quickdev16/tools/bsnes/dsp/sdsp/sdsp.cpp

/*
  S-DSP emulator
  license: LGPLv2

  Note: this is basically a C++ cothreaded implementation of Shay Green's (blargg's) S-DSP emulator.
  The actual algorithms, timing information, tables, variable names, etc were all from him.
*/

#include <../base.hpp>
#define SDSP_CPP

#define REG(n) state.regs[r_##n]
#define VREG(n) state.regs[v.vidx + v_##n]

#if !defined(USE_STATE_MACHINE)
  #define phase_start() while(true) {
  #define phase(n)
  #define tick()          scheduler.addclocks_dsp(3 * 8)
  #define phase_end()   }
#else
  #define phase_start() switch(phase_index) {
  #define phase(n)        case n:
  #define tick()          scheduler.addclocks_dsp(3 * 8); break
  #define phase_end()   } phase_index = (phase_index + 1) & 31;
#endif

#include "gaussian.cpp"
#include "counter.cpp"
#include "envelope.cpp"
#include "brr.cpp"
#include "misc.cpp"
#include "voice.cpp"
#include "echo.cpp"

/* timing */

void sDSP::enter() {
  phase_start()

  phase(0)
    voice_5(voice[0]);
    voice_2(voice[1]);
    tick();

  phase(1)
    voice_6(voice[0]);
    voice_3(voice[1]);
    tick();

  phase(2)
    voice_7(voice[0]);
    voice_4(voice[1]);
    voice_1(voice[3]);
    tick();

  phase(3)
    voice_8(voice[0]);
    voice_5(voice[1]);
    voice_2(voice[2]);
    tick();

  phase(4)
    voice_9(voice[0]);
    voice_6(voice[1]);
    voice_3(voice[2]);
    tick();

  phase(5)
    voice_7(voice[1]);
    voice_4(voice[2]);
    voice_1(voice[4]);
    tick();

  phase(6)
    voice_8(voice[1]);
    voice_5(voice[2]);
    voice_2(voice[3]);
    tick();

  phase(7)
    voice_9(voice[1]);
    voice_6(voice[2]);
    voice_3(voice[3]);
    tick();

  phase(8)
    voice_7(voice[2]);
    voice_4(voice[3]);
    voice_1(voice[5]);
    tick();

  phase(9)
    voice_8(voice[2]);
    voice_5(voice[3]);
    voice_2(voice[4]);
    tick();

  phase(10)
    voice_9(voice[2]);
    voice_6(voice[3]);
    voice_3(voice[4]);
    tick();

  phase(11)
    voice_7(voice[3]);
    voice_4(voice[4]);
    voice_1(voice[6]);
    tick();

  phase(12)
    voice_8(voice[3]);
    voice_5(voice[4]);
    voice_2(voice[5]);
    tick();

  phase(13)
    voice_9(voice[3]);
    voice_6(voice[4]);
    voice_3(voice[5]);
    tick();

  phase(14)
    voice_7(voice[4]);
    voice_4(voice[5]);
    voice_1(voice[7]);
    tick();

  phase(15)
    voice_8(voice[4]);
    voice_5(voice[5]);
    voice_2(voice[6]);
    tick();

  phase(16)
    voice_9(voice[4]);
    voice_6(voice[5]);
    voice_3(voice[6]);
    tick();

  phase(17)
    voice_1(voice[0]);
    voice_7(voice[5]);
    voice_4(voice[6]);
    tick();

  phase(18)
    voice_8(voice[5]);
    voice_5(voice[6]);
    voice_2(voice[7]);
    tick();

  phase(19)
    voice_9(voice[5]);
    voice_6(voice[6]);
    voice_3(voice[7]);
    tick();

  phase(20)
    voice_1(voice[1]);
    voice_7(voice[6]);
    voice_4(voice[7]);
    tick();

  phase(21)
    voice_8(voice[6]);
    voice_5(voice[7]);
    voice_2(voice[0]);
    tick();

  phase(22)
    voice_3a(voice[0]);
    voice_9(voice[6]);
    voice_6(voice[7]);
    echo_22();
    tick();

