/*****************************************************************************/
/* D2K: A Doom Source Port for the 21st Century                              */
/*                                                                           */
/* Copyright (C) 2014: See COPYRIGHT file                                    */
/*                                                                           */
/* This file is part of D2K.                                                 */
/*                                                                           */
/* D2K 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.                                                            */
/*                                                                           */
/* D2K 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 D2K.  If not, see <http://www.gnu.org/licenses/>.                    */
/*                                                                           */
/*****************************************************************************/


#ifndef M_FIXED_H__
#define M_FIXED_H__

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <stdlib.h>
#include "doomtype.h"

/*
 * Fixed point, 32bit as 16.16.
 */

#define FRACBITS 16
#define FRACUNIT (1<<FRACBITS)

typedef int fixed_t;

/*
 * Absolute Value
 *
 * killough 5/10/98: In djgpp, use inlined assembly for performance
 * killough 9/05/98: better code seems to be gotten from using inlined C
 */

// e6y
// Microsoft and Intel compilers produce stupid and slow code for asm version of D_abs:
//
// mov    DWORD PTR $T49478[esp+12], eax
// mov    eax, DWORD PTR $T49478[esp+12]
//
// Plane abs() generates absolutely the same code as in asm version of D_abs(),
// so we do not need additional implementations for abs() at all.
//
// btw, GCC generates code without nonsenses

#if 0
inline static CONSTFUNC fixed_t D_abs(fixed_t x)
{
  fixed_t _t = (x),_s;
  _s = _t >> (8*sizeof _t-1);
  return (_t^_s)-_s;
}
#else
#define D_abs abs
#endif

/*
 * Fixed Point Multiplication
 */


/* CPhipps - made __inline__ to inline, as specified in the gcc docs
 * Also made const */

inline static CONSTFUNC fixed_t FixedMul(fixed_t a, fixed_t b)
{
  return (fixed_t)((int_64_t) a*b >> FRACBITS);
}

/*
 * Fixed Point Division
 */

inline static CONSTFUNC fixed_t FixedDiv(fixed_t a, fixed_t b)
{
  return (D_abs(a)>>14) >= D_abs(b) ? ((a^b)>>31) ^ INT_MAX :
    (fixed_t)(((int_64_t) a << FRACBITS) / b);
}

/* CPhipps -
 * FixedMod - returns a % b, guaranteeing 0<=a<b
 * (notice that the C standard for % does not guarantee this)
 */

inline static CONSTFUNC fixed_t FixedMod(fixed_t a, fixed_t b)
{
  if (b & (b-1)) {
    fixed_t r = a % b;
    return ((r<0) ? r+b : r);
  } else
    return (a & (b-1));
}

#endif

/* vi: set et ts=2 sw=2: */

