// Highly accurate SNES SPC-700 DSP emulator

 

 // snes_spc 0.9.0

 #ifndef SPC_DSP_H

 #define SPC_DSP_H

 

 #include "blargg_common.h"

 

 extern "C" { typedef void (*dsp_copy_func_t)( unsigned char** io, void* state, size_t ); }

 

 class SPC_DSP {

 public:

 	typedef BOOST::uint8_t uint8_t;

 	

 // Setup

 

 	// Initializes DSP and has it use the 64K RAM provided

 	void init( void* ram_64k );

 

 	// Sets destination for output samples. If out is NULL or out_size is 0,

 	// doesn't generate any.

 	typedef short sample_t;

 	void set_output( sample_t* out, int out_size );

 

 	// Number of samples written to output since it was last set, always

 	// a multiple of 2. Undefined if more samples were generated than

 	// output buffer could hold.

 	int sample_count() const;

 

 // Emulation

 

 	// Resets DSP to power-on state

 	void reset();

 

 	// Emulates pressing reset switch on SNES

 	void soft_reset();

 	

 	// Reads/writes DSP registers. For accuracy, you must first call run()

 	// to catch the DSP up to present.

 	int  read ( int addr ) const;

 	void write( int addr, int data );

 

 	// Runs DSP for specified number of clocks (~1024000 per second). Every 32 clocks

 	// a pair of samples is be generated.

 	void run( int clock_count );

 	

 // Sound control

 

 	// Mutes voices corresponding to non-zero bits in mask (issues repeated KOFF events).

 	// Reduces emulation accuracy.

 	enum { voice_count = 8 };

 	void mute_voices( int mask );

 

 // State

 	

 	// Resets DSP and uses supplied values to initialize registers

 	enum { register_count = 128 };

 	void load( uint8_t const regs [register_count] );

 

 	// Saves/loads exact emulator state

 	enum { state_size = 640 }; // maximum space needed when saving

 	typedef dsp_copy_func_t copy_func_t;

 	void copy_state( unsigned char** io, copy_func_t );

 

 	// Returns non-zero if new key-on events occurred since last call

 	bool check_kon();

 	

 // DSP register addresses

 

 	// Global registers

 	enum {

 	    r_mvoll = 0x0C, r_mvolr = 0x1C,

 	    r_evoll = 0x2C, r_evolr = 0x3C,

 	    r_kon   = 0x4C, r_koff  = 0x5C,

 	    r_flg   = 0x6C, r_endx  = 0x7C,

 	    r_efb   = 0x0D, r_pmon  = 0x2D,

 	    r_non   = 0x3D, r_eon   = 0x4D,

 	    r_dir   = 0x5D, r_esa   = 0x6D,

 	    r_edl   = 0x7D,

 	    r_fir   = 0x0F // 8 coefficients at 0x0F, 0x1F ... 0x7F

 	};

 

 	// Voice registers

 	enum {

 		v_voll   = 0x00, v_volr   = 0x01,

 		v_pitchl = 0x02, v_pitchh = 0x03,

 		v_srcn   = 0x04, v_adsr0  = 0x05,

 		v_adsr1  = 0x06, v_gain   = 0x07,

 		v_envx   = 0x08, v_outx   = 0x09

 	};

 

 public:

 	enum { extra_size = 16 };

 	sample_t* extra()               { return m.extra; }

 	sample_t const* out_pos() const { return m.out; }

 	void disable_surround( bool ) { } // not supported

 public:

 	BLARGG_DISABLE_NOTHROW

 	

 	typedef BOOST::int8_t   int8_t;

 	typedef BOOST::int16_t int16_t;

 	

 	enum { echo_hist_size = 8 };

 	

 	enum env_mode_t { env_release, env_attack, env_decay, env_sustain };

 	enum { brr_buf_size = 12 };

 	struct voice_t

 	{

 		int buf [brr_buf_size*2];// decoded samples (twice the size to simplify wrap handling)

 		int buf_pos;            // place in buffer where next samples will be decoded

 		int interp_pos;         // relative fractional position in sample (0x1000 = 1.0)

 		int brr_addr;           // address of current BRR block

 		int brr_offset;         // current decoding offset in BRR block

 		uint8_t* regs;          // pointer to voice's DSP registers

 		int vbit;               // bitmask for voice: 0x01 for voice 0, 0x02 for voice 1, etc.

 		int kon_delay;          // KON delay/current setup phase

 		env_mode_t env_mode;

 		int env;                // current envelope level

 		int hidden_env;         // used by GAIN mode 7, very obscure quirk

 		uint8_t t_envx_out;

 	};

 private:

 	enum { brr_block_size = 9 };

 	

 	struct state_t

 	{

 		uint8_t regs [register_count];

 		

 		// Echo history keeps most recent 8 samples (twice the size to simplify wrap handling)

 		int echo_hist [echo_hist_size * 2] [2];

 		int (*echo_hist_pos) [2]; // &echo_hist [0 to 7]

