Begin source generation.

Start out easy by emiting an opcodes.rs file containing an opcode enumeration.

meta/gen_instr.py

@@ -0,0 +1,31 @@
+"""
+Generate sources with instruction info.
+"""
+
+import srcgen
+
+def collect_instr_groups(targets):
+    seen = set()
+    groups = []
+    for t in targets:
+        for g in t.instruction_groups:
+            if g not in seen:
+                groups.append(g)
+                seen.add(g)
+    return groups
+
+def gen_opcodes(groups, out_dir):
+    """Generate opcode enumerations."""
+    fmt = srcgen.Formatter()
+    fmt.line('enum Opcode {')
+    fmt.indent_push()
+    for g in groups:
+        for i in g.instructions:
+            fmt.line(i.camel_name + ',')
+    fmt.indent_pop()
+    fmt.line('}')
+    fmt.update_file('opcodes.rs', out_dir)
+
+def generate(targets, out_dir):
+    groups = collect_instr_groups(targets)
+    gen_opcodes(groups, out_dir)