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1 # Alpha 21064 __mpn_rshift --
2
3 # Copyright (C) 1994-2019 Free Software Foundation, Inc.
4
5 # This file is part of the GNU MP Library.
6
7 # The GNU MP Library is free software; you can redistribute it and/or modify
8 # it under the terms of the GNU Lesser General Public License as published by
9 # the Free Software Foundation; either version 2.1 of the License, or (at your
10 # option) any later version.
11
12 # The GNU MP Library is distributed in the hope that it will be useful, but
13 # WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY
14 # or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public
15 # License for more details.
16
17 # You should have received a copy of the GNU Lesser General Public License
18 # along with the GNU MP Library. If not, see <http://www.gnu.org/licenses/>.
19
20
21 # INPUT PARAMETERS
22 # res_ptr r16
23 # s1_ptr r17
24 # size r18
25 # cnt r19
26
27 # This code runs at 4.8 cycles/limb on the 21064. With infinite unrolling,
28 # it would take 4 cycles/limb. It should be possible to get down to 3
29 # cycles/limb since both ldq and stq can be paired with the other used
30 # instructions. But there are many restrictions in the 21064 pipeline that
31 # makes it hard, if not impossible, to get down to 3 cycles/limb:
32
33 # 1. ldq has a 3 cycle delay, srl and sll have a 2 cycle delay.
34 # 2. Only aligned instruction pairs can be paired.
35 # 3. The store buffer or silo might not be able to deal with the bandwidth.
36
37 .set noreorder
38 .set noat
39.text
40 .align 3
41 .globl __mpn_rshift
42 .ent __mpn_rshift
43__mpn_rshift:
44 .frame $30,0,$26,0
45
46 ldq $4,0($17) # load first limb
47 addq $17,8,$17
48 subq $31,$19,$7
49 subq $18,1,$18
50 and $18,4-1,$20 # number of limbs in first loop
51 sll $4,$7,$0 # compute function result
52
53 beq $20,.L0
54 subq $18,$20,$18
55
56 .align 3
57.Loop0:
58 ldq $3,0($17)
59 addq $16,8,$16
60 addq $17,8,$17
61 subq $20,1,$20
62 srl $4,$19,$5
63 sll $3,$7,$6
64 bis $3,$3,$4
65 bis $5,$6,$8
66 stq $8,-8($16)
67 bne $20,.Loop0
68
69.L0: beq $18,.Lend
70
71 .align 3
72.Loop: ldq $3,0($17)
73 addq $16,32,$16
74 subq $18,4,$18
75 srl $4,$19,$5
76 sll $3,$7,$6
77
78 ldq $4,8($17)
79 srl $3,$19,$1
80 bis $5,$6,$8
81 stq $8,-32($16)
82 sll $4,$7,$2
83
84 ldq $3,16($17)
85 srl $4,$19,$5
86 bis $1,$2,$8
87 stq $8,-24($16)
88 sll $3,$7,$6
89
90 ldq $4,24($17)
91 srl $3,$19,$1
92 bis $5,$6,$8
93 stq $8,-16($16)
94 sll $4,$7,$2
95
96 addq $17,32,$17
97 bis $1,$2,$8
98 stq $8,-8($16)
99
100 bgt $18,.Loop
101
102.Lend: srl $4,$19,$8
103 stq $8,0($16)
104 ret $31,($26),1
105 .end __mpn_rshift
106

Warning: That file was not part of the compilation database. It may have many parsing errors.