common/tables.h

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// Emacs style mode select   -*- C++ -*-
//-----------------------------------------------------------------------------
//
// $Id: tables.h 2079 2011-02-05 01:48:56Z russellrice $
//
// Copyright (C) 1993-1996 by id Software, Inc.
// Copyright (C) 2006-2010 by The Odamex Team.
//
// This source is available for distribution and/or modification
// only under the terms of the DOOM Source Code License as
// published by id Software. All rights reserved.
//
// The source is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// FITNESS FOR A PARTICULAR PURPOSE. See the DOOM Source Code 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_H__
#define __TABLES_H__

#include "m_fixed.h"

#define PI                              3.141592657

#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 phase shift.
extern const fixed_t*           finecosine;


// Effective size is 4096.
extern const fixed_t            finetangent[FINEANGLES/2];

// Binary Angle Measument, BAM.
#define ANG45                   0x20000000
#define ANG90                   0x40000000
#define ANG180                  0x80000000
#define ANG270                  0xc0000000
#define ANG(n)                  ((ANG45/45)*(n))

#define ANG360  0xffffffff

#define SLOPERANGE              2048
#define SLOPEBITS               11
#define DBITS                   (FRACBITS-SLOPEBITS)

typedef DWORD                   angle_t;


// Effective size is 2049;
// The +1 size is to handle the case when x==y without additional checking.
// [ML] 2/2/10: Updated with R_PointToAngle2 changes (from EE)
extern const angle_t tantoangle[2049];
extern angle_t tantoangle_acc[2049];

extern const angle_t *p_tantoangle;

void Table_InitTanToAngle(void);
void Table_SetTanToAngle(int version);



#endif // __TABLES_H__