1 # Alpha 21064 __mpn_mul_1 -- Multiply a limb vector with a limb and store
2 # the result in a second limb vector.
3
4 # Copyright (C) 1992-2021 Free Software Foundation, Inc.
5
6 # This file is part of the GNU MP Library.
7
8 # The GNU MP Library is free software; you can redistribute it and/or modify
9 # it under the terms of the GNU Lesser General Public License as published by
10 # the Free Software Foundation; either version 2.1 of the License, or (at your
11 # option) any later version.
12
13 # The GNU MP Library is distributed in the hope that it will be useful, but
14 # WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
15 # or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU Lesser General Public
16 # License for more details.
17
18 # You should have received a copy of the GNU Lesser General Public License
19 # along with the GNU MP Library.  If not, see <https://www.gnu.org/licenses/>.
20
21
22 # INPUT PARAMETERS
23 # res_ptr	r16
24 # s1_ptr	r17
25 # size		r18
26 # s2_limb	r19
27
28 # This code runs at 42 cycles/limb on the EV4 and 18 cycles/limb on the EV5.
29
30 # To improve performance for long multiplications, we would use
31 # 'fetch' for S1 and 'fetch_m' for RES.  It's not obvious how to use
32 # these instructions without slowing down the general code: 1. We can
33 # only have two prefetches in operation at any time in the Alpha
34 # architecture.  2. There will seldom be any special alignment
35 # between RES_PTR and S1_PTR.  Maybe we can simply divide the current
36 # loop into an inner and outer loop, having the inner loop handle
37 # exactly one prefetch block?
38
39	.set	noreorder
40	.set	noat
41.text
42	.align	3
43	.globl	__mpn_mul_1
44	.ent	__mpn_mul_1 2
45__mpn_mul_1:
46	.frame	$30,0,$26
47
48	ldq	$2,0($17)	# $2 = s1_limb
49	subq	$18,1,$18	# size--
50	mulq	$2,$19,$3	# $3 = prod_low
51	bic	$31,$31,$4	# clear cy_limb
52	umulh	$2,$19,$0	# $0 = prod_high
53	beq	$18,Lend1	# jump if size was == 1
54	ldq	$2,8($17)	# $2 = s1_limb
55	subq	$18,1,$18	# size--
56	stq	$3,0($16)
57	beq	$18,Lend2	# jump if size was == 2
58
59	.align	3
60Loop:	mulq	$2,$19,$3	# $3 = prod_low
61	addq	$4,$0,$0	# cy_limb = cy_limb + 'cy'
62	subq	$18,1,$18	# size--
63	umulh	$2,$19,$4	# $4 = cy_limb
64	ldq	$2,16($17)	# $2 = s1_limb
65	addq	$17,8,$17	# s1_ptr++
66	addq	$3,$0,$3	# $3 = cy_limb + prod_low
67	stq	$3,8($16)
68	cmpult	$3,$0,$0	# $0 = carry from (cy_limb + prod_low)
69	addq	$16,8,$16	# res_ptr++
70	bne	$18,Loop
71
72Lend2:	mulq	$2,$19,$3	# $3 = prod_low
73	addq	$4,$0,$0	# cy_limb = cy_limb + 'cy'
74	umulh	$2,$19,$4	# $4 = cy_limb
75	addq	$3,$0,$3	# $3 = cy_limb + prod_low
76	cmpult	$3,$0,$0	# $0 = carry from (cy_limb + prod_low)
77	stq	$3,8($16)
78	addq	$4,$0,$0	# cy_limb = prod_high + cy
79	ret	$31,($26),1
80Lend1:	stq	$3,0($16)
81	ret	$31,($26),1
82
83	.end	__mpn_mul_1
84