diff --git a/generator/main.zig b/generator/main.zig
index f162908..cb408ca 100644
--- a/generator/main.zig
+++ b/generator/main.zig
@@ -1,7 +1,13 @@
 const std = @import("std");
 const xml = @import("xml.zig");
+const spec = @import("spec.zig");
 
 pub fn main() !void {
+    if (std.os.argv.len <= 1) {
+        std.debug.warn("Usage: vulkan-zig-gen <path-to-vk.xml>\n", .{});
+        return;
+    }
+
     const file = try std.fs.cwd().openFileC(std.os.argv[1], .{});
     defer file.close();
 
@@ -11,10 +17,16 @@ pub fn main() !void {
 
     _ = try file.inStream().stream.read(source);
 
-    var doc = try xml.parse(std.heap.page_allocator, source);
-    defer doc.deinit();
+    var registry = try xml.parse(std.heap.page_allocator, source);
+    defer registry.deinit();
+
+    const vk_spec = spec.generate(std.heap.page_allocator, registry);
+    defer vk_spec.deinit();
+
+    vk_spec.dump();
 }
 
 test "main" {
     _ = @import("xml.zig");
+    _ = @import("spec.zig");
 }
diff --git a/generator/spec.zig b/generator/spec.zig
new file mode 100644
index 0000000..fe64c14
--- /dev/null
+++ b/generator/spec.zig
@@ -0,0 +1,238 @@
+const std = @import("std");
+const xml = @import("xml.zig");
+const mem = std.mem;
+const Allocator = mem.Allocator;
+const SegmentedList = std.SegmentedList;
+
+const Spec = struct {
+    backing_allocator: *Allocator,
+    enums: std.StringHashMap(Enum),
+
+    fn deinit(self: Spec) void {
+        self.enums.deinit();
+    }
+
+    fn dump(self: Spec) void {
+        {
+            std.debug.warn("enums:\n", .{});
+            var it = self.enums.iterator();
+            while (it.next()) |e| {
+                const kind_text = if (e.value.kind == .Bitmask) " (bitmask)" else "";
+                std.debug.warn("    {}{}:\n", .{e.key, kind_text});
+
+                for (e.value.fields.toSlice()) |field| {
+                    std.debug.warn("        {}\n", .{field.name});
+                }
+            }
+        }
+    }
+};
+
+const Enum = struct {
+    const Kind = enum {
+        Bitmask,
+        Enum,
+
+        fn parse(str: []const u8) !Kind {
+            if (mem.eql(u8, str, "bitmask")) {
+                return .Bitmask;
+            } else if (mem.eql(u8, str, "enum")) {
+                return .Enum;
+            } else {
+                return error.InvalidEnumKind;
+            }
+        }
+    };
+
+    const Value = union(enum) {
+        Bitpos: u5, //log2(u32.bit_count)
+        Value: i32,
+        Alias: []const u8,
+
+        fn fromXml(elem: *xml.Element) !Value {
+            if (elem.getAttribute("value")) |value_str| {
+                if (mem.startsWith(u8, value_str, "0x")) {
+                    return Value{.Value = try std.fmt.parseInt(i32, value_str[2..], 16)};
+                } else {
+                    return Value{.Value = try std.fmt.parseInt(i32, value_str, 10)};
+                }
+            } else if (elem.getAttribute("bitpos")) |bitpos_str| {
+                return Value{.Bitpos = try std.fmt.parseInt(u5, bitpos_str, 10)};
+            } else if (elem.getAttribute("alias")) |alias| {
+                return Value{.Alias = alias};
+            } else {
+                return error.InvalidValueElement;
+            }
+        }
+    };
+
+    const Field = struct {
+        name: []const u8,
+        value: Value
+    };
+
+    const backwards_compat_note = "Backwards-compatible alias containing a typo";
+    const deprecation_note = "Deprecated name for backwards compatibility";
+
+    kind: Kind,
+    fields: std.ArrayList(Field),
+
+    fn init(backing_allocator: *Allocator, kind: Kind) Enum {
+        return .{
+            .kind = kind,
+            .fields = std.ArrayList(Field).init(backing_allocator)
+        };
+    }
+
+    fn fromXml(backing_allocator: *Allocator, enums: *xml.Element) Enum {
+        const kind = Enum.Kind.parse(enums.getAttribute("type").?) catch unreachable;
+        var e = Enum.init(backing_allocator, kind);
+        var it = enums.findChildrenByTag("enum");
+        while (it.next()) |field| {
+            e.processFieldFromXml(field, null);
+        }
+
+        return e;
+    }
+
+    fn addField(self: *Enum, name: []const u8, value: Value) void {
+        const ptr = self.fields.append(.{.name = name, .value = value}) catch unreachable;
+    }
+
+    fn processFieldFromXml(self: *Enum, field: *xml.Element, ext_nr: ?i32) void {
+        if (Enum.isBackwardsCompatAlias(field)) return;
+        const name = field.getAttribute("name").?;
+        const value = blk: {
+            if (field.getAttribute("value")) |value_str| {
+                const value = if (mem.startsWith(u8, value_str, "0x"))
+                        std.fmt.parseInt(i32, value_str[2..], 16) catch unreachable
+                    else
+                        std.fmt.parseInt(i32, value_str, 10) catch unreachable;
+
