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Reimplement BCPS/OCPS & CC
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@IsaacMarovitz
IsaacMarovitz committed May 2, 2024
1 parent 79b210a commit 5df2abc
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Showing 3 changed files with 83 additions and 72 deletions.
49 changes: 49 additions & 0 deletions src/components/ppu/cc.rs
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Original file line number Diff line number Diff line change
@@ -0,0 +1,49 @@
const GB_COLOR_LUT_LEN: usize = 0x8000;
const GAMMA: f32 = 2.2;
const CGB_COLOR_CURVE: [u8; 32] = [ 0, 6, 12, 20, 28, 36, 45, 56, 66, 76, 88, 100, 113, 125, 137, 149, 161, 172, 182, 192, 202, 210, 218, 225, 232, 238, 243, 247, 250, 252, 254, 255 ];

// Adapted from SameBoy Color Correction
pub struct ColorCorrection {
pub true_color_lut: [[u8; 3]; GB_COLOR_LUT_LEN],
pub cgb_color_lut: [[u8; 3]; GB_COLOR_LUT_LEN]
}

impl ColorCorrection {
pub fn new() -> Self {
let mut true_color_lut = [[0; 3]; GB_COLOR_LUT_LEN];
let mut cgb_color_lut = [[0; 3]; GB_COLOR_LUT_LEN];

for i in 0..GB_COLOR_LUT_LEN {
let r = (i & 0x1F) as u8;
let g = ((i >> 5) & 0x1F) as u8;
let b = ((i >> 10) & 0x1F) as u8;

true_color_lut[i] = Self::to_true_color(r, g, b);
cgb_color_lut[i] = Self::to_cgb_color(r, g, b);
}

Self {
true_color_lut,
cgb_color_lut
}
}

fn to_true_color(r: u8, g: u8, b: u8) -> [u8; 3] {
let r = (r * 0xFF + 0xF) / 0x1F;
let g = (g * 0xFF + 0xF) / 0x1F;
let b = (b * 0xFF + 0xF) / 0x1F;
[r, g, b]
}

fn to_cgb_color(r: u8, g: u8, b: u8) -> [u8; 3] {
let r = CGB_COLOR_CURVE[r as usize];
let mut g = CGB_COLOR_CURVE[g as usize];
let b = CGB_COLOR_CURVE[b as usize];

if g != b {
g = (((g as f32 / 255.0).powf(GAMMA) * 3.0 + (b as f32 / 255.0).powf(GAMMA) / 4.0).powf(1.0 / GAMMA) * 255.0).round() as u8;
}

[r, g, b]
}
}
3 changes: 2 additions & 1 deletion src/components/ppu/mod.rs
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Original file line number Diff line number Diff line change
@@ -1 +1,2 @@
pub mod ppu;
pub mod ppu;
mod cc;
103 changes: 32 additions & 71 deletions src/components/ppu/ppu.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@ use crate::components::prelude::*;
use crate::config::{Color, Config, Palette};
use crate::Framebuffer;
use bitflags::bitflags;
use crate::components::ppu::cc::ColorCorrection;

/// RGBA (4 bytes) per pixel
pub const FRAMEBUFFER_SIZE: usize = 4 * SCREEN_W * SCREEN_H;
Expand All @@ -11,6 +12,7 @@ pub const SCREEN_H: usize = 144;
pub struct PPU {
mode: GBMode,
palette: Palette,
cc: ColorCorrection,
ppu_mode: PPUMode,
cycle_count: u32,
vblanked_lines: u32,
Expand All @@ -27,9 +29,9 @@ pub struct PPU {
lcdc: LCDC,
lcds: LCDS,
bcps: BGPI,
bcpd: [[[u8; 3]; 4]; 8],
bcpd: [u8; 64],
ocps: BGPI,
ocpd: [[[u8; 3]; 4]; 8],
ocpd: [u8; 64],
vram: [u8; 0x4000],
vram_bank: usize,
oam: [u8; 0xA0],
Expand Down Expand Up @@ -105,14 +107,14 @@ bitflags! {
}

struct BGPI {
i: u8,
address: u8,
auto_increment: bool
}

impl BGPI {
fn new() -> Self {
Self {
i: 0,
address: 0,
auto_increment: false
}
}
Expand All @@ -123,19 +125,20 @@ impl BGPI {
} else {
0x00
};
a | self.i
a | self.address
}

fn write(&mut self, v: u8) {
self.auto_increment = v & 0x80 != 0x00;
self.i = v & 0x3F;
self.address = v & 0x3F;
}
}

impl PPU {
pub fn new(config: Config, framebuffer: Framebuffer) -> Self {
Self {
mode: config.mode,
cc: ColorCorrection::new(),
palette: config.palette,
ppu_mode: PPUMode::OAMScan,
cycle_count: 0,
Expand All @@ -153,9 +156,9 @@ impl PPU {
lcdc: LCDC::empty(),
lcds: LCDS::empty(),
bcps: BGPI::new(),
bcpd: [[[0; 3]; 4]; 8],
bcpd: [0; 64],
ocps: BGPI::new(),
ocpd: [[[0; 3]; 4]; 8],
ocpd: [0; 64],
vram: [0; 0x4000],
vram_bank: 0,
oam: [0; 0xA0],
Expand Down Expand Up @@ -285,16 +288,10 @@ impl PPU {
}
}

fn set_rgb_mapped(&mut self, x: usize, r: u8, g: u8, b: u8) {
let r_init = r as u32;
let g_init = g as u32;
let b_init = b as u32;
fn set_rgb_mapped(&mut self, x: usize, color: u16) {
let color = self.cc.cgb_color_lut[color as usize];

