paoda
/
zba
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity
zba/src/ppu.zig

1031 lines
36 KiB
Zig
Raw Blame History

const std = @import("std");
const io = @import("bus/io.zig");
const EventKind = @import("scheduler.zig").EventKind;
const Scheduler = @import("scheduler.zig").Scheduler;
const Arm7tdmi = @import("cpu.zig").Arm7tdmi;
const Bit = @import("bitfield").Bit;
const Bitfield = @import("bitfield").Bitfield;
const Allocator = std.mem.Allocator;
const log = std.log.scoped(.PPU);
const pollBlankingDma = @import("bus/dma.zig").pollBlankingDma;
/// 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);
pub const Ppu = struct {
const Self = @This();
// Registers
bg: [4]Background,
aff_bg: [2]AffineBackground,
dispcnt: io.DisplayControl,
dispstat: io.DisplayStatus,
vcount: io.VCount,
vram: Vram,
palette: Palette,
oam: Oam,
sched: *Scheduler,
framebuf: FrameBuffer,
alloc: Allocator,
scanline_sprites: [128]?Sprite,
scanline_buf: [width]?u16,
pub fn init(alloc: Allocator, sched: *Scheduler) !Self {
// Queue first Hblank
sched.push(.Draw, 240 * 4);
const framebufs = try alloc.alloc(u8, (framebuf_pitch * height) * 2);
std.mem.set(u8, framebufs, 0);
return Self{
.vram = try Vram.init(alloc),
.palette = try Palette.init(alloc),
.oam = try Oam.init(alloc),
.sched = sched,
.framebuf = FrameBuffer.init(framebufs),
.alloc = alloc,
// Registers
.bg = [_]Background{Background.init()} ** 4,
.aff_bg = [_]AffineBackground{AffineBackground.init()} ** 2,
.dispcnt = .{ .raw = 0x0000 },
.dispstat = .{ .raw = 0x0000 },
.vcount = .{ .raw = 0x0000 },
.scanline_buf = [_]?u16{null} ** width,
.scanline_sprites = [_]?Sprite{null} ** 128,
};
}
pub fn deinit(self: Self) void {
self.framebuf.deinit(self.alloc);
self.vram.deinit();
self.palette.deinit();
self.oam.deinit();
}
pub fn setBgOffsets(self: *Self, comptime n: u3, word: u32) void {
self.bg[n].hofs.raw = @truncate(u16, word);
self.bg[n].vofs.raw = @truncate(u16, word >> 16);
}
pub fn setAdjCnts(self: *Self, comptime n: u3, word: u32) void {
self.bg[n].cnt.raw = @truncate(u16, word);
self.bg[n + 1].cnt.raw = @truncate(u16, word >> 16);
}
/// Search OAM for Sprites that might be rendered on this scanline
fn fetchSprites(self: *Self) void {
const y = self.vcount.scanline.read();
var i: usize = 0;
search: while (i < self.oam.buf.len) : (i += 8) {
// Attributes in OAM are 6 bytes long, with 2 bytes of padding
// Grab Attributes from OAM
const attr0 = @bitCast(Attr0, self.oam.read(u16, i));
// Only consider enabled Sprites
if (attr0.is_affine.read() or !attr0.disabled.read()) {
const attr1 = @bitCast(Attr1, self.oam.read(u16, i + 2));
// When fetching sprites we only care about ones that could be rendered
// on this scanline
const iy = @bitCast(i8, y);
const start = attr0.y.read();
const istart = @bitCast(i8, start);
const end = start +% spriteDimensions(attr0.shape.read(), attr1.size.read())[1];
const iend = @bitCast(i8, end);
// Sprites are expected to be able to wraparound, we perform the same check
// for unsigned and signed values so that we handle all valid sprite positions
if ((start <= y and y < end) or (istart <= iy and iy < iend)) {
for (self.scanline_sprites) |*maybe_sprite| {
if (maybe_sprite.* == null) {
maybe_sprite.* = Sprite.init(attr0, attr1, @bitCast(Attr2, self.oam.read(u16, i + 4)));
continue :search;
}
}
log.err("Found more than 128 sprites in OAM Search", .{});
unreachable; // TODO: Is this truly unreachable?
