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dnl Alpha mpn_sub_n -- Subtract two limb vectors of the same length > 0
dnl and store difference in a third limb vector.
dnl Copyright 1995, 1999, 2000, 2005, 2011 Free Software 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 3 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. If not, see http://www.gnu.org/licenses/.
include(`../config.m4')
C cycles/limb
C EV4: ?
C EV5: 4.75
C EV6: 3
dnl INPUT PARAMETERS
dnl res_ptr r16
dnl s1_ptr r17
dnl s2_ptr r18
dnl size r19
ASM_START()
PROLOGUE(mpn_sub_nc)
bis r31,r20,r25
br L(com)
EPILOGUE()
PROLOGUE(mpn_sub_n)
bis r31,r31,r25 C clear cy
L(com): subq r19,4,r19 C decr loop cnt
blt r19,$Lend2 C if less than 4 limbs, goto 2nd loop
C Start software pipeline for 1st loop
ldq r0,0(r18)
ldq r4,0(r17)
ldq r1,8(r18)
ldq r5,8(r17)
addq r17,32,r17 C update s1_ptr
subq r4,r0,r28 C 1st main subtract
ldq r2,16(r18)
subq r28,r25,r20 C 1st carry subtract
ldq r3,24(r18)
cmpult r4,r0,r8 C compute cy from last subtract
ldq r6,-16(r17)
cmpult r28,r25,r25 C compute cy from last subtract
ldq r7,-8(r17)
bis r8,r25,r25 C combine cy from the two subtracts
subq r19,4,r19 C decr loop cnt
subq r5,r1,r28 C 2nd main subtract
addq r18,32,r18 C update s2_ptr
subq r28,r25,r21 C 2nd carry subtract
cmpult r5,r1,r8 C compute cy from last subtract
blt r19,$Lend1 C if less than 4 limbs remain, jump
C 1st loop handles groups of 4 limbs in a software pipeline
ALIGN(16)
$Loop: cmpult r28,r25,r25 C compute cy from last subtract
ldq r0,0(r18)
bis r8,r25,r25 C combine cy from the two subtracts
ldq r1,8(r18)
subq r6,r2,r28 C 3rd main subtract
ldq r4,0(r17)
subq r28,r25,r22 C 3rd carry subtract
ldq r5,8(r17)
cmpult r6,r2,r8 C compute cy from last subtract
cmpult r28,r25,r25 C compute cy from last subtract
stq r20,0(r16)
bis r8,r25,r25 C combine cy from the two subtracts
stq r21,8(r16)
subq r7,r3,r28 C 4th main subtract
subq r28,r25,r23 C 4th carry subtract
cmpult r7,r3,r8 C compute cy from last subtract
cmpult r28,r25,r25 C compute cy from last subtract
addq r17,32,r17 C update s1_ptr
bis r8,r25,r25 C combine cy from the two subtracts
addq r16,32,r16 C update res_ptr
subq r4,r0,r28 C 1st main subtract
ldq r2,16(r18)
subq r28,r25,r20 C 1st carry subtract
ldq r3,24(r18)
cmpult r4,r0,r8 C compute cy from last subtract
ldq r6,-16(r17)
cmpult r28,r25,r25 C compute cy from last subtract
ldq r7,-8(r17)
bis r8,r25,r25 C combine cy from the two subtracts
subq r19,4,r19 C decr loop cnt
stq r22,-16(r16)
subq r5,r1,r28 C 2nd main subtract
stq r23,-8(r16)
subq r28,r25,r21 C 2nd carry subtract
addq r18,32,r18 C update s2_ptr
cmpult r5,r1,r8 C compute cy from last subtract
bge r19,$Loop
C Finish software pipeline for 1st loop
$Lend1: cmpult r28,r25,r25 C compute cy from last subtract
bis r8,r25,r25 C combine cy from the two subtracts
subq r6,r2,r28 C cy add
subq r28,r25,r22 C 3rd main subtract
cmpult r6,r2,r8 C compute cy from last subtract
cmpult r28,r25,r25 C compute cy from last subtract
stq r20,0(r16)
bis r8,r25,r25 C combine cy from the two subtracts
stq r21,8(r16)
subq r7,r3,r28 C cy add
subq r28,r25,r23 C 4th main subtract
cmpult r7,r3,r8 C compute cy from last subtract
cmpult r28,r25,r25 C compute cy from last subtract
bis r8,r25,r25 C combine cy from the two subtracts
addq r16,32,r16 C update res_ptr
stq r22,-16(r16)
stq r23,-8(r16)
$Lend2: addq r19,4,r19 C restore loop cnt
beq r19,$Lret
C Start software pipeline for 2nd loop
ldq r0,0(r18)
ldq r4,0(r17)
subq r19,1,r19
beq r19,$Lend0
C 2nd loop handles remaining 1-3 limbs
ALIGN(16)
$Loop0: subq r4,r0,r28 C main subtract
cmpult r4,r0,r8 C compute cy from last subtract
ldq r0,8(r18)
ldq r4,8(r17)
subq r28,r25,r20 C carry subtract
addq r18,8,r18
addq r17,8,r17
stq r20,0(r16)
cmpult r28,r25,r25 C compute cy from last subtract
subq r19,1,r19 C decr loop cnt
bis r8,r25,r25 C combine cy from the two subtracts
addq r16,8,r16
bne r19,$Loop0
$Lend0: subq r4,r0,r28 C main subtract
subq r28,r25,r20 C carry subtract
cmpult r4,r0,r8 C compute cy from last subtract
cmpult r28,r25,r25 C compute cy from last subtract
stq r20,0(r16)
bis r8,r25,r25 C combine cy from the two subtracts
$Lret: bis r25,r31,r0 C return cy
ret r31,(r26),1
EPILOGUE()
ASM_END()
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