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Enabling lcd and vblank flag registers

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This commit is contained in:
Franco Colmenarez 2021-10-28 22:13:23 -05:00
parent c401726da5
commit f90900a4c1
2 changed files with 65 additions and 70 deletions
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32
src/bus.rs
View File

@ -1,5 +1,12 @@
use crate::utils::{join_bytes};
use crate::utils::{
get_bit,
set_bit,
BitIndex,
join_bytes
};
use crate::rom::ROM;
use crate::ppu::{PPU, LCDStatus, LCDStatusModeFlag};
use crate::cpu::{InterruptFlag};
pub struct AddressRange {
begin: u16,
@ -32,6 +39,7 @@ pub const NOT_USABLE: AddressRange = AddressRange{begin: 0xFEA0,
pub const IO_REGISTERS: AddressRange = AddressRange{begin: 0xFF00, end: 0xFF7F};
pub const HIGH_RAM: AddressRange = AddressRange{begin: 0xFF80, end: 0xFFFE};
pub const INTERRUPT_ENABLE_REGISTER: AddressRange = AddressRange{begin: 0xFFFF, end: 0xFFFF};
pub const INTERRUPT_FLAG_ADDRESS: u16 = 0xFF0F;
pub struct Bus {
game_rom: ROM,
@ -65,6 +73,10 @@ impl Bus {
pub fn read(&self, address: u16) -> u8 {
if BANK_ZERO.in_range(address) || BANK_SWITCHABLE.in_range(address) {
return self.game_rom.read(address);
} else if VIDEO_RAM.in_range(address) {
if PPU::get_lcd_status(self, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD)) {
return 0xFF
}
} else if IO_REGISTERS.in_range(address) {
return self.data[address as usize];
}
@ -91,8 +103,13 @@ impl Bus {
} else if ECHO_RAM.in_range(address) {
self.data[address as usize] = data;
self.data[(WORK_RAM_1.begin() + (address - ECHO_RAM.begin())) as usize] = data; // Copy to the working RAM
}
} else if VIDEO_RAM.in_range(address) {
//if !PPU::get_lcd_status(self, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD)) {
self.data[address as usize] = data;
// }
} else {
self.data[address as usize] = data;
}
}
pub fn write_16bit(&mut self, address: u16, data: u16) {
@ -100,4 +117,15 @@ impl Bus {
self.write(address, bytes[0]);
self.write(address.wrapping_add(1), bytes[1]);
}
pub fn set_flag(&mut self, flag: InterruptFlag, val: bool) {
let byte = self.read(INTERRUPT_FLAG_ADDRESS);
self.write(INTERRUPT_FLAG_ADDRESS, match flag {
InterruptFlag::VBlank => set_bit(byte, val, BitIndex::I0),
InterruptFlag::LCDSTAT => set_bit(byte, val, BitIndex::I1),
InterruptFlag::Timer => set_bit(byte, val, BitIndex::I2),
InterruptFlag::Serial => set_bit(byte, val, BitIndex::I3),
InterruptFlag::Joypad => set_bit(byte, val, BitIndex::I4),
});
}
}

