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chore(ppu): remove BGR555 -> RGBA888 LUT 

LUT probably couldn't fit in CPU cache anyways.

TODO: Consider whether LUTs for separate channels (size 32 * 3 * 3
instead of std.math.maxInt(u15))
This commit is contained in:
Rekai Nyangadzayi Musuka 2022-10-09 15:59:57 -03:00
parent 3a3e6acc6a
commit e60b556f72
1 changed files with 7 additions and 43 deletions
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50
src/core/ppu.zig
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@ -12,9 +12,6 @@ const Allocator = std.mem.Allocator;
const log = std.log.scoped(.PPU);
const pollDmaOnBlank = @import("bus/dma.zig").pollDmaOnBlank;
/// This is used to generate byuu / Talurabi's Color Correction algorithm
const COLOUR_LUT = genColourLut();
pub const width = 240;
pub const height = 160;
pub const framebuf_pitch = width * @sizeOf(u32);
@ -392,7 +389,7 @@ pub const Ppu = struct {
const maybe_btm = self.scanline.btm()[i];
const bgr555 = self.getBgr555(maybe_top, maybe_btm);
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], COLOUR_LUT[bgr555 & 0x7FFF]);
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], rgba888(bgr555));
}
// Reset Current Scanline Pixel Buffer and list of fetched sprites
@ -419,7 +416,7 @@ pub const Ppu = struct {
const maybe_btm = self.scanline.btm()[i];
const bgr555 = self.getBgr555(maybe_top, maybe_btm);
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], COLOUR_LUT[bgr555 & 0x7FFF]);
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], rgba888(bgr555));
}
// Reset Current Scanline Pixel Buffer and list of fetched sprites
@ -445,7 +442,7 @@ pub const Ppu = struct {
const maybe_btm = self.scanline.btm()[i];
const bgr555 = self.getBgr555(maybe_top, maybe_btm);
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], COLOUR_LUT[bgr555 & 0x7FFF]);
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], rgba888(bgr555));
}
// Reset Current Scanline Pixel Buffer and list of fetched sprites
@ -460,7 +457,7 @@ pub const Ppu = struct {
var i: usize = 0;
while (i < width) : (i += 1) {
const bgr555 = self.vram.read(u16, vram_base + i * @sizeOf(u16));
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], COLOUR_LUT[bgr555 & 0x7FFF]);
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], rgba888(bgr555));
}
},
0x4 => {
@ -471,7 +468,7 @@ pub const Ppu = struct {
// Render Current Scanline
for (self.vram.buf[vram_base .. vram_base + width]) |byte, i| {
const bgr555 = self.palette.read(u16, @as(u16, byte) * @sizeOf(u16));
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], COLOUR_LUT[bgr555 & 0x7FFF]);
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], rgba888(bgr555));
}
},
0x5 => {
@ -488,7 +485,7 @@ pub const Ppu = struct {
const bgr555 =
if (scanline < m5_height and i < m5_width) self.vram.read(u16, vram_base + i * @sizeOf(u16)) else self.palette.getBackdrop();
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], COLOUR_LUT[bgr555 & 0x7FFF]);
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], rgba888(bgr555));
}
},
else => std.debug.panic("[PPU] TODO: Implement BG Mode {}", .{bg_mode}),
@ -1063,7 +1060,7 @@ fn spriteDimensions(shape: u2, size: u2) [2]u8 {
};
}
fn toRgba8888(bgr555: u16) u32 {
inline fn rgba888(bgr555: u16) u32 {
const b = @as(u32, bgr555 >> 10 & 0x1F);
const g = @as(u32, bgr555 >> 5 & 0x1F);
const r = @as(u32, bgr555 & 0x1F);
@ -1071,39 +1068,6 @@ fn toRgba8888(bgr555: u16) u32 {
return (r << 3 | r >> 2) << 24 | (g << 3 | g >> 2) << 16 | (b << 3 | b >> 2) << 8 | 0xFF;
}
fn genColourLut() [0x8000]u32 {
return comptime {
@setEvalBranchQuota(0x10001);
var lut: [0x8000]u32 = undefined;
for (lut) |*px, i| px.* = toRgba8888(i);
return lut;
};
}
// FIXME: The implementation is incorrect and using it in the LUT crashes the compiler (OOM)
/// Implementation courtesy of byuu and Talarubi at https://near.sh/articles/video/color-emulation
fn toRgba8888Talarubi(bgr555: u16) u32 {
@setRuntimeSafety(false);
const lcd_gamma: f64 = 4;
const out_gamma: f64 = 2.2;
const b = @as(u32, bgr555 >> 10 & 0x1F);
const g = @as(u32, bgr555 >> 5 & 0x1F);
const r = @as(u32, bgr555 & 0x1F);
const lb = std.math.pow(f64, @intToFloat(f64, b << 3 | b >> 2) / 31, lcd_gamma);
const lg = std.math.pow(f64, @intToFloat(f64, g << 3 | g >> 2) / 31, lcd_gamma);
const lr = std.math.pow(f64, @intToFloat(f64, r << 3 | r >> 2) / 31, lcd_gamma);
const out_b = std.math.pow(f64, (220 * lb + 10 * lg + 50 * lr) / 255, 1 / out_gamma);
const out_g = std.math.pow(f64, (30 * lb + 230 * lg + 10 * lr) / 255, 1 / out_gamma);
const out_r = std.math.pow(f64, (0 * lb + 50 * lg + 255 * lr) / 255, 1 / out_gamma);
return @floatToInt(u32, out_r) << 24 | @floatToInt(u32, out_g) << 16 | @floatToInt(u32, out_b) << 8 | 0xFF;
}
fn alphaBlend(top: u16, btm: u16, bldalpha: io.BldAlpha) u16 {
const eva: u16 = bldalpha.eva.read();
const evb: u16 = bldalpha.evb.read();