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
|
/** @file
Calculate the quotient of a 64-bit integer by a 64-bit integer and returns
both the quotient and the remainderSet error flag for all division functions
Copyright (c) 2006 - 2007, Intel Corporation<BR>
All rights reserved. This program and the accompanying materials
are licensed and made available under the terms and conditions of the BSD License
which accompanies this distribution. The full text of the license may be found at
http://opensource.org/licenses/bsd-license.php
THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
**/
UINT64
EFIAPI
InternalMathDivRemU64x64 (
IN UINT64 Dividend,
IN UINT64 Divisor,
OUT UINT64 *Remainder OPTIONAL
)
{
_asm {
mov edx, dword ptr [Dividend + 4]
mov eax, dword ptr [Dividend + 0] // edx:eax <- dividend
mov edi, edx
mov esi, eax // edi:esi <- dividend
mov ecx, dword ptr [Divisor + 4]
mov ebx, dword ptr [Divisor + 0] // ecx:ebx <- divisor
BitLoop:
shr edx, 1
rcr eax, 1
shrd ebx, ecx, 1
shr ecx, 1
jnz BitLoop
div ebx
mov ebx, eax // ebx <- quotient
mov ecx, dword ptr [Divisor + 4]
mul dword ptr [Divisor]
imul ecx, ebx
add edx, ecx
mov ecx, Remainder
jc TooLarge // product > 2^64
cmp edi, edx // compare high 32 bits
ja Correct
jb TooLarge // product > dividend
cmp esi, eax
jae Correct // product <= dividend
TooLarge:
dec ebx // adjust quotient by -1
jecxz Return // return if Remainder == NULL
sub eax, dword ptr [Divisor + 0]
sbb edx, dword ptr [Divisor + 4]
Correct:
jecxz Return
sub esi, eax
sbb edi, edx // edi:esi <- remainder
mov [ecx], esi
mov [ecx + 4], edi
Return:
mov eax, ebx // eax <- quotient
xor edx, edx
}
}
|
