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6522via.cpp: Count negative PB6 pulses in T2 counter mode

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(nw) VIA interrupt remains disconnected in tv950 due to CRTC-related problems. This is fairly likely to cause regressions in other drivers which may need explicit writes to PB6.
This commit is contained in:
AJR 2018-12-27 15:48:33 -05:00
parent bbc1fcfed3
commit 6aa1dbe27d
3 changed files with 103 additions and 54 deletions
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154
src/devices/machine/6522via.cpp
View File

@ -7,8 +7,6 @@
This is based on the M6821 emulation in MAME.
To do:
T2 pulse counting mode
Pulse mode handshake output
**********************************************************************/
@ -139,6 +137,29 @@ uint16_t via6522_device::get_counter1_value()
return val;
}
void via6522_device::counter2_decrement()
{
if (!T2_COUNT_PB6(m_acr))
return;
// count down on T2CL
if (m_t2cl-- != 0)
return;
// borrow from T2CH
if (m_t2ch-- != 0)
return;
// underflow causes only one interrupt between T2CH writes
if (m_t2_active)
{
m_t2_active = 0;
LOGINT("T2 INT request ");
set_int(INT_T2);
}
}
//**************************************************************************
// LIVE DEVICE
@ -170,7 +191,7 @@ via6522_device::via6522_device(const machine_config &mconfig, const char *tag, d
m_in_ca1(0),
m_in_ca2(0),
m_out_ca2(0),
m_in_b(0),
m_in_b(0xff),
m_in_cb1(0),
m_in_cb2(0),
m_pcr(0),
@ -283,6 +304,12 @@ void via6522_device::device_reset()
m_ca2_handler(m_out_ca2);
m_cb1_handler(m_out_cb1);
m_cb2_handler(m_out_cb2);
m_t1->adjust(attotime::never);
m_t2->adjust(attotime::never);
m_ca2_timer->adjust(attotime::never);
m_shift_timer->adjust(attotime::never);
m_shift_irq_timer->adjust(attotime::never);
}
@ -487,16 +514,15 @@ void via6522_device::device_timer(emu_timer &timer, device_timer_id id, int para
uint8_t via6522_device::input_pa()
{
uint8_t pa = m_in_a & ~m_ddr_a;
/// TODO: REMOVE THIS
if (!m_in_a_handler.isnull())
{
if (m_ddr_a != 0xff)
m_in_a = m_in_a_handler(0);
if (m_ddr_a != 0xff && !m_in_a_handler.isnull())
pa &= m_in_a_handler();
return (m_out_a & m_ddr_a) + (m_in_a & ~m_ddr_a);
}
pa |= m_out_a & m_ddr_a;
return m_in_a & (m_out_a | ~m_ddr_a);
return pa;
}
void via6522_device::output_pa()
@ -507,13 +533,15 @@ void via6522_device::output_pa()
uint8_t via6522_device::input_pb()
{
uint8_t pb = m_in_b & ~m_ddr_b;
/// TODO: REMOVE THIS
if (m_ddr_b != 0xff && !m_in_b_handler.isnull())
{
m_in_b = m_in_b_handler(0);
pb &= m_in_b_handler();
}
uint8_t pb = (m_out_b & m_ddr_b) + (m_in_b & ~m_ddr_b);
pb |= m_out_b & m_ddr_b;
if (T1_SET_PB7(m_acr))
pb = (pb & 0x7f) | (m_t1_pb7 << 7);
@ -538,9 +566,6 @@ void via6522_device::output_pb()
u8 via6522_device::read(offs_t offset)
{
int val = 0;
if (machine().side_effects_disabled())
return 0;
offset &= 0xf;
switch (offset)
@ -556,8 +581,11 @@ u8 via6522_device::read(offs_t offset)
val = m_latch_b;
}
LOGINT("PB INT ");
CLR_PB_INT();
if (!machine().side_effects_disabled())
{
LOGINT("PB INT ");
CLR_PB_INT();
}
break;
case VIA_PA:
@ -571,17 +599,20 @@ u8 via6522_device::read(offs_t offset)
val = m_latch_a;
}
LOGINT("PA INT ");
CLR_PA_INT();
if (m_out_ca2 && (CA2_PULSE_OUTPUT(m_pcr) || CA2_AUTO_HS(m_pcr)))
if (!machine().side_effects_disabled())
{
m_out_ca2 = 0;
m_ca2_handler(m_out_ca2);
}
LOGINT("PA INT ");
CLR_PA_INT();
if (CA2_PULSE_OUTPUT(m_pcr))
m_ca2_timer->adjust(clocks_to_attotime(1));
if (m_out_ca2 && (CA2_PULSE_OUTPUT(m_pcr) || CA2_AUTO_HS(m_pcr)))
