screen: add vsync and double buffering

1 files changed, 30 insertions, 2 deletions

diff --git a/src/screen/drm/crtc/root.zig b/src/screen/drm/crtc/root.zig
index 3c9d6f9..f1f1d5c 100644
--- a/src/screen/drm/crtc/root.zig
+++ b/src/screen/drm/crtc/root.zig
@@ -2,7 +2,9 @@ const std = @import("std");
 const Card = @import("../card.zig").Card;
 const Drm = @import("../request.zig").Drm;
 const Connector = @import("../connector/root.zig").Connector;
-const FrameBuffer = @import("../frame-buffer/root.zig").FrameBuffer;
+const fb = @import("../frame-buffer/root.zig");
+const FrameBuffer = fb.FrameBuffer;
+const DoubleBuffer = fb.DoubleBuffer;
 const Mode = @import("../connector/mode.zig").Mode;
 
 pub const RawCrtc = extern struct {
@@ -17,6 +19,22 @@ pub const RawCrtc = extern struct {
     mode: Mode,
 };
 
+const PageFlipEvent = packed struct(u32) {
+    event: bool,
+    is_async: bool,
+    absolute: bool,
+    relative: bool,
+    __padding: u28,
+};
+
+const PageFlip = extern struct {
+    crtc_id: u32,
+    buffer_id: u32,
+    flags: PageFlipEvent,
+    __reserved: u32,
+    user_data: u64,
+};
+
 pub const Crtc = struct {
     const Self = @This();
 
@@ -65,8 +83,18 @@ pub const Crtc = struct {
         };
 
         try Drm.set_crtc.request(self.card.file.handle, RawCrtc, &crtc);
+    }
+
+    pub fn page_flip(self: *Self, double_buffer: *DoubleBuffer) !void {
+        double_buffer.swap();
+
+        var flip = std.mem.zeroInit(PageFlip, .{
+            .buffer_id = double_buffer.crtc_buffer().id,
+            .crtc_id = self.id,
+            .flags = std.mem.zeroInit(PageFlipEvent, .{ .event = true }),
+        });
 
-        std.debug.print("crtc = {any}\n", .{self});
+        try Drm.page_flip.request(self.card.file.handle, PageFlip, &flip);
     }
 
     pub fn detach(self: *Self) void {