}
}
}
}
fn drawSprites(self: *Self, layer: u2) void {
// Loop over every fetched sprite
for (self.scanline_sprites) |maybe_sprite| {
if (maybe_sprite) |sprite| {
// Skip this sprite if it isn't on the current priority
if (sprite.priority() != layer) continue;
if (sprite.attr0.is_affine.read()) self.drawAffineSprite(AffineSprite.from(sprite)) else self.drawSprite(sprite);
} else break;
}
}
fn drawAffineSprite(self: *Self, sprite: AffineSprite) void {
const iy = @bitCast(i8, self.vcount.scanline.read());
const is_8bpp = sprite.is8bpp();
const tile_id: u32 = sprite.tileId();
const obj_mapping = self.dispcnt.obj_mapping.read();
const tile_row_offset: u32 = if (is_8bpp) 8 else 4;
const tile_len: u32 = if (is_8bpp) 0x40 else 0x20;
const char_base = 0x4000 * 4;
var i: u9 = 0;
while (i < sprite.width) : (i += 1) {
const x = (sprite.x() +% i) % width;
const ix = @bitCast(i9, x);
if (self.scanline_buf[x] != null) continue;
const sprite_start = sprite.x();
const isprite_start = @bitCast(i9, sprite_start);
const sprite_end = sprite_start +% sprite.width;
const isprite_end = @bitCast(i9, sprite_end);
const condition = (sprite_start <= x and x < sprite_end) or (isprite_start <= ix and ix < isprite_end);
if (!condition) continue;
// Sprite is within bounds and therefore should be rendered
// std.math.absInt is branchless
const tile_x = @bitCast(u9, std.math.absInt(ix - @bitCast(i9, sprite.x())) catch unreachable);
const tile_y = @bitCast(u8, std.math.absInt(iy -% @bitCast(i8, sprite.y())) catch unreachable);
const row = @truncate(u3, tile_y);
const col = @truncate(u3, tile_x);
// TODO: Finish that 2D Sprites Test ROM
const tile_base = char_base + (tile_id * 0x20) + (row * tile_row_offset) + if (is_8bpp) col else col >> 1;
const mapping_offset = if (obj_mapping) sprite.width >> 3 else if (is_8bpp) @as(u32, 0x10) else 0x20;
const tile_offset = (tile_x >> 3) * tile_len + (tile_y >> 3) * tile_len * mapping_offset;
const tile = self.vram.buf[tile_base + tile_offset];
const pal_id: u16 = if (!is_8bpp) get4bppTilePalette(sprite.palBank(), col, tile) else tile;
// Sprite Palette starts at 0x0500_0200
if (pal_id != 0) self.scanline_buf[x] = self.palette.read(u16, 0x200 + pal_id * 2);
}
}
fn drawSprite(self: *Self, sprite: Sprite) void {
const iy = @bitCast(i8, self.vcount.scanline.read());
const is_8bpp = sprite.is8bpp();
const tile_id: u32 = sprite.tileId();
const obj_mapping = self.dispcnt.obj_mapping.read();
const tile_row_offset: u32 = if (is_8bpp) 8 else 4;
const tile_len: u32 = if (is_8bpp) 0x40 else 0x20;
const char_base = 0x4000 * 4;
var i: u9 = 0;
while (i < sprite.width) : (i += 1) {
const x = (sprite.x() +% i) % width;
const ix = @bitCast(i9, x);
if (self.scanline_buf[x] != null) continue;
const sprite_start = sprite.x();
const isprite_start = @bitCast(i9, sprite_start);
const sprite_end = sprite_start +% sprite.width;
const isprite_end = @bitCast(i9, sprite_end);
const condition = (sprite_start <= x and x < sprite_end) or (isprite_start <= ix and ix < isprite_end);
if (!condition) continue;
// Sprite is within bounds and therefore should be rendered
// std.math.absInt is branchless
const x_diff = @bitCast(u9, std.math.absInt(ix - @bitCast(i9, sprite.x())) catch unreachable);
const y_diff = @bitCast(u8, std.math.absInt(iy -% @bitCast(i8, sprite.y())) catch unreachable);
// Note that we flip the tile_pos not the (tile_pos % 8) like we do for
// Background Tiles. By doing this we mirror the entire sprite instead of
// just a specific tile (see how sprite.width and sprite.height are involved)
const tile_y = y_diff ^ if (sprite.vFlip()) (sprite.height - 1) else 0;
const tile_x = x_diff ^ if (sprite.hFlip()) (sprite.width - 1) else 0;
const row = @truncate(u3, tile_y);