let r = ((r_init * 13 + g_init * 2 + b_init) >> 1) as u8;
let g = ((g_init * 3 + b_init) << 1) as u8;
let b = ((r_init * 3 + g_init * 2 + b_init * 11) >> 1) as u8;

self.set_rgb(x, r, g, b);
self.set_rgb(x, color[0], color[1], color[2]);
}

fn set_rgb(&mut self, x: usize, r: u8, g: u8, b: u8) {
Expand Down Expand Up @@ -403,11 +400,11 @@ impl PPU {

if self.mode == GBMode::CGB {
let palette_no_1 = (tile_attributes.bits() & 0b0000_0111) as usize;
let r = self.bcpd[palette_no_1][color][0];
let g = self.bcpd[palette_no_1][color][1];
let b = self.bcpd[palette_no_1][color][2];
let palette_address = palette_no_1 * 8 + color * 2;

let color: u16 = (self.bcpd[palette_address] as u16) | ((self.bcpd[palette_address + 1] as u16) << 8) & 0x7FFF;

self.set_rgb_mapped(x, r, g, b);
self.set_rgb_mapped(x, color);
} else {
let color = if !self.lcdc.contains(LCDC::WINDOW_PRIORITY) {
Self::grey_to_l(self.palette.clone(), self.bgp, 0)
Expand Down Expand Up @@ -512,11 +509,11 @@ impl PPU {

if self.mode == GBMode::CGB {
let palette_no_1 = (tile_attributes.bits() & 0b0000_0111) as usize;
let r = self.ocpd[palette_no_1][color][0];
let g = self.ocpd[palette_no_1][color][1];
let b = self.ocpd[palette_no_1][color][2];
let palette_address = palette_no_1 * 8 + color * 2;

self.set_rgb_mapped(px.wrapping_add(x) as usize, r, g, b);
let color: u16 = (self.ocpd[palette_address] as u16) | ((self.ocpd[palette_address + 1] as u16) << 8) & 0x7FFF;

self.set_rgb_mapped(px.wrapping_add(x) as usize, color);
} else {
let color = if tile_attributes.contains(Attributes::PALETTE_NO_0) {
Self::grey_to_l(self.palette.clone(), self.op1, color)
Expand Down Expand Up @@ -572,33 +569,9 @@ impl Memory for PPU {
// TODO: DMA
0xFF51..=0xFF55 => 0x00,
0xFF68 => self.bcps.read(),
0xFF69 => {
let r = self.bcps.i as usize >> 3;
let c = self.bcps.i as usize >> 1 & 0x03;
if self.bcps.i & 0x01 == 0x00 {
let a = self.bcpd[r][c][0] >> 0;
let b = self.bcpd[r][c][1] << 5;
a | b
} else {
let a = self.bcpd[r][c][1] >> 3;
let b = self.bcpd[r][c][2] << 2;
a | b
}
}
0xFF69 => self.bcpd[self.bcps.address as usize],
0xFF6A => self.ocps.read(),
0xFF6B => {
let r = self.ocps.i as usize >> 3;
let c = self.ocps.i as usize >> 1 & 0x03;
if self.ocps.i & 0x01 == 0x00 {
let a = self.ocpd[r][c][0] >> 0;
let b = self.ocpd[r][c][1] << 5;
a | b
} else {
let a = self.ocpd[r][c][1] >> 3;
let b = self.ocpd[r][c][2] << 2;
a | b
}
}
0xFF6B => self.ocpd[self.ocps.address as usize],
0xFF6C => self.opri as u8,
_ => panic!("Read to unsupported PPU address ({:#06x})!", a),
}
Expand Down Expand Up @@ -651,36 +624,24 @@ impl Memory for PPU {
0xFF51..=0xFF55 => {}
0xFF68 => self.bcps.write(v),
0xFF69 => {
let r = self.bcps.i as usize >> 3;
let c = self.bcps.i as usize >> 1 & 0x03;
if self.bcps.i & 0x01 == 0x00 {
self.bcpd[r][c][0] = v & 0x1F;
self.bcpd[r][c][1] = (self.bcpd[r][c][1] & 0x18) | (v >> 5);
} else {
self.bcpd[r][c][1] = (self.bcpd[r][c][1] & 0x07) | ((v & 0x03) << 3);
self.bcpd[r][c][2] = (v >> 2) & 0x1F;
if self.ppu_mode != PPUMode::Draw {
self.bcpd[self.bcps.address as usize] = v;
}

if self.bcps.auto_increment {
self.bcps.i += 1;
self.bcps.i &= 0x3F;
self.bcps.address += 1;
self.bcps.address &= 0x3F;
}
}
0xFF6A => self.ocps.write(v),
0xFF6B => {
let r = self.ocps.i as usize >> 3;
let c = self.ocps.i as usize >> 1 & 0x03;
if self.ocps.i & 0x01 == 0x00 {
self.ocpd[r][c][0] = v & 0x1F;
self.ocpd[r][c][1] = (self.ocpd[r][c][1] & 0x18) | (v >> 5);
} else {
self.ocpd[r][c][1] = (self.ocpd[r][c][1] & 0x07) | ((v & 0x03) << 3);
self.ocpd[r][c][2] = (v >> 2) & 0x1F;
if self.ppu_mode != PPUMode::Draw {
self.ocpd[self.ocps.address as usize] = v;
}

if self.ocps.auto_increment {
self.ocps.i += 1;
self.ocps.i &= 0x3F;
self.ocps.address += 1;
self.ocps.address &= 0x3F;
}
}
// TODO: Object Priority Mode
Expand Down

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