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feat(ppu): improve timings + implement BG mode 3 bitmap

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This commit is contained in:
Rekai Nyangadzayi Musuka
2022-01-09 10:22:50 -04:00
parent 581285a434
commit ead6d1ce49
3 changed files with 49 additions and 34 deletions
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55
src/scheduler.zig
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@@ -37,45 +37,48 @@ pub const Scheduler = struct {
std.debug.panic("[Scheduler] Somehow, a u64 overflowed", .{});
},
.HBlank => {
std.log.debug("[Scheduler] tick {}: Hblank", .{self.tick});
// We've reached the end of a scanline
// The End of a Hblank
const scanline = bus.io.vcount.scanline.read();
bus.io.vcount.scanline.write(scanline + 1);
const new_scanline = scanline + 1;
bus.io.dispstat.hblank.set();
// TODO: Should this be done @ end of Draw instead of end of Hblank?
bus.ppu.drawScanline(&bus.io);
if (scanline < 160) {
self.push(.{ .kind = .Visible, .tick = self.tick + (68 * 4) });
bus.io.vcount.scanline.write(new_scanline);
bus.io.dispstat.hblank.unset();
if (new_scanline < 160) {
// Transitioning to another Draw
self.push(.{ .kind = .Draw, .tick = self.tick + (240 * 4) });
} else {
self.push(.{ .kind = .VBlank, .tick = self.tick + (68 * 4) });
// Transitioning to a Vblank
bus.io.dispstat.vblank.set();
self.push(.{ .kind = .VBlank, .tick = self.tick + (308 * 4) });
}
},
.Visible => {
std.log.debug("[Scheduler] tick {}: Visible", .{self.tick});
.Draw => {
// The end of a Draw
// Beginning of a Scanline
bus.io.dispstat.hblank.unset();
bus.io.dispstat.vblank.unset();
self.push(.{ .kind = .HBlank, .tick = self.tick + (240 * 4) });
// Transitioning to a Hblank
bus.io.dispstat.hblank.set();
self.push(.{ .kind = .HBlank, .tick = self.tick + (68 * 4) });
},
.VBlank => {
std.log.debug("[Scheduler] tick {}: VBlank", .{self.tick});
// Beginning of a Scanline, not visible though
bus.io.dispstat.hblank.unset();
bus.io.dispstat.vblank.set();
// The end of a Vblank
const scanline = bus.io.vcount.scanline.read();
bus.io.vcount.scanline.write(scanline + 1);
const new_scanline = scanline + 1;
bus.io.vcount.scanline.write(new_scanline);
if (scanline < 227) {
// Another Vblank Scanline
self.push(.{ .kind = .VBlank, .tick = self.tick + 68 * (308 * 4) });
if (new_scanline < 228) {
// Transition to another Vblank
self.push(.{ .kind = .VBlank, .tick = self.tick + (308 * 4) });
} else {
// Transition to another Draw
bus.io.vcount.scanline.write(0); // Reset Scanline
self.push(.{ .kind = .Visible, .tick = self.tick + 68 * (308 * 4) });
bus.io.dispstat.vblank.unset();
self.push(.{ .kind = .Draw, .tick = self.tick + (240 * 4) });
}
},
}
@@ -106,5 +109,5 @@ pub const EventKind = enum {
HeatDeath,
HBlank,
VBlank,
Visible,
Draw,
};