apps/codecs/libgme/hes_apu_adpcm.h

   1 // Turbo Grafx 16 (PC Engine) ADPCM sound chip emulator
   2
   3 // Game_Music_Emu 0.6-pre
   4 #ifndef HES_APU_ADPCM_H
   5 #define HES_APU_ADPCM_H
   6
   7 #include "blargg_source.h"
   8 #include "blargg_common.h"
   9 #include "blip_buffer.h"
  10
  11 enum { adpcm_amp_range = 2048 };
  12 enum { adpcm_osc_count = 1 }; // 0 <= chan < osc_count
  13
  14 // Registers are at io_addr to io_addr+io_size-1
  15 enum { io_addr = 0x1800 };
  16 enum { io_size = 0x400 };
  17
  18 struct State
  19 {
  20         byte           pcmbuf [0x10000];
  21         byte           port [0x10];
  22         int            ad_sample;
  23         int            ad_ref_index;
  24         bool           ad_low_nibble;
  25         int            freq;
  26         unsigned short addr;
  27         unsigned short writeptr;
  28         unsigned short readptr;
  29         unsigned short playptr;
  30         byte           playflag;
  31         byte           repeatflag;
  32         int            length;
  33         int            playlength;
  34         int            playedsamplecount;
  35         int            volume;
  36         int            fadetimer;
  37         int            fadecount;
  38 };
  39
  40 struct Hes_Apu_Adpcm {
  41         struct State state;
  42         struct Blip_Synth synth;
  43
  44         struct Blip_Buffer* output;
  45         blip_time_t  last_time;
  46         double       next_timer;
  47         int          last_amp;
  48 };
  49
  50 // Init HES adpcm sound chip
  51 void Adpcm_init( struct Hes_Apu_Adpcm* this );
  52
  53 // Rest HES adpcm sound chip
  54 void Adpcm_reset( struct Hes_Apu_Adpcm* this );
  55
  56 // Sets buffer(s) to generate sound into, or 0 to mute. If only center is not 0,
  57 // output is mono.
  58 static inline void Adpcm_set_output( struct Hes_Apu_Adpcm* this, int chan, struct Blip_Buffer* center, struct Blip_Buffer* left, struct Blip_Buffer* right )
  59 {
  60         // Must be silent (all NULL), mono (left and right NULL), or stereo (none NULL)
  61         require( !center || (center && !left && !right) || (center && left && right) );
  62         require( (unsigned) chan < adpcm_osc_count ); // fails if you pass invalid osc index
  63
  64 #if defined(ROCKBOX)
  65     (void) chan;
  66 #endif
  67
  68         if ( !center || !left || !right )
  69         {
  70                 left  = center;
  71                 right = center;
  72         }
  73
  74         this->output = center;
  75 }
  76
  77 // Emulates to time t, then writes data to addr
  78 void Adpcm_write_data( struct Hes_Apu_Adpcm* this, blip_time_t t, int addr, int data ) ICODE_ATTR;
  79
  80 // Emulates to time t, then reads from addr
  81 int Adpcm_read_data( struct Hes_Apu_Adpcm* this, blip_time_t t, int addr ) ICODE_ATTR;
  82
  83 // Emulates to time t, then subtracts t from the current time.
  84 // OK if previous write call had time slightly after t.
  85 void Adpcm_end_frame( struct Hes_Apu_Adpcm* this,blip_time_t t ) ICODE_ATTR;
  86
  87 // Sets overall volume, where 1.0 is normal
  88 static inline void Adpcm_volume( struct Hes_Apu_Adpcm* this, double v ) { Synth_volume( &this->synth, 0.6 / adpcm_osc_count / adpcm_amp_range * v ); }
  89 #endif