shithub: choc

ref: 8258632f22992446473a55bf31a9c8d5f53fe4a6
dir: /src/m_fixed.c/

// Emacs style mode select   -*- C++ -*- 
//-----------------------------------------------------------------------------
//
// Copyright(C) 1993-1996 Id Software, Inc.
// Copyright(C) 2005 Simon Howard
//
// This program is free software; you can redistribute it and/or
// modify it under the terms of the GNU General Public License
// as published by the Free Software Foundation; either version 2
// of the License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU General Public License for more details.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
// 02111-1307, USA.
//
// DESCRIPTION:
//	Fixed point implementation.
//
//-----------------------------------------------------------------------------



#include "stdlib.h"

#include "doomtype.h"
#include "i_system.h"

#include "m_fixed.h"




// Fixme. __USE_C_FIXED__ or something.

fixed_t
FixedMul
( fixed_t	a,
  fixed_t	b )
{
    return ((long long) a * (long long) b) >> FRACBITS;
}



//
// FixedDiv, C version.
//

fixed_t
FixedDiv
( fixed_t	a,
  fixed_t	b )
{
    if ( (abs(a)>>14) >= abs(b))
	return (a^b)<0 ? INT_MIN : INT_MAX;
    return FixedDiv2 (a,b);
}



fixed_t
FixedDiv2
( fixed_t	a,
  fixed_t	b )
{
#if 0
    long long c;
    c = ((long long)a<<16) / ((long long)b);
    return (fixed_t) c;
#endif

    double c;

    c = ((double)a) / ((double)b) * FRACUNIT;

    if (c >= 2147483648.0 || c < -2147483648.0)
	I_Error("FixedDiv: divide by zero");
    return (fixed_t) c;
}