apps/codecs/libgme/sms_apu.h

   1 // Sega Master System SN76489 PSG sound chip emulator
   2
   3 // Sms_Snd_Emu 0.1.2
   4 #ifndef SMS_APU_H
   5 #define SMS_APU_H
   6
   7 #include "blargg_common.h"
   8 #include "blip_buffer.h"
   9
  10 // 0: Square 1, 1: Square 2, 2: Square 3, 3: Noise
  11 enum { sms_osc_count = 4 }; // 0 <= chan < osc_count
  12
  13 struct Osc
  14 {
  15         struct Blip_Buffer* outputs [4]; // NULL, right, left, center
  16         struct Blip_Buffer* output;
  17         int          last_amp;
  18
  19         int         volume;
  20         int         period;
  21         int         delay;
  22         unsigned    phase;
  23 };
  24
  25 struct Sms_Apu {
  26         struct Osc     oscs [sms_osc_count];
  27         int     ggstereo;
  28         int     latch;
  29
  30         blip_time_t last_time;
  31         int         min_tone_period;
  32         unsigned    noise_feedback;
  33         unsigned    looped_feedback;
  34         struct Blip_Synth synth;
  35 };
  36
  37 // Basics
  38
  39 void Sms_apu_init( struct Sms_Apu* this );
  40
  41 // Sets buffer(s) to generate sound into, or 0 to mute. If only center is not 0,
  42 // output is mono.
  43 void Sms_apu_set_output( struct Sms_Apu* this, int i, struct Blip_Buffer* center, struct Blip_Buffer* left, struct Blip_Buffer* right);
  44
  45 // Emulates to time t, then writes data to Game Gear left/right assignment byte
  46 void Sms_apu_write_ggstereo( struct Sms_Apu* this, blip_time_t t, int data ) ICODE_ATTR;
  47
  48 // Emulates to time t, then writes data
  49 void Sms_apu_write_data( struct Sms_Apu* this, blip_time_t t, int data ) ICODE_ATTR;
  50
  51 // Emulates to time t, then subtracts t from the current time.
  52 // OK if previous write call had time slightly after t.
  53 void Sms_apu_end_frame( struct Sms_Apu* this, blip_time_t t ) ICODE_ATTR;
  54
  55 // More features
  56
  57 // Resets sound chip and sets noise feedback bits and width
  58 void Sms_apu_reset( struct Sms_Apu* this, unsigned noise_feedback, int noise_width );
  59
  60 // Sets overall volume, where 1.0 is normal
  61 void Sms_apu_volume( struct Sms_Apu* this, double vol );
  62
  63 #endif