const col = @truncate(u3, tile_x);
// TODO: Finish that 2D Sprites Test ROM
const tile_base = char_base + (tile_id * 0x20) + (row * tile_row_offset) + if (is_8bpp) col else col >> 1;
const mapping_offset = if (obj_mapping) sprite.width >> 3 else if (is_8bpp) @as(u32, 0x10) else 0x20;
const tile_offset = (tile_x >> 3) * tile_len + (tile_y >> 3) * tile_len * mapping_offset;
const tile = self.vram.buf[tile_base + tile_offset];
const pal_id: u16 = if (!is_8bpp) get4bppTilePalette(sprite.palBank(), col, tile) else tile;
// Sprite Palette starts at 0x0500_0200
if (pal_id != 0) self.scanline_buf[x] = self.palette.read(u16, 0x200 + pal_id * 2);
}
}
fn drawAffineBackground(self: *Self, comptime n: u3) void {
comptime std.debug.assert(n == 2 or n == 3); // Only BG2 and BG3 can be affine
const char_base = @as(u32, 0x4000) * self.bg[n].cnt.char_base.read();
const screen_base = @as(u32, 0x800) * self.bg[n].cnt.screen_base.read();
const size: u2 = self.bg[n].cnt.size.read();
const tile_width = @as(i32, 0x10) << size;
const px_width = tile_width << 3;
const px_height = px_width;
var aff_x = self.aff_bg[n - 2].x_latch.?;
var aff_y = self.aff_bg[n - 2].y_latch.?;
var i: u32 = 0;
while (i < width) : (i += 1) {
var ix = aff_x >> 8;
var iy = aff_y >> 8;
aff_x += self.aff_bg[n - 2].pa;
aff_y += self.aff_bg[n - 2].pc;
if (self.scanline_buf[@as(usize, i)] != null) continue;
if (self.bg[n].cnt.display_overflow.read()) {
ix = if (ix > px_width) @rem(ix, px_width) else if (ix < 0) px_width + @rem(ix, px_width) else ix;
iy = if (iy > px_height) @rem(iy, px_height) else if (iy < 0) px_height + @rem(iy, px_height) else iy;
} else if (ix > px_width or iy > px_height or ix < 0 or iy < 0) continue;
const x = @bitCast(u32, ix);
const y = @bitCast(u32, iy);
const tile_id: u32 = self.vram.read(u8, screen_base + ((y / 8) * @bitCast(u32, tile_width) + (x / 8)));
const row = y & 7;
const col = x & 7;
const tile_addr = char_base + (tile_id * 0x40) + (row * 0x8) + col;
const pal_id: u16 = self.vram.buf[tile_addr];
if (pal_id != 0) self.scanline_buf[i] = self.palette.read(u16, pal_id * 2);
}
// Update BGxX and BGxY
self.aff_bg[n - 2].x_latch.? += self.aff_bg[n - 2].pb; // PB is added to BGxX
self.aff_bg[n - 2].y_latch.? += self.aff_bg[n - 2].pd; // PD is added to BGxY
}
fn drawBackround(self: *Self, comptime n: u3) void {
// A Tile in a charblock is a byte, while a Screen Entry is a halfword
const char_base = 0x4000 * @as(u32, self.bg[n].cnt.char_base.read());
const screen_base = 0x800 * @as(u32, self.bg[n].cnt.screen_base.read());
const is_8bpp: bool = self.bg[n].cnt.colour_mode.read(); // Colour Mode
const size: u2 = self.bg[n].cnt.size.read(); // Background Size
// In 4bpp: 1 byte represents two pixels so the length is (8 x 8) / 2
// In 8bpp: 1 byte represents one pixel so the length is 8 x 8
const tile_len = if (is_8bpp) @as(u32, 0x40) else 0x20;
const tile_row_offset = if (is_8bpp) @as(u32, 0x8) else 0x4;
const vofs: u32 = self.bg[n].vofs.offset.read();
const hofs: u32 = self.bg[n].hofs.offset.read();
const y = vofs + self.vcount.scanline.read();
var i: u32 = 0;
while (i < width) : (i += 1) {
// Exit early if a pixel is already here
if (self.scanline_buf[i] != null) continue;
const x = hofs + i;
// Grab the Screen Entry from VRAM
const entry_addr = screen_base + tilemapOffset(size, x, y);
const entry = @bitCast(ScreenEntry, self.vram.read(u16, entry_addr));
// Calculate the Address of the Tile in the designated Charblock
// We also take this opportunity to flip tiles if necessary
const tile_id: u32 = entry.tile_id.read();
// Calculate row and column offsets. Understand that
// `tile_len`, `tile_row_offset` and `col` are subject to different
// values depending on whether we are in 4bpp or 8bpp mode.
