Store 'diff' bytes by run-length encoding zeros....

Improvements to Courgette's version of bsdiff

* Store 'diff' bytes by run-length encoding zeros. This reduces the memory
  needed to store the zeros by ~30MB for chrome.7z.
* Store the control tuple elements in separate streams.  The 'extra_bytes'
  counts are often zero so this brings all the zeros together.

The uncompressed patch file is much smaller due to the run-length encoded
zeros.  It is slightly smaller (3-8%) after compression with lzma.


Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=16343

[huanr, 2009-05-18 18:38:00]

LGTM

http://codereview.chromium.org/115435/diff/1012/1016
File courgette/third_party/bsdiff_apply.cc (right):

http://codereview.chromium.org/115435/diff/1012/1016#newcode72
Line 72: SourceStream* extra_bytes = patch_streams.stream(5);
consider using enum instead of 0-5 since they are used in multiple places.

http://codereview.chromium.org/115435/diff/1012/1016#newcode74
Line 74: //const uint8* control_start = patch_stream->Buffer();
I'd remove it if not needed.