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Pad: Fix timing issues w/ BIOS

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This commit is contained in:
Connor McLaughlin
2019-09-23 01:25:58 +10:00
parent 734d1a7ee1
commit 5d1c12c9ad
4 changed files with 127 additions and 22 deletions
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119
src/pse/pad.cpp
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@ -3,14 +3,16 @@
#include "common/state_wrapper.h"
#include "interrupt_controller.h"
#include "pad_device.h"
#include "system.h"
Log_SetChannel(Pad);
Pad::Pad() = default;
Pad::~Pad() = default;
bool Pad::Initialize(InterruptController* interrupt_controller)
bool Pad::Initialize(System* system, InterruptController* interrupt_controller)
{
m_system = system;
m_interrupt_controller = interrupt_controller;
return true;
}
@ -22,6 +24,8 @@ void Pad::Reset()
bool Pad::DoState(StateWrapper& sw)
{
sw.Do(&m_state);
sw.Do(&m_ticks_remaining);
sw.Do(&m_JOY_CTRL.bits);
sw.Do(&m_JOY_STAT.bits);
sw.Do(&m_JOY_MODE.bits);
@ -49,7 +53,11 @@ u32 Pad::ReadRegister(u32 offset)
}
case 0x04: // JOY_STAT
return m_JOY_STAT.bits;
{
const u32 bits = m_JOY_STAT.bits;
m_JOY_STAT.ACKINPUT = false;
return bits;
}
case 0x08: // JOY_MODE
return ZeroExtend32(m_JOY_MODE.bits);
@ -78,8 +86,8 @@ void Pad::WriteRegister(u32 offset, u32 value)
m_TX_FIFO.Push(Truncate8(value));
if (m_JOY_CTRL.SELECT)
DoTransfer();
if (!IsTransmitting() && CanTransfer())
BeginTransfer();
return;
}
@ -96,13 +104,19 @@ void Pad::WriteRegister(u32 offset, u32 value)
if (m_JOY_CTRL.ACK)
{
// reset stat bits
m_JOY_STAT.ACKINPUTLEVEL = false;
m_JOY_STAT.INTR = false;
m_JOY_CTRL.ACK = true;
}
if (!old_select && m_JOY_CTRL.SELECT && !m_TX_FIFO.IsEmpty())
DoTransfer();
if (!m_JOY_CTRL.SELECT || !m_JOY_CTRL.TXEN)
{
if (IsTransmitting())
EndTransfer();
}
else
{
if (!IsTransmitting() && CanTransfer())
BeginTransfer();
}
return;
}
@ -126,8 +140,28 @@ void Pad::WriteRegister(u32 offset, u32 value)
}
}
void Pad::Execute(TickCount ticks)
{
switch (m_state)
{
case State::Idle:
break;
case State::Transmitting:
{
m_ticks_remaining -= ticks;
if (m_ticks_remaining <= 0)
DoTransfer();
}
break;
}
}
void Pad::SoftReset()
{
if (IsTransmitting())
EndTransfer();
m_JOY_CTRL.bits = 0;
m_JOY_STAT.bits = 0;
m_JOY_MODE.bits = 0;
@ -143,35 +177,84 @@ void Pad::UpdateJoyStat()
m_JOY_STAT.TXRDY = !m_TX_FIFO.IsFull();
}
void Pad::BeginTransfer()
{
DebugAssert(m_state == State::Idle && CanTransfer());
Log_DebugPrintf("Starting transfer");
m_JOY_CTRL.RXEN = true;
// The transfer or the interrupt must be delayed, otherwise the BIOS thinks there's no device detected.
// It seems to do something resembling the following:
// 1) Sets the control register up for transmitting, interrupt on ACK.
// 2) Writes 0x01 to the TX FIFO.
// 3) Delays for a bit.
// 4) Writes ACK to the control register, clearing the interrupt flag.
// 5) Clears IRQ7 in the interrupt controller.
// 6) Waits until the RX FIFO is not empty, reads the first byte to $zero.
// 7) Checks if the interrupt status register had IRQ7 set. If not, no device connected.
//
// Performing the transfer immediately will result in both the INTR bit and the bit in the interrupt
// controller being discarded in (4)/(5), but this bit was set by the *new* transfer. Therefore, the
// test in (7) will fail, and it won't send any more data. So, the transfer/interrupt must be delayed
// until after (4) and (5) have been completed.
m_system->Synchronize();
m_state = State::Transmitting;
m_ticks_remaining = TRANSFER_TICKS;
m_system->SetDowncount(m_ticks_remaining);
}
void Pad::DoTransfer()
{
Log_DebugPrintf("Transferring slot %d", m_JOY_CTRL.SLOT.GetValue());
const std::shared_ptr<PadDevice>& dev = m_devices[m_JOY_CTRL.SLOT];
if (!dev)
if (!dev || !CanTransfer())
{
// no device present, don't set ACK and read hi-z
m_TX_FIFO.Clear();
m_RX_FIFO.Clear();
m_RX_FIFO.Push(0xFF);
UpdateJoyStat();
EndTransfer();
return;
}
while (!m_TX_FIFO.IsEmpty())
{
const u8 data_out = m_TX_FIFO.Pop();
u8 data_in;
m_JOY_STAT.ACKINPUTLEVEL |= dev->Transfer(data_out, &data_in);
m_RX_FIFO.Push(data_in);
m_JOY_CTRL.RXEN = true;
}
// set rx?
m_JOY_CTRL.RXEN = true;
if (m_JOY_STAT.ACKINPUTLEVEL && m_JOY_CTRL.ACKINTEN)
const u8 data_out = m_TX_FIFO.Pop();
u8 data_in;
m_JOY_STAT.ACKINPUT |= dev->Transfer(data_out, &data_in);
m_RX_FIFO.Push(data_in);
if (m_JOY_STAT.ACKINPUT && m_JOY_CTRL.ACKINTEN)
{
Log_DebugPrintf("Triggering interrupt");
m_JOY_STAT.INTR = true;
m_interrupt_controller->InterruptRequest(InterruptController::IRQ::IRQ7);
}
if (m_TX_FIFO.IsEmpty())
{
EndTransfer();
}
else
{
// queue the next byte
m_ticks_remaining += TRANSFER_TICKS;
m_system->SetDowncount(m_ticks_remaining);
}
UpdateJoyStat();
}
void Pad::EndTransfer()
{
DebugAssert(m_state == State::Transmitting);
Log_DebugPrintf("Ending transfer");
m_state = State::Idle;
m_ticks_remaining = 0;
}