const row = @truncate(u3, y) ^ if (entry.v_flip.read()) 7 else @as(u3, 0);
const col = @truncate(u3, x) ^ if (entry.h_flip.read()) 7 else @as(u3, 0);
const tile_addr = char_base + (tile_id * tile_len) + (row * tile_row_offset) + if (is_8bpp) col else col >> 1;
const tile = self.vram.buf[tile_addr];
// If we're in 8bpp, then the tile value is an index into the palette,
// If we're in 4bpp, we have to account for a pal bank value in the Screen entry
// and then we can index the palette
const pal_id: u16 = if (!is_8bpp) get4bppTilePalette(entry.pal_bank.read(), col, tile) else tile;
if (pal_id != 0) self.scanline_buf[i] = self.palette.read(u16, pal_id * 2);
}
}
inline fn get4bppTilePalette(pal_bank: u4, col: u3, tile: u8) u8 {
const nybble_tile = tile >> ((col & 1) << 2) & 0xF;
if (nybble_tile == 0) return 0;
return (@as(u8, pal_bank) << 4) | nybble_tile;
}
pub fn drawScanline(self: *Self) void {
const bg_mode = self.dispcnt.bg_mode.read();
const bg_enable = self.dispcnt.bg_enable.read();
const obj_enable = self.dispcnt.obj_enable.read();
const scanline = self.vcount.scanline.read();
switch (bg_mode) {
0x0 => {
const fb_base = framebuf_pitch * @as(usize, scanline);
if (obj_enable) self.fetchSprites();
var layer: usize = 0;
while (layer < 4) : (layer += 1) {
self.drawSprites(@truncate(u2, layer));
if (layer == self.bg[0].cnt.priority.read() and bg_enable & 1 == 1) self.drawBackround(0);
if (layer == self.bg[1].cnt.priority.read() and bg_enable >> 1 & 1 == 1) self.drawBackround(1);
if (layer == self.bg[2].cnt.priority.read() and bg_enable >> 2 & 1 == 1) self.drawBackround(2);
if (layer == self.bg[3].cnt.priority.read() and bg_enable >> 3 & 1 == 1) self.drawBackround(3);
}
// Copy Drawn Scanline to Frame Buffer
// If there are any nulls present in self.scanline_buf it means that no background drew a pixel there, so draw backdrop
for (self.scanline_buf) |maybe_px, i| {
const bgr555 = if (maybe_px) |px| px else self.palette.getBackdrop();
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], COLOUR_LUT[bgr555 & 0x7FFF]);
}
// Reset Current Scanline Pixel Buffer and list of fetched sprites
// in prep for next scanline
std.mem.set(?u16, &self.scanline_buf, null);
std.mem.set(?Sprite, &self.scanline_sprites, null);
},
0x1 => {
const fb_base = framebuf_pitch * @as(usize, scanline);
if (obj_enable) self.fetchSprites();
var layer: usize = 0;
while (layer < 4) : (layer += 1) {
self.drawSprites(@truncate(u2, layer));
if (layer == self.bg[0].cnt.priority.read() and bg_enable & 1 == 1) self.drawBackround(0);
if (layer == self.bg[1].cnt.priority.read() and bg_enable >> 1 & 1 == 1) self.drawBackround(1);
if (layer == self.bg[2].cnt.priority.read() and bg_enable >> 2 & 1 == 1) self.drawAffineBackground(2);
}
// Copy Drawn Scanline to Frame Buffer
// If there are any nulls present in self.scanline_buf it means that no background drew a pixel there, so draw backdrop
for (self.scanline_buf) |maybe_px, i| {
const bgr555 = if (maybe_px) |px| px else self.palette.getBackdrop();
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], COLOUR_LUT[bgr555 & 0x7FFF]);
}
// Reset Current Scanline Pixel Buffer and list of fetched sprites
// in prep for next scanline
std.mem.set(?u16, &self.scanline_buf, null);
std.mem.set(?Sprite, &self.scanline_sprites, null);
},
0x2 => {
