| 1 | ; $Id: bs3-wc16-U8RS.asm 62484 2016-07-22 18:35:33Z vboxsync $
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| 2 | ;; @file
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| 3 | ; BS3Kit - 16-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) 2007-2016 Oracle Corporation
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| 8 | ;
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| 9 | ; This file is part of VirtualBox Open Source Edition (OSE), as
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| 10 | ; available from http://www.virtualbox.org. This file is free software;
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| 11 | ; you can redistribute it and/or modify it under the terms of the GNU
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| 12 | ; General Public License (GPL) as published by the Free Software
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| 13 | ; Foundation, in version 2 as it comes in the "COPYING" file of the
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| 14 | ; VirtualBox OSE distribution. VirtualBox OSE is distributed in the
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| 15 | ; hope that it will be useful, but WITHOUT ANY WARRANTY of any kind.
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| 16 | ;
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| 17 | ; The contents of this file may alternatively be used under the terms
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| 18 | ; of the Common Development and Distribution License Version 1.0
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| 19 | ; (CDDL) only, as it comes in the "COPYING.CDDL" file of the
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| 20 | ; VirtualBox OSE distribution, in which case the provisions of the
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| 21 | ; CDDL are applicable instead of those of the GPL.
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| 22 | ;
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| 23 | ; You may elect to license modified versions of this file under the
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| 24 | ; terms and conditions of either the GPL or the CDDL or both.
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| 25 | ;
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| 26 |
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| 27 | %include "bs3kit-template-header.mac"
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| 28 |
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| 29 |
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| 30 | ;;
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| 31 | ; 64-bit unsigned integer left shift.
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| 32 | ;
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| 33 | ; @returns AX:BX:CX:DX (AX is the most significant, DX the least)
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| 34 | ; @param AX:BX:CX:DX Value to shift.
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| 35 | ; @param SI Shift count.
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| 36 | ;
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| 37 | global $_?U8RS
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| 38 | $_?U8RS:
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| 39 | push si
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| 40 |
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| 41 | ;
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| 42 | ; The 16-bit watcom code differs from the 32-bit one in the way it
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| 43 | ; handles the shift count. All 16-bit bits are used in the 16-bit
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| 44 | ; code, we do the same as the 32-bit one as we don't want to wast
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| 45 | ; time in the below loop.
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| 46 | ;
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| 47 | ; Using 8086 comatible approach here as it's less hazzle to write
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| 48 | ; and smaller.
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| 49 | ;
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| 50 | and si, 3fh
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| 51 | jz .return
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| 52 |
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| 53 | .next_shift:
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| 54 | shr ax, 1
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| 55 | rcr bx, 1
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| 56 | rcr cx, 1
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| 57 | rcr dx, 1
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| 58 | dec si
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| 59 | jnz .next_shift
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| 60 |
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| 61 | .return:
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| 62 | pop si
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| 63 | %ifdef ASM_MODEL_FAR_CODE
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| 64 | retf
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| 65 | %else
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| 66 | ret
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| 67 | %endif
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| 68 |
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