aiie/apple/applemmu.cpp

#ifdef TEENSYDUINO
#include <Arduino.h>
#else
#include <stdio.h>
#include <unistd.h>

#endif

#include "applemmu.h"
#include "applemmu-rom.h"
#include "physicalspeaker.h"
#include "cpu.h"

#include "globals.h"

// apple //e memory map

/*
page 0x00: zero page (straight ram)
page 0x01: stack (straight ram)
page 0x02: 
page 0x03: 
text/lores page 1: 0x0400 - 0x7FF
text/lores page 2: 0x0800 - 0xBFF
pages 0x0C - 0x1F: straight ram
hires page 1: pages 0x20 - 0x3F
hires page 2: pages 0x40 - 0x5F
pages 0x60 - 0xBF: straight ram
page 0xc0: I/O switches
pages 0xc1 - 0xcf: slot ROMs
pages 0xd0 - 0xdf: Basic ROM
pages 0xe0 - 0xff: monitor ROM
*/

AppleMMU::AppleMMU(AppleDisplay *display)
{
  anyKeyDown = false;
  keyboardStrobe = 0x00;

  isOpenApplePressed = false;
  isClosedApplePressed = false;

  for (int8_t i=0; i<=7; i++) {
    slots[i] = NULL;
  }

  allocateMemory();

  this->display = display;
  this->display->setSwitches(&switches);
  resetRAM(); // initialize RAM, load ROM
}

AppleMMU::~AppleMMU()
{
  delete display;
  // FIXME: clean up the memory we allocated
}

void AppleMMU::Reset()
{
  resetRAM();
  resetDisplay(); // sets the switches properly
}

uint8_t AppleMMU::read(uint16_t address)
{
  if (address >= 0xC000 &&
      address <= 0xC0FF) {
    return readSwitches(address);
  }
  
  uint8_t res = readPages[(address & 0xFF00) >> 8][address & 0xFF];

  return res;
}

// Bypass MMU and read directly from a given page - also bypasses switches
uint8_t AppleMMU::readDirect(uint16_t address, uint8_t fromPage)
{
  return ramPages[(address & 0xFF00) >> 8][fromPage][address & 0xFF];
}

void AppleMMU::write(uint16_t address, uint8_t v)
{
  if (address >= 0xC000 &&
      address <= 0xC0FF) {
    return writeSwitches(address, v);
  }

  // Don't allow writes to ROM
  if (address >= 0xC100 && address <= 0xCFFF)
    return;
  if (address >= 0xD000 && address <= 0xFFFF && !writebsr) {
    // memory-protected, so don't allow writes
    return;
  }

  writePages[(address & 0xFF00) >> 8][address & 0xFF] = v;

  if (address >= 0x400 &&
      address <= 0x7FF) {
    display->writeLores(address, v);
    return;
  }

  if (address >= 0x2000 &&
      address <= 0x5FFF) {
    display->writeHires(address, v);
  }
}

// FIXME: this is no longer "MMU", is it?
void AppleMMU::resetDisplay()
{
  updateMemoryPages();
  display->modeChange();
}

void AppleMMU::handleMemorySwitches(uint16_t address, uint16_t lastSwitch)
{
  // many of these are spelled out here: 
  // http://apple2.org.za/gswv/a2zine/faqs/csa2pfaq.html
  switch (address) {

    // These are write-only and perform no action on read

  case 0xC000: // CLR80STORE
    switches &= ~S_80STORE;
    updateMemoryPages();
    break;
  case 0xC001: // SET80STORE
    switches |= S_80STORE;
    updateMemoryPages();
    break;
  case 0xC002: // CLRAUXRD read from main 48k RAM
    auxRamRead = false;
    break;
  case 0xC003: // SETAUXRD read from aux/alt 48k
    auxRamRead = true;
    break;
  case 0xC004: // CLRAUXWR write to main 48k RAM
    auxRamWrite = false;
    break;
  case 0xC005: // SETAUXWR write to aux/alt 48k
    auxRamWrite = true;
    break;
  case 0xC006: // CLRCXROM use ROM on cards
    intcxrom = false;
    break;
  case 0xC007: // SETCXROM use internal ROM
    intcxrom = true;
    break;
  case 0xC008: // CLRAUXZP use main zero page, stack, LC
    altzp = false;
    break;
  case 0xC009: // SETAUXZP use alt zero page, stack, LC
    altzp = true;
    break;
  case 0xC00A: // CLRC3ROM use internal slot 3 ROM
    slot3rom = false;
    break;
  case 0xC00B: // SETC3ROM use external slot 3 ROM
    slot3rom = true;
    break;