const fb_base = framebuf_pitch * @as(usize, scanline);
if (obj_enable) self.fetchSprites();
var layer: usize = 0;
while (layer < 4) : (layer += 1) {
self.drawSprites(@truncate(u2, layer));
if (layer == self.bg[2].cnt.priority.read() and bg_enable >> 2 & 1 == 1) self.drawAffineBackground(2);
if (layer == self.bg[3].cnt.priority.read() and bg_enable >> 3 & 1 == 1) self.drawAffineBackground(3);
}
// Copy Drawn Scanline to Frame Buffer
// If there are any nulls present in self.scanline_buf it means that no background drew a pixel there, so draw backdrop
for (self.scanline_buf) |maybe_px, i| {
const bgr555 = if (maybe_px) |px| px else self.palette.getBackdrop();
std.mem.writeIntNative(u32, self.framebuf.get(.Emulator)[fb_base + i * @sizeOf(u32) ..][0..@sizeOf(u32)], COLOUR_LUT[bgr555 & 0x7FFF]);
}
// Reset Current Scanline Pixel Buffer and list of fetched sprites
// in prep for next scanline
std.mem.set(?u16, &self.scanline_buf, null);
std.mem.set(?Sprite, &self.scanline_sprites, null);
},
0x3 => {
const vram_base = width * @sizeOf(u16) * @as(usize, scanline);
const fb_base = framebuf_pitch * @as(usize, scanline);
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]);
}
},
0x4 => {
const sel = self.dispcnt.frame_select.read();
const vram_base = width * @as(usize, scanline) + if (sel) 0xA000 else @as(usize, 0);
const fb_base = framebuf_pitch * @as(usize, scanline);
// 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]);
}
},
0x5 => {
const m5_width = 160;
const m5_height = 128;
const sel = self.dispcnt.frame_select.read();
const vram_base = m5_width * @sizeOf(u16) * @as(usize, scanline) + if (sel) 0xA000 else @as(usize, 0);
const fb_base = framebuf_pitch * @as(usize, scanline);
var i: usize = 0;
while (i < width) : (i += 1) {
// If we're outside of the bounds of mode 5, draw the background colour
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]);
}
},
else => std.debug.panic("[PPU] TODO: Implement BG Mode {}", .{bg_mode}),
}
}
// TODO: Comment this + get a better understanding
fn tilemapOffset(size: u2, x: u32, y: u32) u32 {
// Current Row: (y % PIXEL_COUNT) / 8
// Current COlumn: (x % PIXEL_COUNT) / 8
// Length of 1 row of Screen Entries: 0x40
// Length of 1 Screen Entry: 0x2 is the size of a screen entry
@setRuntimeSafety(false);
return switch (size) {
0 => (x % 256 / 8) * 2 + (y % 256 / 8) * 0x40, // 256 x 256
1 => blk: {
// 512 x 256
const offset: u32 = if (x & 0x1FF > 0xFF) 0x800 else 0;
break :blk offset + (x % 256 / 8) * 2 + (y % 256 / 8) * 0x40;
},
2 => blk: {
// 256 x 512
const offset: u32 = if (y & 0x1FF > 0xFF) 0x800 else 0;
break :blk offset + (x % 256 / 8) * 2 + (y % 256 / 8) * 0x40;
},
3 => blk: {
// 512 x 512
const offset: u32 = if (x & 0x1FF > 0xFF) 0x800 else 0;
const offset_2: u32 = if (y & 0x1FF > 0xFF) 0x800 else 0;
break :blk offset + offset_2 + (x % 256 / 8) * 2 + (y % 512 / 8) * 0x40;
},
};
}
pub fn handleHDrawEnd(self: *Self, cpu: *Arm7tdmi, late: u64) void {
// Transitioning to a Hblank
if (self.dispstat.hblank_irq.read()) {
cpu.bus.io.irq.hblank.set();
cpu.handleInterrupt();
}
// See if HBlank DMA is present and not enabled
pollBlankingDma(&cpu.bus, .HBlank);
self.dispstat.hblank.set();
self.sched.push(.HBlank, 68 * 4 -| late);
}
pub fn handleHBlankEnd(self: *Self, cpu: *Arm7tdmi, late: u64) void {
