// Fast SNES SPC-700 DSP emulator (about 3x speed of accurate one)

 

 // snes_spc 0.9.0

 #ifndef SPC_DSP_H

 #define SPC_DSP_H

 

 #include "blargg_common.h"

 

 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 spc_run_dsp()

 	// 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 (overrides VxVOL with 0).

 	// Reduces emulation accuracy.

 	enum { voice_count = 8 };

 	void mute_voices( int mask );

 

 	// If true, prevents channels and global volumes from being phase-negated

 	void disable_surround( bool disable = true );

 

 // State

 	

 	// Resets DSP and uses supplied values to initialize registers

 	enum { register_count = 128 };

 	void load( uint8_t const regs [register_count] );

 

 // 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; }

 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

 		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

 		int volume [2];         // copy of volume from DSP registers, with surround disabled

 		int enabled;            // -1 if enabled, 0 if muted

 	};

 private:

 	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 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)

 		unsigned counters [4];

 		

 		int new_kon;

 		int t_koff;

 		

 		voice_t voices [voice_count];

 		

 		unsigned* counter_select [32];

 		

 		// non-emulation state

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

 		int mute_mask;

 		int surround_threshold;

 		sample_t* out;

 		sample_t* out_end;

 		sample_t* out_begin;

 		sample_t extra [extra_size];

 	};

 	state_t m;

 	

 	void init_counter();

 	void run_counter( int );

 	void soft_reset_common();

 	void write_outline( int addr, int data );

 	void update_voice_vol( int addr );

 };

 

 #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::update_voice_vol( int addr )

 {

 	int l = (int8_t) m.regs [addr + v_voll];

 	int r = (int8_t) m.regs [addr + v_volr];

 	

 	if ( l * r < m.surround_threshold )

 	{

 		// signs differ, so negate those that are negative

 		l ^= l >> 7;

 		r ^= r >> 7;

 	}

 	

 	voice_t& v = m.voices [addr >> 4];

 	int enabled = v.enabled;

 	v.volume [0] = l & enabled;

 	v.volume [1] = r & enabled;

 }

 

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

 {

 	assert( (unsigned) addr < register_count );

 	

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

 	int low = addr & 0x0F;

 	if ( low < 0x2 ) // voice volumes

 	{

 		update_voice_vol( low ^ addr );

 	}

 	else if ( low == 0xC )

 	{

 		if ( addr == r_kon )

 			m.new_kon = (uint8_t) data;

 		

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

 			m.regs [r_endx] = 0;

 	}

 }

 

 inline void SPC_DSP::disable_surround( bool disable )

 {

 	m.surround_threshold = disable ? 0 : -0x4000;

 }

 

 #define SPC_NO_COPY_STATE_FUNCS 1

 

 #define SPC_LESS_ACCURATE 1

 

 #endif