    // these are probably read/write ?

  case 0xC080: // READBSR2 and shadow copy
  case 0xC084:
    bank1 = false;      // LC RAM bank2, Read and Write-prot RAM
    readbsr = true;     //    read from bank2
    writebsr = false;   //    write-protected
    break;

  case 0xC081: // ROMIN
  case 0xC085:
    bank1 = false;     // LC RAM bank2, read ROM, write-enable RAM
    readbsr = false;   //    if it's read twice in a row
    writebsr = writebsr || ((lastSwitch & 0xF3) == (address & 0xF3));
    break;

  case 0xC082:
  case 0xC086:
    bank1 = false;    // LC RAM bank2, Read ROM instead of RAM,
    readbsr = false;  // WR-protect RAM
    writebsr = false;
    break;

  case 0xC083: // READWRBSR2
  case 0xC087:
    bank1 = false;
    readbsr = true;
    writebsr = writebsr || ((lastSwitch & 0xF3) == (address & 0xF3));
    break;

  case 0xC088: // READBSR1
  case 0xC08C:
    bank1 = true;
    readbsr = true;
    writebsr = false;
    break;
    
  case 0xC089: // WRITEBSR1
  case 0xC08D:
    bank1 = true;
    readbsr = false;
    writebsr = writebsr || ((lastSwitch & 0xF3) == (address & 0xF3));
    break;

  case 0xC08A: // OFFBSR1
  case 0xC08E:
    bank1 = true;
    readbsr = false;
    writebsr = false;
    break;

  case 0xC08B: // READWRBSR1
  case 0xC08F:
    bank1 = true;
    readbsr = true;
    writebsr = writebsr || ((lastSwitch & 0xF3) == (address & 0xF3));
    break;
  }

  updateMemoryPages();
}

// many (most? all?) switches are documented here:
//   http://apple2.org.za/gswv/a2zine/faqs/csa2pfaq.html

uint8_t AppleMMU::readSwitches(uint16_t address)
{
  static uint16_t lastReadSwitch = 0x0000;
  static uint16_t thisReadSwitch = 0x0000;

  lastReadSwitch = thisReadSwitch;
  thisReadSwitch = address;

  // If this is a read for any of the slot switches, and we have
  // hardware in that slot, then return its result.
  if (address >= 0xC090 && address <= 0xC0FF) {
    for (uint8_t i=1; i<=7; i++) {
      if (address >= (0xC080 | (i << 4)) &&
	  address <= (0xC08F | (i << 4))) {
	if (slots[i]) {
	  return slots[i]->readSwitches(address & ~(0xC080 | (i<<4)));
	}
	else
	  return FLOATING;
      }
    }
  }

  switch (address) {
  case 0xC010:
    // consume the keyboard strobe flag
    keyboardStrobe &= 0x7F;
    return (anyKeyDown ? 0x80 :  0x00);

#if 0
  case 0xC000:

  case 0xC001:
  case 0xC002:
  case 0xC003:
  case 0xC004:
  case 0xC005:
  case 0xC006:
  case 0xC007:
  case 0xC008:
  case 0xC009:
  case 0xC00A:
  case 0xC00B:
    // nothing happens in read mode for these, so don't call this:
    // handleMemorySwitches(address, lastReadSwitch);

  case 0xC00C:
  case 0xC00D:
  case 0xC00E:
  case 0xC00F:

    // But according to UTA2E, these ALL return keyboard strobe data.
    // We do that after the switch statement so we get the other affects 
    // from reads to these addresses within the switch statement.