// The End of a Hblank (During Draw or Vblank)
const old_scanline = self.vcount.scanline.read();
const scanline = (old_scanline + 1) % 228;
self.vcount.scanline.write(scanline);
self.dispstat.hblank.unset();
// Perform Vc == VcT check
const coincidence = scanline == self.dispstat.vcount_trigger.read();
self.dispstat.coincidence.write(coincidence);
if (coincidence and self.dispstat.vcount_irq.read()) {
cpu.bus.io.irq.coincidence.set();
cpu.handleInterrupt();
}
if (scanline < 160) {
// Transitioning to another Draw
self.sched.push(.Draw, 240 * 4 -| late);
} else {
// Transitioning to a Vblank
if (scanline == 160) {
self.framebuf.swap(); // Swap FrameBuffers
self.dispstat.vblank.set();
if (self.dispstat.vblank_irq.read()) {
cpu.bus.io.irq.vblank.set();
cpu.handleInterrupt();
}
self.aff_bg[0].latchRefPoints();
self.aff_bg[1].latchRefPoints();
// See if Vblank DMA is present and not enabled
pollBlankingDma(&cpu.bus, .VBlank);
}
if (scanline == 227) self.dispstat.vblank.unset();
self.sched.push(.VBlank, 240 * 4 -| late);
}
}
};
const Palette = struct {
const palram_size = 0x400;
const Self = @This();
buf: []u8,
alloc: Allocator,
fn init(alloc: Allocator) !Self {
const buf = try alloc.alloc(u8, palram_size);
std.mem.set(u8, buf, 0);
return Self{
.buf = buf,
.alloc = alloc,
};
}
fn deinit(self: Self) void {
self.alloc.free(self.buf);
}
pub fn read(self: *const Self, comptime T: type, address: usize) T {
const addr = address & 0x3FF;
return switch (T) {
u32, u16, u8 => std.mem.readIntSliceLittle(T, self.buf[addr..][0..@sizeOf(T)]),
else => @compileError("PALRAM: Unsupported read width"),
};
}
pub fn write(self: *Self, comptime T: type, address: usize, value: T) void {
const addr = address & 0x3FF;
switch (T) {
u32, u16 => std.mem.writeIntSliceLittle(T, self.buf[addr..][0..@sizeOf(T)], value),
u8 => {
const halfword: u16 = @as(u16, value) * 0x0101;
// FIXME: I don't think my comment here makes sense?
const weird_addr = addr & ~@as(u32, 1); // *was* 8-bit read so address won't be aligned
std.mem.writeIntSliceLittle(u16, self.buf[weird_addr..(weird_addr + @sizeOf(u16))], halfword);
},
else => @compileError("PALRAM: Unsupported write width"),
}
}
fn getBackdrop(self: *const Self) u16 {
return self.read(u16, 0);
}
};
const Vram = struct {
const vram_size = 0x18000;
const Self = @This();
buf: []u8,
alloc: Allocator,
fn init(alloc: Allocator) !Self {
const buf = try alloc.alloc(u8, vram_size);
std.mem.set(u8, buf, 0);
return Self{
.buf = buf,
.alloc = alloc,
};
}
fn deinit(self: Self) void {
self.alloc.free(self.buf);
}
pub fn read(self: *const Self, comptime T: type, address: usize) T {
const addr = Self.mirror(address);
return switch (T) {
u32, u16, u8 => std.mem.readIntSliceLittle(T, self.buf[addr..][0..@sizeOf(T)]),
else => @compileError("VRAM: Unsupported read width"),
};
}
pub fn write(self: *Self, comptime T: type, dispcnt: io.DisplayControl, address: usize, value: T) void {
const mode: u3 = dispcnt.bg_mode.read();
const addr = Self.mirror(address);
switch (T) {
u32, u16 => std.mem.writeIntSliceLittle(T, self.buf[addr..][0..@sizeOf(T)], value),
u8 => {
// Ignore if write is in OBJ
switch (mode) {
0, 1, 2 => if (0x0601_0000 <= address and address < 0x0601_8000) return,
else => if (0x0601_4000 <= address and address < 0x0601_8000) return,
}
