furnace/src/engine/platform/vera.cpp

/**
 * Furnace Tracker - multi-system chiptune tracker
 * Copyright (C) 2021-2022 tildearrow and contributors
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License along
 * with this program; if not, write to the Free Software Foundation, Inc.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#include "vera.h"
#include "../engine.h"
#include <string.h>
#include <math.h>

#define rWrite(c,a,d) {regPool[(c)*4+(a)]=(d);}
#define rWriteLo(c,a,d) rWrite(c,a,(regPool[(c)*4+(a)]&(~0x3f))|((d)&0x3f))
#define rWriteHi(c,a,d) rWrite(c,a,(regPool[(c)*4+(a)]&(~0xc0))|(((d)<<6)&0xc0))
#define rWriteFIFOVol(d) rWrite(16,0,(regPool[64]&(~0x3f))|((d)&0x3f))

const char* regCheatSheetVERA[]={
  "CHxFreq",    "00+x*4",
  "CHxVol",     "02+x*4",
  "CHxWave",    "03+x*4",

  "AUDIO_CTRL", "40",
  "AUDIO_RATE", "41",

  NULL
};

const char** DivPlatformVERA::getRegisterSheet() {
  return regCheatSheetVERA;
}

const char* DivPlatformVERA::getEffectName(unsigned char effect) {
  switch (effect) {
    case 0x20:
      return "20xx: Change waveform";
      break;
    case 0x22:
      return "22xx: Set duty cycle (0 to 63)";
      break;
  }
  return NULL;
}

void DivPlatformVERA::acquire(short* bufL, short* bufR, size_t start, size_t len) {
  // taken from the official X16 emulator's source code, (c) 2020 Frank van den Hoef
  const uint8_t volume_lut_psg[64]={0, 1, 1, 1, 2, 2, 2, 2, 2, 2, 2, 3, 3, 3, 3, 3, 4, 4, 4, 4, 5, 5, 5, 6, 6, 7, 7, 7, 8, 8, 9, 9, 10, 11, 11, 12, 13, 14, 14, 15, 16, 17, 18, 19, 21, 22, 23, 25, 26, 28, 29, 31, 33, 35, 37, 39, 42, 44, 47, 50, 52, 56, 59, 63};
  const uint8_t volume_lut_pcm[16]={0, 1, 2, 3, 4, 5, 6, 8, 11, 14, 18, 23, 30, 38, 49, 64};
  for (size_t pos=start; pos<start+len; pos++) {
    int32_t lout=0;
    int32_t rout=0;
    // PSG
    // TODO this is a currently speculated noise generation
    // as the hardware and sources for it are not out in the public
    // and the official emulator just uses rand()
    noiseState=(noiseState<<1)|(((noiseState>>1)^(noiseState>>2)^(noiseState>>4)^(noiseState>>15))&1);
    noiseOut=((noiseOut<<1)|(noiseState&1))&63;
    for (int i=0; i<16; i++) {
      unsigned freq=regPool[i*4+0] | (regPool[i*4+1] << 8);
      unsigned old_accum=chan[i].accum;
      unsigned new_accum=old_accum+freq;
      int val=0x20;
      if ((old_accum^new_accum)&0x10000) chan[i].noiseval=noiseOut;
      new_accum&=0x1ffff;
      chan[i].accum=new_accum;
      switch (regPool[i*4+3]>>6) {
        case 0: val=(new_accum>>10)>(regPool[i*4+3]&(unsigned)0x3f)?0:63; break;
        case 1: val=(new_accum>>11); break;
        case 2: val=(new_accum&0x10000)?(~(new_accum>>10)&0x3f):((new_accum>>10)&0x3f); break;
        case 3: val=chan[i].noiseval; break;
      }
      val=(val-0x20)*volume_lut_psg[regPool[i*4+2]&0x3f];
      lout+=(regPool[i*4+2]&0x40)?val:0;
      rout+=(regPool[i*4+2]&0x80)?val:0;
    }
    // PCM
    // simple one-channel sample player, actual hardware is essentially a DAC
    // with buffering
    if (chan[16].pcm.sample>=0) {
      chan[16].accum+=regPool[65];
      if (chan[16].accum>=128) {
        DivSample* s=parent->getSample(chan[16].pcm.sample);
        if (s->samples>0) {
          // TODO stereo samples once DivSample has a support for it
          switch (s->depth) {
            case 8:
              chan[16].pcm.out_l=chan[16].pcm.pan&1?(s->data8[chan[16].pcm.pos]*256):0;
              chan[16].pcm.out_r=chan[16].pcm.pan&2?(s->data8[chan[16].pcm.pos]*256):0;
              regPool[64]|=0x20; // for register viewer purposes
              break;
            case 16:
              chan[16].pcm.out_l=chan[16].pcm.pan&1?(s->data16[chan[16].pcm.pos]):0;
              chan[16].pcm.out_r=chan[16].pcm.pan&2?(s->data16[chan[16].pcm.pos]):0;
              regPool[64]&=~0x20;
              break;
          }
        } else {
          chan[16].pcm.sample=-1;
        }
        chan[16].accum&=0x7f;
        chan[16].pcm.pos++;
        if (chan[16].pcm.pos>=s->samples) {
          if (s->loopStart>=0 && s->loopStart<=(int)s->samples) {
            chan[16].pcm.pos=s->loopStart;
          } else {
            chan[16].pcm.sample=-1;
          }
        }
      }
    }
    int pcmvol=volume_lut_pcm[regPool[64]&0x0f];
    lout+=chan[16].pcm.out_l*pcmvol/64;
    rout+=chan[16].pcm.out_r*pcmvol/64;

