reactos/lib/kernel32/misc/muldiv.c

   1 /* $Id: muldiv.c,v 1.1 2002/12/06 13:14:14 robd Exp $
   2  *
   3  */
   4 #include <windows.h>
   5
   6
   7 /***********************************************************************
   8  *           MulDiv   (KERNEL32.@)
   9  * RETURNS
  10  *      Result of multiplication and division
  11  *      -1: Overflow occurred or Divisor was 0
  12  */
  13
  14 //FIXME! move to correct file
  15 INT STDCALL MulDiv(
  16              INT nMultiplicand,
  17              INT nMultiplier,
  18              INT nDivisor)
  19 {
  20 #if SIZEOF_LONG_LONG >= 8
  21     long long ret;
  22
  23     if (!nDivisor) return -1;
  24
  25     /* We want to deal with a positive divisor to simplify the logic. */
  26     if (nDivisor < 0)
  27     {
  28       nMultiplicand = - nMultiplicand;
  29       nDivisor = -nDivisor;
  30     }
  31
  32     /* If the result is positive, we "add" to round. else, we subtract to round. */
  33     if ( ( (nMultiplicand <  0) && (nMultiplier <  0) ) ||
  34          ( (nMultiplicand >= 0) && (nMultiplier >= 0) ) )
  35       ret = (((long long)nMultiplicand * nMultiplier) + (nDivisor/2)) / nDivisor;
  36     else
  37       ret = (((long long)nMultiplicand * nMultiplier) - (nDivisor/2)) / nDivisor;
  38
  39     if ((ret > 2147483647) || (ret < -2147483647)) return -1;
  40     return ret;
  41 #else
  42     if (!nDivisor) return -1;
  43
  44     /* We want to deal with a positive divisor to simplify the logic. */
  45     if (nDivisor < 0)
  46     {
  47       nMultiplicand = - nMultiplicand;
  48       nDivisor = -nDivisor;
  49     }
  50
  51     /* If the result is positive, we "add" to round. else, we subtract to round. */
  52     if ( ( (nMultiplicand <  0) && (nMultiplier <  0) ) ||
  53          ( (nMultiplicand >= 0) && (nMultiplier >= 0) ) )
  54       return ((nMultiplicand * nMultiplier) + (nDivisor/2)) / nDivisor;
  55
  56     return ((nMultiplicand * nMultiplier) - (nDivisor/2)) / nDivisor;
  57
  58 #endif
  59 }
  60
  61