joncampbell123/dosbox-x
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add option to emulate the PC/XT NMI mask register (port A0h). since A0h

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conflicts with the slave PIC, the option does nothing unless the slave
PIC is disabled.
This commit is contained in:
Jonathan Campbell
2014-06-09 02:21:33 -07:00
parent 0df73cd96f
commit 3e804d9f09
2 changed files with 21 additions and 0 deletions
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3
src/dosbox.cpp
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@@ -912,6 +912,9 @@ void DOSBOX_Init(void) {
Pbool = secprop->Add_bool("enable slave pic",Property::Changeable::WhenIdle,true);
Pbool->Set_help("Enable slave PIC (IRQ 8-15). Set this to 0 if you want to emulate a PC/XT type arrangement with IRQ 0-7 and no IRQ 2 cascade.");
Pbool = secprop->Add_bool("enable pc nmi mask",Property::Changeable::WhenIdle,true);
Pbool->Set_help("Enable PC/XT style NMI mask register (0xA0). Note that this option conflicts with the secondary PIC and will be ignored if the slave PIC is enabled.");
secprop->AddInitFunction(&CALLBACK_Init);
secprop->AddInitFunction(&DMA_Init);//done
secprop->AddInitFunction(&PIC_Init);//done

18
src/hardware/pic.cpp
View File

@@ -115,6 +115,7 @@ static PIC_Controller& slave = pics[1];
Bitu PIC_Ticks = 0;
Bitu PIC_IRQCheck = 0; //Maybe make it a bool and/or ensure 32bit size (x86 dynamic core seems to assume 32 bit variable size)
bool enable_slave_pic = true; /* if set, emulate slave with cascade to master. if clear, emulate only master, and no cascade (IRQ 2 is open) */
bool enable_pc_xt_nmi_mask = false;
void PIC_Controller::set_imr(Bit8u val) {
Bit8u change = (imr) ^ (val); //Bits that have changed become 1.
@@ -280,6 +281,14 @@ static Bitu read_data(Bitu port,Bitu iolen) {
return pic->imr;
}
/* PC/XT NMI mask register 0xA0. Documentation on the other bits
* is sparse and spread across the internet, but many seem to
* agree that bit 7 is used to enable/disable the NMI (1=enable,
* 0=disable) */
static void pc_xt_nmi_write(Bitu port,Bitu val,Bitu iolen) {
CPU_NMI_gate = (val & 0x80) ? true : false;
}
void PIC_ActivateIRQ(Bitu irq) {
/* Remember what was once IRQ 2 on PC/XT is IRQ 9 on PC/AT */
if (enable_slave_pic) { /* PC/AT emulation with slave PIC cascade to master */
@@ -609,6 +618,8 @@ void TIMER_AddTick(void) {
}
}
static IO_WriteHandleObject PCXT_NMI_WriteHandler;
/* Use full name to avoid name clash with compile option for position-independent code */
class PIC_8259A: public Module_base {
private:
@@ -619,6 +630,7 @@ public:
Section_prop * section=static_cast<Section_prop *>(configuration);
enable_slave_pic = section->Get_bool("enable slave pic");
enable_pc_xt_nmi_mask = section->Get_bool("enable pc nmi mask");
/* Setup pic0 and pic1 with initial values like DOS has normally */
PIC_IRQCheck=0;
@@ -648,12 +660,18 @@ public:
ReadHandler[1].Install(0x21,read_data,IO_MB);
WriteHandler[0].Install(0x20,write_command,IO_MB);
WriteHandler[1].Install(0x21,write_data,IO_MB);
/* the secondary slave PIC takes priority over PC/XT NMI mask emulation */
if (enable_slave_pic) {
ReadHandler[2].Install(0xa0,read_command,IO_MB);
ReadHandler[3].Install(0xa1,read_data,IO_MB);
WriteHandler[2].Install(0xa0,write_command,IO_MB);
WriteHandler[3].Install(0xa1,write_data,IO_MB);
}
else if (enable_pc_xt_nmi_mask) {
PCXT_NMI_WriteHandler.Install(0xa0,pc_xt_nmi_write,IO_MB);
}
/* Initialize the pic queue */
for (i=0;i<PIC_QUEUESIZE-1;i++) {
pic_queue.entries[i].next=&pic_queue.entries[i+1];