1 | ; $Id: bs3-wc32-I8RS.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 signed 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 "bs3kit-template-header.mac"
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38 |
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39 |
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40 | ;;
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41 | ; 64-bit signed integer left shift.
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42 | ;
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43 | ; @returns EDX:EAX
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44 | ; @param EDX:EAX Value to shift.
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45 | ; @param BL Shift count (it's specified as ECX:EBX, but we only use BL).
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46 | ;
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47 | global $??I8RS
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48 | $??I8RS:
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49 | push ecx ; We're allowed to trash ECX, but why bother.
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50 |
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51 | mov cl, bl
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52 | and cl, 3fh
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53 | test cl, 20h
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54 | jnz .big_shift
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55 |
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56 | ; Shifting less than 32.
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57 | shrd eax, edx, cl
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58 | sar edx, cl
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59 |
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60 | .return:
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61 | pop ecx
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62 | ret
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63 |
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64 | .big_shift:
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65 | ; Shifting 32 or more.
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66 | mov eax, edx
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67 | sar eax, cl ; Only uses lower 5 bits.
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68 | sar edx, 1fh ; Sign extend it.
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69 | jmp .return
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70 |
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