mpir/mpn/thumb/sub_n.s

51 lines
1.5 KiB
ArmAsm

@ ARM/Thumb mpn_sub_n -- Subtract two limb vectors of the same length > 0 and
@ store difference in a third limb vector.
@ Copyright 1997, 2000 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; see the file COPYING.LIB. If not, write to
@ the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
@ MA 02110-1301, USA.
@ INPUT PARAMETERS
@ RES_ptr r0
@ S1_ptr r1
@ S2_ptr r2
@ SIZE r3
@ NOT TESTED CODE
.text
.thumb
.align 0
.global ___gmpn_sub_n
___gmpn_sub_n:
push {r4, r5, r6, lr}
mov r6, #1 @ init carry save register
Loop: sub r6, #1 @ restore carry (set iff r6 was 0)
ldmia r1!, {r4} @ load next limb from S1
ldmia r2!, {r5} @ load next limb from S2
sbc r4, r5
stmia r0!, {r4} @ store result limb to RES
sbc r6, r6 @ save negated carry
sub r3, #1
bge Loop @ loop back while remaining count >= 4
mov r0, r6
pop {r4, r5, r6, pc}