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CDROM: Implement a heuristic for command cancelling

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See note in source. Fixes loading times and slowed down audio in Voice
Idol Collection - Pool Bar Story.
This commit is contained in:
Connor McLaughlin 2020-05-30 22:04:12 +10:00
parent a4f79de7f6
commit 0672cf4873
1 changed files with 34 additions and 8 deletions
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42
src/core/cdrom.cpp
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@ -563,13 +563,7 @@ void CDROM::WriteRegister(u32 offset, u8 value)
{
case 0:
{
Log_DebugPrintf("CDROM command register <- 0x%02X", value);
if (HasPendingCommand())
{
Log_WarningPrintf("Cancelling pending command 0x%02X", static_cast<u8>(m_command));
AbortCommand();
}
Log_WarningPrintf("CDROM command register <- 0x%02X (%s)", value, s_command_info[value].name);
BeginCommand(static_cast<Command>(value));
return;
}
@ -857,8 +851,40 @@ TickCount CDROM::GetTicksForStop(bool motor_was_on)
void CDROM::BeginCommand(Command command)
{
TickCount ack_delay = GetAckDelayForCommand(command);
if (HasPendingCommand())
{
// The behavior here is kinda.. interesting. Some commands seem to take precedence over others, for example
// sending a Nop command followed by a GetlocP will return the GetlocP response, and the same for the inverse.
// However, other combinations result in strange behavior, for example sending a Setloc followed by a ReadN will
// fail with ERROR_REASON_INCORRECT_NUMBER_OF_PARAMETERS. This particular example happens in Voice Idol
// Collection - Pool Bar Story, and the loading time is lengthened as well as audio slowing down if this
// behavior is not correct. So, let's use a heuristic; if the number of parameters of the "old" command is
// greater than the "new" command, empty the FIFO, which will return the error when the command executes.
// Otherwise, override the command with the new one.
if (s_command_info[static_cast<u8>(m_command)].expected_parameters >
s_command_info[static_cast<u8>(command)].expected_parameters)
{
Log_WarningPrintf("Ignoring command 0x%02X (%s) and emptying FIFO as 0x%02x (%s) is still pending",
static_cast<u8>(command), s_command_info[static_cast<u8>(command)].name,
static_cast<u8>(m_command), s_command_info[static_cast<u8>(m_command)].name);
m_param_fifo.Clear();
return;
}
Log_WarningPrintf("Cancelling pending command 0x%02X (%s) for new command 0x%02X (%s)", static_cast<u8>(m_command),
s_command_info[static_cast<u8>(m_command)].name, static_cast<u8>(command),
s_command_info[static_cast<u8>(command)].name);
// subtract the currently-elapsed ack ticks from the new command
const TickCount elapsed_ticks = m_command_event->GetInterval() - m_command_event->GetTicksUntilNextExecution();
ack_delay = std::max(ack_delay - elapsed_ticks, 1);
m_command_event->Deactivate();
}
m_command = command;
m_command_event->Schedule(GetAckDelayForCommand(command));
m_command_event->SetIntervalAndSchedule(ack_delay);
UpdateCommandEvent();
UpdateStatusRegister();
}