2 files changed, 141 insertions, 0 deletions
diff --git a/src/screen/drm/buffer/raw.zig b/src/screen/drm/buffer/raw.zig
new file mode 100644
index 0000000..e4674eb
--- /dev/null
+++ b/src/screen/drm/buffer/raw.zig
@@ -0,0 +1,109 @@
+const std = @import("std");
+const os = std.os.linux;
+const drm = @import("../root.zig");
+const cerror = @import("../../cerror.zig");
+
+pub const Raw = struct {
+	const Self = @This();
+
+	card: *drm.Card,
+	id: u32,
+	width: u32,
+	height: u32,
+	bpp: u32,
+	stride: u32,
+	data_size: u64,
+	canvas_size: u64,
+	handle: u32,
+	data: [*]volatile drm.Pixel,
+
+	pub fn init(card: *drm.Card, width: u32, height: u32, bpp: u32) !Self {
+		var create_dumb = std.mem.zeroInit(drm.request.CreateDumb, .{
+			.width = width,
+			.height = height,
+			.bpp = bpp,
+		});
+		try card.request(
+			.create_dumb,
+			&create_dumb
+		);
+
+		var fb = Self {
+			.id = 0,
+			.width = create_dumb.width,
+			.height = create_dumb.height,
+			.bpp = create_dumb.bpp,
+			.stride = create_dumb.pitch,
+			.data_size = create_dumb.size,
+			.canvas_size = create_dumb.size / (bpp / 8),
+			.handle = create_dumb.handle,
+			.data = undefined,
+			.card = card,
+		};
+
+		var buffer_cmd = drm.request.FrameBufferCmd2 {
+			.id = 0,
+			.width = fb.width,
+			.height = fb.height,
+			.pixel_format = drm.Pixel.Format.xrgb8888,
+			.flags = 0,
+			.handles = [_] u32 { fb.handle, 0, 0, 0 },
+			.pitches = [_] u32 { fb.stride, 0, 0, 0 },
+			.offsets = [_] u32 { 0, 0, 0, 0 },
+			.modifier = [_] u32 { 0, 0, 0, 0 },
+		};
+
+		try card.request(
+			.add_frame_buffer2,
+			&buffer_cmd
+		);
+
+		fb.id = buffer_cmd.id;
+
+		var map_dumb = std.mem.zeroInit(drm.request.MapDumb, .{ .handle = fb.handle });
+
+		try card.request(
+			.map_dumb,
+			&map_dumb
+		);
+
+		const address = os.mmap(
+			null,
+			fb.data_size,
+			os.PROT.READ | os.PROT.WRITE,
+			.{ .TYPE = os.MAP_TYPE.SHARED },
+			card.file.handle,
+			map_dumb.offset
+		);
+
+		try cerror.from_usize(address);
+
+		fb.data = @ptrFromInt(address);
+
+		return fb;
+	}
+
+	pub fn set(self: *Self, x: u32, y: u32, p: drm.Pixel) void {
+		self.data[x + self.width * y] = p;
+	}
+
+	pub fn fill(self: *Self, p: drm.Pixel) void {
+		@memset(self.data[0..self.canvas_size], p);
+	}
+
+	pub fn deinit(self: *Self) void {
+		cerror.from_usize(
+			os.munmap(@ptrCast(@volatileCast(self.data)), self.data_size)
+		) catch |err| std.debug.panic("munmap failed in frame-buffer: {}", .{err});
+
+		self.card.request(
+			.remove_frame_buffer,
+			&self.id
+		) catch @panic("failed to remove frame-buffer");
+
+		self.card.request(
+			.destroy_dumb,
+			&self.handle
+		) catch @panic("failed to destroy dumb-buffer");
+	}
+};
diff --git a/src/screen/drm/buffer/root.zig b/src/screen/drm/buffer/root.zig
new file mode 100644
index 0000000..e967d51
--- /dev/null
+++ b/src/screen/drm/buffer/root.zig
@@ -0,0 +1,32 @@
+const drm = @import("../root.zig");
+
+pub const Buffer = struct {
+	const Self = @This();
+	pub const Raw = @import("raw.zig").Raw;
+
+	current: Raw,
+	crtc: Raw,
+
+	pub fn init(card: *drm.Card, width: u32, height: u32, bpp: u32) !Self {
+		return .{
+			.current = try Raw.init(card, width, height, bpp),
+			.crtc = try Raw.init(card, width, height, bpp),
+		};
+	}
+
+	pub fn swap(self: *Self) void {
+		const data = self.current.data;
+		self.current.data = self.crtc.data;
+		self.crtc.data = data;
+
+		const id = self.current.id;
+		self.current.id = self.crtc.id;
+		self.crtc.id = id;
+	}
+
+	pub fn deinit(self: *Self) void {
+		self.current.deinit();
+		self.crtc.deinit();
+	}
+};
+