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// Emacs style mode select -*- C++ -*-
//-----------------------------------------------------------------------------
//
// $Id$
//
// Copyright (C) 1993-1996 by id Software, Inc.
//
// 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.
//
// DESCRIPTION:
// Fixed point arithemtics, implementation.
//
//-----------------------------------------------------------------------------
#ifndef __M_FIXED__
#define __M_FIXED__
#ifdef __GNUG__
#pragma interface
#endif
#include "doomtype.h"
#include "rockmacros.h"
//
// Fixed point, 32bit as 16.16.
//
#define FRACBITS 16
#define FRACUNIT (1<<FRACBITS)
#define D_abs(x) ({fixed_t _t = (x), _s = _t >> (8*sizeof _t-1); (_t^_s)-_s;})
typedef int fixed_t;
inline static int FixedMul( int a, int b )
{
#if defined(CPU_COLDFIRE)
// Code contributed by Thom Johansen
register int result;
asm (
"mac.l %[x],%[y],%%acc0 \n" /* multiply */
"move.l %[y],%%d2 \n"
"mulu.l %[x],%%d2 \n" /* get lower half, avoid emac stall */
"movclr.l %%acc0,%[result] \n" /* get higher half */
"asl.l #8,%[result] \n" /* hi <<= 15, plus one free */
"asl.l #7,%[result] \n" /* hi <<= 15, plus one free */
"lsr.l #8,%%d2 \n" /* (unsigned)lo >>= 16 */
"lsr.l #8,%%d2 \n" /* (unsigned)lo >>= 16 */
"or.l %%d2 ,%[result] \n" /* combine result */
: /* outputs */
[result]"=&d"(result)
: /* inputs */
[x] "d" (a),
[y] "d" (b)
: /* clobbers */
"d2"
);
return result;
#else
return (fixed_t)((long long) a*b >> FRACBITS);
#endif
}
inline static fixed_t FixedDiv( fixed_t a, fixed_t b )
{
return (D_abs(a)>>14) >= D_abs(b) ? ((a^b)>>31) ^ MAXINT :
(fixed_t)(((long long) a << FRACBITS) / b);
}
/* CPhipps -
* FixedMod - returns a % b, guaranteeing 0<=a<b
* (notice that the C standard for % does not guarantee this)
*/
inline static 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
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