1 files changed, 88 insertions, 0 deletions

diff --git a/lib/rbcodec/codecs/libgme/nes_vrc7_apu.c b/lib/rbcodec/codecs/libgme/nes_vrc7_apu.c
new file mode 100644
index 0000000000..8d3c2e88a6
--- /dev/null
+++ b/lib/rbcodec/codecs/libgme/nes_vrc7_apu.c
@@ -0,0 +1,88 @@
+
+#include "nes_vrc7_apu.h"
+#include "blargg_source.h"
+
+int const period = 36; // NES CPU clocks per FM clock
+
+void Vrc7_init( struct Nes_Vrc7_Apu* this )
+{
+        Synth_init( &this->synth );
+        
+        OPLL_new ( &this->opll, 3579545, 3579545 / 72 );
+    OPLL_reset_patch( &this->opll, OPLL_VRC7_TONE );
+        
+        this->osc.output = 0;
+        this->osc.last_amp = 0;
+        this->mask = 0;
+
+        Vrc7_volume( this, (int)FP_ONE_VOLUME );
+        Vrc7_reset( this );
+}
+
+void Vrc7_reset( struct Nes_Vrc7_Apu* this )
+{
+        this->addr      = 0;
+        this->next_time = 0;
+        this->osc.last_amp = 0;
+
+        OPLL_reset (&this->opll);       
+        OPLL_setMask(&this->opll, this->mask);
+}
+
+void Vrc7_set_rate( struct Nes_Vrc7_Apu* this, int r )
+{
+        OPLL_set_quality( &this->opll, r < 44100 ? 0 : 1 );
+}
+
+void Vrc7_write_reg( struct Nes_Vrc7_Apu* this, int data )
+{
+        this->addr = data;
+}
+
+void Vrc7_run_until( struct Nes_Vrc7_Apu* this, blip_time_t end_time );
+void Vrc7_write_data( struct Nes_Vrc7_Apu* this, blip_time_t time, int data )
+{       
+        if ( time > this->next_time )
+                Vrc7_run_until( this, time );
+
+        OPLL_writeIO( &this->opll, 0, this->addr );
+        OPLL_writeIO( &this->opll, 1, data );
+}
+
+void Vrc7_end_frame( struct Nes_Vrc7_Apu* this, blip_time_t time )
+{
+        if ( time > this->next_time )
+                Vrc7_run_until( this, time );
+        
+        this->next_time -= time;
+        assert( this->next_time >= 0 );
+        
+        if ( this->osc.output )
+                Blip_set_modified( this->osc.output );
+}
+
+void Vrc7_run_until( struct Nes_Vrc7_Apu* this, blip_time_t end_time )
+{
+        require( end_time > this->next_time );
+
+        blip_time_t time = this->next_time;
+        OPLL* opll = &this->opll; // cache
+        struct Blip_Buffer* const output = this-> osc.output;
+        if ( output )
+        {
+                do
+                {
+                        int amp = OPLL_calc( opll ) << 1;
+                        int delta = amp - this->osc.last_amp;
+                        if ( delta )
+                        {
+                                this->osc.last_amp = amp;
+                                Synth_offset_inline( &this->synth, time, delta, output );
+                        }
+                        time += period;
+                }
+                while ( time < end_time );
+        }
+
+        this->next_time = time;
+}