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PIC: Now let the user play with IRQ delays

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This commit is contained in:
Jonathan Campbell 2018-02-12 11:50:44 -08:00
parent e14a1fef1b
commit f84deba128
2 changed files with 34 additions and 13 deletions
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10
src/dosbox.cpp
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@ -1074,6 +1074,12 @@ void DOSBOX_SetupConfigSections(void) {
Pint->SetMinMax(0,128);
Pint->Set_help("Once ROM BIOS layout is finalized, trim total region down to a minimum amount in KB");
Pint = secprop->Add_int("irq delay ns", Property::Changeable::WhenIdle,-1);
Pint->SetMinMax(-1,100000);
Pint->Set_help( "IRQ delay in nanoseconds. Set to -1 to use default, 0 to disable.\n"
"This is a more precise version of the irqdelay= setting.\n"
"There are some old DOS games and demos that have race conditions with IRQs that need a nonzero value here to work properly.");
Pint = secprop->Add_int("iodelay", Property::Changeable::WhenIdle,-1);
Pint->SetMinMax(-1,100000);
Pint->Set_help( "I/O delay in nanoseconds for I/O port access. Set to -1 to use default, 0 to disable.\n"
@ -1245,8 +1251,8 @@ void DOSBOX_SetupConfigSections(void) {
"has been verified to occur on some old (early 90s) BIOSes.");
Pint = secprop->Add_int("irq delay",Property::Changeable::OnlyAtStart,-1);
Pint->Set_help("If 0 or greater, apply a delay (in cycles) to IRQ handling in the CPU. A value of -1 means to use a default value.\n"
"There are some old DOS games and demos that have race conditions with IRQs that need a nonzero value here to work properly.");
Pint->Set_help("If 0 or greater, apply a delay (in cycles) to IRQ handling in the CPU.\n"
"A value of -1 means to use a default value computed from the irq delay ns= setting.");
Pbool = secprop->Add_bool("allow port 92 reset",Property::Changeable::OnlyAtStart,true);
Pbool->Set_help("If set (default), allow the application to reset the CPU through port 92h");

37
src/hardware/pic.cpp
View File

@ -29,6 +29,7 @@
unsigned long PIC_irq_delay_ns = 1000000000UL / (unsigned long)PIT_TICK_RATE_IBM; // initial guess
unsigned long PIC_irq_delay_ns_from_cycles = 0;
int PIC_irq_delay_user = -1;
int PIC_irq_delay = 2;
struct PIC_Controller {
@ -316,7 +317,11 @@ static void pc_xt_nmi_write(Bitu port,Bitu val,Bitu iolen) {
void PIC_irq_delay_update() {
PIC_irq_delay_ns_from_cycles = CPU_CycleMax;
PIC_irq_delay = (int)((PIC_irq_delay_ns * (unsigned long)CPU_CycleMax) / 1000000UL); /* remember cycles counts are per 1ms */
if (PIC_irq_delay_user < 0)
PIC_irq_delay = (int)((PIC_irq_delay_ns * (unsigned long)CPU_CycleMax) / 1000000UL); /* remember cycles counts are per 1ms */
else
PIC_irq_delay = PIC_irq_delay_user;
}
/* FIXME: This should be called something else that's true to the ISA bus, like PIC_PulseIRQ, not Activate IRQ.
@ -747,22 +752,32 @@ void PIC_Reset(Section *sec) {
WriteHandler[3].Uninstall();
PCXT_NMI_WriteHandler.Uninstall();
/* initial guess: perhaps the time delay from IRQ to CPU interrupt is related to the
* 1.19MHz clock rate also given to the PIT (divided down from 14MHz
* on IBM PC/XT hardware). Perhaps it takes a few of these clock ticks
* for the PIC to process the interrupt? --Jonathan C. */
/* let's guess that it takes the PIC 2 PIC clock cycles for IRQ to CPU interrupt to happen */
PIC_irq_delay_ns = 1000000000UL / ((unsigned long)PIT_TICK_RATE * 2UL);
PIC_irq_delay_update(); // precompute into CPU cycles counts for emulation
/* NTS: Parsing this on reset allows PIC configuration changes on reboot instead of restarting the entire emulator */
Section_prop * section=static_cast<Section_prop *>(control->GetSection("dosbox"));
assert(section != NULL);
enable_slave_pic = section->Get_bool("enable slave pic");
enable_pc_xt_nmi_mask = section->Get_bool("enable pc nmi mask");
PIC_irq_delay = section->Get_int("irq delay");
if (PIC_irq_delay < 0) PIC_irq_delay = 2; /* default */
/* initial guess: perhaps the time delay from IRQ to CPU interrupt is related to the
* 1.19MHz clock rate also given to the PIT (divided down from 14MHz
* on IBM PC/XT hardware). Perhaps it takes a few of these clock ticks
* for the PIC to process the interrupt? --Jonathan C. */
/* let's guess that it takes the PIC 2 PIC clock cycles for IRQ to CPU interrupt to happen */
/* Make our initial setting, but let the user override our guess from dosbox.conf.
* For backwards compat with "irq delay" as a count of CPU cycles, let that override as well. */
PIC_irq_delay_ns = 1000000000UL / ((unsigned long)PIT_TICK_RATE * 2UL);
PIC_irq_delay_user = section->Get_int("irq delay");
{
int x = section->Get_int("irq delay ns");
if (x >= 0) PIC_irq_delay_ns = x;
}
PIC_irq_delay_update(); // precompute into CPU cycles counts for emulation
LOG_MSG("PIC: IRQ user delay cycles=%d ns delay=%lu final cycles=%d",
PIC_irq_delay_user,
PIC_irq_delay_ns,
PIC_irq_delay);
if (enable_slave_pic)
master_cascade_irq = IS_PC98_ARCH ? 7 : 2;