67
src/ppu.rs
View File

@ -5,7 +5,7 @@ use crate::utils::{
to_bit_index,
};
use crate::bus::{Bus, AddressRange, BANK_ZERO, VIDEO_RAM};
use crate::cpu::{Cycles};
use crate::cpu::{Cycles, InterruptFlag};
#[derive(Debug, Copy, Clone)]
enum Pixel {
@ -90,28 +90,37 @@ impl PPU {
pub fn do_cycle(&mut self, bus: &mut Bus) {
// Mode 1 Vertical blank
if PPU::get_lcd_y(bus) >= 144 {
if PPU::get_lcd_y(bus) == 144 {
bus.set_flag(InterruptFlag::VBlank, true);
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::VBlank), true);
}
} else {
if self.cycles.0 <= 80 {
if self.cycles.0 == 0 {
// Mode 2 OAM scan
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::SearchingOAM), true);
} else if self.cycles.0 <= 80 + 172 {
} else if self.cycles.0 == 80 + 1 {
// Mode 3 drawing pixel line. This could also last 289 cycles
if !PPU::get_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD)) {
bus.set_flag(InterruptFlag::LCDSTAT, true);
self.draw_line(bus);
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::TransferringToLCD), true);
}
} else if self.cycles.0 <= 80 + 172 + 204 {
} else if self.cycles.0 == 80 + 172 + 1 {
// Mode 0 Horizontal blank. This could last 87 or 204 cycles depending on the mode 3
bus.set_flag(InterruptFlag::LCDSTAT, true);
PPU::set_lcd_status(bus, LCDStatus::ModeFlag(LCDStatusModeFlag::HBlank), true);
}
}
let lyc_compare = PPU::get_lcd_y(bus) == bus.read(LCD_Y_COMPARE_ADDRESS);
PPU::set_lcd_status(bus, LCDStatus::LYCInterrupt, lyc_compare);
if lyc_compare {
bus.set_flag(InterruptFlag::LCDSTAT, true);
}
self.increment_cycles(Cycles(1));
// Horizontal scan completed
if self.cycles.0 > 456 {
self.reset_cycles();
PPU::set_lcd_y(bus, PPU::get_lcd_y(bus) + 1);
// Frame completed
@ -145,7 +154,7 @@ impl PPU {
bus.write(SCROLL_Y_ADDRESS, val);
}
fn get_lcd_control(bus: &Bus, control: LCDControl) -> bool {
pub fn get_lcd_control(bus: &Bus, control: LCDControl) -> bool {
let byte = bus.read(LCD_CONTROL_ADDRESS);
match control {
LCDControl::DisplayEnable => get_bit(byte, BitIndex::I7),
@ -174,7 +183,7 @@ impl PPU {
bus.write(LCD_CONTROL_ADDRESS, byte);
}
fn get_lcd_status(bus: &Bus, status: LCDStatus) -> bool {
pub fn get_lcd_status(bus: &Bus, status: LCDStatus) -> bool {
let byte = bus.read(LCD_STATUS_ADDRESS);
match status {
LCDStatus::LYCInterrupt => get_bit(byte, BitIndex::I6),
@ -238,48 +247,6 @@ impl PPU {
}
}
pub fn draw_background(&mut self, bus: &mut Bus) {
let mut lcd_y: u8 = 0;
PPU::set_lcd_y(bus, lcd_y);
while lcd_y < 144 {
self.draw_line(bus);
lcd_y += 1;
PPU::set_lcd_y(bus, lcd_y);
}
}
/* pub fn draw_background_old(&mut self, bus: &Bus) {
let mut idx = 0;
// let mut tile_line: u16 = 0;
let mut lcd_y: u8 = 0;
while lcd_y < 144 {
let mut lcd_x: u8 = 0;
while lcd_x < 160 {
let y = lcd_y.wrapping_add(PPU::get_scroll_y(bus));
let x = lcd_x.wrapping_add(PPU::get_scroll_x(bus));
let index_x = (x as u16 / 8);
let index_y = (y as u16 / 8) * 32;
let index = index_x + index_y;
let tile_line = (y).rem_euclid(8) * 2;
let index_byte = (bus.read(0x9800 + index as u16) as u16) * 16;
let tile_byte_1 = bus.read(0x8000 + tile_line as u16 + index_byte);
let tile_byte_2 = bus.read(0x8000 + tile_line as u16 + index_byte + 1);
let pixels = PPU::get_byte_pixels(tile_byte_1, tile_byte_2);
for pixel in pixels {
self.rgba_frame[idx] = PPU::get_rgba(pixel);
idx += 1;
}
lcd_x += 8;
}
lcd_y += 1;
// tile_line += 2;
}
} */
fn get_pixel(two_bit_pixel: u8) -> Pixel {
match two_bit_pixel {
0x00 => Pixel::White,