or $8,$25,$25 # combine cy from the two adds
ldq $1,8($18)
addq $2,$25,$28 # cy add
ldq $4,0($17)
subq $6,$28,$22 # 3rd main sub
ldq $5,8($17)
cmpult $28,$25,$8 # compute cy from last add
cmpult $6,$22,$25 # compute cy from last add
stq $20,0($16)
or $8,$25,$25 # combine cy from the two adds
stq $21,8($16)
addq $3,$25,$28 # cy add
subq $7,$28,$23 # 4th main sub
cmpult $28,$25,$8 # compute cy from last add
cmpult $7,$23,$25 # compute cy from last add
addq $17,32,$17 # update s1_ptr
or $8,$25,$25 # combine cy from the two adds
addq $16,32,$16 # update res_ptr
addq $0,$25,$28 # cy add
ldq $2,16($18)
subq $4,$28,$20 # 1st main sub
ldq $3,24($18)
cmpult $28,$25,$8 # compute cy from last add
ldq $6,-16($17)
cmpult $4,$20,$25 # compute cy from last add
ldq $7,-8($17)
or $8,$25,$25 # combine cy from the two adds
subq $19,4,$19 # decr loop cnt
stq $22,-16($16)
addq $1,$25,$28 # cy add
stq $23,-8($16)
subq $5,$28,$21 # 2nd main sub
addq $18,32,$18 # update s2_ptr
cmpult $28,$25,$8 # compute cy from last add
bge $19,.Loop
# Finish software pipeline for 1st loop
.Lend1: cmpult $5,$21,$25 # compute cy from last add
or $8,$25,$25 # combine cy from the two adds
addq $2,$25,$28 # cy add
subq $6,$28,$22 # 3rd main sub
cmpult $28,$25,$8 # compute cy from last add
cmpult $6,$22,$25 # compute cy from last add
stq $20,0($16)
or $8,$25,$25 # combine cy from the two adds
stq $21,8($16)
addq $3,$25,$28 # cy add
subq $7,$28,$23 # 4th main sub
cmpult $28,$25,$8 # compute cy from last add
cmpult $7,$23,$25 # compute cy from last add
or $8,$25,$25 # combine cy from the two adds
addq $16,32,$16 # update res_ptr
stq $22,-16($16)
stq $23,-8($16)
.Lend2: addq $19,4,$19 # restore loop cnt
beq $19,.Lret
# Start software pipeline for 2nd loop
ldq $0,0($18)
ldq $4,0($17)
subq $19,1,$19
beq $19,.Lend0
# 2nd loop handles remaining 1-3 limbs
.align 4
.Loop0: addq $0,$25,$28 # cy add
ldq $0,8($18)
subq $4,$28,$20 # main sub
ldq $1,8($17)
addq $18,8,$18
cmpult $28,$25,$8 # compute cy from last add
addq $17,8,$17
stq $20,0($16)
cmpult $4,$20,$25 # compute cy from last add
subq $19,1,$19 # decr loop cnt
or $8,$25,$25 # combine cy from the two adds
addq $16,8,$16
or $1,$31,$4
bne $19,.Loop0
.Lend0: addq $0,$25,$28 # cy add
subq $4,$28,$20 # main sub
cmpult $28,$25,$8 # compute cy from last add
cmpult $4,$20,$25 # compute cy from last add
stq $20,0($16)
or $8,$25,$25 # combine cy from the two adds
.Lret: or $25,$31,$0 # return cy
ret $31,($26),1
.end __mpn_sub_n
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