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Fix MulDiv. This fixes almost any progress-bar to stop showing negative values during installations or etc. Thanks to kichik for originally having found the bug.

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Patch by alex ionescu

svn path=/trunk/; revision=18386
This commit is contained in:
Gunnar Dalsnes 2005-10-09 22:12:56 +00:00
parent 315e77dfab
commit 690727fe99
1 changed files with 35 additions and 41 deletions
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76
reactos/lib/kernel32/misc/muldiv.c
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@ -13,48 +13,42 @@
* *
* @implemented * @implemented
*/ */
INT STDCALL MulDiv( INT
INT nMultiplicand, WINAPI
INT nMultiplier, MulDiv(INT nNumber,
INT nDivisor) INT nNumerator,
INT nDenominator)
{ {
#if SIZEOF_LONG_LONG >= 8 LARGE_INTEGER Result;
long long ret; LONG Negative;
if (!nDivisor) return -1; /* Find out if this will be a negative result */
Negative = nNumber ^ nNumerator ^ nDenominator;
/* We want to deal with a positive divisor to simplify the logic. */
if (nDivisor < 0) /* Turn all the parameters into absolute values */
if (nNumber < 0) nNumber *= -1;
if (nNumerator < 0) nNumerator *= -1;
if (nDenominator < 0) nDenominator *= -1;
/* Calculate the result */
Result.QuadPart = Int32x32To64(nNumber, nNumerator) + (nDenominator / 2);
/* Now check for overflow */
if (nDenominator > Result.HighPart)
{ {
nMultiplicand = - nMultiplicand; /* Divide the product to get the quotient and remainder */
nDivisor = -nDivisor; Result.LowPart = RtlEnlargedUnsignedDivide(*(PULARGE_INTEGER)&Result,
(ULONG)nDenominator,
&Result.HighPart);
/* Do the sign changes */
if ((LONG)Result.LowPart >= 0)
{
return (Negative >= 0) ? Result.LowPart : -(LONG)Result.LowPart;
}
} }
/* If the result is positive, we "add" to round. else, we subtract to round. */ /* Return overflow */
if ( ( (nMultiplicand < 0) && (nMultiplier < 0) ) || return - 1;
( (nMultiplicand >= 0) && (nMultiplier >= 0) ) )
ret = (((long long)nMultiplicand * nMultiplier) + (nDivisor/2)) / nDivisor;
else
ret = (((long long)nMultiplicand * nMultiplier) - (nDivisor/2)) / nDivisor;
if ((ret > 2147483647) || (ret < -2147483647)) return -1;
return ret;
#else
if (!nDivisor) return -1;
/* We want to deal with a positive divisor to simplify the logic. */
if (nDivisor < 0)
{
nMultiplicand = - nMultiplicand;
nDivisor = -nDivisor;
}
/* If the result is positive, we "add" to round. else, we subtract to round. */
if ( ( (nMultiplicand < 0) && (nMultiplier < 0) ) ||
( (nMultiplicand >= 0) && (nMultiplier >= 0) ) )
return ((nMultiplicand * nMultiplier) + (nDivisor/2)) / nDivisor;
return ((nMultiplicand * nMultiplier) - (nDivisor/2)) / nDivisor;
#endif
} }