mixer.h

基于lpc2148（arm7）的wav音乐格式播放器的设计

// -*- tab-width: 4 -*-
// TRAXMOD Audio Mixer
//
// Copyright (c) 2006-2008, K9spud LLC.
// http://www.k9spud.com/traxmod/
//
// 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.
//
// You should have received a copy of the GNU General Public License
// along with this program; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.

#ifndef __MIXER_H
#define __MIXER_H

#include "audio.h"
#include "types.h"
#include "stdlib.h"
#include "modplay/music.h"

#define CHANNELS 4
#define MAXVOLUME 64

//#define GRAPHDBG(x) uart0Putch(x)
#define GRAPHDBG(x) 

// WARNING: DO NOT MODIFY THE ORDER OF EXISTING MEMBERS OF THIS STRUCTURE.
// Otherwise, you will have to fix isr.S so that it can reach the readingData->Length variable.
typedef struct
{
	eint8* Data;				// RAM buffer for sample data to be mixed.
	int iSDLoc;	 				// sample offset (iLoc) that beginning of RAM buffer corresponds to.
	eint16 Length;				// current number of samples that have been read into the RAM buffer.
	eint16 Channel;				// Channel number this data belongs to.
} StreamDataType;

extern StreamDataType StreamData[];
extern StreamDataType* readingData;	// data that is being read into RAM
extern StreamDataType* mixingData;	// data that has been fully read into RAM and ready for mixing
extern StreamDataType* waitingData;	// data that is has been read into RAM, but is not being mixed until the mixingData buffer is finished mixing.

typedef struct
{
	eint16* outputPointer;		// pointer into the main output audio buffer where this channel is currently mixing into.

	unsigned int iSDLocation;	// physical SD Card location for the beginning of the sample

	int iEnd;
	int iLoopStart;

	int iStep;
	int iStepFract;

	int iLoc;
	unsigned int iLocFract;

	euint16 iVolLeft;
	euint16 iVolRight;

	unsigned bActive	:1;
	unsigned bLoop  	:1;
	
	unsigned int mixingFrame;
//	unsigned bBiDi		:1;
//	unsigned b16		:1;
//	unsigned bStereo	:1;
} MixChannelType;

extern MixChannelType MixChannel[];

extern unsigned int iFramePeriod;
extern int frameCountdown;
extern eint16* framePointer;
extern unsigned int waitForFrame;

extern int skipMisaligned;

void stopSD(void);
void doFrameWatch(void);
int doMix(void);
void initMixer(void);

void copyEventToChannel(MixChannelType* mixChannel, EventChannelType* eventChannel);
//void PostProcess(unsigned int iPtr, unsigned int iLength);

int bufferLength(eint16* mixPtr /* tail */, eint16* playPtr /* head */);

void startNextReader(void);
void finishReading(void);

void printStatus(int i);

#endif // __MIXER_H