1 files changed, 82 insertions, 0 deletions

diff --git a/lib/rbcodec/codecs/libgme/sms_fm_apu.c b/lib/rbcodec/codecs/libgme/sms_fm_apu.c
new file mode 100644
index 0000000000..ee5ce48932
--- /dev/null
+++ b/lib/rbcodec/codecs/libgme/sms_fm_apu.c
@@ -0,0 +1,82 @@
+#include "sms_fm_apu.h"
+
+#include "blargg_source.h"
+
+void Fm_apu_create( struct Sms_Fm_Apu* this )
+{ 
+        Synth_init( &this->synth );
+        Ym2413_init( &this->apu );
+}
+
+blargg_err_t Fm_apu_init( struct Sms_Fm_Apu* this, int clock_rate, int sample_rate )
+{
+        this->period_ = (blip_time_t) (clock_rate / sample_rate);
+        CHECK_ALLOC( !Ym2413_set_rate( &this->apu, sample_rate, clock_rate ) );
+        
+        Fm_apu_set_output( this, 0 );
+        Fm_apu_volume( this, (int)FP_ONE_VOLUME );
+        Fm_apu_reset( this );
+        return 0;
+}
+
+void Fm_apu_reset( struct Sms_Fm_Apu* this )
+{
+        this->addr      = 0;
+        this->next_time = 0;
+        this->last_amp  = 0;
+        
+        Ym2413_reset( &this->apu );
+}
+
+void fm_run_until( struct Sms_Fm_Apu* this, blip_time_t end_time );
+void Fm_apu_write_data( struct Sms_Fm_Apu* this, blip_time_t time, int data )
+{
+        if ( time > this->next_time )
+                fm_run_until( this, time );
+        
+        Ym2413_write( &this->apu, this->addr, data );
+}
+
+void fm_run_until( struct Sms_Fm_Apu* this, blip_time_t end_time )
+{
+        assert( end_time > this->next_time );
+        
+        struct Blip_Buffer* const output = this->output_;
+        if ( !output )
+        {
+                this->next_time = end_time;
+                return;
+        }
+        
+        blip_time_t time = this->next_time;
+        struct Ym2413_Emu* emu = &this->apu;
+        do
+        {
+                short samples [2];
+                Ym2413_run( emu, 1, samples );
+                int amp = (samples [0] + samples [1]) >> 1;
+                
+                int delta = amp - this->last_amp;
+                if ( delta )
+                {
+                        this->last_amp = amp;
+                        Synth_offset_inline( &this->synth, time, delta, output );
+                }
+                time += this->period_;
+        }
+        while ( time < end_time );
+        
+        this->next_time = time;
+}
+
+void Fm_apu_end_frame( struct Sms_Fm_Apu* this, blip_time_t time )
+{
+        if ( time > this->next_time )
+                fm_run_until( this, time );
+        
+        this->next_time -= time;
+        assert( this->next_time >= 0 );
+        
+        if ( this->output_ )
+                Blip_set_modified( this->output_ );
+}