shithub: rott

ref: c6da73fdd9464580baa8461952480d17e580ae1a
dir: /src/watcom.c/

#include "rt_def.h"

#include "watcom.h"

/*
  C versions of watcom.h assembly.
  Uses the '__int64' type (see rt_def.h).
 */

fixed FixedMul(fixed a, fixed b)
{
    __int64 scratch1 = (__int64) a * (__int64) b + (__int64) 0x8000;
    return (scratch1 >> 16) & 0xffffffff;
}

fixed FixedMulShift(fixed a, fixed b, fixed shift)
{
    __int64 x = a;
    __int64 y = b;
    __int64 z = x * y;

    return (((unsigned __int64)z) >> shift) & 0xffffffff;
}

fixed FixedDiv2(fixed a, fixed b)
{
    __int64 x = (signed int)a;
    __int64 y = (signed int)b;
    __int64 z = x * 65536 / y;

    return (z) & 0xffffffff;
}

fixed FixedScale(fixed orig, fixed factor, fixed divisor)
{
/*
    __int64 x = orig;
    __int64 y = factor;
    __int64 z = divisor;

    __int64 w = (x * y) / z;

    return (w) & 0xffffffff;
*/
    //changed to this because arithmetic errors occurred with resolutions > 800x600
    return (float)orig * factor / divisor;
}