/* ***** BEGIN LICENSE BLOCK *****
 * Source last modified: $Id: crosfade.h,v 1.2.36.1 2004/07/09 02:08:04 hubbe Exp $
 * 
 * Portions Copyright (c) 1995-2004 RealNetworks, Inc. All Rights Reserved.
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 * the file under the current version of the RealNetworks Community
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 * ***** END LICENSE BLOCK ***** */

#ifndef _CROSS_FADER_
#define _CROSS_FADER_

/*
 * Since (oldsamp-newsamp) can be -65535..65535 (17 bits),
 * could use 17.15 format (without rounding),
 * or use 18.14 format to allow rounding without overflow.
 */
#define FRACBITS	14		/* allow rounding */
#define FRACMASK	((1<<FRACBITS) - 1)
#define FRACROUND	(1 << (FRACBITS-1))

/* table parameters */
#define NALPHA		128		/* size of alpha table */
#define DBSTART		0.0		/* starting gain, in dB */
#define DBEND		-90.0	/* ending gain, in dB */

#define DB2GAIN(d) (pow(10.0, (d)/20.0))

// XXXHP: NEED TO REGENERATE ON WIN16 EVERYTIME THIS ARRAY
//	  IS MODIFIED!!!
#ifdef _WIN16
extern INT32* alpha;
extern INT32* adelta;
#else

#ifdef GENERATE_TABLE
static INT32 alpha[NALPHA+1] = {
#else
static const INT32 alpha[NALPHA+1] = {
#endif
				16384, 15100, 13917, 12827, 11822, 
				10896, 10042, 9255, 8530, 7862, 
				7246, 6678, 6155, 5673, 5228, 
				4819, 4441, 4093, 3772, 3477, 
				3204, 2953, 2722, 2509, 2312, 
				2131, 1964, 1810, 1668, 1538, 
				1417, 1306, 1204, 1110, 1023, 
				942, 869, 801, 738, 680, 
				627, 578, 532, 491, 452, 
				417, 384, 354, 326, 301, 
				277, 255, 235, 217, 200, 
				184, 170, 157, 144, 133, 
				123, 113, 104, 96, 88, 
				82, 75, 69, 64, 59, 
				54, 50, 46, 42, 39, 
				36, 33, 31, 28, 26, 
				24, 22, 20, 19, 17, 
				16, 15, 14, 12, 12, 
				11, 10, 9, 8, 8, 
				7, 6, 6, 6, 5, 
				5, 4, 4, 4, 3, 
				3, 3, 3, 2, 2, 
				2, 2, 2, 2, 1, 
				1, 1, 1, 1, 1, 
				1, 1, 1, 1, 1, 
				1, 1, 1, 1
};

#ifdef GENERATE_TABLE
static INT32 adelta[NALPHA] = {
#else
static const INT32 adelta[NALPHA] = {
#endif
				-1284, -1183, -1090, -1005, -926, 
				-854, -787, -725, -668, -616, 
				-568, -523, -482, -445, -409, 
				-378, -348, -321, -295, -273, 
				-251, -231, -213, -197, -181, 
				-167, -154, -142, -130, -121, 
				-111, -102, -94, -87, -81, 
				-73, -68, -63, -58, -53, 
				-49, -46, -41, -39, -35, 
				-33, -30, -28, -25, -24, 
				-22, -20, -18, -17, -16, 
				-14, -13, -13, -11, -10, 
				-10, -9, -8, -8, -6, 
				-7, -6, -5, -5, -5, 
				-4, -4, -4, -3, -3, 
				-3, -2, -3, -2, -2, 
				-2, -2, -1, -2, -1, 
				-1, -1, -2, 0, -1, 
				-1, -1, -1, 0, -1, 
				-1, 0, 0, -1, 0, 
				-1, 0, 0, -1, 0, 
				0, 0, -1, 0, 0, 
				0, 0, 0, -1, 0, 
				0, 0, 0, 0, 0, 
				0, 0, 0, 0, 0, 
				0, 0, 0 
};
#endif

class CrossFader
{
public:

    CrossFader();
    ~CrossFader();
    HX_RESULT	Initialize(UINT16 uNumSamplesToFadeOn, UINT16 uNumChannels);
    void	CrossFade(INT16* sampold, INT16* sampnew, UINT16 uNumSamples);

    
#ifdef GENERATE_TABLE
    /* This is for reference use only. this routine is used to generate
     * the static tables 
     */
    void	CrossFadeInit(void);
#endif

protected:

    /* table steppers */
    INT32	tabstep;
    INT32	tabacc;
    INT32	tabint;	
    UINT16	m_uNumChannels : 16;
    HX_BITFIELD	m_bInitialized : 1;

};
#endif /*_CROSS_FADER_*/