Revise file_format

The changes should allow for the .simplearchive file to be directly
outputted to standard out in a single pass.

Resolves #10 .

diff --git a/file_format.md b/file_format.md
index c563124935c607237570051c2e6cad270c350ee2..b8ceb5059dc5b1b2a36e53ed7b47eb407f32f477 100644 (file)
--- a/file_format.md
+++ b/file_format.md
@@ -9,26 +9,30 @@ First 18 bytes of file will be:
     SIMPLE_ARCHIVE_VER
 
 Next 2 bytes is 16-bit unsigned integer "version" in big-endian. In this case,
-will be zero.
+it will be zero.
 
-Next 4 bytes is 32-bit unsigned integer "file count" in big-endian which will
-indicate the number of files in this archive.
+Next 4 bytes are bit-flags.
 
-For each file:
+1. The first byte
+    1. The first bit is set if de/compressor is set for this archive.
+
+The remaining unused flags are reserved for future revisions and are currently
+ignored.
+
+If the previous "de/compressor is set" flag is enabled, then the next section is
+added:
+
+1. 2 bytes is 16-bit unsigned integer "compressor cmd+args" in big-endian.
+2. X bytes of "compressor cmd+args" (length defined by previous value).
+3. 2 bytes is 16-bit unsigned integer "decompressor cmd+args" in big-endian.
+4. X bytes of "decompressor cmd+args" (length defined by previous value).
+
+The next 4 bytes is 32-bit unsigned integer "file count" in big-endian which
+will indicate the number of files in this archive.
+
+Following the file-count bytes, the following bytes are added for each file:
 
 1. 2 bytes is 16-bit unsigned integer "filename length" in big-endian.
-2. X bytes of filename (defined by previous value).
-3. 2 bytes is 16-bit unsigned integer "compressor cmd+args" in big-endian.
-4. X bytes of "compressor cmd+args" (defined by previous value).
-5. 2 bytes is 16-bit unsigned integer "decompressor cmd+args" in big-endian.
-6. X bytes of "decompressor cmd+args" (defined by previous value).
-7. 8 bytes 64-bit unsigned integer "location of filename in this archive file".
-8. 8 bytes 64-bit unsigned integer "size of filename in this archive file".
-
-Note that if archiving without compressor/decompressor, the byte values for
-them will be 0 and there will be no strings for the compressor/decompressor
-commands (lines 4 and 6 in previous per-file entry will not exist).
-
-The remaining bytes in the file are the files to be included in the archive file
-concatenated together. Their locations and sizes should match what was listed
-before.
+2. X bytes of filename (length defined by previous value).
+3. 8 bytes 64-bit unsigned integer "size of filename in this archive file".
+4. X bytes file data (length defined by previous value).