furnace/src/engine/platform/sound/nes/mmc5.cpp

/*
 *  Copyright (C) 2010-2019 Fabio Cavallo (aka FHorse)
 *
 *  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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include <string.h>
#include "apu.h"
#include "mmc5.h"

enum { MODE0, MODE1, MODE2, MODE3 };
enum { CHR_S, CHR_B };
enum { SPLIT_LEFT, SPLIT_RIGHT = 0x40 };

BYTE prg_ram_mode;

void map_init_MMC5(struct _mmc5* mmc5) {
  memset(mmc5,0,sizeof(struct _mmc5));

  mmc5->S3.frequency = 1;
  mmc5->S4.frequency = 1;
  mmc5->S3.length.enabled = 0;
  mmc5->S3.length.value = 0;
  mmc5->S4.length.enabled = 0;
  mmc5->S4.length.value = 0;
}
void extcl_cpu_wr_mem_MMC5(struct _mmc5* mmc5, WORD address, BYTE value) {
  if (address < 0x5000) {
    return;
  }

  switch (address) {
    case 0x5000:
      square_reg0(mmc5->S3);
      return;
    case 0x5001:
      /* lo sweep non e' utilizzato */
      return;
    case 0x5002:
      square_reg2(mmc5->S3);
      return;
    case 0x5003:
      square_reg3(mmc5->S3,0);
      return;
    case 0x5004:
      square_reg0(mmc5->S4);
      return;
    case 0x5005:
      /* lo sweep non e' utilizzato */
      return;
    case 0x5006:
      square_reg2(mmc5->S4);
      return;
    case 0x5007:
      square_reg3(mmc5->S4,0);
      return;
    case 0x5010:
      mmc5->pcm.enabled = ~value & 0x01;
      mmc5->pcm.output = 0;
      if (mmc5->pcm.enabled) {
        mmc5->pcm.output = mmc5->pcm.amp;
      }
      mmc5->clocked = TRUE;
      return;
    case 0x5011:
      mmc5->pcm.amp = value;
      mmc5->pcm.output = 0;
      if (mmc5->pcm.enabled) {
        mmc5->pcm.output = mmc5->pcm.amp;
      }
      mmc5->clocked = TRUE;
      return;
    case 0x5015:
      if (!(mmc5->S3.length.enabled = value & 0x01)) {
        mmc5->S3.length.value = 0;
      }
      if (!(mmc5->S4.length.enabled = value & 0x02)) {
        mmc5->S4.length.value = 0;
      }
      return;
  }
}
void extcl_length_clock_MMC5(struct _mmc5* mmc5) {
  length_run(mmc5->S3)
  length_run(mmc5->S4)
}
void extcl_envelope_clock_MMC5(struct _mmc5* mmc5) {
  envelope_run(mmc5->S3)
  envelope_run(mmc5->S4)
}
void extcl_apu_tick_MMC5(struct _mmc5* mmc5) {
        // SQUARE 3 TICK
  if (!(--mmc5->S3.frequency)) {
    square_output(mmc5->S3, 0)
    mmc5->S3.frequency = (mmc5->S3.timer + 1) << 1;
    mmc5->S3.sequencer = (mmc5->S3.sequencer + 1) & 0x07;
    mmc5->clocked = TRUE;
  }

        // SQUARE 4 TICK
  if (!(--mmc5->S4.frequency)) {
    square_output(mmc5->S4, 0)
    mmc5->S4.frequency = (mmc5->S4.timer + 1) << 1;
    mmc5->S4.sequencer = (mmc5->S4.sequencer + 1) & 0x07;
    mmc5->clocked = TRUE;
  }
}