1 files changed, 211 insertions, 0 deletions

diff --git a/apps/codecs/libgme/vgm_emu.h b/apps/codecs/libgme/vgm_emu.h
new file mode 100644
index 0000000000..deb64bc7e0
--- /dev/null
+++ b/apps/codecs/libgme/vgm_emu.h
@@ -0,0 +1,211 @@
+// Sega Master System/Mark III, Sega Genesis/Mega Drive, BBC Micro VGM music file emulator
+
+// Game_Music_Emu 0.5.5
+#ifndef VGM_EMU_H
+#define VGM_EMU_H
+
+#include "blargg_common.h"
+#include "blargg_source.h"
+#include "resampler.h"
+#include "multi_buffer.h"
+#include "ym2413_emu.h"
+#include "ym2612_emu.h"
+#include "sms_apu.h"
+
+typedef short sample_t;
+typedef int vgm_time_t;
+typedef int fm_time_t;
+
+enum { fm_time_bits = 12 };
+enum { blip_time_bits = 12 };
+enum { buf_size = 2048 };
+
+// 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];
+};
+
+enum { gme_max_field = 63 };
+struct track_info_t
+{
+        /* times in milliseconds; -1 if unknown */
+        long length;
+        long intro_length;
+        long loop_length;
+        
+        /* empty string if not available */
+        char game      [64];
+        char song      [96];
+        char author    [64];
+};
+
+// 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.
+struct Vgm_Emu {
+        double fm_rate;
+        long psg_rate;
+        long vgm_rate;
+        bool disable_oversampling;
+        
+        long fm_time_offset;
+        int fm_time_factor;
+
+        int blip_time_factor;
+        
+        byte const* file_begin;
+        byte const* file_end;
+        
+        vgm_time_t vgm_time;
+        byte const* loop_begin;
+        byte const* pos;
+        
+        byte const* pcm_data;
+        byte const* pcm_pos;
+        int dac_amp;
+        int dac_disabled; // -1 if disabled
+
+        struct Blip_Buffer* blip_buf;
+
+        // general
+        long clock_rate_;
+        unsigned buf_changed_count;
+        int max_initial_silence;
+        int voice_count;
+        int mute_mask_;
+        double tempo;
+        double gain;
+        
+        long sample_rate;
+        
+        // track-specific
+        blargg_long out_time;  // number of samples played since start of track
+        blargg_long emu_time;  // number of samples emulator has generated since start of track
+        bool emu_track_ended_; // emulator has reached end of track
+        volatile bool track_ended;
+        
+        // fading
+        blargg_long fade_start;
+        int fade_step;
+        
+        // silence detection
+        int silence_lookahead; // speed to run emulator when looking ahead for silence
+        bool ignore_silence;
+        long silence_time;     // number of samples where most recent silence began
+        long silence_count;    // number of samples of silence to play before using buf
+        long buf_remain;       // number of samples left in silence buffer
+        
+        // larger items at the end
+        struct track_info_t info;
+        sample_t buf_ [buf_size];
+
+        struct Ym2612_Emu ym2612;
+        struct Ym2413_Emu ym2413;
+        
+        struct Sms_Apu psg;
+        struct Blip_Synth pcm;
+        struct Stereo_Buffer stereo_buf;
+        
+        struct Resampler resampler;
+        
+        struct Stereo_Buffer buf;
+};
+
+void Vgm_init( struct Vgm_Emu* this );
+
+// Disable running FM chips at higher than normal rate. Will result in slightly
+// more aliasing of high notes.
+static inline void Vgm_disable_oversampling( struct Vgm_Emu* this, bool disable ) { this->disable_oversampling = disable; }
+
+// Header for currently loaded file
+static inline struct header_t *header( struct Vgm_Emu* this ) { return (struct header_t*) this->file_begin; }
+        
+// Basic functionality (see Gme_File.h for file loading/track info functions)
+blargg_err_t Vgm_load_mem( struct Vgm_Emu* this, byte const* new_data, long new_size, bool parse_info );
+
+// True if any FM chips are used by file. Always false until init_fm()
+// is called.
+static inline bool uses_fm( struct Vgm_Emu* this ) { return Ym2612_enabled( &this->ym2612 ) || Ym2413_enabled( &this->ym2413 ); }
+
+// Set output sample rate. Must be called only once before loading file.
+blargg_err_t Vgm_set_sample_rate( struct Vgm_Emu* this, long sample_rate );
+        
+// Start a track, where 0 is the first track. Also clears warning string.
+blargg_err_t Vgm_start_track( struct Vgm_Emu* this );
+        
+// Generate 'count' samples info 'buf'. Output is in stereo. Any emulation
+// errors set warning string, and major errors also end track.
+blargg_err_t Vgm_play( struct Vgm_Emu* this, long count, sample_t* buf ) ICODE_ATTR;
+                
+// Track status/control
+
+// Number of milliseconds (1000 msec = 1 second) played since beginning of track
+long Track_tell( struct Vgm_Emu* this );
+        
+// Seek to new time in track. Seeking backwards or far forward can take a while.
+blargg_err_t Track_seek( struct Vgm_Emu* this, long msec );
+        
+// Skip n samples
+blargg_err_t Track_skip( struct Vgm_Emu* this, long n );
+                
+// Set start time and length of track fade out. Once fade ends track_ended() returns
+// true. Fade time can be changed while track is playing.
+void Track_set_fade( struct Vgm_Emu* this, long start_msec, long length_msec );
+
+// Get track length in milliseconds
+static inline long Track_get_length( struct Vgm_Emu* this )
+{
+        long length = this->info.length;
+        if ( length <= 0 )
+        {
+                length = this->info.intro_length + 2 * this->info.loop_length; // intro + 2 loops
+                if ( length <= 0 )
+                        length = 150 * 1000; // 2.5 minutes
+        }
+        
+        return length;
+}
+        
+// Sound customization
+        
+// Adjust song tempo, where 1.0 = normal, 0.5 = half speed, 2.0 = double speed.
+// Track length as returned by track_info() assumes a tempo of 1.0.
+void Sound_set_tempo( struct Vgm_Emu* this, double t );
+        
+// Mute/unmute voice i, where voice 0 is first voice
+void Sound_mute_voice( struct Vgm_Emu* this, int index, bool mute );
+        
+// Set muting state of all voices at once using a bit mask, where -1 mutes them all,
+// 0 unmutes them all, 0x01 mutes just the first voice, etc.
+void Sound_mute_voices( struct Vgm_Emu* this, int mask );
+        
+// Change overall output amplitude, where 1.0 results in minimal clamping.
+// Must be called before set_sample_rate().
+static inline void Sound_set_gain( struct Vgm_Emu* this, double g )
+{
+        assert( !this->sample_rate ); // you must set gain before setting sample rate
+        this->gain = g;
+}
+
+
+#endif