1 files changed, 69 insertions, 0 deletions
diff --git a/mod/mutil.h b/mod/mutil.h
new file mode 100644
index 0000000..215508b
--- /dev/null
+++ b/mod/mutil.h
@@ -0,0 +1,69 @@
+/*
+ * melisma - extensible and scriptable audio engine
+ * Copyright (C) 2026  Ludvig Gunne Lindström
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+#ifndef MUTIL_H
+#define MUTIL_H
+
+/* TODO: Move to main repo? */
+
+#include "melisma.h"
+#include <lauxlib.h>
+
+#define MUTIL_OUTPUT_CHANNEL_FUNCTION "__ml_out"
+
+static ml_channel *mutil_get_optchannel(lua_State *s, int i)
+{
+	ml_channel **c;
+
+	if ((c = luaL_testudata(s,i,MELISMA_OUTPUT_CHANNEL_TYPENAME)) != NULL)
+	{
+		return *c;
+	}
+
+	lua_getfield(s,i,MUTIL_OUTPUT_CHANNEL_FUNCTION);
+
+	if (!lua_isfunction(s,-1))
+	{
+		lua_pop(s,1);
+		return NULL;
+	}
+
+	lua_pushvalue(s,i);
+	lua_call(s,1,1);
+
+	if ((c = luaL_testudata(s,-1,MELISMA_OUTPUT_CHANNEL_TYPENAME)) != NULL)
+	{
+		lua_pop(s,1);
+		return *c;
+	}
+
+	lua_pop(s,1);
+	return NULL;
+}
+
+static ml_channel *mutil_get_channel(lua_State *s, int i)
+{
+	ml_channel *c = mutil_get_optchannel(s,i);
+	if (c == NULL)
+	{
+		luaL_argerror(s,i,"expected output channel");
+	}
+	return c;
+}
+
+#endif