1 /** @file
2 64-bit Math Worker Function.
3 The 32-bit versions of C compiler generate calls to library routines
4 to handle 64-bit math. These functions use non-standard calling conventions.
5
6 Copyright (c) 2009 - 2011, Intel Corporation. All rights reserved.<BR>
7 This program and the accompanying materials are licensed and made available
8 under the terms and conditions of the BSD License which accompanies this
9 distribution. The full text of the license may be found at
10 http://opensource.org/licenses/bsd-license.php.
11
12 THE PROGRAM IS DISTRIBUTED UNDER THE BSD LICENSE ON AN "AS IS" BASIS,
13 WITHOUT WARRANTIES OR REPRESENTATIONS OF ANY KIND, EITHER EXPRESS OR IMPLIED.
14
15 **/
16
17
18 /*
19 * Shifts a 64-bit unsigned value right by a certain number of bits.
20 */
_aullshr(void)21 __declspec(naked) void __cdecl _aullshr (void)
22 {
23 _asm {
24 ;
25 ; Checking: Only handle 64bit shifting or more
26 ;
27 cmp cl, 64
28 jae _Exit
29
30 ;
31 ; Handle shifting between 0 and 31 bits
32 ;
33 cmp cl, 32
34 jae More32
35 shrd eax, edx, cl
36 shr edx, cl
37 ret
38
39 ;
40 ; Handle shifting of 32-63 bits
41 ;
42 More32:
43 mov eax, edx
44 xor edx, edx
45 and cl, 31
46 shr eax, cl
47 ret
48
49 ;
50 ; Invalid number (less then 32bits), return 0
51 ;
52 _Exit:
53 xor eax, eax
54 xor edx, edx
55 ret
56 }
57 }
58