README.chromium

Name: zlib
URL: http://zlib.net/
Version: 1.2.5
Security Critical: yes
License: Custom license
License Android Compatible: yes

Description:
General purpose compression library

Local Modifications:
A few minor changes, all marked with "Google":
- Added #ifdefs to avoid compile warnings when NO_GZCOMPRESS is defined.
- Removed use of strerror for WinCE in gzio.c.
- Added 'int z_errno' global for WinCE, to which 'errno' is defined in zutil.h.
- Added 'mozzconf.h' to mangle the function names.
- Added logic in zlib.h to undef our earlier mangles when defaulting to 64 bit offset versions of API.
The 'google.patch' file represents our changes from the original zlib-1.2.5.

A more significant change to support mixed-source data compression. See
crbug.com/139744 and mixed-source.patch.

Integrated Intel SIMD optimisations from: https://github.com/jtkukunas/zlib/
and modified to accomodate the older version and existing changes in tree.

This introduces new files: simd_stub.c, crc_folding.c, fill_window_sse.c and
x86.[ch]. All but the latter are built into a static library to allow the
compiler to use the desired instructions only when valid. The latter version is
only built on x86 (32-bit and 64-bit) systems with it's functionality stubbed
on the others.

Other changes to accomodate:
- fill_window() implementation calls into _sse() variant when supported and the
  original implementation renamed to _c()
- read_buf was moved from local to ZLIB_INTERNAL for fill_window_sse.c to use
- INSERT_STRING macro was made a function, insert_string() and an implementation using CRC instruction added
- some crc funcionality moved into crc32.c