| 1 | ; $Id: U8RS-x86-32.asm 106061 2024-09-16 14:03:52Z vboxsync $
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| 2 | ;; @file
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| 3 | ; BS3Kit - 32-bit Watcom C/C++, 64-bit unsigned integer right shift.
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| 4 | ;
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| 5 |
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| 6 | ;
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| 7 | ; Copyright (C) 2007-2024 Oracle and/or its affiliates.
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| 8 | ;
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| 9 | ; This file is part of VirtualBox base platform packages, as
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| 10 | ; available from https://www.virtualbox.org.
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| 11 | ;
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| 12 | ; This program is free software; you can redistribute it and/or
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| 13 | ; modify it under the terms of the GNU General Public License
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| 14 | ; as published by the Free Software Foundation, in version 3 of the
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| 15 | ; License.
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| 16 | ;
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| 17 | ; This program is distributed in the hope that it will be useful, but
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| 18 | ; WITHOUT ANY WARRANTY; without even the implied warranty of
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| 19 | ; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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| 20 | ; General Public License for more details.
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| 21 | ;
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| 22 | ; You should have received a copy of the GNU General Public License
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| 23 | ; along with this program; if not, see <https://www.gnu.org/licenses>.
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| 24 | ;
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| 25 | ; The contents of this file may alternatively be used under the terms
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| 26 | ; of the Common Development and Distribution License Version 1.0
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| 27 | ; (CDDL), a copy of it is provided in the "COPYING.CDDL" file included
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| 28 | ; in the VirtualBox distribution, in which case the provisions of the
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| 29 | ; CDDL are applicable instead of those of the GPL.
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| 30 | ;
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| 31 | ; You may elect to license modified versions of this file under the
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| 32 | ; terms and conditions of either the GPL or the CDDL or both.
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| 33 | ;
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| 34 | ; SPDX-License-Identifier: GPL-3.0-only OR CDDL-1.0
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| 35 | ;
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| 36 |
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| 37 | %include "iprt/asmdefs.mac"
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| 38 |
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| 39 |
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| 40 | BEGINCODE
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| 41 |
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| 42 |
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| 43 | ;;
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| 44 | ; 64-bit unsigned integer right shift.
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| 45 | ;
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| 46 | ; @returns EDX:EAX
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| 47 | ; @param EDX:EAX Value to shift.
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| 48 | ; @param BL Shift count (it's specified as ECX:EBX, but we only use BL).
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| 49 | ;
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| 50 | global __U8RS
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| 51 | __U8RS:
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| 52 | push ecx ; We're allowed to trash ECX, but why bother.
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| 53 |
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| 54 | mov cl, bl
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| 55 | and cl, 3fh
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| 56 | test cl, 20h
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| 57 | jnz .big_shift
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| 58 |
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| 59 | ; Shifting less than 32.
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| 60 | shrd eax, edx, cl
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| 61 | shr edx, cl
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| 62 |
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| 63 | .return:
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| 64 | pop ecx
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| 65 | ret
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| 66 |
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| 67 | .big_shift:
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| 68 | ; Shifting 32 or more.
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| 69 | mov eax, edx
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| 70 | shr eax, cl ; Only uses lower 5 bits.
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| 71 | xor edx, edx
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| 72 | jmp .return
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| 73 |
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