const halfword: u16 = @as(u16, value) * 0x0101;
const weird_addr = addr & ~@as(u32, 1);
std.mem.writeIntSliceLittle(u16, self.buf[weird_addr..(weird_addr + @sizeOf(u16))], halfword);
},
else => @compileError("VRAM: Unsupported write width"),
}
}
fn mirror(address: usize) usize {
// Mirrored in steps of 128K (64K + 32K + 32K) (abcc)
const addr = address & 0x1FFFF;
// If the address is within 96K we don't do anything,
// otherwise we want to mirror the last 32K (addresses between 64K and 96K)
return if (addr < vram_size) addr else 0x10000 + (addr & 0x7FFF);
}
};
const Oam = struct {
const oam_size = 0x400;
const Self = @This();
buf: []u8,
alloc: Allocator,
fn init(alloc: Allocator) !Self {
const buf = try alloc.alloc(u8, oam_size);
std.mem.set(u8, buf, 0);
return Self{
.buf = buf,
.alloc = alloc,
};
}
fn deinit(self: Self) void {
self.alloc.free(self.buf);
}
pub fn read(self: *const Self, comptime T: type, address: usize) T {
const addr = address & 0x3FF;
return switch (T) {
u32, u16, u8 => std.mem.readIntSliceLittle(T, self.buf[addr..][0..@sizeOf(T)]),
else => @compileError("OAM: Unsupported read width"),
};
}
pub fn write(self: *Self, comptime T: type, address: usize, value: T) void {
const addr = address & 0x3FF;
switch (T) {
u32, u16 => std.mem.writeIntSliceLittle(T, self.buf[addr..][0..@sizeOf(T)], value),
u8 => return, // 8-bit writes are explicitly ignored
else => @compileError("OAM: Unsupported write width"),
}
}
};
const Background = struct {
const Self = @This();
/// Read / Write
cnt: io.BackgroundControl,
/// Write Only
hofs: io.BackgroundOffset,
/// Write Only
vofs: io.BackgroundOffset,
fn init() Self {
return .{
.cnt = .{ .raw = 0x0000 },
.hofs = .{ .raw = 0x0000 },
.vofs = .{ .raw = 0x0000 },
};
}
};
const AffineBackground = struct {
const Self = @This();
x: i32,
y: i32,
pa: i16,
pb: i16,
pc: i16,
pd: i16,
x_latch: ?i32,
y_latch: ?i32,
fn init() Self {
return .{
.x = 0,
.y = 0,
.pa = 0,
.pb = 0,
.pc = 0,
.pd = 0,
.x_latch = null,
.y_latch = null,
};
}
pub fn writePaPb(self: *Self, value: u32) void {
self.pa = @bitCast(i16, @truncate(u16, value));
self.pb = @bitCast(i16, @truncate(u16, value >> 16));
}
pub fn writePcPd(self: *Self, value: u32) void {
self.pc = @bitCast(i16, @truncate(u16, value));
self.pd = @bitCast(i16, @truncate(u16, value >> 16));
}
// Every Vblank BG?X/Y registers are latched
fn latchRefPoints(self: *Self) void {
self.x_latch = self.x;
self.y_latch = self.y;
}
};
const ScreenEntry = extern union {
tile_id: Bitfield(u16, 0, 10),
h_flip: Bit(u16, 10),
v_flip: Bit(u16, 11),
pal_bank: Bitfield(u16, 12, 4),
raw: u16,
};
const Sprite = struct {
const Self = @This();
attr0: Attr0,
attr1: Attr1,
attr2: Attr2,
width: u8,
height: u8,
fn init(attr0: Attr0, attr1: Attr1, attr2: Attr2) Self {
const d = spriteDimensions(attr0.shape.read(), attr1.size.read());
return .{
.attr0 = attr0,
.attr1 = attr1,
.attr2 = attr2,
.width = d[0],
.height = d[1],
};
}
fn x(self: *const Self) u9 {
return self.attr1.x.read();
}
fn y(self: *const Self) u8 {
return self.attr0.y.read();
}
fn is8bpp(self: *const Self) bool {
return self.attr0.is_8bpp.read();
}
fn tileId(self: *const Self) u10 {
return self.attr2.tile_id.read();
}
fn palBank(self: *const Self) u4 {
return self.attr2.pal_bank.read();
}
fn hFlip(self: *const Self) bool {
return self.attr1.h_flip.read();
