VirtualBox

source: vbox/trunk/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-wc32-I8RS.asm@ 106061

Last change on this file since 106061 was 106061, checked in by vboxsync, 3 months ago

Copyright year updates by scm.

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1; $Id: bs3-wc32-I8RS.asm 106061 2024-09-16 14:03:52Z vboxsync $
2;; @file
3; BS3Kit - 32-bit Watcom C/C++, 64-bit signed integer right shift.
4;
5
6;
7; Copyright (C) 2007-2024 Oracle and/or its affiliates.
8;
9; This file is part of VirtualBox base platform packages, as
10; available from https://www.virtualbox.org.
11;
12; This program is free software; you can redistribute it and/or
13; modify it under the terms of the GNU General Public License
14; as published by the Free Software Foundation, in version 3 of the
15; License.
16;
17; This program is distributed in the hope that it will be useful, but
18; WITHOUT ANY WARRANTY; without even the implied warranty of
19; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
20; General Public License for more details.
21;
22; You should have received a copy of the GNU General Public License
23; along with this program; if not, see <https://www.gnu.org/licenses>.
24;
25; The contents of this file may alternatively be used under the terms
26; of the Common Development and Distribution License Version 1.0
27; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
28; in the VirtualBox distribution, in which case the provisions of the
29; CDDL are applicable instead of those of the GPL.
30;
31; You may elect to license modified versions of this file under the
32; terms and conditions of either the GPL or the CDDL or both.
33;
34; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
35;
36
37%include "bs3kit-template-header.mac"
38
39
40;;
41; 64-bit signed integer left shift.
42;
43; @returns EDX:EAX
44; @param EDX:EAX Value to shift.
45; @param BL Shift count (it's specified as ECX:EBX, but we only use BL).
46;
47global $??I8RS
48$??I8RS:
49 push ecx ; We're allowed to trash ECX, but why bother.
50
51 mov cl, bl
52 and cl, 3fh
53 test cl, 20h
54 jnz .big_shift
55
56 ; Shifting less than 32.
57 shrd eax, edx, cl
58 sar edx, cl
59
60.return:
61 pop ecx
62 ret
63
64.big_shift:
65 ; Shifting 32 or more.
66 mov eax, edx
67 sar eax, cl ; Only uses lower 5 bits.
68 sar edx, 1fh ; Sign extend it.
69 jmp .return
70
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