// license:BSD-3-Clause
// copyright-holders:Wilbert Pol
/***************************************************************************
Z80 CTC (Z8430) implementation
based on original version (c) 1997, Tatsuyuki Satoh
***************************************************************************/
#include "emu.h"
#include "z80ctc.h"
#include "cpu/z80/z80daisy.h"
//**************************************************************************
// DEBUGGING
//**************************************************************************
#define VERBOSE 0
#define VPRINTF(x) do { if (VERBOSE) logerror x; } while (0)
#define VPRINTF_CHANNEL(x) do { if (VERBOSE) m_device->logerror x; } while (0)
//**************************************************************************
// CONSTANTS
//**************************************************************************
// these are the bits of the incoming commands to the CTC
const int INTERRUPT = 0x80;
const int INTERRUPT_ON = 0x80;
//const int INTERRUPT_OFF = 0x00;
const int MODE = 0x40;
const int MODE_TIMER = 0x00;
const int MODE_COUNTER = 0x40;
const int PRESCALER = 0x20;
//const int PRESCALER_256 = 0x20;
const int PRESCALER_16 = 0x00;
const int EDGE = 0x10;
const int EDGE_FALLING = 0x00;
const int EDGE_RISING = 0x10;
const int TRIGGER = 0x08;
const int TRIGGER_AUTO = 0x00;
//const int TRIGGER_CLOCK = 0x08;
const int CONSTANT = 0x04;
const int CONSTANT_LOAD = 0x04;
//const int CONSTANT_NONE = 0x00;
const int RESET = 0x02;
//const int RESET_CONTINUE = 0x00;
const int RESET_ACTIVE = 0x02;
const int CONTROL = 0x01;
const int CONTROL_VECTOR = 0x00;
const int CONTROL_WORD = 0x01;
// these extra bits help us keep things accurate
const int WAITING_FOR_TRIG = 0x100;
//**************************************************************************
// LIVE DEVICE
//**************************************************************************
// device type definition
const device_type Z80CTC = &device_creator<z80ctc_device>;
//-------------------------------------------------
// z80ctc_device - constructor
//-------------------------------------------------
z80ctc_device::z80ctc_device(const machine_config &mconfig, const char *tag, device_t *owner, uint32_t clock)
: device_t(mconfig, Z80CTC, "Z80 CTC", tag, owner, clock, "z80ctc", __FILE__),
device_z80daisy_interface(mconfig, *this),
m_intr_cb(*this),
m_zc0_cb(*this),
m_zc1_cb(*this),
m_zc2_cb(*this),
m_zc3_cb(*this),
m_vector(0)
{
}
//-------------------------------------------------
// read - standard handler for reading
//-------------------------------------------------
READ8_MEMBER( z80ctc_device::read )
{
return m_channel[offset & 3].read();
}
//-------------------------------------------------
// write - standard handler for writing
//-------------------------------------------------
WRITE8_MEMBER( z80ctc_device::write )
{
m_channel[offset & 3].write(data);
}
//-------------------------------------------------
// trg0-3 - standard write line handlers for each
// trigger
//-------------------------------------------------
WRITE_LINE_MEMBER( z80ctc_device::trg0 ) { m_channel[0].trigger(state); }
WRITE_LINE_MEMBER( z80ctc_device::trg1 ) { m_channel[1].trigger(state); }
WRITE_LINE_MEMBER( z80ctc_device::trg2 ) { m_channel[2].trigger(state); }
WRITE_LINE_MEMBER( z80ctc_device::trg3 ) { m_channel[3].trigger(state); }
//-------------------------------------------------
// device_start - device-specific startup
//-------------------------------------------------
void z80ctc_device::device_start()
{
m_period16 = attotime::from_hz(m_clock) * 16;
m_period256 = attotime::from_hz(m_clock) * 256;
// resolve callbacks
m_intr_cb.resolve_safe();
m_zc0_cb.resolve_safe();
m_zc1_cb.resolve_safe();
m_zc2_cb.resolve_safe();
m_zc3_cb.resolve_safe();
// start each channel
m_channel[0].start(this, 0);
m_channel[1].start(this, 1);
m_channel[2].start(this, 2);
m_channel[3].start(this, 3);
// register for save states
save_item(NAME(m_vector));
}
//-------------------------------------------------
// device_reset - device-specific reset
//-------------------------------------------------
void z80ctc_device::device_reset()
{
// reset each channel
m_channel[0].reset();
m_channel[1].reset();
m_channel[2].reset();
m_channel[3].reset();
// check for interrupts
interrupt_check();
VPRINTF(("CTC Reset\n"));
}
//**************************************************************************
// DAISY CHAIN INTERFACE
//**************************************************************************
//-------------------------------------------------
// z80daisy_irq_state - return the overall IRQ
// state for this device
//-------------------------------------------------
int z80ctc_device::z80daisy_irq_state()
{
VPRINTF(("CTC IRQ state = %d%d%d%d\n", m_channel[0].m_int_state, m_channel[1].m_int_state, m_channel[2].m_int_state, m_channel[3].m_int_state));
// loop over all channels
int state = 0;
for (auto & channel : m_channel)
{
// if we're servicing a request, don't indicate more interrupts
if (channel.m_int_state & Z80_DAISY_IEO)
{
state |= Z80_DAISY_IEO;
break;
}
state |= channel.m_int_state;
}
return state;
}
