From 2cb5d032111e765ee11d6079725c3e4914da9efe Mon Sep 17 00:00:00 2001
From: Quinn <quinnthepigeon@proton.me>
Date: Mon, 7 Jul 2025 14:21:33 +0200
Subject: [PATCH] write headers for data processing

---
 src/dat/mcx.h | 19 +++++++++++++++++++
 src/dat/nbt.h | 29 +++++++++++++++++++++++++++++
 2 files changed, 48 insertions(+)
 create mode 100644 src/dat/mcx.h
 create mode 100644 src/dat/nbt.h

diff --git a/src/dat/mcx.h b/src/dat/mcx.h
new file mode 100644
index 0000000..2a97db4
--- /dev/null
+++ b/src/dat/mcx.h
@@ -0,0 +1,19 @@
+// Copyright (c) 2025 Quinn
+// Licensed under the MIT Licence. See LICENSE for details
+#pragma once
+
+/* the MCR (Minecraft region) and MCA (Minecraft anvil) files are similar
+ * MCA is the newer variant, where it includes:
+ *  - a world height of 256, rather than 128.
+ *  - block IDs have been extended to 4096 from 256
+ *  - block ordering is now YZX, rather than XZY.
+ *  - biomes are included in the data per XZ column.
+ * MCR start with an 8KiB header, split in two 4KiB tables
+ * - the first containing the offsets of chunks in the region file itself.
+ * - the second providing timestamps on when they were last updated.
+ * -
+ *
+ *
+ *
+ *
+ */
diff --git a/src/dat/nbt.h b/src/dat/nbt.h
new file mode 100644
index 0000000..6fd4e1e
--- /dev/null
+++ b/src/dat/nbt.h
@@ -0,0 +1,29 @@
+// Copyright (c) 2025 Quinn
+// Licensed under the MIT Licence. See LICENSE for details
+#pragma once
+
+/* NBT (named binary tag) is a tree data structure. Tags have a numeric type ID, name and a payload.
+ * NBT files are a compressed `compound` tag. GZip is the compression used in most cases,
+ * in some (rare) cases it's stored uncompressed.
+ * A tag is an individual part of the data tree.
+ * The first byte is the ID, followed by a `u16`, for the length of the name.
+ * Then the name as `UTF-8`. (end tag does not contain name) */
+
+
+/* specifies the NBT tag IDs.
+ * NOTE: every type is stored as BE (big-endian) in the file. */
+enum nbt_tagid {
+	NBT_END,      // signifies the end of a compound tag
+	NBT_I8,       // next byte is for an 8 bit signed integer.
+	NBT_I16,      // next 2 bytes are for a 16 bit signed integer
+	NBT_I32,      // next 4 bytes are for a 32 bit signed integer
+	NBT_I64,      // next 8 bytes are for a 64 bit signed integer
+	NBT_F32,      // next 4 bytes are for a single-precision floating-point
+	NBT_F64,      // next 8 bytes are for a double-precision floating-point
+	NBT_ARR_I8,   // starts with a i32, denoting size, followed by the i8 data
+	NBT_STR,      // starts with a u16, denoting size, followed by the UTF-8 data
+	NBT_LIST,     // starts with an ID, followed by a 32 bit signed integer denoting the size
+	NBT_COMPOUND, // compound tag, contains tags and is delimited by `NBT_END`
+	NBT_ARR_I32,  // starts with a i32, denoting size, followed by the i32 data
+	NBT_ARR_I64,  // starts with a i32, denoting size, followed by the u32 data
+};