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// Fast SNES SPC-700 DSP emulator (about 3x speed of accurate one)
// Game_Music_Emu 0.5.5
#ifndef SPC_DSP_H
#define SPC_DSP_H
#include "blargg_common.h"
struct 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
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