    bufL[pos]=(short)(lout/2);
    bufR[pos]=(short)(rout/2);
  }
}

void DivPlatformVERA::reset() {
  for (int i=0; i<17; i++) {
    chan[i]=Channel();
  }
  memset(regPool,0,66);
  for (int i=0; i<16; i++) {
    chan[i].vol=63;
    rWriteHi(i,2,3); // default pan
  }
  chan[16].vol=15;
  noiseState=1;
  noiseOut=0;
}

int DivPlatformVERA::calcNoteFreq(int ch, int note) {
  if (ch<16) {
    return parent->calcBaseFreq(chipClock,2097152,note,false);
  } else {
    double off=1.0;
    if (chan[ch].pcm.sample>=0 && chan[ch].pcm.sample<parent->song.sampleLen) {
      DivSample* s=parent->getSample(chan[ch].pcm.sample);
      if (s->centerRate<1) {
        off=1.0;
      } else {
        off=s->centerRate/8363.0;
      }
    }
    return (int)(off*parent->calcBaseFreq(chipClock,65536,note,false));
  }
}

void DivPlatformVERA::tick() {
  for (int i=0; i<16; i++) {
    chan[i].std.next();
    if (chan[i].std.hadVol) {
      chan[i].outVol=MAX(chan[i].vol+chan[i].std.vol-63,0);
      rWriteLo(i,2,isMuted[i]?0:(chan[i].outVol&63));
    }
    if (chan[i].std.hadArp) {
      if (!chan[i].inPorta) {
        if (chan[i].std.arpMode) {
          chan[i].baseFreq=calcNoteFreq(0,chan[i].std.arp);
        } else {
          chan[i].baseFreq=calcNoteFreq(0,chan[i].note+chan[i].std.arp);
        }
      }
      chan[i].freqChanged=true;
    } else {
      if (chan[i].std.arpMode && chan[i].std.finishedArp) {
        chan[i].baseFreq=calcNoteFreq(0,chan[i].note);
        chan[i].freqChanged=true;
      }
    }
    if (chan[i].std.hadDuty) {
      rWriteLo(i,3,chan[i].std.duty);
    }
    if (chan[i].std.hadWave) {
      rWriteHi(i,3,chan[i].std.wave);
    }
    if (chan[i].freqChanged) {
      chan[i].freq=parent->calcFreq(chan[i].baseFreq,chan[i].pitch,false,8);
      if (chan[i].freq>65535) chan[i].freq=65535;
      rWrite(i,0,chan[i].freq&0xff);
      rWrite(i,1,(chan[i].freq>>8)&0xff);
      chan[i].freqChanged=false;
    }
  }
  // PCM
  chan[16].std.next();
  if (chan[16].std.hadVol) {
    chan[16].outVol=MAX(chan[16].vol+MIN(chan[16].std.vol/4,15)-15,0);
    rWriteFIFOVol(isMuted[16]?0:(chan[16].outVol&15));
  }
  if (chan[16].std.hadArp) {
    if (!chan[16].inPorta) {
      if (chan[16].std.arpMode) {
        chan[16].baseFreq=calcNoteFreq(16,chan[16].std.arp);
      } else {
        chan[16].baseFreq=calcNoteFreq(16,chan[16].note+chan[16].std.arp);
      }
    }
    chan[16].freqChanged=true;
  } else {
    if (chan[16].std.arpMode && chan[16].std.finishedArp) {
      chan[16].baseFreq=calcNoteFreq(16,chan[16].note);
      chan[16].freqChanged=true;
    }
  }
  if (chan[16].freqChanged) {
    chan[16].freq=parent->calcFreq(chan[16].baseFreq,chan[16].pitch,false,8);
    if (chan[16].freq>128) chan[16].freq=128;
    rWrite(16,1,chan[16].freq&0xff);
    chan[16].freqChanged=false;
  }
}

