Allow switching the stack pointer automatically on interrupts/exceptions
This commit is contained in:
parent
3ce3af511e
commit
4a18af8f81
52
src/cpu.rs
52
src/cpu.rs
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@ -10,6 +10,7 @@ const DEBUG: bool = false;
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#[derive(Copy, Clone)]
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#[derive(Copy, Clone)]
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pub struct Flag {
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pub struct Flag {
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pub swap_sp: bool,
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pub interrupt: bool,
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pub interrupt: bool,
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pub carry: bool,
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pub carry: bool,
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pub zero: bool,
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pub zero: bool,
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@ -17,6 +18,7 @@ pub struct Flag {
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impl std::convert::From<Flag> for u8 {
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impl std::convert::From<Flag> for u8 {
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fn from(flag: Flag) -> u8 {
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fn from(flag: Flag) -> u8 {
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(if flag.swap_sp { 1 } else { 0 }) << 3 |
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(if flag.interrupt { 1 } else { 0 }) << 2 |
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(if flag.interrupt { 1 } else { 0 }) << 2 |
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(if flag.carry { 1 } else { 0 }) << 1 |
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(if flag.carry { 1 } else { 0 }) << 1 |
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(if flag.zero { 1 } else { 0 }) << 0
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(if flag.zero { 1 } else { 0 }) << 0
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@ -25,10 +27,11 @@ impl std::convert::From<Flag> for u8 {
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impl std::convert::From<u8> for Flag {
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impl std::convert::From<u8> for Flag {
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fn from(byte: u8) -> Self {
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fn from(byte: u8) -> Self {
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let swap_sp = ((byte >> 3) & 1) != 0;
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let interrupt = ((byte >> 2) & 1) != 0;
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let interrupt = ((byte >> 2) & 1) != 0;
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let carry = ((byte >> 1) & 1) != 0;
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let carry = ((byte >> 1) & 1) != 0;
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let zero = ((byte >> 0) & 1) != 0;
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let zero = ((byte >> 0) & 1) != 0;
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Flag { interrupt, carry, zero }
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Flag { swap_sp, interrupt, carry, zero }
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}
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}
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}
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}
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@ -49,6 +52,7 @@ pub enum Interrupt {
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pub struct Cpu {
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pub struct Cpu {
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pub instruction_pointer: u32,
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pub instruction_pointer: u32,
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pub stack_pointer: u32,
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pub stack_pointer: u32,
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pub exception_stack_pointer: u32,
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pub register: [u32; 32],
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pub register: [u32; 32],
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pub flag: Flag,
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pub flag: Flag,
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@ -64,8 +68,9 @@ impl Cpu {
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Cpu {
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Cpu {
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instruction_pointer: 0xF0000000,
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instruction_pointer: 0xF0000000,
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stack_pointer: 0x00000000,
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stack_pointer: 0x00000000,
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exception_stack_pointer: 0x00000000,
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register: [0; 32],
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register: [0; 32],
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flag: Flag { interrupt: false, carry: false, zero: false },
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flag: Flag { swap_sp: false, interrupt: false, carry: false, zero: false },
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halted: false,
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halted: false,
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bus,
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bus,
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onfault: JumpEnv::new(),
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onfault: JumpEnv::new(),
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@ -136,6 +141,7 @@ impl Cpu {
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match register {
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match register {
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0..=31 => self.register[register as usize],
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0..=31 => self.register[register as usize],
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32 => self.stack_pointer,
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32 => self.stack_pointer,
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33 => self.exception_stack_pointer,
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_ => panic!("Invalid register: {}", register),
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_ => panic!("Invalid register: {}", register),
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}
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}
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}
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}
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@ -143,6 +149,7 @@ impl Cpu {
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match register {
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match register {
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0..=31 => self.register[register as usize] = word,
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0..=31 => self.register[register as usize] = word,
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32 => self.stack_pointer = word,
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32 => self.stack_pointer = word,
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33 => self.exception_stack_pointer = word,
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_ => panic!("Invalid register: {}", register),
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_ => panic!("Invalid register: {}", register),
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};
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};
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}
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}
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@ -163,7 +170,7 @@ impl Cpu {
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index + 24, self.register[index + 24]
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index + 24, self.register[index + 24]
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);
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);
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}
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}
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println!("rsp: {:#010X}", self.stack_pointer);
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println!("rsp: {:#010X} | esp: {:#010X}", self.stack_pointer, self.exception_stack_pointer);
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}
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}
