dll/win32/kernel32/wine/muldiv.c

   1 /*
   2  * COPYRIGHT:       See COPYING in the top level directory
   3  * PROJECT:         ReactOS system libraries
   4  * FILE:            dll/win32/kernel32/wine/muldiv.c
   5  * PURPOSE:
   6  * PROGRAMMER:      Casper S. Hornstrup
   7  *                  Gunnar Andre Dalsnes
   8  * UPDATE HISTORY:
   9  *                  Created 06/12/2002
  10  */
  11
  12 #include <k32.h>
  13
  14 /***********************************************************************
  15  *           MulDiv   (KERNEL32.@)
  16  * RETURNS
  17  *      Result of multiplication and division
  18  *      -1: Overflow occurred or Divisor was 0
  19  * FIXME! move to correct file
  20  *
  21  * @implemented
  22  */
  23 INT
  24 WINAPI
  25 MulDiv(INT nNumber,
  26        INT nNumerator,
  27        INT nDenominator)
  28 {
  29     LARGE_INTEGER Result;
  30     LONG Negative;
  31
  32     /* Find out if this will be a negative result */
  33     Negative = nNumber ^ nNumerator ^ nDenominator;
  34
  35     /* Turn all the parameters into absolute values */
  36     if (nNumber < 0) nNumber *= -1;
  37     if (nNumerator < 0) nNumerator *= -1;
  38     if (nDenominator < 0) nDenominator *= -1;
  39
  40     /* Calculate the result */
  41     Result.QuadPart = Int32x32To64(nNumber, nNumerator) + (nDenominator / 2);
  42
  43     /* Now check for overflow */
  44     if (nDenominator > Result.HighPart)
  45     {
  46         /* Divide the product to get the quotient and remainder */
  47         Result.LowPart = RtlEnlargedUnsignedDivide(*(PULARGE_INTEGER)&Result,
  48                                                    (ULONG)nDenominator,
  49                                                    (PULONG)&Result.HighPart);
  50
  51         /* Do the sign changes */
  52         if ((LONG)Result.LowPart >= 0)
  53         {
  54             return (Negative >= 0) ? (LONG)Result.LowPart : -(LONG)Result.LowPart;
  55         }
  56     }
  57
  58     /* Return overflow */
  59     return - 1;
  60 }
  61