//-------------------------------------------------
// z80daisy_irq_ack - acknowledge an IRQ and
// return the appropriate vector
//-------------------------------------------------
int z80ctc_device::z80daisy_irq_ack()
{
// loop over all channels
for (int ch = 0; ch < 4; ch++)
{
ctc_channel &channel = m_channel[ch];
// find the first channel with an interrupt requested
if (channel.m_int_state & Z80_DAISY_INT)
{
VPRINTF(("CTC IRQAck ch%d\n", ch));
// clear interrupt, switch to the IEO state, and update the IRQs
channel.m_int_state = Z80_DAISY_IEO;
interrupt_check();
return m_vector + ch * 2;
}
}
//logerror("z80ctc_irq_ack: failed to find an interrupt to ack!\n");
return m_vector;
}
//-------------------------------------------------
// z80daisy_irq_reti - clear the interrupt
// pending state to allow other interrupts through
//-------------------------------------------------
void z80ctc_device::z80daisy_irq_reti()
{
// loop over all channels
for (int ch = 0; ch < 4; ch++)
{
ctc_channel &channel = m_channel[ch];
// find the first channel with an IEO pending
if (channel.m_int_state & Z80_DAISY_IEO)
{
VPRINTF(("CTC IRQReti ch%d\n", ch));
// clear the IEO state and update the IRQs
channel.m_int_state &= ~Z80_DAISY_IEO;
interrupt_check();
return;
}
}
//logerror("z80ctc_irq_reti: failed to find an interrupt to clear IEO on!\n");
}
//**************************************************************************
// INTERNAL STATE MANAGEMENT
//**************************************************************************
//-------------------------------------------------
// interrupt_check - look for pending interrupts
// and update the line
//-------------------------------------------------
void z80ctc_device::interrupt_check()
{
int state = (z80daisy_irq_state() & Z80_DAISY_INT) ? ASSERT_LINE : CLEAR_LINE;
m_intr_cb(state);
}
//*************************************************************************
// CTC CHANNELS
//**************************************************************************
//-------------------------------------------------
// ctc_channel - constructor
//-------------------------------------------------
z80ctc_device::ctc_channel::ctc_channel()
: m_device(nullptr),
m_index(0),
m_mode(0),
m_tconst(0),
m_down(0),
m_extclk(0),
m_timer(nullptr),
m_int_state(0)
{
}
//-------------------------------------------------
// start - set up at device start time
//-------------------------------------------------
void z80ctc_device::ctc_channel::start(z80ctc_device *device, int index)
{
// initialize state
m_device = device;
m_index = index;
m_timer = m_device->machine().scheduler().timer_alloc(timer_expired_delegate(FUNC(z80ctc_device::ctc_channel::timer_callback), this));
// register for save states
m_device->save_item(NAME(m_mode), m_index);
m_device->save_item(NAME(m_tconst), m_index);
m_device->save_item(NAME(m_down), m_index);
m_device->save_item(NAME(m_extclk), m_index);
m_device->save_item(NAME(m_int_state), m_index);
}
//-------------------------------------------------
// reset - reset the channel
//-------------------------------------------------
void z80ctc_device::ctc_channel::reset()
{
m_mode = RESET_ACTIVE;
m_tconst = 0x100;
m_timer->adjust(attotime::never);
m_int_state = 0;
}
//-------------------------------------------------
// period - return the current channel's period
//-------------------------------------------------
attotime z80ctc_device::ctc_channel::period() const
{
// if reset active, no period
if ((m_mode & RESET) == RESET_ACTIVE)
return attotime::zero;
// if counter mode, no real period
if ((m_mode & MODE) == MODE_COUNTER)
{
m_device->logerror("CTC %d is CounterMode : Can't calculate period\n", m_index);
return attotime::zero;
}
// compute the period
attotime period = ((m_mode & PRESCALER) == PRESCALER_16) ? m_device->m_period16 : m_device->m_period256;
return period * m_tconst;
}
//-------------------------------------------------
// read - read the channel's state
//-------------------------------------------------
uint8_t z80ctc_device::ctc_channel::read()
{
// if we're in counter mode, just return the count
if ((m_mode & MODE) == MODE_COUNTER || (m_mode & WAITING_FOR_TRIG))
return m_down;
// else compute the down counter value
else
{
attotime period = ((m_mode & PRESCALER) == PRESCALER_16) ? m_device->m_period16 : m_device->m_period256;
VPRINTF_CHANNEL(("CTC clock %f\n",ATTOSECONDS_TO_HZ(period.attoseconds())));
if (m_timer != nullptr)
return ((int)(m_timer->remaining().as_double() / period.as_double()) + 1) & 0xff;
else
return 0;
}
}
//-------------------------------------------------
// write - handle writes to a channel
//-------------------------------------------------
void z80ctc_device::ctc_channel::write(uint8_t data)
{
// if we're waiting for a time constant, this is it
if ((m_mode & CONSTANT) == CONSTANT_LOAD)
{
VPRINTF_CHANNEL(("CTC ch.%d constant = %02x\n", m_index, data));
// set the time constant (0 -> 0x100)
m_tconst = data ? data : 0x100;
// clear the internal mode -- we're no longer waiting
m_mode &= ~CONSTANT;
// also clear the reset, since the constant gets it going again
m_mode &= ~RESET;
// if we're in timer mode....
