cpu - Fix timing of delay when enabling interrupts
This commit is contained in:
parent
1194340657
commit
002b745917
2 changed files with 12 additions and 3 deletions
|
@ -191,8 +191,6 @@ void Cpu::handleInterrupts()
|
||||||
u8 si = state.IE & state.IF & INT_MASK;
|
u8 si = state.IE & state.IF & INT_MASK;
|
||||||
|
|
||||||
if (state.IME == IME_SCHEDULED)
|
if (state.IME == IME_SCHEDULED)
|
||||||
state.IME = IME_DELAYED;
|
|
||||||
else if (state.IME == IME_DELAYED)
|
|
||||||
state.IME = IME_ON;
|
state.IME = IME_ON;
|
||||||
else if (state.IME == IME_ON && si != 0)
|
else if (state.IME == IME_ON && si != 0)
|
||||||
{
|
{
|
||||||
|
|
13
cpu/cpu.h
13
cpu/cpu.h
|
@ -43,11 +43,22 @@ enum InterruptType : u8
|
||||||
INT_MASK = 0x1F,
|
INT_MASK = 0x1F,
|
||||||
};
|
};
|
||||||
|
|
||||||
|
|
||||||
|
/**
|
||||||
|
IME - Interrupt Master Enable
|
||||||
|
|
||||||
|
An EI instruction will enable the interrupts, but delayed. During the next instruction after EI,
|
||||||
|
interrupts are still disabled. For this to be emulated we use a small state machine. which works as follows
|
||||||
|
|
||||||
|
instruction EI - sets IME_SCHEDULED
|
||||||
|
handleInterrupts -> IME_SCHEDULED to IME_ON (but no call to isr yet)
|
||||||
|
instruction any - is IME_ON, but no chance for call to isr yet
|
||||||
|
handleInterrupts -> is IME_ON, do a call to isr if necessary
|
||||||
|
*/
|
||||||
enum IME_state
|
enum IME_state
|
||||||
{
|
{
|
||||||
IME_OFF,
|
IME_OFF,
|
||||||
IME_SCHEDULED,
|
IME_SCHEDULED,
|
||||||
IME_DELAYED,
|
|
||||||
IME_ON,
|
IME_ON,
|
||||||
};
|
};
|
||||||
|
|
||||||
|
|
Loading…
Reference in a new issue