screen: start drm implementation

1 files changed, 76 insertions, 0 deletions

diff --git a/src/screen/drm/resources.zig b/src/screen/drm/resources.zig
new file mode 100644
index 0000000..6128f37
--- /dev/null
+++ b/src/screen/drm/resources.zig
@@ -0,0 +1,76 @@
+const std = @import("std");
+const os = std.os.linux;
+const cerror = @import("../cerror.zig");
+const Card = @import("card.zig").Card;
+const Drm = @import("request.zig").Drm;
+
+const RawResources = extern struct {
+    fb_ids: ?*u32,
+    crtc_ids: ?*u32,
+    connector_ids: ?*u32,
+    encoder_ids: ?*u32,
+    count_fbs: u32,
+    count_crtcs: u32,
+    count_connectors: u32,
+    count_encoders: u32,
+    min_width: u32,
+    max_width: u32,
+    min_height: u32,
+    max_height: u32,
+};
+
+pub const Resources = struct {
+    const Self = @This();
+    const Range = struct { min: u32, max: u32 };
+
+    card: *Card,
+
+    fb_ids: []u32,
+    crtc_ids: []u32,
+    connector_ids: []u32,
+    encoder_ids: []u32,
+    width: Range,
+    height: Range,
+
+    pub fn raw_without_ids(card: *Card) !RawResources {
+        var result = std.mem.zeroes(RawResources);
+        try Drm.get_resources.request(card.file.handle, RawResources, &result);
+        return result;
+    }
+
+    // NOTE: This function does not take in account
+    //       that there might be some hot-plugging going
+    //       on. This might have to change in the future.
+    pub fn init(card: *Card) !Self {
+        var raw = try Self.raw_without_ids(card);
+        const resources = .{
+            .fb_ids = try card.allocator.alloc(u32, raw.count_fbs),
+            .crtc_ids = try card.allocator.alloc(u32, raw.count_crtcs),
+            .connector_ids = try card.allocator.alloc(u32, raw.count_connectors),
+            .encoder_ids = try card.allocator.alloc(u32, raw.count_encoders),
+            .width = .{ .min = raw.min_width, .max = raw.max_width },
+            .height = .{ .min = raw.min_height, .max = raw.max_height },
+            .card = card,
+        };
+
+        @memset(resources.fb_ids, 0);
+        @memset(resources.crtc_ids, 0);
+        @memset(resources.connector_ids, 0);
+        @memset(resources.encoder_ids, 0);
+
+        raw.fb_ids = @ptrCast(resources.fb_ids);
+        raw.crtc_ids = @ptrCast(resources.crtc_ids);
+        raw.connector_ids = @ptrCast(resources.connector_ids);
+        raw.encoder_ids = @ptrCast(resources.encoder_ids);
+        try Drm.get_resources.request(card.file.handle, RawResources, &raw);
+
+        return resources;
+    }
+
+    pub fn deinit(self: *Self) void {
+        self.card.allocator.free(self.fb_ids);
+        self.card.allocator.free(self.crtc_ids);
+        self.card.allocator.free(self.connector_ids);
+        self.card.allocator.free(self.encoder_ids);
+    }
+};