if ((m_mode & MODE) == MODE_TIMER)
{
// if we're triggering on the time constant, reset the down counter now
if ((m_mode & TRIGGER) == TRIGGER_AUTO)
{
attotime curperiod = period();
m_timer->adjust(curperiod, m_index, curperiod);
}
// else set the bit indicating that we're waiting for the appropriate trigger
else
m_mode |= WAITING_FOR_TRIG;
}
// also set the down counter in case we're clocking externally
m_down = m_tconst;
}
// if we're writing the interrupt vector, handle it specially
#if 0 /* Tatsuyuki Satoh changes */
// The 'Z80family handbook' wrote,
// interrupt vector is able to set for even channel (0 or 2)
else if ((data & CONTROL) == CONTROL_VECTOR && (m_index & 1) == 0)
#else
else if ((data & CONTROL) == CONTROL_VECTOR && m_index == 0)
#endif
{
m_device->m_vector = data & 0xf8;
VPRINTF_CHANNEL(("CTC Vector = %02x\n", m_device->m_vector));
}
// this must be a control word
else if ((data & CONTROL) == CONTROL_WORD)
{
// (mode change without reset?)
if ((m_mode & MODE) == MODE_TIMER && (data & MODE) == MODE_COUNTER && (data & RESET) == 0)
{
m_timer->adjust(attotime::never);
}
// set the new mode
m_mode = data;
VPRINTF_CHANNEL(("CTC ch.%d mode = %02x\n", m_index, data));
// if we're being reset, clear out any pending timers for this channel
if ((data & RESET) == RESET_ACTIVE)
{
m_timer->adjust(attotime::never);
// note that we don't clear the interrupt state here!
}
}
}
//-------------------------------------------------
// trigger - clock this channel and handle any
// side-effects
//-------------------------------------------------
void z80ctc_device::ctc_channel::trigger(uint8_t data)
{
// normalize data
data = data ? 1 : 0;
// see if the trigger value has changed
if (data != m_extclk)
{
m_extclk = data;
// see if this is the active edge of the trigger
if (((m_mode & EDGE) == EDGE_RISING && data) || ((m_mode & EDGE) == EDGE_FALLING && !data))
{
// if we're waiting for a trigger, start the timer
if ((m_mode & WAITING_FOR_TRIG) && (m_mode & MODE) == MODE_TIMER)
{
attotime curperiod = period();
VPRINTF_CHANNEL(("CTC period %s\n", curperiod.as_string()));
m_timer->adjust(curperiod, m_index, curperiod);
}
// we're no longer waiting
m_mode &= ~WAITING_FOR_TRIG;
// if we're clocking externally, decrement the count
if ((m_mode & MODE) == MODE_COUNTER)
{
// if we hit zero, do the same thing as for a timer interrupt
if (--m_down == 0)
timer_callback(nullptr,0);
}
}
}
}
//-------------------------------------------------
// trigger - clock this channel and handle any
// side-effects
//-------------------------------------------------
TIMER_CALLBACK_MEMBER(z80ctc_device::ctc_channel::timer_callback)
{
// down counter has reached zero - see if we should interrupt
if ((m_mode & INTERRUPT) == INTERRUPT_ON)
{
m_int_state |= Z80_DAISY_INT;
VPRINTF_CHANNEL(("CTC timer ch%d\n", m_index));
m_device->interrupt_check();
}
// generate the clock pulse
switch (m_index)
{
case 0:
m_device->m_zc0_cb(1);
m_device->m_zc0_cb(0);
break;
case 1:
m_device->m_zc1_cb(1);
m_device->m_zc1_cb(0);
break;
case 2:
m_device->m_zc2_cb(1);
m_device->m_zc2_cb(0);
break;
case 3:
m_device->m_zc3_cb(1);
m_device->m_zc3_cb(0);
break;
}
// reset the down counter
m_down = m_tconst;
}