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read_external function

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This commit is contained in:
Franco Colmenarez
2023-07-07 19:11:29 -05:00
parent e7a40db745
commit e6d97f7203
5 changed files with 46 additions and 14 deletions
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16
snes-core/src/cpu/bus.rs
View File

@@ -56,6 +56,22 @@ impl Bus {
}
}
/// This function is meant to be used by external parts of the code,
/// for example, to render register info without mutating them
pub fn read_external(&self, address: u32) -> u8 {
let section = Bus::map_address(address);
match section {
MemoryMap::WRAM => self.read_wram(address),
MemoryMap::PPU => self.ppu.registers.read_external(address as u16),
MemoryMap::CPU => self.internal_registers.read_external(
address as u16,
&self.ppu.registers,
),
MemoryMap::Joypad => 0x00, // TODO: Placeholder
MemoryMap::Cartridge => self.rom.read(address),
}
}
pub fn read(&mut self, address: u32) -> u8 {
let section = Bus::map_address(address);
match section {

17
snes-core/src/cpu/internal_registers.rs
View File

@@ -24,18 +24,31 @@ impl InternalRegisters {
self.registers[(address - INTERNAL_REGISTERS_ADDRESS) as usize] = value
}
pub fn read(&self, address: u16, ppu_registers: &mut PPURegisters) -> u8 {
pub fn read_external(&self, address: u16, ppu_registers: &PPURegisters) -> u8 {
match address {
RDNMI => self.read_vblank_nmi(ppu_registers),
_ => self._read(address),
}
}
pub fn read(&self, address: u16, ppu_registers: &mut PPURegisters) -> u8 {
match address {
RDNMI => self.read_vblank_nmi_mut(ppu_registers),
_ => self._read(address),
}
}
pub fn write(&mut self, address: u16, value: u8) {
self._write(address, value);
}
fn read_vblank_nmi(&self, ppu_registers: &mut PPURegisters) -> u8 {
fn read_vblank_nmi(&self, ppu_registers: &PPURegisters) -> u8 {
let byte = self._read(RDNMI);
let result = (byte & 0x7F) | ((ppu_registers.vblank_nmi as u8) << 7);
result
}
fn read_vblank_nmi_mut(&self, ppu_registers: &mut PPURegisters) -> u8 {
let byte = self._read(RDNMI);
// When register is read, bit 7 is cleared
let result = (byte & 0x7F) | ((ppu_registers.vblank_nmi as u8) << 7);

4
snes-core/src/ppu/registers.rs
View File

@@ -164,6 +164,10 @@ impl PPURegisters {
self.data[(address as usize) - 0x2100] = value;
}
pub fn read_external(&self, address: u16) -> u8 {
self._read(address)
}
pub fn read(&mut self, address: u16) -> u8 {
let result = self._read(address);
match address {

21
snes-frontend/src/cpu.rs
View File

@@ -7,22 +7,21 @@ pub struct CPUDisassembler {
}
impl CPUDisassembler {
// TODO FIXME: please do not mutate the emulator state to fetch upcoming instructions
pub fn get_next_instruction(emulator: &mut Emulator) -> String {
let opcode = emulator.bus.read(emulator.cpu.registers.get_pc_address());
pub fn get_next_instruction(emulator: &Emulator) -> String {
let opcode = emulator.bus.read_external(emulator.cpu.registers.get_pc_address());
let is_cpu_16bit = emulator.cpu.registers.is_16bit_mode();
let is_index_16bit = emulator.cpu.registers.is_16bit_index();
let next_byte = emulator.bus.read(emulator.cpu.registers.get_pc_address() + 1);
let next_second_byte = emulator.bus.read(emulator.cpu.registers.get_pc_address() + 2);
let next_third_byte = emulator.bus.read(emulator.cpu.registers.get_pc_address() + 3);
let next_byte = emulator.bus.read_external(emulator.cpu.registers.get_pc_address() + 1);
let next_second_byte = emulator.bus.read_external(emulator.cpu.registers.get_pc_address() + 2);
let next_third_byte = emulator.bus.read_external(emulator.cpu.registers.get_pc_address() + 3);
let next_word = {
(emulator.bus.read(emulator.cpu.registers.get_pc_address() + 1) as u16) |
((emulator.bus.read(emulator.cpu.registers.get_pc_address() + 2) as u16) << 8)
(emulator.bus.read_external(emulator.cpu.registers.get_pc_address() + 1) as u16) |
((emulator.bus.read_external(emulator.cpu.registers.get_pc_address() + 2) as u16) << 8)
};
let next_word_long = {
(emulator.bus.read(emulator.cpu.registers.get_pc_address() + 1) as u32) |
((emulator.bus.read(emulator.cpu.registers.get_pc_address() + 2) as u32) << 8) |
((emulator.bus.read(emulator.cpu.registers.get_pc_address() + 3) as u32) << 16)
(emulator.bus.read_external(emulator.cpu.registers.get_pc_address() + 1) as u32) |
((emulator.bus.read_external(emulator.cpu.registers.get_pc_address() + 2) as u32) << 8) |
((emulator.bus.read_external(emulator.cpu.registers.get_pc_address() + 3) as u32) << 16)
};
match opcode {
// ADC

2
snes-frontend/src/main.rs
View File

@@ -404,7 +404,7 @@ fn main() {
let mut address_row = format!("{:04X} | ", address);
for page in (page_start..=page_end).rev() {
let bus_address = ((page as u32) << 16) | (address as u32);
address_row = format!("{}{:02X} ", address_row, emulator.bus.read(bus_address));
address_row = format!("{}{:02X} ", address_row, emulator.bus.read_external(bus_address));
}
ui.text(address_row);
}