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63 lines
1.7 KiB
C
63 lines
1.7 KiB
C
/*
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* COPYRIGHT: See COPYING in the top level directory
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* PROJECT: ReactOS system libraries
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* FILE: dll/win32/kernel32/misc/muldiv.c
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* PURPOSE:
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* PROGRAMMER: Casper S. Hornstrup
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* Gunnar Andre Dalsnes
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* UPDATE HISTORY:
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* Created 06/12/2002
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*/
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#include <k32.h>
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/***********************************************************************
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* MulDiv (KERNEL32.@)
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* RETURNS
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* Result of multiplication and division
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* -1: Overflow occurred or Divisor was 0
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* FIXME! move to correct file
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*
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* @implemented
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*/
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INT
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WINAPI
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MulDiv(INT nNumber,
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INT nNumerator,
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INT nDenominator)
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{
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LARGE_INTEGER Result;
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LONG Negative;
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/* Find out if this will be a negative result */
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Negative = nNumber ^ nNumerator ^ nDenominator;
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/* Turn all the parameters into absolute values */
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if (nNumber < 0) nNumber *= -1;
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if (nNumerator < 0) nNumerator *= -1;
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if (nDenominator < 0) nDenominator *= -1;
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/* Calculate the result */
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Result.QuadPart = Int32x32To64(nNumber, nNumerator) + (nDenominator / 2);
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/* Now check for overflow */
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if (nDenominator > Result.HighPart)
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{
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/* Divide the product to get the quotient and remainder */
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Result.LowPart = RtlEnlargedUnsignedDivide(*(PULARGE_INTEGER)&Result,
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(ULONG)nDenominator,
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(PULONG)&Result.HighPart);
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/* Do the sign changes */
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if ((LONG)Result.LowPart >= 0)
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{
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return (Negative >= 0) ? (LONG)Result.LowPart : -(LONG)Result.LowPart;
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}
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}
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/* Return overflow */
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return - 1;
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}
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