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experimental cgram lookup

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This commit is contained in:
Franco Colmenarez
2024-11-04 18:43:45 -05:00
parent a61bf8e01a
commit c0d94b01d3
1 changed files with 11 additions and 9 deletions
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snes-core/src/ppu/interface.rs
+11 -9
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@@ -1,4 +1,5 @@
use super::registers::{PPURegisters, Background, MAX_TV_HEIGHT, MAX_TV_WIDTH}; use super::registers::{PPURegisters, Background, MAX_TV_HEIGHT, MAX_TV_WIDTH};
use crate::utils::color::rgb555_to_rgb888;
const FRAMEBUFFER_SIZE: usize = MAX_TV_HEIGHT * MAX_TV_WIDTH * 4; const FRAMEBUFFER_SIZE: usize = MAX_TV_HEIGHT * MAX_TV_WIDTH * 4;
@@ -98,7 +99,7 @@ impl PPU {
let (tile_size_width, tile_size_height) = self.registers.get_bg_tile_size(background).to_usize(); let (tile_size_width, tile_size_height) = self.registers.get_bg_tile_size(background).to_usize();
let vram = self.registers.vram(); let vram = self.registers.vram();
let x = (self.registers.h_count as usize) - 22; // H count ranges from 0 to 339. Pixels become visible at 22. let x = (self.registers.h_count as usize) - 22; // H count ranges from 0 to 339. Pixels become visible at 22.
let y = (self.registers.v_count as usize) - 1; // V count ranges from 0 to 261 (depending on the region). Pixels become visible at 1. let y = (self.registers.v_count as usize) - 1; // V count ranges from 0 to 261 (depending on the region and video mode). Pixels become visible at 1.
let current_tile = (x / tile_size_width) + ((y / tile_size_height) * bg_size_width); let current_tile = (x / tile_size_width) + ((y / tile_size_height) * bg_size_width);
let tile_byte = vram[tileset_vram_base_address + current_tile]; let tile_byte = vram[tileset_vram_base_address + current_tile];
@@ -116,15 +117,16 @@ impl PPU {
let msb_bitplane= (vram_word >> 8) as u8; let msb_bitplane= (vram_word >> 8) as u8;
let pixels = Self::mix_pixel_bitplanes(lsb_bitplane, msb_bitplane); let pixels = Self::mix_pixel_bitplanes(lsb_bitplane, msb_bitplane);
let effective_pixel = pixels[current_char_column]; let effective_pixel_index = pixels[current_char_column];
return match effective_pixel { // TODO: this cgram lookup is experimental, it will eventually be replaced by actual cgram lookup
0b00 => (0xFF, 0xFF, 0xFF), let base_cgram_address: u8 = 0x00;
0b01 => (0xAC, 0xAC, 0xAC), let rgb555_pixel = self.registers.read_cgram(base_cgram_address.wrapping_add(effective_pixel_index));
0b10 => (0x56, 0x56, 0x56), rgb555_to_rgb888((
0b11 => (0x00, 0x00, 0x00), (rgb555_pixel & 0b11111) as u8,
_ => unreachable!(), ((rgb555_pixel >> 5) & 0b11111) as u8,
} ((rgb555_pixel >> 10) & 0b11111) as u8,
))
} }
fn mix_pixel_bitplanes(lsb_bitplane: u8, msb_bitplane: u8) -> [u8; 8] { fn mix_pixel_bitplanes(lsb_bitplane: u8, msb_bitplane: u8) -> [u8; 8] {