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authorRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
committerRoland McGrath <roland@gnu.org>1995-02-18 01:27:10 +0000
commit28f540f45bbacd939bfd07f213bcad2bf730b1bf (patch)
tree15f07c4c43d635959c6afee96bde71fb1b3614ee /sysdeps/m88k/m88100/sub_n.S
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+; mc88100 __mpn_sub -- Subtract two limb vectors of the same length > 0 and
+; store difference in a third limb vector.
+
+; Copyright (C) 1992, 1994 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 General Public License as published by
+; the Free Software Foundation; either version 2, 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 General Public License for more details.
+
+; You should have received a copy of the GNU General Public License
+; along with the GNU MP Library; see the file COPYING.  If not, write to
+; the Free Software Foundation, 675 Mass Ave, Cambridge, MA 02139, USA.
+
+
+; INPUT PARAMETERS
+; res_ptr	r2
+; s1_ptr	r3
+; s2_ptr	r4
+; size		r5
+
+; This code has been optimized to run one instruction per clock, avoiding
+; load stalls and writeback contention.  As a result, the instruction
+; order is not always natural.
+
+; The speed is approximately 4.3 clocks/limb + 18 clocks/limb-vector.
+
+#include "sysdep.h"
+
+ENTRY (__mpn_sub_n)
+	ld	r6,r3,0			; read first limb from s1_ptr
+	extu	r10,r5,4
+	ld	r7,r4,0			; read first limb from s2_ptr
+
+	subu.co	r5,r0,r5		; (clear carry as side effect)
+	mak	r5,r5,4<4>
+	bcnd	eq0,r5,Lzero
+
+	or	r12,r0,lo16(Lbase)
+	or.u	r12,r12,hi16(Lbase)
+	addu	r12,r12,r5		; r12 is address for entering in loop
+
+	extu	r5,r5,2			; divide by 4
+	subu	r2,r2,r5		; adjust res_ptr
+	subu	r3,r3,r5		; adjust s1_ptr
+	subu	r4,r4,r5		; adjust s2_ptr
+
+	or	r8,r6,r0
+
+	jmp.n	r12
+	 or	r9,r7,r0
+
+Loop:	addu	r3,r3,64
+	st	r8,r2,60
+	addu	r4,r4,64
+	ld	r6,r3,0
+	addu	r2,r2,64
+	ld	r7,r4,0
+Lzero:	subu	r10,r10,1	; subtract 0 + 16r limbs (adjust loop counter)
+Lbase:	ld	r8,r3,4
+	subu.cio r6,r6,r7
+	ld	r9,r4,4
+	st	r6,r2,0
+	ld	r6,r3,8		; subtract 15 + 16r limbs
+	subu.cio r8,r8,r9
+	ld	r7,r4,8
+	st	r8,r2,4
+	ld	r8,r3,12	; subtract 14 + 16r limbs
+	subu.cio r6,r6,r7
+	ld	r9,r4,12
+	st	r6,r2,8
+	ld	r6,r3,16	; subtract 13 + 16r limbs
+	subu.cio r8,r8,r9
+	ld	r7,r4,16
+	st	r8,r2,12
+	ld	r8,r3,20	; subtract 12 + 16r limbs
+	subu.cio r6,r6,r7
+	ld	r9,r4,20
+	st	r6,r2,16
+	ld	r6,r3,24	; subtract 11 + 16r limbs
+	subu.cio r8,r8,r9
+	ld	r7,r4,24
+	st	r8,r2,20
+	ld	r8,r3,28	; subtract 10 + 16r limbs
+	subu.cio r6,r6,r7
+	ld	r9,r4,28
+	st	r6,r2,24
+	ld	r6,r3,32	; subtract 9 + 16r limbs
+	subu.cio r8,r8,r9
+	ld	r7,r4,32
+	st	r8,r2,28
+	ld	r8,r3,36	; subtract 8 + 16r limbs
+	subu.cio r6,r6,r7
+	ld	r9,r4,36
+	st	r6,r2,32
+	ld	r6,r3,40	; subtract 7 + 16r limbs
+	subu.cio r8,r8,r9
+	ld	r7,r4,40
+	st	r8,r2,36
+	ld	r8,r3,44	; subtract 6 + 16r limbs
+	subu.cio r6,r6,r7
+	ld	r9,r4,44
+	st	r6,r2,40
+	ld	r6,r3,48	; subtract 5 + 16r limbs
+	subu.cio r8,r8,r9
+	ld	r7,r4,48
+	st	r8,r2,44
+	ld	r8,r3,52	; subtract 4 + 16r limbs
+	subu.cio r6,r6,r7
+	ld	r9,r4,52
+	st	r6,r2,48
+	ld	r6,r3,56	; subtract 3 + 16r limbs
+	subu.cio r8,r8,r9
+	ld	r7,r4,56
+	st	r8,r2,52
+	ld	r8,r3,60	; subtract 2 + 16r limbs
+	subu.cio r6,r6,r7
+	ld	r9,r4,60
+	st	r6,r2,56
+	bcnd.n	ne0,r10,Loop	; subtract 1 + 16r limbs
+	 subu.cio r8,r8,r9
+
+	st	r8,r2,60		; store most significant limb
+
+	addu.ci r2,r0,r0		; return carry-out from most sign. limb
+	jmp.n	 r1
+	 xor	r2,r2,1