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Initial CPU Interrupt implementation (#7)

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This commit is contained in:
Franco
2024-04-15 00:07:18 +00:00
committed by GitHub
parent 2ce51c8b8b
commit 214722a45d
3 changed files with 34 additions and 21 deletions
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6
snes-core/src/cpu/interface.rs
View File

@@ -34,9 +34,9 @@ impl CPU {
return false;
}
if self.registers.is_cpu_waiting_interrupt {
// TODO: check for interrupts here
let (bytes, cycles) = cycles::increment_cycles_while_stopped();
self.registers.increment_pc(bytes); self.registers.cycles += cycles;
self.check_interrupts(bus);
let (_, cycles) = cycles::increment_cycles_while_stopped();
self.registers.cycles += cycles;
return false;
}
if self.registers.is_moving {

41
snes-core/src/cpu/vectors.rs
View File

@@ -1,4 +1,4 @@
use super::{interface::CPU, instructions::{phk::PHK, CPUInstruction, php::PHP, push_common}};
use super::{instructions::push_common, interface::CPU, internal_registers::RDNMI};
use crate::cpu::bus::Bus;
@@ -38,33 +38,40 @@ impl CPU {
self.registers.is_cpu_stopped = false;
}
fn get_vector_from_interrupts(&self) -> Option<Vector> {
if self.registers.get_irq_disable_flag() {
return None;
}
Some(Vector::Reset)
}
fn push_emulation_interrupt(&mut self, bus: &mut Bus) {
fn push_interrupt(&mut self, bus: &mut Bus) {
let pbr = self.registers.pbr;
if !self.registers.emulation_mode {
PHK{}.execute(&mut self.registers, bus);
push_common::do_push(&mut self.registers, bus, &[pbr]);
}
let values = [
(self.registers.pc >> 8) as u8,
self.registers.pc as u8,
];
push_common::do_push(&mut self.registers, bus, &values);
PHP{}.execute(&mut self.registers, bus);
let p = self.registers.p;
push_common::do_push(&mut self.registers, bus, &[p]);
}
pub fn handle_interrupts(&mut self, bus: &mut Bus) {
self.push_emulation_interrupt(bus);
if let Some(vector) = self.get_vector_from_interrupts() {
let effective_vector = vector.get_base_address();
self.registers.pc = effective_vector as u16;
self.registers.pbr = (effective_vector >> 16) as u8;
fn handle_interrupt(&mut self, bus: &mut Bus, vector: Vector) {
self.push_interrupt(bus);
let base_address = vector.get_base_address();
let effective_vector = CPU::get_vector(base_address, bus);
self.registers.pc = effective_vector;
self.registers.pbr = 0x00;
}
pub fn check_interrupts(&mut self, bus: &mut Bus) {
let rdnmi_byte = bus.read(RDNMI as u32);
if rdnmi_byte >> 7 != 0 {
self.registers.is_cpu_waiting_interrupt = false;
self.handle_interrupt(bus, Vector::NMI);
}
if !self.registers.get_irq_disable_flag() && bus.ppu.is_irq_set {
self.registers.is_cpu_waiting_interrupt = false;
self.handle_interrupt(bus, Vector::IRQ);
}
}
}

8
snes-core/src/ppu/interface.rs
View File

@@ -3,6 +3,8 @@ use super::registers::PPURegisters;
pub struct PPU {
framebuffer: Vec<u8>,
pub registers: PPURegisters,
was_vblank_nmi_set: bool,
pub is_irq_set: bool,
}
impl PPU {
@@ -10,6 +12,8 @@ impl PPU {
Self {
framebuffer: vec![],
registers: PPURegisters::new(),
was_vblank_nmi_set: false,
is_irq_set: false,
}
}
@@ -28,10 +32,12 @@ impl PPU {
if self.registers.h_count > 339 {
self.registers.h_count = 0;
self.registers.v_count += 1;
if self.registers.v_count > 224 {
if self.registers.v_count > 224 && !self.was_vblank_nmi_set {
self.registers.vblank_nmi = true;
self.was_vblank_nmi_set = true;
}
if self.registers.v_count > 261 {
self.was_vblank_nmi_set = false;
self.registers.v_count = 0;
}
}