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Attempt at fixing 8155 timer behavior so 8085 doesn't lose interrupts in equites

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This commit is contained in:
AJR 2016-12-11 18:19:50 -05:00
parent f0bceea105
commit 95d24633de
1 changed files with 27 additions and 20 deletions
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45
src/devices/machine/i8155.cpp
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@ -294,18 +294,9 @@ void i8155_device::device_timer(emu_timer &timer, device_timer_id id, int param,
{
if (LOG) logerror("8155 Timer Count Reached\n");
switch (m_command & COMMAND_TM_MASK)
{
case COMMAND_TM_STOP_AFTER_TC:
// stop timer
m_timer->enable(0);
if (LOG) logerror("8155 Timer Stopped\n");
break;
}
switch (get_timer_mode())
{
case TIMER_MODE_LOW:
case TIMER_MODE_SQUARE_WAVE:
// toggle timer output
m_to = !m_to;
@ -313,15 +304,8 @@ void i8155_device::device_timer(emu_timer &timer, device_timer_id id, int param,
break;
case TIMER_MODE_SINGLE_PULSE:
// single pulse upon TC being reached
pulse_timer_output();
// clear timer mode setting
m_command &= ~COMMAND_TM_MASK;
break;
case TIMER_MODE_AUTOMATIC_RELOAD:
// automatic reload, i.e. single pulse every time TC is reached
// pulse upon TC being reached
pulse_timer_output();
break;
}
@ -329,8 +313,28 @@ void i8155_device::device_timer(emu_timer &timer, device_timer_id id, int param,
// set timer flag
m_status |= STATUS_TIMER;
// reload timer counter
if ((m_command & COMMAND_TM_MASK) == COMMAND_TM_START)
{
// load new timer counter
m_counter = m_count_length & 0x3fff;
if (LOG) logerror("8155 Timer New Start\n");
}
else if ((m_command & COMMAND_TM_MASK) == COMMAND_TM_STOP_AFTER_TC || get_timer_mode() == TIMER_MODE_SINGLE_PULSE)
{
// stop timer
m_timer->enable(0);
if (LOG) logerror("8155 Timer Stopped\n");
}
else
{
// automatically reload the counter
m_counter = m_count_length & 0x3fff;
}
// clear timer command
m_command &= ~COMMAND_TM_MASK;
}
}
@ -455,6 +459,9 @@ void i8155_device::register_w(int offset, uint8_t data)
// load mode and CNT length and start immediately after loading (if timer is not running)
m_counter = m_count_length & 0x3fff;
m_timer->adjust(attotime::zero, 0, attotime::from_hz(clock()));
// clear timer command so this won't execute twice
m_command &= ~COMMAND_TM_MASK;
}
break;
}