reactos/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/misc/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 /***********************************************************************
  16  *           MulDiv   (KERNEL32.@)
  17  * RETURNS
  18  *      Result of multiplication and division
  19  *      -1: Overflow occurred or Divisor was 0
  20  * FIXME! move to correct file
  21  *
  22  * @implemented
  23  */
  24 INT
  25 WINAPI
  26 MulDiv(INT nNumber,
  27        INT nNumerator,
  28        INT nDenominator)
  29 {
  30     LARGE_INTEGER Result;
  31     LONG Negative;
  32
  33     /* Find out if this will be a negative result */
  34     Negative = nNumber ^ nNumerator ^ nDenominator;
  35
  36     /* Turn all the parameters into absolute values */
  37     if (nNumber < 0) nNumber *= -1;
  38     if (nNumerator < 0) nNumerator *= -1;
  39     if (nDenominator < 0) nDenominator *= -1;
  40
  41     /* Calculate the result */
  42     Result.QuadPart = Int32x32To64(nNumber, nNumerator) + (nDenominator / 2);
  43
  44     /* Now check for overflow */
  45     if (nDenominator > Result.HighPart)
  46     {
  47         /* Divide the product to get the quotient and remainder */
  48         Result.LowPart = RtlEnlargedUnsignedDivide(*(PULARGE_INTEGER)&Result,
  49                                                    (ULONG)nDenominator,
  50                                                    (PULONG)&Result.HighPart);
  51
  52         /* Do the sign changes */
  53         if ((LONG)Result.LowPart >= 0)
  54         {
  55             return (Negative >= 0) ? (LONG)Result.LowPart : -(LONG)Result.LowPart;
  56         }
  57     }
  58
  59     /* Return overflow */
  60     return - 1;
  61 }
  62