{
m_out_ca2 = 0;
m_ca2_handler(m_out_ca2);
}
if (CA2_PULSE_OUTPUT(m_pcr))
m_ca2_timer->adjust(clocks_to_attotime(1));
}
break;
@ -606,8 +637,11 @@ u8 via6522_device::read(offs_t offset)
break;
case VIA_T1CL:
LOGINT("T1CL INT ");
clear_int(INT_T1);
if (!machine().side_effects_disabled())
{
LOGINT("T1CL INT ");
clear_int(INT_T1);
}
val = get_counter1_value() & 0xFF;
break;
@ -624,9 +658,12 @@ u8 via6522_device::read(offs_t offset)
break;
case VIA_T2CL:
LOGINT("T2CL INT ");
clear_int(INT_T2);
if (m_t2_active)
if (!machine().side_effects_disabled())
{
LOGINT("T2CL INT ");
clear_int(INT_T2);
}
if (m_t2_active && m_t2->enabled())
{
val = attotime_to_clocks(m_t2->remaining()) & 0xff;
}
@ -644,7 +681,7 @@ u8 via6522_device::read(offs_t offset)
break;
case VIA_T2CH:
if (m_t2_active)
if (m_t2_active && m_t2->enabled())
{
val = attotime_to_clocks(m_t2->remaining()) >> 8;
}
@ -664,28 +701,31 @@ u8 via6522_device::read(offs_t offset)
case VIA_SR:
LOGSHIFT("Read SR: %02x ", m_sr);
val = m_sr;
m_out_cb1 = 1;
m_cb1_handler(m_out_cb1);
m_shift_counter = 0x0f;
LOGINT("SR INT ");
clear_int(INT_SR);
LOGSHIFT(" - ACR: %02x ", m_acr);
if (SI_O2_CONTROL(m_acr) || SO_O2_CONTROL(m_acr))
if (!machine().side_effects_disabled())
{
m_shift_timer->adjust(clocks_to_attotime(8) / 2); // 8 flanks to start shifter from a read
LOGSHIFT(" - read SR starts O2 timer ");
m_out_cb1 = 1;
m_cb1_handler(m_out_cb1);
m_shift_counter = 0x0f;
LOGINT("SR INT ");
clear_int(INT_SR);
LOGSHIFT(" - ACR: %02x ", m_acr);
if (SI_O2_CONTROL(m_acr) || SO_O2_CONTROL(m_acr))
{
m_shift_timer->adjust(clocks_to_attotime(8) / 2); // 8 flanks to start shifter from a read
LOGSHIFT(" - read SR starts O2 timer ");
}
else if (SI_T2_CONTROL(m_acr) || SO_T2_CONTROL(m_acr))
{
m_shift_timer->adjust(clocks_to_attotime(m_t2ll + 2) / 2);
LOGSHIFT(" - read SR starts T2 timer ");
}
else if (!SO_T2_RATE(m_acr))
{
m_shift_timer->adjust(attotime::never);
LOGSHIFT("Timer stops");
}
LOGSHIFT("\n");
}
else if (SI_T2_CONTROL(m_acr) || SO_T2_CONTROL(m_acr))
{
m_shift_timer->adjust(clocks_to_attotime(m_t2ll + 2) / 2);
LOGSHIFT(" - read SR starts T2 timer ");
}
else if (! SO_T2_RATE(m_acr))
{
m_shift_timer->adjust(attotime::never);
LOGSHIFT("Timer stops");
}
LOGSHIFT("\n");
break;
case VIA_PCR:
@ -839,7 +879,7 @@ void via6522_device::write(offs_t offset, u8 data)
}
else
{
m_t2->adjust(clocks_to_attotime(TIMER2_VALUE));
//m_t2->adjust(clocks_to_attotime(TIMER2_VALUE));
m_t2_active = 1;
m_time2 = machine().time();
}
@ -1025,11 +1065,19 @@ void via6522_device::set_pb_line(int line, int state)
if (state)
m_in_b |= (1 << line);
else
{
if (line == 6 && BIT(m_in_b, 6))
counter2_decrement();
m_in_b &= ~(1 << line);
}
}
WRITE8_MEMBER( via6522_device::write_pb )
{
if (!BIT(data, 6) && BIT(m_in_b, 6))
counter2_decrement();
m_in_b = data;
}

1
src/devices/machine/6522via.h
View File

@ -107,6 +107,7 @@ private:
static constexpr device_timer_id TIMER_SHIFT_IRQ = 4;
uint16_t get_counter1_value();
void counter2_decrement();
void set_int(int data);
void clear_int(int data);

2
src/mame/drivers/esprit.cpp
View File

@ -201,7 +201,7 @@ void esprit_state::esprit3(machine_config &config)
crtc.set_char_width(9);
crtc.set_update_row_callback(FUNC(esprit_state::crtc_update_row), this);
crtc.set_on_update_addr_change_callback(FUNC(esprit_state::crtc_update_addr), this);
//crtc.out_hsync_callback().set("via", FUNC(via6522_device::write_pb6)).invert();
crtc.out_hsync_callback().set("via", FUNC(via6522_device::write_pb6)).invert();
}
ROM_START( esprit )