+                break :blk Value{.Value = value};
+            } else if (field.getAttribute("bitpos")) |bitpos_str| {
+                break :blk Value{.Bitpos = std.fmt.parseInt(u5, bitpos_str, 10) catch unreachable};
+            } else if (field.getAttribute("alias")) |alias| {
+                break :blk Value{.Alias = alias};
+            } else if (field.getAttribute("offset")) |offset_str| {
+                const offset = std.fmt.parseInt(i32, offset_str, 10) catch unreachable;
+
+                const actual_ext_nr = ext_nr orelse blk: {
+                    const ext_nr_str = field.getAttribute("extnumber").?;
+                    break :blk std.fmt.parseInt(i32, ext_nr_str, 10) catch unreachable;
+                };
+
+                var value = Enum.extensionEnumValue(actual_ext_nr, offset);
+
+                if (field.getAttribute("dir")) |_| {
+                    // Special case for VkResult
+                    value = -value;
+                }
+
+                break :blk Value{.Value = value};
+            } else {
+                unreachable;
+            }
+        };
+
+        self.addField(name, value);
+    }
+
+    fn isBackwardsCompatAlias(field: *xml.Element) bool {
+        if (field.getAttribute("comment")) |comment| {
+            return mem.eql(u8, comment, Enum.backwards_compat_note) or
+                mem.eql(u8, comment, Enum.deprecation_note);
+        }
+
+        return false;
+    }
+
+    fn extensionEnumValue(ext_nr: i32, offset: i32) i32 {
+        const extension_value_base = 1000000000;
+        const extension_block = 1000;
+        return extension_value_base + (ext_nr - 1) * extension_block + offset;
+    }
+};
+
+pub fn generate(backing_allocator: *Allocator, registry: xml.Document) Spec {
+    std.debug.assert(mem.eql(u8, registry.root.tag, "registry"));
+
+    var spec = Spec{
+        .backing_allocator = backing_allocator,
+        .enums = std.StringHashMap(Enum).init(backing_allocator)
+    };
+
+    errdefer spec.deinit();
+
+    processEnums(&spec, registry);
+    processFeatures(&spec, registry);
+    processExtensions(&spec, registry);
+
+    return spec;
+}
+
+fn readChildTextOrFail(element: *xml.Element, child_name: []const u8) ![]const u8 {
+    const child = element.findChildByTag(child_name).?;
+    const content = child.children.at(0).*;
+    if (content != .CharData) {
+        return error.InvalidRegistry;
+    }
+
+    return content.CharData;
+}
+
+fn processEnums(spec: *Spec, registry: xml.Document) void {
+    var it = registry.root.findChildrenByTag("enums");
+    while (it.next()) |enums| {
+        const name = enums.getAttribute("name").?;
+        if (!mem.eql(u8, name, "API Constants")) {
+            const e = Enum.fromXml(spec.backing_allocator, enums);
+            if (spec.enums.put(name, e) catch unreachable) |_| unreachable;
+        }
+    }
+}
+
+fn processExtensions(spec: *Spec, registry: xml.Document) void {
+    var extensions = registry.root.findChildByTag("extensions").?;
+    var ext_it = extensions.findChildrenByTag("extension");
+    while (ext_it.next()) |ext| {
+        var req_it = ext.findChildrenByTag("require");
+        while (req_it.next()) |req| {
+            processExtension(spec, ext, req);
+        }
+    }
+}
+
+fn processExtension(spec: *Spec, ext: *xml.Element, req: *xml.Element) void {
+    const ext_nr_str = ext.getAttribute("number").?;
+    const ext_nr = std.fmt.parseInt(i32, ext_nr_str, 10) catch unreachable;
+
+    var it = req.findChildrenByTag("enum");
+    while (it.next()) |field| {
+        const enum_name = field.getAttribute("extends") orelse continue;
+        if (Enum.isBackwardsCompatAlias(field)) continue;
+
+        // Some extensions define fields for other extensions,
+        // these are also defined in those extensions, so just skip them
+        if (field.getAttribute("extnumber")) |_| continue;
+        const kv = spec.enums.get(enum_name).?;
+        kv.value.processFieldFromXml(field, ext_nr);
+    }
+}
+
+fn processFeatures(spec: *Spec, registry: xml.Document) void {
+    var feature_it = registry.root.findChildrenByTag("feature");
+    while (feature_it.next()) |feature| {
+        var req_it = feature.findChildrenByTag("require");
+        while (req_it.next()) |req| {
+            var enum_it = req.findChildrenByTag("enum");
+            while (enum_it.next()) |field| {
+                const enum_name = field.getAttribute("extends") orelse continue;
+                if (Enum.isBackwardsCompatAlias(field)) continue;
+
+                const kv = spec.enums.get(enum_name).?;
+                kv.value.processFieldFromXml(field, null);
+            }
+        }
+    }
+}
diff --git a/generator/xml.zig b/generator/xml.zig
index 7e50c4a..41c5f18 100644
--- a/generator/xml.zig
+++ b/generator/xml.zig
@@ -17,17 +17,59 @@ pub const Content = union(enum) {
 };
 
