apps/codecs/libgme/vgm_emu.h

   1 // Sega Master System/Mark III, Sega Genesis/Mega Drive, BBC Micro VGM music file emulator
   2
   3 // Game_Music_Emu 0.5.5
   4 #ifndef VGM_EMU_H
   5 #define VGM_EMU_H
   6
   7 #include "blargg_common.h"
   8 #include "blargg_source.h"
   9 #include "resampler.h"
  10 #include "multi_buffer.h"
  11 #include "ym2413_emu.h"
  12 #include "ym2612_emu.h"
  13 #include "sms_apu.h"
  14
  15 typedef short sample_t;
  16 typedef int vgm_time_t;
  17 typedef int fm_time_t;
  18
  19 enum { fm_time_bits = 12 };
  20 enum { blip_time_bits = 12 };
  21 enum { buf_size = 2048 };
  22
  23 // VGM header format
  24 enum { header_size = 0x40 };
  25 struct header_t
  26 {
  27         char tag [4];
  28         byte data_size [4];
  29         byte version [4];
  30         byte psg_rate [4];
  31         byte ym2413_rate [4];
  32         byte gd3_offset [4];
  33         byte track_duration [4];
  34         byte loop_offset [4];
  35         byte loop_duration [4];
  36         byte frame_rate [4];
  37         byte noise_feedback [2];
  38         byte noise_width;
  39         byte unused1;
  40         byte ym2612_rate [4];
  41         byte ym2151_rate [4];
  42         byte data_offset [4];
  43         byte unused2 [8];
  44 };
  45
  46 enum { gme_max_field = 63 };
  47 struct track_info_t
  48 {
  49         /* times in milliseconds; -1 if unknown */
  50         long length;
  51         long intro_length;
  52         long loop_length;
  53
  54         /* empty string if not available */
  55         char game      [64];
  56         char song      [96];
  57         char author    [64];
  58 };
  59
  60 // Emulates VGM music using SN76489/SN76496 PSG, YM2612, and YM2413 FM sound chips.
  61 // Supports custom sound buffer and frequency equalization when VGM uses just the PSG.
  62 // FM sound chips can be run at their proper rates, or slightly higher to reduce
  63 // aliasing on high notes. Currently YM2413 support requires that you supply a
  64 // YM2413 sound chip emulator. I can provide one I've modified to work with the library.
  65 struct Vgm_Emu {
  66         double fm_rate;
  67         long psg_rate;
  68         long vgm_rate;
  69         bool disable_oversampling;
  70
  71         long fm_time_offset;
  72         int fm_time_factor;
  73
  74         int blip_time_factor;
  75
  76         byte const* file_begin;
  77         byte const* file_end;
  78
  79         vgm_time_t vgm_time;
  80         byte const* loop_begin;
  81         byte const* pos;
  82
  83         byte const* pcm_data;
  84         byte const* pcm_pos;
  85         int dac_amp;
  86         int dac_disabled; // -1 if disabled
  87
  88         struct Blip_Buffer* blip_buf;
  89
  90         // general
  91         long clock_rate_;
  92         unsigned buf_changed_count;
  93         int max_initial_silence;
  94         int voice_count;
  95         int mute_mask_;
  96         double tempo;
  97         double gain;
  98
  99         long sample_rate;
 100
 101         // track-specific
 102         blargg_long out_time;  // number of samples played since start of track
 103         blargg_long emu_time;  // number of samples emulator has generated since start of track
 104         bool emu_track_ended_; // emulator has reached end of track
 105         volatile bool track_ended;
 106
 107         // fading
 108         blargg_long fade_start;
 109         int fade_step;
 110
 111         // silence detection
 112         int silence_lookahead; // speed to run emulator when looking ahead for silence
 113         bool ignore_silence;
 114         long silence_time;     // number of samples where most recent silence began
 115         long silence_count;    // number of samples of silence to play before using buf
 116         long buf_remain;       // number of samples left in silence buffer
 117
 118         // larger items at the end
 119         struct track_info_t info;
 120         sample_t buf_ [buf_size];
 121
 122         struct Ym2612_Emu ym2612;
 123         struct Ym2413_Emu ym2413;
 124
 125         struct Sms_Apu psg;
 126         struct Blip_Synth pcm;
 127         struct Stereo_Buffer stereo_buf;
 128
 129         struct Resampler resampler;
 130
 131         struct Stereo_Buffer buf;
 132 };
 133
 134 void Vgm_init( struct Vgm_Emu* this );
 135
 136 // Disable running FM chips at higher than normal rate. Will result in slightly
 137 // more aliasing of high notes.
