| 1 | ; $Id: U8M-I8M-x86-32.asm 75129 2018-10-28 17:00:27Z vboxsync $
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| 2 | ;; @file
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| 3 | ; BS3Kit - 32-bit Watcom C/C++, 64-bit unsigned integer division.
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| 4 | ;
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| 5 |
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| 6 | ;
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| 7 | ; Copyright (C) 2007-2017 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 "iprt/asmdefs.mac"
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| 28 |
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| 29 |
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| 30 | BEGINCODE
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| 31 |
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| 32 |
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| 33 | ;;
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| 34 | ; 64-bit signed & unsigned integer multiplication.
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| 35 | ;
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| 36 | ; @returns EDX:EAX product
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| 37 | ; @param EDX:EAX Factor #1.
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| 38 | ; @param ECX:EBX Factor #2.
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| 39 | ; @uses ECX, EBX
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| 40 | ;
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| 41 | global __U8M
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| 42 | __U8M:
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| 43 | global __I8M
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| 44 | __I8M:
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| 45 | ;
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| 46 | ; See if this is a pure 32-bit multiplication. We might get lucky.
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| 47 | ;
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| 48 | test edx, edx
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| 49 | jnz .complicated
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| 50 | test ecx, ecx
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| 51 | jnz .complicated
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| 52 |
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| 53 | mul ebx ; eax * ebx -> edx:eax
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| 54 | ret
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| 55 |
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| 56 | .complicated:
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| 57 | push eax
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| 58 | push edx
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| 59 |
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| 60 | ; ecx = F1.lo * F2.hi (edx contains overflow here can be ignored)
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| 61 | mul ecx
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| 62 | mov ecx, eax
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| 63 |
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| 64 | ; ecx += F1.hi * F2.lo (edx can be ignored again)
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| 65 | pop eax
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| 66 | mul ebx
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| 67 | add ecx, eax
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| 68 |
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| 69 | ; edx:eax = F1.lo * F2.lo
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| 70 | pop eax
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| 71 | mul ebx
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| 72 |
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| 73 | ; Add ecx to the high part (edx).
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| 74 | add edx, ecx
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| 75 |
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| 76 | ret
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| 77 |
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