tables.h

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//
// Copyright(C) 1993-1996 Id Software, Inc.
// Copyright(C) 1993-2008 Raven Software
// Copyright(C) 2005-2014 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.
//
// DESCRIPTION:
//  Lookup tables.
//  Do not try to look them up :-).
//  In the order of appearance: 
//
//  int finetangent[4096]   - Tangens LUT.
//   Should work with BAM fairly well (12 of 16bit,
//      effectively, by shifting).
//
//  int finesine[10240]     - Sine lookup.
//   Guess what, serves as cosine, too.
//   Remarkable thing is, how to use BAMs with this? 
//
//  int tantoangle[2049]    - ArcTan LUT,
//    maps tan(angle) to angle fast. Gotta search.  
//    
 
 
#ifndef __TABLES__
#define __TABLES__
 
#include "doomtype.h"
 
#include "m_fixed.h"
    
#define FINEANGLES      8192
#define FINEMASK        (FINEANGLES-1)
 
 
// 0x100000000 to 0x2000
#define ANGLETOFINESHIFT    19      
 
// Effective size is 10240.
extern const fixed_t finesine[5*FINEANGLES/4];
 
// Re-use data, is just PI/2 pahse shift.
extern const fixed_t *finecosine;
 
 
// Effective size is 4096.
extern const fixed_t finetangent[FINEANGLES/2];
 
// Gamma correction tables.
extern const byte gammatable[5][256];
 
// Binary Angle Measument, BAM.
 
#define ANG45           0x20000000
#define ANG90           0x40000000
#define ANG180          0x80000000
#define ANG270          0xc0000000
#define ANG_MAX         0xffffffff
 
#define ANG1            (ANG45 / 45)
#define ANG60           (ANG180 / 3)
 
// Heretic code uses this definition as though it represents one 
// degree, but it is not!  This is actually ~1.40 degrees.
 
#define ANG1_X          0x01000000
 
#define SLOPERANGE      2048
#define SLOPEBITS       11
#define DBITS           (FRACBITS-SLOPEBITS)
 
typedef unsigned angle_t;
 
 
// Effective size is 2049;
// The +1 size is to handle the case when x==y
//  without additional checking.
extern const angle_t tantoangle[SLOPERANGE+1];
 
 
// Utility function,
//  called by R_PointToAngle.
int SlopeDiv(unsigned int num, unsigned int den);
 
 
#endif