 138 static inline void Vgm_disable_oversampling( struct Vgm_Emu* this, bool disable ) { this->disable_oversampling = disable; }
 139
 140 // Header for currently loaded file
 141 static inline struct header_t *header( struct Vgm_Emu* this ) { return (struct header_t*) this->file_begin; }
 142
 143 // Basic functionality (see Gme_File.h for file loading/track info functions)
 144 blargg_err_t Vgm_load_mem( struct Vgm_Emu* this, byte const* new_data, long new_size, bool parse_info );
 145
 146 // True if any FM chips are used by file. Always false until init_fm()
 147 // is called.
 148 static inline bool uses_fm( struct Vgm_Emu* this ) { return Ym2612_enabled( &this->ym2612 ) || Ym2413_enabled( &this->ym2413 ); }
 149
 150 // Set output sample rate. Must be called only once before loading file.
 151 blargg_err_t Vgm_set_sample_rate( struct Vgm_Emu* this, long sample_rate );
 152
 153 // Start a track, where 0 is the first track. Also clears warning string.
 154 blargg_err_t Vgm_start_track( struct Vgm_Emu* this );
 155
 156 // Generate 'count' samples info 'buf'. Output is in stereo. Any emulation
 157 // errors set warning string, and major errors also end track.
 158 blargg_err_t Vgm_play( struct Vgm_Emu* this, long count, sample_t* buf ) ICODE_ATTR;
 159
 160 // Track status/control
 161
 162 // Number of milliseconds (1000 msec = 1 second) played since beginning of track
 163 long Track_tell( struct Vgm_Emu* this );
 164
 165 // Seek to new time in track. Seeking backwards or far forward can take a while.
 166 blargg_err_t Track_seek( struct Vgm_Emu* this, long msec );
 167
 168 // Skip n samples
 169 blargg_err_t Track_skip( struct Vgm_Emu* this, long n );
 170
 171 // Set start time and length of track fade out. Once fade ends track_ended() returns
 172 // true. Fade time can be changed while track is playing.
 173 void Track_set_fade( struct Vgm_Emu* this, long start_msec, long length_msec );
 174
 175 // Get track length in milliseconds
 176 static inline long Track_get_length( struct Vgm_Emu* this )
 177 {
 178         long length = this->info.length;
 179         if ( length <= 0 )
 180         {
 181                 length = this->info.intro_length + 2 * this->info.loop_length; // intro + 2 loops
 182                 if ( length <= 0 )
 183                         length = 150 * 1000; // 2.5 minutes
 184         }
 185
 186         return length;
 187 }
 188
 189 // Sound customization
 190
 191 // Adjust song tempo, where 1.0 = normal, 0.5 = half speed, 2.0 = double speed.
 192 // Track length as returned by track_info() assumes a tempo of 1.0.
 193 void Sound_set_tempo( struct Vgm_Emu* this, double t );
 194
 195 // Mute/unmute voice i, where voice 0 is first voice
 196 void Sound_mute_voice( struct Vgm_Emu* this, int index, bool mute );
 197
 198 // Set muting state of all voices at once using a bit mask, where -1 mutes them all,
 199 // 0 unmutes them all, 0x01 mutes just the first voice, etc.
 200 void Sound_mute_voices( struct Vgm_Emu* this, int mask );
 201
 202 // Change overall output amplitude, where 1.0 results in minimal clamping.
 203 // Must be called before set_sample_rate().
 204 static inline void Sound_set_gain( struct Vgm_Emu* this, double g )
 205 {
 206         assert( !this->sample_rate ); // you must set gain before setting sample rate
 207         this->gain = g;
 208 }
 209
 210
 211 #endif