1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
|
dnl x86-64 mpn_div_qr_2n_pi1
dnl -- Divide an mpn number by a normalized 2-limb number,
dnl using a single-limb inverse.
dnl Copyright 2007, 2008, 2010, 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 c/l
C INPUT PARAMETERS
define(`qp', `%rdi')
define(`rp', `%rsi')
define(`up_param', `%rdx')
define(`un', `%rcx')
define(`d1', `%r8')
define(`d0', `%r9')
define(`di_param', `8(%rsp)')
define(`di', `%r10')
define(`up', `%r11')
define(`u2', `%rbx')
define(`u1', `%r12')
define(`t1', `%r13')
define(`t0', `%r14')
define(`md1', `%r15')
C TODO
C * Store qh in the same stack slot as di_param, instead of pushing
C it. (we could put it in register %rbp, but then we would need to
C save and restore that instead, which doesn't seem like a win).
ASM_START()
TEXT
ALIGN(16)
PROLOGUE(mpn_div_qr_2n_pi1)
mov di_param, di
mov up_param, up
push %r15
push %r14
push %r13
push %r12
push %rbx
mov -16(up, un, 8), u1
mov -8(up, un, 8), u2
mov u1, t0
mov u2, t1
sub d0, t0
sbb d1, t1
cmovnc t0, u1
cmovnc t1, u2
C push qh which is !carry
sbb %rax, %rax
inc %rax
push %rax
lea -2(un), un
mov d1, md1
neg md1
jmp L(next)
ALIGN(16)
L(loop):
C udiv_qr_3by2 (q,u2,u1,u2,u1,n0, d1,d0,di)
C Based on the optimized divrem_2.asm code.
mov di, %rax
mul u2
mov u1, t0
add %rax, t0 C q0 in t0
adc u2, %rdx
mov %rdx, t1 C q in t1
imul md1, %rdx
mov d0, %rax
lea (%rdx, u1), u2
mul t1
mov (up, un, 8), u1
sub d0, u1
sbb d1, u2
sub %rax, u1
sbb %rdx, u2
xor R32(%rax), R32(%rax)
xor R32(%rdx), R32(%rdx)
cmp t0, u2
cmovnc d0, %rax
cmovnc d1, %rdx
adc $0, t1
nop
add %rax, u1
adc %rdx, u2
cmp d1, u2
jae L(fix)
L(bck):
mov t1, (qp, un, 8)
L(next):
sub $1, un
jnc L(loop)
L(end):
mov u2, 8(rp)
mov u1, (rp)
C qh on stack
pop %rax
pop %rbx
pop %r12
pop %r13
pop %r14
pop %r15
ret
L(fix): C Unlikely update. u2 >= d1
seta %dl
cmp d0, u1
setae %al
orb %dl, %al C "orb" form to placate Sun tools
je L(bck)
inc t1
sub d0, u1
sbb d1, u2
jmp L(bck)
EPILOGUE()
|