    break;
#endif

  case 0xC080:
  case 0xC081:
  case 0xC082:
  case 0xC083:
  case 0xC084:
  case 0xC085:
  case 0xC086:
  case 0xC087:
  case 0xC088:
  case 0xC089:
  case 0xC08A:
  case 0xC08B:
  case 0xC08C:
  case 0xC08D:
  case 0xC08E:
  case 0xC08F:
    // but read does affect these, same as write
    handleMemorySwitches(address, lastReadSwitch);
    break;

  case 0xC00C: // CLR80VID disable 80-col video mode
    if (switches & S_80COL) {
      switches &= ~S_80COL;
      resetDisplay();
    }
    break;
  case 0xC00D: // SET80VID enable 80-col video mode
    if (!(switches & S_80COL)) {
      switches |= S_80COL;
      resetDisplay();
    }
    break;

  case 0xC00E: // CLRALTCH use main char set - norm LC, flash UC
    switches &= ~S_ALTCH;
    break;
  case 0xC00F: // SETALTCH use alt char set - norm inverse, LC; no flash
    switches |= S_ALTCH;
    break;


  case 0xC011: // RDLCBNK2
    return bank1 ? 0x00 : 0x80;
  case 0xC012: // RDLCRAM
    return readbsr ? 0x80 : 0x00;
  case 0xC013: // RDRAMRD
    return auxRamRead ? 0x80 : 0x00;
  case 0xC014: // RDRAMWR
    return auxRamWrite ? 0x80 : 0x00;
  case 0xC015: // RDCXROM
    return intcxrom ? 0x80 : 0x00;
  case 0xC016: // RDAUXZP
    return altzp ? 0x80 : 0x00;
  case 0xC017: // RDC3ROM
    return slot3rom ? 0x80 : 0x00;

  case 0xC018: // RD80COL
    return (switches & S_80STORE) ? 0x80 : 0x00;
    // 0xC019: RDVBLBAR -- is the vertical blanking low?
  case 0xC01A: // RDTEXT
    return ( (switches & S_TEXT) ? 0x80 : 0x00 );
  case 0xC01B: // RDMIXED
    return ( (switches & S_MIXED) ? 0x80 : 0x00 );
  case 0xC01C: // RDPAGE2
    return ( (switches & S_PAGE2) ? 0x80 : 0x00 );
  case 0xC01D: // RDHIRES
    return ( (switches & S_HIRES) ? 0x80 : 0x00 );
  case 0xC01E: // RDALTCH
    return ( (switches & S_ALTCH) ? 0x80 : 0x00 );
  case 0xC01F: // RD80VID
    return ( (switches & S_80COL) ? 0x80 : 0x00 );


  case 0xC030: // SPEAKER
    g_speaker->toggleAtCycle(g_cpu->cycles);
    break;

  case 0xC050: // CLRTEXT
    if (switches & S_TEXT) {
      switches &= ~S_TEXT;
      resetDisplay();
    }
    return FLOATING;
  case 0xC051: // SETTEXT
    if (!(switches & S_TEXT)) {
      switches |= S_TEXT;
      resetDisplay();
    }
    return FLOATING;
  case 0xC052: // CLRMIXED
    if (switches & S_MIXED) {
      switches &= ~S_MIXED;
      resetDisplay();
    }
    return FLOATING;
  case 0xC053: // SETMIXED
    if (!(switches & S_MIXED)) {
      switches |= S_MIXED;
      resetDisplay();
    }
    return FLOATING;

  case 0xC054: // PAGE1
    if (switches & S_PAGE2) {
      switches &= ~S_PAGE2;
      if (!(switches & S_80COL)) {
	resetDisplay();
      } else {
	updateMemoryPages();
      }
    }
    return FLOATING;

  case 0xC055: // PAGE2
    if (!(switches & S_PAGE2)) {
      switches |= S_PAGE2;
      if (!(switches & S_80COL)) {
	resetDisplay();
      } else {
	updateMemoryPages();
      }
    }
    return FLOATING;

  case 0xC056: // CLRHIRES
    if (switches & S_HIRES) {
      switches &= ~S_HIRES;
      resetDisplay();
    }
    return FLOATING;
  case 0xC057: // SETHIRES
    if (!(switches & S_HIRES)) {
      switches |= S_HIRES;
      resetDisplay();
    }
    return FLOATING;

  case 0xC05E: // DHIRES ON
    if (!(switches & S_DHIRES)) {
      switches |= S_DHIRES;
      resetDisplay();
    }
    return FLOATING;

  case 0xC05F: // DHIRES OFF
    if (switches & S_DHIRES) {
      switches &= ~S_DHIRES;
      resetDisplay();
    }
    return FLOATING;

