Vgm_Emu.h

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// Sega Master System/Mark III, Sega Genesis/Mega Drive, BBC Micro VGM music file emulator
 
// Game_Music_Emu https://bitbucket.org/mpyne/game-music-emu/
#ifndef VGM_EMU_H
#define VGM_EMU_H
 
#include "Vgm_Emu_Impl.h"
 
// Emulates VGM music using SN76489/SN76496 PSG, YM2612, and YM2413 FM sound chips.
// Supports custom sound buffer and frequency equalization when VGM uses just the PSG.
// FM sound chips can be run at their proper rates, or slightly higher to reduce
// aliasing on high notes. Currently YM2413 support requires that you supply a
// YM2413 sound chip emulator. I can provide one I've modified to work with the library.
class Vgm_Emu : public Vgm_Emu_Impl {
public:
        // True if custom buffer and custom equalization are supported
        // TODO: move into Music_Emu and rename to something like supports_custom_buffer()
        bool is_classic_emu() const { return !uses_fm; }
        
        blargg_err_t set_multi_channel ( bool is_enabled ) override;
        
        // Disable running FM chips at higher than normal rate. Will result in slightly
        // more aliasing of high notes.
        void disable_oversampling( bool disable = true ) { disable_oversampling_ = disable; }
        
        // VGM header format
        enum { header_size = 0x40 };
        struct header_t
        {
                char tag [4];
                byte data_size [4];
                byte version [4];
                byte psg_rate [4];
                byte ym2413_rate [4];
                byte gd3_offset [4];
                byte track_duration [4];
                byte loop_offset [4];
                byte loop_duration [4];
                byte frame_rate [4];
                byte noise_feedback [2];
                byte noise_width;
                byte unused1;
                byte ym2612_rate [4];
                byte ym2151_rate [4];
                byte data_offset [4];
                byte unused2 [8];
        };
        
        // Header for currently loaded file
        header_t const& header() const { return *(header_t const*) data; }
        
        static gme_type_t static_type() { return gme_vgm_type; }
        
public:
        // deprecated
        using Music_Emu::load;
        blargg_err_t load( header_t const& h, Data_Reader& in ) // use Remaining_Reader
                        { return load_remaining_( &h, sizeof h, in ); }
        byte const* gd3_data( int* size_out = 0 ) const; // use track_info()
 
public:
        Vgm_Emu();
        ~Vgm_Emu();
protected:
        blargg_err_t track_info_( track_info_t*, int track ) const;
        blargg_err_t load_mem_( byte const*, long );
        blargg_err_t set_sample_rate_( long sample_rate );
        blargg_err_t start_track_( int );
        blargg_err_t play_( long count, sample_t* );
        blargg_err_t run_clocks( blip_time_t&, int );
        void set_tempo_( double );
        void mute_voices_( int mask );
        void set_voice( int, Blip_Buffer*, Blip_Buffer*, Blip_Buffer* );
        void update_eq( blip_eq_t const& );
private:
        // removed; use disable_oversampling() and set_tempo() instead
        Vgm_Emu( bool oversample, double tempo = 1.0 );
        double fm_rate;
        long psg_rate;
        long vgm_rate;
        bool disable_oversampling_;
        bool uses_fm;
        blargg_err_t setup_fm();
};
 
#endif