  phase(23)
    voice_7(voice[7]);
    echo_23();
    tick();

  phase(24)
    voice_8(voice[7]);
    echo_24();
    tick();

  phase(25)
    voice_3b(voice[0]);
    voice_9(voice[7]);
    echo_25();
    tick();

  phase(26)
    echo_26();
    tick();

  phase(27)
    misc_27();
    echo_27();
    tick();

  phase(28)
    misc_28();
    echo_28();
    tick();

  phase(29)
    misc_29();
    echo_29();
    tick();

  phase(30)
    misc_30();
    voice_3c(voice[0]);
    echo_30();
    tick();

  phase(31)
    voice_4(voice[0]);
    voice_1(voice[2]);
    tick();

  phase_end()
}

/* register interface for S-SMP $00f2,$00f3 */

uint8 sDSP::read(uint8 addr) {
  return state.regs[addr];
}

void sDSP::write(uint8 addr, uint8 data) {
  state.regs[addr] = data;

  if((addr & 0x0f) == v_envx) {
    state.envx_buf = data;
  } else if((addr & 0x0f) == v_outx) {
    state.outx_buf = data;
  } else if(addr == r_kon) {
    state.new_kon = data;
  } else if(addr == r_endx) {
    //always cleared, regardless of data written
    state.endx_buf = 0;
    state.regs[r_endx] = 0;
  }
}

/* initialization */

void sDSP::power() {
  memset(&state.regs, 0, sizeof state.regs);
  state.echo_hist_pos = 0;
  state.every_other_sample = false;
  state.kon = 0;
  state.noise = 0;
  state.counter = 0;
  state.echo_offset = 0;
  state.echo_length = 0;
  state.new_kon = 0;
  state.endx_buf = 0;
  state.envx_buf = 0;
  state.outx_buf = 0;
  state.t_pmon = 0;
  state.t_non = 0;
  state.t_eon = 0;
  state.t_dir = 0;
  state.t_koff = 0;
  state.t_brr_next_addr = 0;
  state.t_adsr0 = 0;
  state.t_brr_header = 0;
  state.t_brr_byte = 0;
  state.t_srcn = 0;
  state.t_esa = 0;
  state.t_echo_disabled = 0;
  state.t_dir_addr = 0;
  state.t_pitch = 0;
  state.t_output = 0;
  state.t_looped = 0;
  state.t_echo_ptr = 0;
  state.t_main_out[0] = state.t_main_out[1] = 0;
  state.t_echo_out[0] = state.t_echo_out[1] = 0;
  state.t_echo_in[0] = state.t_echo_in[1] = 0;

  for(unsigned i = 0; i < 8; i++) {
    voice[i].buf_pos = 0;
    voice[i].interp_pos = 0;
    voice[i].brr_addr = 0;
    voice[i].brr_offset = 1;
    voice[i].vbit = 1 << i;
    voice[i].vidx = i * 0x10;
    voice[i].kon_delay = 0;
    voice[i].env_mode = env_release;
    voice[i].env = 0;
    voice[i].t_envx_out = 0;
    voice[i].hidden_env = 0;
  }

  reset();
}

void sDSP::reset() {
  REG(flg) = 0xe0;

  state.noise              = 0x4000;
  state.echo_hist_pos      = 0;
  state.every_other_sample = 1;
  state.echo_offset        = 0;
  state.counter            = 0;

  phase_index = 0;
}

sDSP::sDSP() {
  static_assert<sizeof(int) >= 32 / 8>();      //int >= 32-bits
  static_assert<(int8_t)0x80 == -0x80>();      //8-bit sign extension
  static_assert<(int16_t)0x8000 == -0x8000>(); //16-bit sign extension
  static_assert<(uint16_t)0xffff0000 == 0>();  //16-bit unsigned clip
  static_assert<(-1 >> 1) == -1>();            //arithmetic shift right

  //-0x8000 <= n <= +0x7fff
  assert(sclamp<16>(+0x8000) == +0x7fff);
  assert(sclamp<16>(-0x8001) == -0x8000);
}

sDSP::~sDSP() {
}