First step in the support of multiple formats of macro (or object) libraries.

No test included since I don't have a distributable RSX .MLB file
available at this time.

mlb2.c

@@ -0,0 +1,49 @@
+#include <stdlib.h>
+#include <string.h>
+#include "mlb.h"
+
+MLB_VTBL *mlb_vtbls[] = {
+    &mlb_rsx_vtbl,
+    NULL
+};
+
+MLB     *mlb_open(
+    char *name,
+    int allow_object_library)
+{
+    MLB_VTBL *vtbl;
+    MLB *mlb = NULL;
+    int i;
+
+    for (i = 0; (vtbl = mlb_vtbls[i]); i++) {
+        mlb = vtbl->mlb_open(name, allow_object_library);
+        if (mlb != NULL) {
+            mlb->name = strdup(name);
+            break;
+        }
+    }
+
+    return mlb;
+}
+
+BUFFER  *mlb_entry(
+    MLB *mlb,
+    char *name)
+{
+    return mlb->vtbl->mlb_entry(mlb, name);
+}
+
+void     mlb_close(
+    MLB *mlb)
+{
+    free(mlb->name);
+    mlb->vtbl->mlb_close(mlb);
+}
+
+void     mlb_extract(
+    MLB *mlb)
+{
+    mlb->vtbl->mlb_extract(mlb);
+}
+
+