apps/codecs/libgme/sms_fm_apu.c

   1 #include "sms_fm_apu.h"
   2
   3 #include "blargg_source.h"
   4
   5 void Fm_apu_create( struct Sms_Fm_Apu* this )
   6 {
   7         Synth_init( &this->synth );
   8         Ym2413_init( &this->apu );
   9 }
  10
  11 blargg_err_t Fm_apu_init( struct Sms_Fm_Apu* this, int clock_rate, int sample_rate )
  12 {
  13         this->period_ = (blip_time_t) (clock_rate / sample_rate);
  14         CHECK_ALLOC( !Ym2413_set_rate( &this->apu, sample_rate, clock_rate ) );
  15
  16         Fm_apu_set_output( this, 0 );
  17         Fm_apu_volume( this, (int)FP_ONE_VOLUME );
  18         Fm_apu_reset( this );
  19         return 0;
  20 }
  21
  22 void Fm_apu_reset( struct Sms_Fm_Apu* this )
  23 {
  24         this->addr      = 0;
  25         this->next_time = 0;
  26         this->last_amp  = 0;
  27
  28         Ym2413_reset( &this->apu );
  29 }
  30
  31 void fm_run_until( struct Sms_Fm_Apu* this, blip_time_t end_time ) ICODE_ATTR;
  32 void Fm_apu_write_data( struct Sms_Fm_Apu* this, blip_time_t time, int data )
  33 {
  34         if ( time > this->next_time )
  35                 fm_run_until( this, time );
  36
  37         Ym2413_write( &this->apu, this->addr, data );
  38 }
  39
  40 void fm_run_until( struct Sms_Fm_Apu* this, blip_time_t end_time )
  41 {
  42         assert( end_time > this->next_time );
  43
  44         struct Blip_Buffer* const output = this->output_;
  45         if ( !output )
  46         {
  47                 this->next_time = end_time;
  48                 return;
  49         }
  50
  51         blip_time_t time = this->next_time;
  52         struct Ym2413_Emu* emu = &this->apu;
  53         do
  54         {
  55                 short samples [2];
  56                 Ym2413_run( emu, 1, samples );
  57                 int amp = (samples [0] + samples [1]) >> 1;
  58
  59                 int delta = amp - this->last_amp;
  60                 if ( delta )
  61                 {
  62                         this->last_amp = amp;
  63                         Synth_offset_inline( &this->synth, time, delta, output );
  64                 }
  65                 time += this->period_;
  66         }
  67         while ( time < end_time );
  68
  69         this->next_time = time;
  70 }
  71
  72 void Fm_apu_end_frame( struct Sms_Fm_Apu* this, blip_time_t time )
  73 {
  74         if ( time > this->next_time )
  75                 fm_run_until( this, time );
  76
  77         this->next_time -= time;
  78         assert( this->next_time >= 0 );
  79
  80         if ( this->output_ )
  81                 Blip_set_modified( this->output_ );
  82 }