    // paddles
  case 0xC061: // OPNAPPLE
    return isOpenApplePressed ? 0x80 : 0x00;
  case 0xC062: // CLSAPPLE
    return isClosedApplePressed ? 0x80 : 0x00;
    
  case 0xC070: // PDLTRIG
    // It doesn't matter if we update readPages or writePages, because 0xC0 
    // has only one page.
    readPages[0xC0][0x64] = readPages[0xC0][0x65] = 0xFF;
    g_paddles->startReading();
    return FLOATING;
  }

  if (address >= 0xc000 && address <= 0xc00f) {
    // This is the keyboardStrobe support referenced in the switch statement above.
    return keyboardStrobe;
  }

  return readPages[address >> 8][address & 0xFF];
}

void AppleMMU::writeSwitches(uint16_t address, uint8_t v)
{
  // fixme: combine these with the last read switch
  static uint16_t lastWriteSwitch = 0x0000;
  static uint16_t thisWriteSwitch = 0x0000;
  lastWriteSwitch = thisWriteSwitch;
  thisWriteSwitch = address;

  // If this is a write for any of the slot switches, and we have
  // hardware in that slot, then return its result.
  if (address >= 0xC090 && address <= 0xC0FF) {
    for (uint8_t i=1; i<=7; i++) {
      if (address >= (0xC080 | (i << 4)) &&
	  address <= (0xC08F | (i << 4))) {
	if (slots[i]) {
	  slots[i]->writeSwitches(address & ~(0xC080 | (i<<4)), v);
	  return;
	}
      }
    }
  }

  switch (address) {
  case 0xC010:
  case 0xC011: // Per Understanding the Apple //e, p. 7-3:
  case 0xC012: //   a write to any $C01x address causes 
  case 0xC013: //   a clear of the keyboard strobe.
  case 0xC014:
  case 0xC015:
  case 0xC016:
  case 0xC017:
  case 0xC018:
  case 0xC019:
  case 0xC01A:
  case 0xC01B:
  case 0xC01C:
  case 0xC01D:
  case 0xC01E:
  case 0xC01F:
    keyboardStrobe &= 0x7F;
    return;

  case 0xC050: // graphics mode
    if (switches & S_TEXT) {
      switches &= ~S_TEXT;
      resetDisplay();
    }
    return;
     
  case 0xC051:
    if (!(switches & S_TEXT)) {
      switches |= S_TEXT;
      resetDisplay();
    }
    return;

  case 0xC052: // "no mixed"
    if (switches & S_MIXED) {
      switches &= ~S_MIXED;
      resetDisplay();
    }
    return;

  case 0xC053: // "mixed"
    if (!(switches & S_MIXED)) {
      switches |= S_MIXED;
      resetDisplay();
    }
    return;

  case 0xC054: // page2 off
    if (switches & S_PAGE2) {
      switches &= ~S_PAGE2;
      if (!(switches & S_80COL)) {
	resetDisplay();
      } else {
	updateMemoryPages();
      }
    }
    return;

  case 0xC055: // page2 on
    if (!(switches & S_PAGE2)) {
      switches |= S_PAGE2;
      if (!(switches & S_80COL)) {
	resetDisplay();
      } else {
	updateMemoryPages();
      }
    }
    return;

  case 0xC056: // hires off
    if (switches & S_HIRES) {
      switches &= ~S_HIRES;
      resetDisplay();
    }
    return;

  case 0xC057: // hires on
    if (!(switches & S_HIRES)) {
      switches |= S_HIRES;
      resetDisplay();
    }
    return;

  case 0xC05E: // DHIRES ON
    if (!(switches & S_DHIRES)) {
      switches |= S_DHIRES;
      resetDisplay();
    }
    return;

  case 0xC05F: // DHIRES OFF
    if (switches & S_DHIRES) {
      switches &= ~S_DHIRES;
      resetDisplay();
    }
    return;

