math.c File Reference

#include <win32k.h>

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Functions
INT APIENTRY	EngMulDiv (_In_ INT iMultiplicand, _In_ INT iMultiplier, _In_ INT iDivisor)

Function Documentation

EngMulDiv()

INT APIENTRY EngMulDiv	(	_In_ INT	iMultiplicand,
		_In_ INT	iMultiplier,
		_In_ INT	iDivisor
	)

Definition at line 26 of file math.c.

{
    INT64 i64Multiplied, i64Result;
 
    /* Check for divide by zero */
    if (iDivisor == 0)
    {
        /* Quick sign check and return "infinite" */
        return ((iMultiplicand ^ iMultiplier) < 0) ? INT_MIN : INT_MAX;
    }
 
    /* We want to deal with a positive divisor to simplify the logic. */
    if (iDivisor < 0)
    {
        iMultiplicand = -iMultiplicand;
        iDivisor = -iDivisor;
    }
 
    /* Do the multiplication */
    i64Multiplied = Int32x32To64(iMultiplicand, iMultiplier);
 
    /* If the result is positive, we add to round, else we subtract to round. */
    if (i64Multiplied >= 0)
    {
        i64Multiplied += (iDivisor / 2);
    }
    else
    {
        i64Multiplied -= (iDivisor / 2);
    }
 
    /* Now do the divide */
    i64Result = i64Multiplied / iDivisor;
 
    /* Check for positive overflow */
    if (i64Result > INT_MAX)
    {
        return INT_MAX;
    }
 
    /* Check for negative overflow. */
    if (i64Result < INT_MIN)
    {
        return INT_MIN;
    }
 
    return (INT)i64Result;
}

Referenced by IntCalculateThumb(), IntGdiSetMapMode(), IntPaintDesktop(), PATH_Ellipse(), and PATH_RoundRect().