int DivPlatformVERA::dispatch(DivCommand c) {
  int tmp;
  switch (c.cmd) {
    case DIV_CMD_NOTE_ON:
      tmp = isMuted[c.chan]?0:chan[c.chan].vol;
      if(c.chan<16) {
        rWriteLo(c.chan,2,tmp)
      } else {
        chan[c.chan].pcm.sample=parent->getIns(chan[16].ins)->amiga.initSample;
        if (chan[c.chan].pcm.sample<0 || chan[c.chan].pcm.sample>=parent->song.sampleLen) {
          chan[c.chan].pcm.sample=-1;
        }
        chan[16].pcm.pos=0;
        rWriteFIFOVol(tmp);
      }
      if (c.value!=DIV_NOTE_NULL) {
        chan[c.chan].baseFreq=calcNoteFreq(c.chan,c.value);
        chan[c.chan].freqChanged=true;
        chan[c.chan].note=c.value;
      }
      chan[c.chan].active=true;
      chan[c.chan].std.init(parent->getIns(chan[c.chan].ins));
      break;
    case DIV_CMD_NOTE_OFF:
      chan[c.chan].active=false;
      if(c.chan<16) {
        rWriteLo(c.chan,2,0)
      } else {
        chan[16].pcm.sample=-1;
        rWriteFIFOVol(0);
        rWrite(16,1,0);
      }
      chan[c.chan].std.init(NULL);
      break;
    case DIV_CMD_NOTE_OFF_ENV:
    case DIV_CMD_ENV_RELEASE:
      chan[c.chan].std.release();
      break;
    case DIV_CMD_INSTRUMENT:
      chan[c.chan].ins=(unsigned char)c.value;
      break;
    case DIV_CMD_VOLUME:
      if (c.chan<16) {
        tmp=c.value&0x3f;
        chan[c.chan].vol=tmp;
        rWriteLo(c.chan,2,(isMuted[c.chan]?0:tmp));
      } else {
        tmp=c.value&0x0f;
        chan[c.chan].vol=tmp;
        rWriteFIFOVol(isMuted[c.chan]?0:tmp);
      }
      break;
    case DIV_CMD_GET_VOLUME:
      return chan[c.chan].vol;
      break;
    case DIV_CMD_PITCH:
      chan[c.chan].pitch=c.value;
      chan[c.chan].freqChanged=true;
      break;
    case DIV_CMD_NOTE_PORTA: {
      int destFreq=calcNoteFreq(c.chan,c.value2);
      bool return2=false;
      if (destFreq>chan[c.chan].baseFreq) {
        chan[c.chan].baseFreq+=c.value;
        if (chan[c.chan].baseFreq>=destFreq) {
          chan[c.chan].baseFreq=destFreq;
          return2=true;
        }
      } else {
        chan[c.chan].baseFreq-=c.value;
        if (chan[c.chan].baseFreq<=destFreq) {
          chan[c.chan].baseFreq=destFreq;
          return2=true;
        }
      }
      chan[c.chan].freqChanged=true;
