1 | ; $Id: bs3-wc16-U8LS.asm 82968 2020-02-04 10:35:17Z vboxsync $
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2 | ;; @file
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3 | ; BS3Kit - 16-bit Watcom C/C++, 64-bit integer left shift.
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4 | ;
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5 |
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6 | ;
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7 | ; Copyright (C) 2007-2020 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 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 $_?U8LS
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38 | $_?U8LS:
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39 | global $_?I8LS
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40 | $_?I8LS:
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41 | push si
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42 |
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43 | ;
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44 | ; The 16-bit watcom code differs from the 32-bit one in the way it
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45 | ; handles the shift count. All 16-bit bits are used in the 16-bit
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46 | ; code, we do the same as the 32-bit one as we don't want to wast
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47 | ; time in the below loop.
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48 | ;
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49 | ; Using 8086 compatible approach here as it's less hazzle to write
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50 | ; and smaller.
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51 | ;
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52 | and si, 3fh
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53 |
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54 | jz .return
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55 | .next_shift:
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56 | shl dx, 1
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57 | rcl cx, 1
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58 | rcl bx, 1
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59 | rcl ax, 1
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60 | dec si
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61 | jnz .next_shift
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62 |
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63 | .return:
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64 | pop si
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65 | %ifdef ASM_MODEL_FAR_CODE
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66 | retf
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67 | %else
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68 | ret
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69 | %endif
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70 |
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