1 files changed, 105 insertions, 0 deletions
diff --git a/ports/sysdeps/alpha/rshift.S b/ports/sysdeps/alpha/rshift.S
new file mode 100644
index 0000000000..558eeccda4
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+++ b/ports/sysdeps/alpha/rshift.S
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+ # Alpha 21064 __mpn_rshift --
+
+ # Copyright (C) 1994, 1995 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 <http://www.gnu.org/licenses/>.
+
+
+ # INPUT PARAMETERS
+ # res_ptr	r16
+ # s1_ptr	r17
+ # size		r18
+ # cnt		r19
+
+ # This code runs at 4.8 cycles/limb on the 21064.  With infinite unrolling,
+ # it would take 4 cycles/limb.  It should be possible to get down to 3
+ # cycles/limb since both ldq and stq can be paired with the other used
+ # instructions.  But there are many restrictions in the 21064 pipeline that
+ # makes it hard, if not impossible, to get down to 3 cycles/limb:
+
+ # 1. ldq has a 3 cycle delay, srl and sll have a 2 cycle delay.
+ # 2. Only aligned instruction pairs can be paired.
+ # 3. The store buffer or silo might not be able to deal with the bandwidth.
+
+	.set	noreorder
+	.set	noat
+.text
+	.align	3
+	.globl	__mpn_rshift
+	.ent	__mpn_rshift
+__mpn_rshift:
+	.frame	$30,0,$26,0
+
+	ldq	$4,0($17)	# load first limb
+	addq	$17,8,$17
+	subq	$31,$19,$7
+	subq	$18,1,$18
+	and	$18,4-1,$20	# number of limbs in first loop
+	sll	$4,$7,$0	# compute function result
+
+	beq	$20,.L0
+	subq	$18,$20,$18
+
+	.align	3
+.Loop0:
+	ldq	$3,0($17)
+	addq	$16,8,$16
+	addq	$17,8,$17
+	subq	$20,1,$20
+	srl	$4,$19,$5
+	sll	$3,$7,$6
+	bis	$3,$3,$4
+	bis	$5,$6,$8
+	stq	$8,-8($16)
+	bne	$20,.Loop0
+
+.L0:	beq	$18,.Lend
+
+	.align	3
+.Loop:	ldq	$3,0($17)
+	addq	$16,32,$16
+	subq	$18,4,$18
+	srl	$4,$19,$5
+	sll	$3,$7,$6
+
+	ldq	$4,8($17)
+	srl	$3,$19,$1
+	bis	$5,$6,$8
+	stq	$8,-32($16)
+	sll	$4,$7,$2
+
+	ldq	$3,16($17)
+	srl	$4,$19,$5
+	bis	$1,$2,$8
+	stq	$8,-24($16)
+	sll	$3,$7,$6
+
+	ldq	$4,24($17)
+	srl	$3,$19,$1
+	bis	$5,$6,$8
+	stq	$8,-16($16)
+	sll	$4,$7,$2
+
+	addq	$17,32,$17
+	bis	$1,$2,$8
+	stq	$8,-8($16)
+
+	bgt	$18,.Loop
+
+.Lend:	srl	$4,$19,$8
+	stq	$8,0($16)
+	ret	$31,($26),1
+	.end	__mpn_rshift