1 files changed, 35 insertions, 0 deletions
diff --git a/src/bin/xi/xi2path.h b/src/bin/xi/xi2path.h
new file mode 100644
index 0000000..954c554
--- /dev/null
+++ b/src/bin/xi/xi2path.h
@@ -0,0 +1,35 @@
+#pragma once
+
+#include <stdio.h>
+#include <assert.h>
+#include <stdint.h>
+
+static inline void
+xi2path(char out[12], const uint16_t id)
+{
+   // Forms path like: section/id.DAT, from 16bit id.
+   // First 7 bits are used for DAT and rest of the bits for ROM section.
+   //
+   // e.g. ID of 1000 would look like 11101000 00000011 in binary.
+   //                                 RDDDDDDD RRRRRRRR
+   //
+   // In the above graph, 'R' bits form the ROM section (7) and 'D' bits form the DAT (104).
+   // Thus maximum DAT and ROM section IDs are 127 and 511 respectively (65535 as decimal).
+
+   snprintf(out, 12, "%u/%u.DAT", id >> 7, id & 0x7F);
+}
+
+static inline void
+xi2rompath(char out[18], const uint8_t rom, const uint16_t id)
+{
+   assert(rom <= 9);
+
+   char path[12];
+   xi2path(path, id);
+
+   if (rom > 1) {
+      snprintf(out, 18, "ROM%u/%s", rom, path);
+   } else {
+      snprintf(out, 18, "ROM/%s", path);
+   }
+}