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// NES FDS sound chip emulator
// Game_Music_Emu 0.6-pre
#ifndef NES_FDS_APU_H
#define NES_FDS_APU_H
#include "blargg_common.h"
#include "blip_buffer.h"
enum { lfo_base_tempo = 8 };
enum { fds_osc_count = 1 };
enum { fds_io_addr = 0x4040 };
enum { fds_io_size = 0x53 };
enum { fds_wave_size = 0x40 };
enum { fds_master_vol_max = 10 };
enum { fds_vol_max = 0x20 };
enum { fds_wave_sample_max = 0x3F };
struct Nes_Fds_Apu {
unsigned char regs_ [fds_io_size];// last written value to registers
int lfo_tempo; // normally 8; adjusted by set_tempo()
int env_delay;
int env_speed;
int env_gain;
int sweep_delay;
int sweep_speed;
int sweep_gain;
int wave_pos;
int last_amp;
blip_time_t wave_fract;
int mod_fract;
int mod_pos;
int mod_write_pos;
unsigned char mod_wave [fds_wave_size];
// synthesis
blip_time_t last_time;
struct Blip_Buffer* output_;
struct Blip_Synth synth;
};
// init
void Fds_init( struct Nes_Fds_Apu* this );
// setup
void Fds_set_tempo( struct Nes_Fds_Apu* this, int t );
// emulation
void Fds_reset( struct Nes_Fds_Apu* this );
static inline void Fds_volume( struct Nes_Fds_Apu* this, int v )
{
Synth_volume( &this->synth, (v*14) / 100 / fds_master_vol_max / fds_vol_max / fds_wave_sample_max );
}
static inline void Fds_set_output( struct Nes_Fds_Apu* this, int i, struct Blip_Buffer* b )
{
#if defined(ROCKBOX)
(void) i;
#endif
assert( (unsigned) i < fds_osc_count );
this->output_ = b;
}
void Fds_run_until( struct Nes_Fds_Apu* this, blip_time_t );
static inline void Fds_end_frame( struct Nes_Fds_Apu* this, blip_time_t end_time )
{
if ( end_time > this->last_time )
Fds_run_until( this, end_time );
this->last_time -= end_time;
assert( this->last_time >= 0 );
}
void Fds_write_( struct Nes_Fds_Apu* this, unsigned addr, int data );
static inline void Fds_write( struct Nes_Fds_Apu* this, blip_time_t time, unsigned addr, int data )
{
Fds_run_until( this, time );
Fds_write_( this, addr, data );
}
static inline int Fds_read( struct Nes_Fds_Apu* this, blip_time_t time, unsigned addr )
{
Fds_run_until( this, time );
int result = 0xFF;
switch ( addr )
{
case 0x4090:
result = this->env_gain;
break;
case 0x4092:
result = this->sweep_gain;
break;
default:
{
unsigned i = addr - fds_io_addr;
if ( i < fds_wave_size )
result = this->regs_ [i];
}
}
return result | 0x40;
}
// allow access to registers by absolute address (i.e. 0x4080)
static inline unsigned char* regs_nes( struct Nes_Fds_Apu* this, unsigned addr ) { return &this->regs_ [addr - fds_io_addr]; }
#endif
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