add specification for bzip3

Author: armijnhemel

archive/bzip3.ksy

@@ -0,0 +1,35 @@
+meta:
+  id: bzip3
+  title: Bzip3 header
+  file-extension: bz3
+  license: LGPL-3.0
+  encoding: UTF-8
+  endian: le
+doc-ref: https://github.com/kspalaiologos/bzip3
+seq:
+  - id: header
+    type: header
+  - id: blocks
+    type: compressed_data_block
+    repeat: until
+    repeat-until: _io.eof or _.is_last
+types:
+  header:
+    seq:
+      - id: signature
+        contents: 'BZ3v1'
+      - id: block_size
+        type: u4
+  compressed_data_block:
+    seq:
+      - id: len_compressed
+        type: u4
+      - id: len_uncompressed
+        type: u4
+        valid:
+          max: _root.header.block_size
+      - id: data
+        size: len_compressed
+    instances:
+      is_last:
+        value: len_uncompressed < _root.header.block_size