adding spirv header parsing

src/Module.zig

@@ -1,5 +1,6 @@
 const std = @import("std");
 const lib = @import("lib.zig");
+const spv_data = @import("spv_data.zig");
 
 const SpvVoid = lib.SpvVoid;
 const SpvByte = lib.SpvByte;
@@ -20,13 +21,21 @@ const SpvEntryPoint = struct {
     globals: []const SpvWord,
 };
 
+const ModuleError = error{
+    InvalidSpirV,
+    InvalidMagic,
+    OutOfMemory,
+};
+
 ctx: *const Interpreter,
 
 it: WordIterator,
 
 version_major: SpvByte,
 version_minor: SpvByte,
-generator_magic: SpvWord,
+
+generator_id: u16,
+generator_version: u16,
 
 bound: SpvWord,
 
@@ -42,14 +51,45 @@ local_size_x: SpvWord,
 local_size_y: SpvWord,
 local_size_z: SpvWord,
 
-pub fn init(allocator: std.mem.Allocator, ctx: *const Interpreter, source: []const SpvWord) !Self {
+pub fn init(allocator: std.mem.Allocator, ctx: *const Interpreter, source: []const SpvWord) ModuleError!Self {
     var self: Self = std.mem.zeroInit(Self, .{
         .ctx = ctx,
-        .code = try allocator.dupe(SpvWord, source),
+        .code = allocator.dupe(SpvWord, source) catch return ModuleError.OutOfMemory,
+        .local_size_x = 1,
+        .local_size_y = 1,
+        .local_size_z = 1,
     });
+    errdefer allocator.free(self.code);
 
     self.it = WordIterator.init(self.code);
 
+    const magic = self.it.next() orelse return ModuleError.InvalidSpirV;
+    if (magic != lib.spv.SpvMagicNumber) return ModuleError.InvalidMagic;
+
+    const version = self.it.next() orelse return ModuleError.InvalidSpirV;
+    self.version_major = @intCast((version & 0x00FF0000) >> 16);
+    self.version_minor = @intCast((version & 0x0000FF00) >> 8);
+
+    const generator = self.it.next() orelse return ModuleError.InvalidSpirV;
+    self.generator_id = @intCast((generator & 0xFFFF0000) >> 16);
+    self.generator_version = @intCast(generator & 0x0000FFFF);
+
+    self.bound = self.it.next() orelse return ModuleError.InvalidSpirV;
+
+    _ = self.it.skip(); // Skip schema
+
+    std.log.scoped(.SPIRV_Interpreter).debug(
+        \\Loaded shader module with infos:
+        \\    SPIR-V version: {d}.{d}
+        \\    Generator:      {s} (ID {d}), encoded version {d}
+    , .{
+        self.version_major,
+        self.version_minor,
+        spv_data.vendorName(self.generator_id),
+        self.generator_id,
+        self.generator_version,
+    });
+
     return self;
 }