      if (return2) {
        chan[c.chan].inPorta=false;
        return 2;
      }
      break;
    }
    case DIV_CMD_LEGATO:
      chan[c.chan].baseFreq=calcNoteFreq(c.chan,c.value+((chan[c.chan].std.willArp && !chan[c.chan].std.arpMode)?(chan[c.chan].std.arp):(0)));
      chan[c.chan].freqChanged=true;
      chan[c.chan].note=c.value;
      break;
    case DIV_CMD_PRE_PORTA:
      if (chan[c.chan].active && c.value2) {
        if (parent->song.resetMacroOnPorta) chan[c.chan].std.init(parent->getIns(chan[c.chan].ins));
      }
      chan[c.chan].inPorta=c.value;
      break;
    case DIV_CMD_STD_NOISE_MODE:
      if (c.chan<16) rWriteLo(c.chan,3,c.value);
      break;
    case DIV_CMD_WAVE:
      if (c.chan<16) rWriteHi(c.chan,3,c.value);
      break;
    case DIV_CMD_PANNING: {
      tmp=0;
      tmp|=(c.value&0x10)?1:0;
      tmp|=(c.value&0x01)?2:0;
      if (c.chan<16) {
        rWriteHi(c.chan,2,tmp);
      } else {
        chan[c.chan].pcm.pan = tmp&3;
      }
      break;
    }
    case DIV_CMD_GET_VOLMAX:
      if(c.chan<16) {
        return 63;
      } else {
        return 15;
      }
      break;
    case DIV_ALWAYS_SET_VOLUME:
      return 0;
      break;
    default:
      break;
  }
  return 1;
}

void* DivPlatformVERA::getChanState(int ch) {
  return &chan[ch];
}

unsigned char* DivPlatformVERA::getRegisterPool() {
  return regPool;
}

int DivPlatformVERA::getRegisterPoolSize() {
  return 66;
}

void DivPlatformVERA::muteChannel(int ch, bool mute) {
  isMuted[ch]=mute;
}

bool DivPlatformVERA::isStereo() {
  return true;
}

void DivPlatformVERA::notifyInsDeletion(void* ins) {
  for (int i=0; i<2; i++) {
    chan[i].std.notifyInsDeletion((DivInstrument*)ins);
  }
}

void DivPlatformVERA::poke(unsigned int addr, unsigned short val) {
  regPool[addr] = (unsigned char)val;
}

void DivPlatformVERA::poke(std::vector<DivRegWrite>& wlist) {
  for (auto &i: wlist) regPool[i.addr] = (unsigned char)i.val;
}

int DivPlatformVERA::init(DivEngine* p, int channels, int sugRate, unsigned int flags) {
  for (int i=0; i<17; i++) {
    isMuted[i]=false;
  }
  parent=p;
  dumpWrites=false;
  skipRegisterWrites=false;
  chipClock=25000000;
  rate=chipClock/512;
  reset();
  return 17;
}

DivPlatformVERA::~DivPlatformVERA() {
}