    // paddles
  case 0xC070:
    g_paddles->startReading();
    writePages[0xC0][0x64] = writePages[0xC0][0x65] = 0xFF;
    break;

  case 0xC000:
  case 0xC001:
  case 0xC002:
  case 0xC003:
  case 0xC004:
  case 0xC005:
  case 0xC006:
  case 0xC007:
  case 0xC008:
  case 0xC009:
  case 0xC00A:
  case 0xC00B:
  case 0xC080:
  case 0xC081:
  case 0xC082:
  case 0xC083:
  case 0xC084:
  case 0xC085:
  case 0xC086:
  case 0xC087:
  case 0xC088:
  case 0xC089:
  case 0xC08A:
  case 0xC08B:
  case 0xC08C:
  case 0xC08D:
  case 0xC08E:
  case 0xC08F:
    handleMemorySwitches(address, lastWriteSwitch);
    break;

  case 0xC00C: // CLR80VID disable 80-col video mode
    if (switches & S_80COL) {
      switches &= ~S_80COL;
      resetDisplay();
    }
    break;
  case 0xC00D: // SET80VID enable 80-col video mode
    if (!(switches & S_80COL)) {
      switches |= S_80COL;
      resetDisplay();
    }
    break;

  case 0xC00E: // CLRALTCH use main char set - norm LC, flash UC
    switches &= ~S_ALTCH;
    break;
  case 0xC00F: // SETALTCH use alt char set - norm inverse, LC; no flash
    switches |= S_ALTCH;
    break;
  }
}

void AppleMMU::keyboardInput(uint8_t v)
{
  keyboardStrobe = v | 0x80;
  anyKeyDown = true;
}

void AppleMMU::setKeyDown(bool isTrue)
{
  anyKeyDown = isTrue;
}

void AppleMMU::triggerPaddleTimer(uint8_t paddle)
{
  writePages[0xC0][0x64 + paddle] = 0x00;
}

void AppleMMU::resetRAM()
{
  switches = S_TEXT;

  bank1 = true;
  auxRamRead = auxRamWrite = false;
  readbsr = writebsr = false;
  altzp = false;
  intcxrom = false;
  slot3rom = false;

  for (uint8_t i=0; i<0xFF; i++) {
    for (uint8_t j=0; j<5; j++) {
      if (ramPages[i][j]) {
	for (uint16_t k=0; k<0x100; k++) {
	  ramPages[i][j][k] = 0;
	}
      }
    }
    readPages[i] = writePages[i] = ramPages[i][0];
  }

  // Load ROM

#ifdef TEENSYDUINO
  for (uint16_t i=0x80; i<=0xFF; i++) {
    for (uint16_t k=0; k<0x100; k++) {
      uint16_t idx = ((i-0x80) << 8) | k;
      uint8_t v = pgm_read_byte(&romData[idx]);
      for (uint8_t j=0; j<5; j++) {
	if (ramPages[i][j]) {
	  ramPages[i][j][k] = v;
	}
      }
    }
  }
#else
  for (uint16_t i=0x80; i<=0xFF; i++) {
    for (uint16_t k=0; k<0x100; k++) {
      uint16_t idx = ((i-0x80) << 8) | k;
      uint8_t v = romData[idx];
      for (uint8_t j=0; j<5; j++) {
	if (ramPages[i][j]) {
	  ramPages[i][j][k] = v;
	}
      }
    }
  }
#endif

  for (uint8_t slotnum = 0; slotnum <= 7; slotnum++) {
    if (slots[slotnum]) {
      slots[slotnum]->loadROM(ramPages[0xC0 + slotnum][0]);
    }
  }
}

void AppleMMU::setSlot(int8_t slotnum, Slot *peripheral)
{
  slots[slotnum] = peripheral;
  if (slots[slotnum]) {
    slots[slotnum]->loadROM(ramPages[0xC0 + slotnum][0]);
  }
}

void AppleMMU::allocateMemory()
{
  for (uint16_t i=0; i<0xC0; i++) {
    for (uint8_t j=0; j<2; j++) {
      ramPages[i][j] = (uint8_t *)malloc(0x100);
    }
    for (uint8_t j=2; j<5; j++) {
      ramPages[i][j] = NULL;
    }
    readPages[i] = ramPages[i][0];
    writePages[i] = ramPages[i][0];
  }
  for (uint16_t i=0xC0; i<0x100; i++) {
    for (uint8_t j=0; j<5; j++) {
      ramPages[i][j] = (uint8_t *)malloc(0x100);
    }
    readPages[i] = ramPages[i][0];
    writePages[i] = ramPages[i][0];
  }
}