 		

 		int every_other_sample; // toggles every sample

 		int kon;                // KON value when last checked

 		int noise;

 		int counter;

 		int echo_offset;        // offset from ESA in echo buffer

 		int echo_length;        // number of bytes that echo_offset will stop at

 		int phase;              // next clock cycle to run (0-31)

 		bool kon_check;         // set when a new KON occurs

 		

 		// Hidden registers also written to when main register is written to

 		int new_kon;

 		uint8_t endx_buf;

 		uint8_t envx_buf;

 		uint8_t outx_buf;

 		

 		// Temporary state between clocks

 		

 		// read once per sample

 		int t_pmon;

 		int t_non;

 		int t_eon;

 		int t_dir;

 		int t_koff;

 		

 		// read a few clocks ahead then used

 		int t_brr_next_addr;

 		int t_adsr0;

 		int t_brr_header;

 		int t_brr_byte;

 		int t_srcn;

 		int t_esa;

 		int t_echo_enabled;

 		

 		// internal state that is recalculated every sample

 		int t_dir_addr;

 		int t_pitch;

 		int t_output;

 		int t_looped;

 		int t_echo_ptr;

 		

 		// left/right sums

 		int t_main_out [2];

 		int t_echo_out [2];

 		int t_echo_in  [2];

 		

 		voice_t voices [voice_count];

 		

 		// non-emulation state

 		uint8_t* ram; // 64K shared RAM between DSP and SMP

 		int mute_mask;

 		sample_t* out;

 		sample_t* out_end;

 		sample_t* out_begin;

 		sample_t extra [extra_size];

 	};

 	state_t m;

 	

 	void init_counter();

 	void run_counters();

 	unsigned read_counter( int rate );

 	

 	int  interpolate( voice_t const* v );

 	void run_envelope( voice_t* const v );

 	void decode_brr( voice_t* v );

 

 	void misc_27();

 	void misc_28();

 	void misc_29();

 	void misc_30();

 

 	void voice_output( voice_t const* v, int ch );

 	void voice_V1( voice_t* const );

 	void voice_V2( voice_t* const );

 	void voice_V3( voice_t* const );

 	void voice_V3a( voice_t* const );

 	void voice_V3b( voice_t* const );

 	void voice_V3c( voice_t* const );

 	void voice_V4( voice_t* const );

 	void voice_V5( voice_t* const );

 	void voice_V6( voice_t* const );

 	void voice_V7( voice_t* const );

 	void voice_V8( voice_t* const );

 	void voice_V9( voice_t* const );

 	void voice_V7_V4_V1( voice_t* const );

 	void voice_V8_V5_V2( voice_t* const );

 	void voice_V9_V6_V3( voice_t* const );

 

 	void echo_read( int ch );

 	int  echo_output( int ch );

 	void echo_write( int ch );

 	void echo_22();

 	void echo_23();

 	void echo_24();

 	void echo_25();

 	void echo_26();

 	void echo_27();

 	void echo_28();

 	void echo_29();

 	void echo_30();

 	

 	void soft_reset_common();

 };

 

 #include <assert.h>

 

 inline int SPC_DSP::sample_count() const { return m.out - m.out_begin; }

 

 inline int SPC_DSP::read( int addr ) const

 {

 	assert( (unsigned) addr < register_count );

 	return m.regs [addr];

 }

 

 inline void SPC_DSP::write( int addr, int data )

 {

 	assert( (unsigned) addr < register_count );

 	

 	m.regs [addr] = (uint8_t) data;

 	switch ( addr & 0x0F )

 	{

 	case v_envx:

 		m.envx_buf = (uint8_t) data;

 		break;

 		

 	case v_outx:

 		m.outx_buf = (uint8_t) data;

 		break;

 	

 	case 0x0C:

 		if ( addr == r_kon )

 			m.new_kon = (uint8_t) data;

 		

 		if ( addr == r_endx ) // always cleared, regardless of data written

 		{

 			m.endx_buf = 0;

 			m.regs [r_endx] = 0;

 		}

 		break;

 	}

 }

 

 inline void SPC_DSP::mute_voices( int mask ) { m.mute_mask = mask; }

 

 inline bool SPC_DSP::check_kon()

 {

 	bool old = m.kon_check;

 	m.kon_check = 0;

 	return old;

 }

 

 #if !SPC_NO_COPY_STATE_FUNCS

 

 class SPC_State_Copier {

 	SPC_DSP::copy_func_t func;

 	unsigned char** buf;

 public:

 	SPC_State_Copier( unsigned char** p, SPC_DSP::copy_func_t f ) { func = f; buf = p; }

 	void copy( void* state, size_t size );

 	int copy_int( int state, int size );

 	void skip( int count );

 	void extra();

 };

 

 #define SPC_COPY( type, state )\

 {\

 	state = (BOOST::type) copier.copy_int( state, sizeof (BOOST::type) );\

 	assert( (BOOST::type) state == state );\

 }

 

 #endif

 

 #endif