}
fn vFlip(self: *const Self) bool {
return self.attr1.v_flip.read();
}
fn priority(self: *const Self) u2 {
return self.attr2.rel_prio.read();
}
};
const AffineSprite = struct {
const Self = @This();
attr0: AffineAttr0,
attr1: AffineAttr1,
attr2: Attr2,
width: u8,
height: u8,
fn from(sprite: Sprite) AffineSprite {
return .{
.attr0 = .{ .raw = sprite.attr0.raw },
.attr1 = .{ .raw = sprite.attr1.raw },
.attr2 = sprite.attr2,
.width = sprite.width,
.height = sprite.height,
};
}
fn x(self: *const Self) u9 {
return self.attr1.x.read();
}
fn y(self: *const Self) u8 {
return self.attr0.y.read();
}
fn is8bpp(self: *const Self) bool {
return self.attr0.is_8bpp.read();
}
fn tileId(self: *const Self) u10 {
return self.attr2.tile_id.read();
}
fn palBank(self: *const Self) u4 {
return self.attr2.pal_bank.read();
}
fn matrixId(self: *const Self) u5 {
return self.attr1.aff_sel.read();
}
};
const Attr0 = extern union {
y: Bitfield(u16, 0, 8),
is_affine: Bit(u16, 8), // This SBZ
disabled: Bit(u16, 9),
mode: Bitfield(u16, 10, 2),
mosaic: Bit(u16, 12),
is_8bpp: Bit(u16, 13),
shape: Bitfield(u16, 14, 2),
raw: u16,
};
const AffineAttr0 = extern union {
y: Bitfield(u16, 0, 8),
rot_scaling: Bit(u16, 8), // This SB1
double_size: Bit(u16, 9),
mode: Bitfield(u16, 10, 2),
mosaic: Bit(u16, 12),
is_8bpp: Bit(u16, 13),
shape: Bitfield(u16, 14, 2),
raw: u16,
};
const Attr1 = extern union {
x: Bitfield(u16, 0, 9),
h_flip: Bit(u16, 12),
v_flip: Bit(u16, 13),
size: Bitfield(u16, 14, 2),
raw: u16,
};
const AffineAttr1 = extern union {
x: Bitfield(u16, 0, 9),
aff_sel: Bitfield(u16, 9, 5),
size: Bitfield(u16, 14, 2),
raw: u16,
};
const Attr2 = extern union {
tile_id: Bitfield(u16, 0, 10),
rel_prio: Bitfield(u16, 10, 2),
pal_bank: Bitfield(u16, 12, 4),
raw: u16,
};
fn spriteDimensions(shape: u2, size: u2) [2]u8 {
@setRuntimeSafety(false);
return switch (shape) {
0b00 => switch (size) {
// Square
0b00 => [_]u8{ 8, 8 },
0b01 => [_]u8{ 16, 16 },
0b10 => [_]u8{ 32, 32 },
0b11 => [_]u8{ 64, 64 },
},
0b01 => switch (size) {
0b00 => [_]u8{ 16, 8 },
0b01 => [_]u8{ 32, 8 },
0b10 => [_]u8{ 32, 16 },
0b11 => [_]u8{ 64, 32 },
},
0b10 => switch (size) {
0b00 => [_]u8{ 8, 16 },
0b01 => [_]u8{ 8, 32 },
0b10 => [_]u8{ 16, 32 },
0b11 => [_]u8{ 32, 64 },
},
else => std.debug.panic("{} is an invalid sprite shape", .{shape}),
};
}
fn toRgba8888(bgr555: u16) u32 {
const b = @as(u32, bgr555 >> 10 & 0x1F);
const g = @as(u32, bgr555 >> 5 & 0x1F);
const r = @as(u32, bgr555 & 0x1F);
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;
}
// Double Buffering Implementation
const FrameBuffer = struct {
const Self = @This();
buf: [2][]u8,
original: []u8,
current: u1,
// TODO: Rename
const Device = enum {
Emulator,
Renderer,
};
pub fn init(bufs: []u8) Self {
std.debug.assert(bufs.len == framebuf_pitch * height * 2);
const front = bufs[0 .. framebuf_pitch * height];
const back = bufs[framebuf_pitch * height ..];
return .{
.buf = [2][]u8{ front, back },
.original = bufs,
.current = 0,
};
}
fn deinit(self: Self, alloc: Allocator) void {
alloc.free(self.original);
}
pub fn swap(self: *Self) void {
self.current = ~self.current;
}
pub fn get(self: *Self, comptime dev: Device) []u8 {
return self.buf[if (dev == .Emulator) self.current else ~self.current];
}
};
Reference in New Issue View Git Blame Copy Permalink