80 lines
2.1 KiB
C
80 lines
2.1 KiB
C
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// AY-3-8910 sound chip ulator
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// Game_Music_Emu 0.6-pre
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#ifndef AY_APU_H
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#define AY_APU_H
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#include "blargg_common.h"
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#include "blargg_source.h"
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#include "blip_buffer.h"
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// Number of registers
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enum { ay_reg_count = 16 };
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enum { ay_osc_count = 3 };
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enum { ay_amp_range = 255 };
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struct osc_t
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{
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blip_time_t period;
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blip_time_t delay;
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short last_amp;
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short phase;
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struct Blip_Buffer* output;
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};
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struct Ay_Apu {
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struct osc_t oscs [ay_osc_count];
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blip_time_t last_time;
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byte addr_;
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byte regs [ay_reg_count];
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blip_time_t noise_delay;
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unsigned noise_lfsr;
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blip_time_t env_delay;
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byte const* env_wave;
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int env_pos;
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byte env_modes [8] [48]; // values already passed through volume table
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struct Blip_Synth synth_; // used by Ay_Core for beeper sound
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};
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void Ay_apu_init( struct Ay_Apu* this );
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// Writes to address register
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static inline void Ay_apu_write_addr( struct Ay_Apu* this, int data ) { this->addr_ = data & 0x0F; }
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// Emulates to time t, then writes to current data register
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void run_until( struct Ay_Apu* this, blip_time_t final_end_time ) ICODE_ATTR;;
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void write_data_( struct Ay_Apu* this, int addr, int data ) ICODE_ATTR;
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static inline void Ay_apu_write_data( struct Ay_Apu* this, blip_time_t t, int data ) { run_until( this, t ); write_data_( this, this->addr_, data ); }
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// Reads from current data register
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int Ay_apu_read( struct Ay_Apu* this );
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// Resets sound chip
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void Ay_apu_reset( struct Ay_Apu* this );
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// Sets overall volume, where 1.0 is normal
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static inline void Ay_apu_volume( struct Ay_Apu* this, double v ) { Synth_volume( &this->synth_, 0.7/ay_osc_count/ay_amp_range * v ); }
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static inline void Ay_apu_set_output( struct Ay_Apu* this, int i, struct Blip_Buffer* out )
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{
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assert( (unsigned) i < ay_osc_count );
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this->oscs [i].output = out;
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}
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// Emulates to time t, then subtracts t from the current time.
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// OK if previous write call had time slightly after t.
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static inline void Ay_apu_end_frame( struct Ay_Apu* this, blip_time_t time )
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{
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if ( time > this->last_time )
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run_until( this, time );
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this->last_time -= time;
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assert( this->last_time >= 0 );
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}
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#endif
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