gzdoom-gles/libraries/game-music-emu/gme/Effects_Buffer.h

// Multi-channel effects buffer with panning, echo and reverb

// Game_Music_Emu https://bitbucket.org/mpyne/game-music-emu/
#ifndef EFFECTS_BUFFER_H
#define EFFECTS_BUFFER_H

#include "Multi_Buffer.h"

#include <vector>

// Effects_Buffer uses several buffers and outputs stereo sample pairs.
class Effects_Buffer : public Multi_Buffer {
public:
	// nVoices indicates the number of voices for which buffers will be allocated
	// to make Effects_Buffer work as "mix everything to one", nVoices will be 1
	// If center_only is true, only center buffers are created and
	// less memory is used.
	Effects_Buffer( int nVoices = 1, bool center_only = false );
	
	// Channel  Effect    Center Pan
	// ---------------------------------
	//    0,5    reverb       pan_1
	//    1,6    reverb       pan_2
	//    2,7    echo         -
	//    3      echo         -
	//    4      echo         -
	
	// Channel configuration
	struct config_t {
		double pan_1;           // -1.0 = left, 0.0 = center, 1.0 = right
		double pan_2;
		double echo_delay;      // msec
		double echo_level;      // 0.0 to 1.0
		double reverb_delay;    // msec
		double delay_variance;  // difference between left/right delays (msec)
		double reverb_level;    // 0.0 to 1.0
		bool effects_enabled;   // if false, use optimized simple mixer
		config_t();
	};
	
	// Set configuration of buffer
	virtual void config( const config_t& );
	void set_depth( double );
	
public:
	~Effects_Buffer();
	blargg_err_t set_sample_rate( long samples_per_sec, int msec = blip_default_length );
	void clock_rate( long );
	void bass_freq( int );
	void clear();
	channel_t channel( int, int );
	void end_frame( blip_time_t );
	long read_samples( blip_sample_t*, long );
	long samples_avail() const;
private:
	typedef long fixed_t;
	int max_voices;
	enum { max_buf_count = 7 };
	std::vector<Blip_Buffer> bufs;
	enum { chan_types_count = 3 };
	std::vector<channel_t> chan_types;
	config_t config_;
	long stereo_remain;
	long effect_remain;
	int buf_count;
	bool effects_enabled;
	
	std::vector<std::vector<blip_sample_t> > reverb_buf;
	std::vector<std::vector<blip_sample_t> > echo_buf;
	std::vector<int> reverb_pos;
	std::vector<int> echo_pos;
	
	struct {
		fixed_t pan_1_levels [2];
		fixed_t pan_2_levels [2];
		int echo_delay_l;
		int echo_delay_r;
		fixed_t echo_level;
		int reverb_delay_l;
		int reverb_delay_r;
		fixed_t reverb_level;
	} chans;
	
	void mix_mono( blip_sample_t*, blargg_long );
	void mix_stereo( blip_sample_t*, blargg_long );
	void mix_enhanced( blip_sample_t*, blargg_long );
	void mix_mono_enhanced( blip_sample_t*, blargg_long );
};

#endif