 pub const Element = struct {
+    const AttributeList = SegmentedList(*Attribute, 0);
+    const ContentList = SegmentedList(Content, 0);
+
     tag: []const u8,
-    attributes: SegmentedList(*Attribute, 0),
-    children: SegmentedList(Content, 0),
+    attributes: AttributeList,
+    children: ContentList,
 
     fn init(tag: []const u8, alloc: *Allocator) Element {
         return .{
             .tag = tag,
-            .attributes = SegmentedList(*Attribute, 0).init(alloc),
-            .children = SegmentedList(Content, 0).init(alloc),
+            .attributes = AttributeList.init(alloc),
+            .children = ContentList.init(alloc),
         };
     }
+
+    fn getAttribute(self: *Element, attrib_name: []const u8) ?[]const u8 {
+        var it = self.attributes.iterator(0);
+        while (it.next()) |child| {
+            if (mem.eql(u8, child.*.name, attrib_name)) {
+                return child.*.value;
+            }
+        }
+
+        return null;
+    }
+
+    fn findChildByTag(self: *Element, tag: []const u8) ?*Element {
+        return self.findChildrenByTag(tag).next();
+    }
+
+    fn findChildrenByTag(self: *Element, tag: []const u8) FindChildrenByTagIterator {
+        return .{
+            .inner = self.children.iterator(0),
+            .tag = tag
+        };
+    }
+
+    pub const FindChildrenByTagIterator = struct {
+        inner: ContentList.Iterator,
+        tag: []const u8,
+
+        fn next(self: *FindChildrenByTagIterator) ?*Element {
+            while (self.inner.next()) |child| {
+                if (child.* != .Element or !mem.eql(u8, child.*.Element.tag, self.tag)) {
+                    continue;
+                }
+
+                return child.*.Element;
+            }
+
+            return null;
+        }
+    };
 };
 
 pub const XmlDecl = struct {
@@ -229,6 +271,8 @@ fn parseDocument(ctx: *ParseContext, backing_allocator: *Allocator) !Document {
         .root = undefined
     };
 
+    errdefer doc.deinit();
+
     doc.xml_decl = try tryParseProlog(ctx, &doc.arena.allocator);
     _ = ctx.eatWs();
     doc.root = (try tryParseElement(ctx, &doc.arena.allocator)) orelse return error.InvalidDocument;