193 lines
5.7 KiB
C
193 lines
5.7 KiB
C
//==========================================================================;
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//
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// THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY
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// KIND, EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE
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// IMPLIED WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR
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// PURPOSE.
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//
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// Copyright (c) 1993, 1994 Microsoft Corporation. All Rights Reserved.
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//
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//--------------------------------------------------------------------------;
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//
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// muldiv32.c
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//
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// Description: math routines for 32 bit signed and unsiged numbers.
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//
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// MulDiv32(a,b,c) = (a * b) / c (round down, signed)
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//
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// MulDivRD(a,b,c) = (a * b) / c (round down, unsigned)
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// MulDivRN(a,b,c) = (a * b + c/2) / c (round nearest, unsigned)
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// MulDivRU(a,b,c) = (a * b + c-1) / c (round up, unsigned)
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//
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// History:
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// 9/21/93 cjp [curtisp]
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// 9/23/93 stl [toddla]
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//
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//==========================================================================;
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#include <windows.h>
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#include "muldiv32.h"
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#if !defined(_WIN32) && !defined(_WIN32)
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#pragma warning(disable:4035 4704)
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#define ASM66 _asm _emit 0x66 _asm
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#define DB _asm _emit
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#define EAX_TO_DXAX \
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DB 0x66 \
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DB 0x0F \
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DB 0xA4 \
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DB 0xC2 \
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DB 0x10
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//--------------------------------------------------------------------------;
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//
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// LONG MulDiv32(a,b,c) = (a * b) / c
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//
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//--------------------------------------------------------------------------;
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LONG FAR PASCAL MulDiv32(LONG a,LONG b,LONG c)
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{
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ASM66 mov ax,word ptr a // mov eax, a
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ASM66 mov bx,word ptr b // mov ebx, b
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ASM66 mov cx,word ptr c // mov ecx, c
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ASM66 imul bx // imul ebx
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ASM66 idiv cx // idiv ecx
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EAX_TO_DXAX
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} // MulDiv32()
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//--------------------------------------------------------------------------;
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//
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// DWORD MulDivRN(a,b,c) = (a * b + c/2) / c
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//
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//--------------------------------------------------------------------------;
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DWORD FAR PASCAL MulDivRN(DWORD a,DWORD b,DWORD c)
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{
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ASM66 mov ax,word ptr a // mov eax, a
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ASM66 mov bx,word ptr b // mov ebx, b
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ASM66 mov cx,word ptr c // mov ecx, c
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ASM66 mul bx // mul ebx
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ASM66 mov bx,cx // mov ebx,ecx
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ASM66 shr bx,1 // sar ebx,1
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ASM66 add ax,bx // add eax,ebx
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ASM66 adc dx,0 // adc edx,0
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ASM66 div cx // div ecx
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EAX_TO_DXAX
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} // MulDiv32()
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//--------------------------------------------------------------------------;
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//
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// DWORD MulDivRU(a,b,c) = (a * b + c-1) / c
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//
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//--------------------------------------------------------------------------;
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DWORD FAR PASCAL MulDivRU(DWORD a,DWORD b,DWORD c)
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{
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ASM66 mov ax,word ptr a // mov eax, a
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ASM66 mov bx,word ptr b // mov ebx, b
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ASM66 mov cx,word ptr c // mov ecx, c
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ASM66 mul bx // mul ebx
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ASM66 mov bx,cx // mov ebx,ecx
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ASM66 dec bx // dec ebx
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ASM66 add ax,bx // add eax,ebx
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ASM66 adc dx,0 // adc edx,0
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ASM66 div cx // div ecx
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EAX_TO_DXAX
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} // MulDivRU32()
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//--------------------------------------------------------------------------;
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//
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// DWORD MulDivRD(a,b,c) = (a * b) / c
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//
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//--------------------------------------------------------------------------;
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DWORD FAR PASCAL MulDivRD(DWORD a,DWORD b,DWORD c)
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{
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ASM66 mov ax,word ptr a // mov eax, a
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ASM66 mov bx,word ptr b // mov ebx, b
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ASM66 mov cx,word ptr c // mov ecx, c
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ASM66 mul bx // mul ebx
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ASM66 div cx // div ecx
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EAX_TO_DXAX
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} // MulDivRD32()
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#pragma warning(default:4035 4704)
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#else // _WIN32
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#include <largeint.h>
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//--------------------------------------------------------------------------;
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//
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// LONG MulDiv32(a,b,c) = (a * b) / c
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//
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//--------------------------------------------------------------------------;
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LONG FAR PASCAL MulDiv32(LONG a,LONG b,LONG c)
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{
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LARGE_INTEGER lRemain;
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return LargeIntegerDivide(
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EnlargedIntegerMultiply(a,b),
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ConvertLongToLargeInteger(c),
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&lRemain).LowPart;
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} // MulDiv32()
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//--------------------------------------------------------------------------;
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//
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// DWORD MulDivRD(a,b,c) = (a * b) / c
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//
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//--------------------------------------------------------------------------;
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DWORD FAR PASCAL MulDivRD(DWORD a,DWORD b,DWORD c)
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{
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return ExtendedLargeIntegerDivide(
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EnlargedUnsignedMultiply(a,b), c, &a).LowPart;
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} // MulDivRD()
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//--------------------------------------------------------------------------;
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//
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// DWORD MulDivRU(a,b,c) = (a * b + c-1) / c
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//
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//--------------------------------------------------------------------------;
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DWORD FAR PASCAL MulDivRU(DWORD a,DWORD b,DWORD c)
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{
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return ExtendedLargeIntegerDivide(
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LargeIntegerAdd(
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EnlargedUnsignedMultiply(a,b),
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ConvertUlongToLargeInteger(c-1)),
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c,&a).LowPart;
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} // MulDivRU()
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#if 0 // we use Win32 GDI MulDiv function, not this.
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//--------------------------------------------------------------------------;
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//
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// DWORD MulDivRN(a,b,c) = (a * b + c/2) / c
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//
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//--------------------------------------------------------------------------;
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DWORD FAR PASCAL MulDivRN(DWORD a,DWORD b,DWORD c)
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{
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return ExtendedLargeIntegerDivide(
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LargeIntegerAdd(
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EnlargedUnsignedMultiply(a,b),
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ConvertUlongToLargeInteger(c/2)),
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c,&a).LowPart;
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} // MulDivRN()
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#endif
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#endif // _WIN32
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