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pub fn push_stack_8(&mut self, byte: u8) {
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pub fn push_stack_8(&mut self, byte: u8) {
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let decremented_stack_pointer = self.stack_pointer.overflowing_sub(1);
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let decremented_stack_pointer = self.stack_pointer.overflowing_sub(1);
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@ -231,27 +238,52 @@ impl Cpu {
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fn handle_interrupt(&mut self, vector: u16) {
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fn handle_interrupt(&mut self, vector: u16) {
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if DEBUG { println!("interrupt!!! vector: {:#04X}", vector); }
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if DEBUG { println!("interrupt!!! vector: {:#04X}", vector); }
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let address_of_pointer = vector as u32 * 4;
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let address_of_pointer = vector as u32 * 4;
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let old_mmu_state = *self.bus.memory.mmu_enabled();
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let old_mmu_state = *self.bus.memory.mmu_enabled();
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*self.bus.memory.mmu_enabled() = false;
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*self.bus.memory.mmu_enabled() = false;
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let address = self.bus.memory.read_32(&self.onfault, address_of_pointer);
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let address = self.bus.memory.read_32(&self.onfault, address_of_pointer);
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*self.bus.memory.mmu_enabled() = old_mmu_state;
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*self.bus.memory.mmu_enabled() = old_mmu_state;
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self.push_stack_32(self.instruction_pointer);
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self.push_stack_8(u8::from(self.flag));
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if self.flag.swap_sp {
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let old_stack_pointer = self.stack_pointer;
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self.stack_pointer = self.exception_stack_pointer;
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self.push_stack_32(old_stack_pointer);
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self.push_stack_32(self.instruction_pointer);
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self.push_stack_8(u8::from(self.flag));
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self.flag.swap_sp = false;
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} else {
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self.push_stack_32(self.instruction_pointer);
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self.push_stack_8(u8::from(self.flag));
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}
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self.flag.interrupt = false; // prevent interrupts while already servicing an interrupt
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self.flag.interrupt = false; // prevent interrupts while already servicing an interrupt
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self.instruction_pointer = address;
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self.instruction_pointer = address;
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}
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}
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fn handle_exception(&mut self, vector: u16, operand: Option<u32>) {
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fn handle_exception(&mut self, vector: u16, operand: Option<u32>) {
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if DEBUG { println!("exception!!! vector: {:#04X}, operand: {:?}", vector, operand); }
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if DEBUG { println!("exception!!! vector: {:#04X}, operand: {:?}", vector, operand); }
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let address_of_pointer = (256 + vector) as u32 * 4;
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let address_of_pointer = (256 + vector) as u32 * 4;
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let old_mmu_state = *self.bus.memory.mmu_enabled();
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let old_mmu_state = *self.bus.memory.mmu_enabled();
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*self.bus.memory.mmu_enabled() = false;
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*self.bus.memory.mmu_enabled() = false;
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let address = self.bus.memory.read_32(&self.onfault, address_of_pointer);
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let address = self.bus.memory.read_32(&self.onfault, address_of_pointer);
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*self.bus.memory.mmu_enabled() = old_mmu_state;
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*self.bus.memory.mmu_enabled() = old_mmu_state;
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self.push_stack_32(self.instruction_pointer);
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self.push_stack_8(u8::from(self.flag));
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if self.flag.swap_sp {
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let old_stack_pointer = self.stack_pointer;
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self.stack_pointer = self.exception_stack_pointer;
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self.push_stack_32(old_stack_pointer);
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self.push_stack_32(self.instruction_pointer);
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self.push_stack_8(u8::from(self.flag));
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self.flag.swap_sp = false;
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} else {
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self.push_stack_32(self.instruction_pointer);
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self.push_stack_8(u8::from(self.flag));
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}
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if let Some(operand) = operand {
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if let Some(operand) = operand {
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self.push_stack_32(operand);
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self.push_stack_32(operand);
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}
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}
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self.flag.interrupt = false; // prevent interrupts while already servicing an interrupt
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self.flag.interrupt = false; // prevent interrupts while already servicing an interrupt
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self.instruction_pointer = address;
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self.instruction_pointer = address;
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}
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}
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@ -2491,7 +2523,11 @@ impl Cpu {
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let should_run = self.check_condition(condition);
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let should_run = self.check_condition(condition);
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if should_run {
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if should_run {
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self.flag = Flag::from(self.pop_stack_8());
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self.flag = Flag::from(self.pop_stack_8());
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self.pop_stack_32()
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let instruction_pointer = self.pop_stack_32();
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if self.flag.swap_sp {
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self.stack_pointer = self.pop_stack_32();
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}
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instruction_pointer
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} else {
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} else {
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self.instruction_pointer + instruction_pointer_offset
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self.instruction_pointer + instruction_pointer_offset
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}
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}
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