1 files changed, 134 insertions, 0 deletions

diff --git a/apps/codecs/libgme/nes_apu.h b/apps/codecs/libgme/nes_apu.h
new file mode 100644
index 0000000000..6a2c2805e1
--- /dev/null
+++ b/apps/codecs/libgme/nes_apu.h
@@ -0,0 +1,134 @@
+// NES 2A03 APU sound chip emulator
+
+// Nes_Snd_Emu 0.1.8
+#ifndef NES_APU_H
+#define NES_APU_H
+
+#include "blargg_common.h"
+#include "nes_oscs.h"
+
+enum { apu_status_addr = 0x4015 };
+enum { apu_osc_count = 5 };
+enum { apu_no_irq = INT_MAX / 2 + 1 };
+enum { apu_irq_waiting = 0 };
+
+enum { apu_io_addr = 0x4000 };
+enum { apu_io_size = 0x18 };
+
+struct apu_state_t;
+
+struct Nes_Apu {        
+        nes_time_t last_dmc_time;       
+        int osc_enables;
+        
+        struct Nes_Osc*            oscs [apu_osc_count];
+        struct Nes_Square          square1;
+        struct Nes_Square          square2;
+        struct Nes_Noise           noise;
+        struct Nes_Triangle        triangle;
+        struct Nes_Dmc             dmc;
+        
+        double tempo_;
+        nes_time_t last_time; // has been run until this time in current frame
+        nes_time_t earliest_irq_;
+        nes_time_t next_irq;
+        int frame_period;
+        int frame_delay; // cycles until frame counter runs next
+        int frame; // current frame (0-3)
+        int frame_mode;
+        bool irq_flag;
+        
+        void (*irq_notifier_)( void* user_data );
+        void* irq_data;
+        
+        Synth square_synth; // shared by squares
+};
+
+// Init Nes apu
+void Apu_init( struct Nes_Apu* this );
+
+// Set buffer to generate all sound into, or disable sound if NULL
+void Apu_output( struct Nes_Apu* this, struct Blip_Buffer* ) ICODE_ATTR;
+        
+// All time values are the number of cpu clock cycles relative to the
+// beginning of the current time frame. Before resetting the cpu clock
+// count, call end_frame( last_cpu_time ).
+
+// Write to register (0x4000-0x4017, except 0x4014 and 0x4016)
+void Apu_write_register( struct Nes_Apu* this, nes_time_t, addr_t, int data ) ICODE_ATTR;
+        
+// Read from status register at 0x4015
+int Apu_read_status( struct Nes_Apu* this, nes_time_t ) ICODE_ATTR;
+        
+// Run all oscillators up to specified time, end current time frame, then
+// start a new time frame at time 0. Time frames have no effect on emulation
+// and each can be whatever length is convenient.
+void Apu_end_frame( struct Nes_Apu* this, nes_time_t ) ICODE_ATTR;
+        
+// Additional optional features (can be ignored without any problem)
+
+// Reset internal frame counter, registers, and all oscillators.
+// Use PAL timing if pal_timing is true, otherwise use NTSC timing.
+// Set the DMC oscillator's initial DAC value to initial_dmc_dac without
+// any audible click.
+void Apu_reset( struct Nes_Apu* this, bool pal_mode, int initial_dmc_dac );
+        
+// Adjust frame period
+void Apu_set_tempo( struct Nes_Apu* this, double );
+        
+// Set overall volume (default is 1.0)
+void Apu_volume( struct Nes_Apu* this, double );
+        
+// Run DMC until specified time, so that any DMC memory reads can be
+// accounted for (i.e. inserting cpu wait states).
+void Apu_run_until( struct Nes_Apu* this, nes_time_t ) ICODE_ATTR;
+
+// Set sound output of specific oscillator to buffer. If buffer is NULL,
+// the specified oscillator is muted and emulation accuracy is reduced.
+// The oscillators are indexed as follows: 0) Square 1, 1) Square 2,
+// 2) Triangle, 3) Noise, 4) DMC.
+static inline void Apu_osc_output( struct Nes_Apu* this, int osc, struct Blip_Buffer* buf )
+{
+        assert( (unsigned) osc < apu_osc_count );
+        this->oscs [osc]->output = buf;
+}
+
+// Set memory reader callback used by DMC oscillator to fetch samples.
+// When callback is invoked, 'user_data' is passed unchanged as the
+// first parameter.
+static inline void Apu_dmc_reader( struct Nes_Apu* this, int (*func)( void*, addr_t ), void* user_data )
+{
+        this->dmc.prg_reader_data = user_data;
+        this->dmc.prg_reader = func;
+}
+
+// Set IRQ time callback that is invoked when the time of earliest IRQ
+// may have changed, or NULL to disable. When callback is invoked,
+// 'user_data' is passed unchanged as the first parameter.
+static inline void Apu_irq_notifier( struct Nes_Apu* this, void (*func)( void* user_data ), void* user_data )
+{
+        this->irq_notifier_ = func;
+        this->irq_data = user_data;
+}
+
+// Count number of DMC reads that would occur if 'run_until( t )' were executed.
+// If last_read is not NULL, set *last_read to the earliest time that
+// 'count_dmc_reads( time )' would result in the same result.
+static inline int Apu_count_dmc_reads( struct Nes_Apu* this, nes_time_t time, nes_time_t* last_read )
+{
+        return Dmc_count_reads( &this->dmc, time, last_read );
+}
+
+static inline nes_time_t Dmc_next_read_time( struct Nes_Dmc* this )
+{
+        if ( this->osc.length_counter == 0 )
+                return apu_no_irq; // not reading
+        
+        return this->apu->last_dmc_time + this->osc.delay + (long) (this->bits_remain - 1) * this->period;
+}
+
+// Time when next DMC memory read will occur
+static inline nes_time_t Apu_next_dmc_read_time( struct Nes_Apu* this ) { return Dmc_next_read_time( &this->dmc ); }
+void Apu_irq_changed( struct Nes_Apu* this ) ICODE_ATTR;
+
+#endif