// Highly accurate SNES SPC-700 DSP emulator
// snes_spc 0.9.0
#pragma once
#include "blargg_common.h"
class SPC_DSP
{
public:
// Setup
// Initializes DSP and has it use the 64K RAM provided
void init(uint8_t *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(const uint8_t regs[register_count]);
// Snes9x Accessor
int stereo_switch;
bool rom_enabled; // mirror
uint8_t *rom, *hi_ram; // mirror
void set_stereo_switch(int);
uint8_t reg_value(int, int);
int envx_value(int);
// 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 this->m.extra; }
const sample_t *out_pos() const { return this->m.out; }
void disable_surround(bool) { } // not supported
public:
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;
int voice_number;
};
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]
bool 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)
// 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(const voice_t *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(const voice_t *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);
// Current echo buffer pointer for left/right channel
uint8_t *ECHO_PTR(int ch) { return &this->m.ram[this->m.t_echo_ptr + ch * 2]; }
// Sample in echo history buffer, where 0 is the oldest
int *ECHO_FIR(size_t i) { return this->m.echo_hist_pos[i]; }
// Calculate FIR point for left/right channel
int CALC_FIR(size_t i, int ch) { return (this->ECHO_FIR(i + 1)[ch] * static_cast<int8_t>(this->m.regs[r_fir + i * 0x10])) >> 6; }
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();
};
inline int SPC_DSP::sample_count() const { return this->m.out - this->m.out_begin; }
inline int SPC_DSP::read(int addr) const
{
assert(static_cast<unsigned>(addr) < register_count);
return this->m.regs[addr];
}
inline void SPC_DSP::write(int addr, int data)
{
assert(static_cast<unsigned>(addr) < register_count);
this->m.regs[addr] = static_cast<uint8_t>(data);
switch (addr & 0x0F)
{
case v_envx:
this->m.envx_buf = static_cast<uint8_t>(data);
break;
case v_outx:
this->m.outx_buf = static_cast<uint8_t>(data);
break;
case 0x0C:
if (addr == r_kon)
this->m.new_kon = static_cast<uint8_t>(data);
if (addr == r_endx) // always cleared, regardless of data written
{
this->m.endx_buf = 0;
this->m.regs[r_endx] = 0;
}
}
}
inline void SPC_DSP::mute_voices(int mask) { this->m.mute_mask = mask; }