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Diffstat (limited to '')
-rw-r--r-- | src/VBox/ValidationKit/bootsectors/bs3kit/bs3-wc32-I8RS.asm | 70 |
1 files changed, 70 insertions, 0 deletions
diff --git a/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-wc32-I8RS.asm b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-wc32-I8RS.asm new file mode 100644 index 00000000..4840a7f7 --- /dev/null +++ b/src/VBox/ValidationKit/bootsectors/bs3kit/bs3-wc32-I8RS.asm @@ -0,0 +1,70 @@ +; $Id: bs3-wc32-I8RS.asm $ +;; @file +; BS3Kit - 32-bit Watcom C/C++, 64-bit signed integer right shift. +; + +; +; Copyright (C) 2007-2023 Oracle and/or its affiliates. +; +; This file is part of VirtualBox base platform packages, as +; available from https://www.virtualbox.org. +; +; This program is free software; you can redistribute it and/or +; modify it under the terms of the GNU General Public License +; as published by the Free Software Foundation, in version 3 of the +; License. +; +; This program is distributed in the hope that it will be useful, but +; WITHOUT ANY WARRANTY; without even the implied warranty of +; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU +; General Public License for more details. +; +; You should have received a copy of the GNU General Public License +; along with this program; if not, see <https://www.gnu.org/licenses>. +; +; The contents of this file may alternatively be used under the terms +; of the Common Development and Distribution License Version 1.0 +; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included +; in the VirtualBox distribution, in which case the provisions of the +; CDDL are applicable instead of those of the GPL. +; +; You may elect to license modified versions of this file under the +; terms and conditions of either the GPL or the CDDL or both. +; +; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0 +; + +%include "bs3kit-template-header.mac" + + +;; +; 64-bit signed integer left shift. +; +; @returns EDX:EAX +; @param EDX:EAX Value to shift. +; @param BL Shift count (it's specified as ECX:EBX, but we only use BL). +; +global $??I8RS +$??I8RS: + push ecx ; We're allowed to trash ECX, but why bother. + + mov cl, bl + and cl, 3fh + test cl, 20h + jnz .big_shift + + ; Shifting less than 32. + shrd eax, edx, cl + sar edx, cl + +.return: + pop ecx + ret + +.big_shift: + ; Shifting 32 or more. + mov eax, edx + sar eax, cl ; Only uses lower 5 bits. + sar edx, 1fh ; Sign extend it. + jmp .return + |