void AppleMMU::updateMemoryPages()
{
  if (auxRamRead) {
    for (uint8_t idx = 0x02; idx < 0xc0; idx++) {
      readPages[idx] = ramPages[idx][1];
    }
  } else {
    for (uint8_t idx = 0x02; idx < 0xc0; idx++) {
      readPages[idx] = ramPages[idx][0];
    }
  }

  if (auxRamWrite) {
    for (uint8_t idx = 0x02; idx < 0xc0; idx++) {
      writePages[idx] = ramPages[idx][1];
    }
  } else {
    for (uint8_t idx = 0x02; idx < 0xc0; idx++) {
      writePages[idx] = ramPages[idx][0];
    }
  }

  if (switches & S_80STORE) {
    if (switches & S_PAGE2) {
      for (uint8_t idx = 0x04; idx < 0x08; idx++) {
	readPages[idx] = ramPages[idx][1];
	writePages[idx] = ramPages[idx][1];
      }

      // If HIRES is on, then we honor the PAGE2 setting; otherwise, we don't
      for (uint8_t idx = 0x20; idx < 0x40; idx++) {
	readPages[idx] = ramPages[idx][(switches & S_HIRES) ? 1 : 0];
	writePages[idx] = ramPages[idx][(switches & S_HIRES) ? 1 : 0];
      }
    } else {
      for (uint8_t idx = 0x04; idx < 0x08; idx++) {
	readPages[idx] = ramPages[idx][0];
	writePages[idx] = ramPages[idx][0];
      }
      if (switches & S_HIRES) {
	// PAGE2 is off, so we set this back to 0 regardless
	for (uint8_t idx = 0x20; idx < 0x40; idx++) {
	  readPages[idx] = ramPages[idx][0];
	  writePages[idx] = ramPages[idx][0];
	}
      }
    }
  }

  if (intcxrom) {
    for (uint8_t idx = 0xc1; idx < 0xd0; idx++) {
      readPages[idx] = ramPages[idx][1];
    }
  } else {
    for (uint8_t idx = 0xc1; idx < 0xd0; idx++) {
      readPages[idx] = ramPages[idx][0];
    }
  }

  if (altzp) {
    for (uint8_t idx = 0x00; idx < 0x02; idx++) {
      readPages[idx] = ramPages[idx][1];
      writePages[idx] = ramPages[idx][1];
    }
  } else {
    for (uint8_t idx = 0x00; idx < 0x02; idx++) {
      readPages[idx] = ramPages[idx][0];
      writePages[idx] = ramPages[idx][0];
    }
  }

  if (readbsr) {
    if (bank1) {
      for (uint8_t idx = 0xd0; idx < 0xe0; idx++) {
	readPages[idx] = ramPages[idx][altzp ? 2 : 1];
      }
    } else {
      for (uint8_t idx = 0xd0; idx < 0xe0; idx++) {
	readPages[idx] = ramPages[idx][altzp ? 4 : 3];
      }
    }
    for (uint16_t idx = 0xe0; idx < 0x100; idx++) {
      readPages[idx] = ramPages[idx][altzp ? 2 : 1];
    }
  } else {
    for (uint16_t idx = 0xd0; idx < 0x100; idx++) {
      readPages[idx] = ramPages[idx][0];
    }
  }

  if (writebsr) {
    if (bank1) {
      for (uint8_t idx = 0xd0; idx < 0xe0; idx++) {
	writePages[idx] = ramPages[idx][altzp ? 2 : 1];
      }
    } else {
      for (uint8_t idx = 0xd0; idx < 0xe0; idx++) {
	writePages[idx] = ramPages[idx][altzp ? 4 : 3];
      }
    }
    for (uint16_t idx = 0xe0; idx < 0x100; idx++) {
      writePages[idx] = ramPages[idx][altzp ? 2 : 1];
    }
  } else {
    for (uint16_t idx = 0xd0; idx < 0x100; idx++) {
      writePages[idx] = ramPages[idx][0];
    }
  }
}