CHDMAN64 - Printable Version

Code:
Major CHD/chdman update: [Aaron Giles]

 The CHD version number has been increased from 4 to 5. This means any

 diff CHDs will no longer work. If you absolutely need to keep the

 data for any existing ones you have, find both the diff CHD and the

 original CHD for the game in question and upgrade using these

 commands:



 rename diff\game.dif diff\game-old.dif chdman copy -i

 diff\game-old.dif -ip roms\game.chd -o diff\game.dif -op roms\game.chd

 -c none



 Specifics regarding this change:



 Defined a new CHD version 5. New features/behaviors of this version:

  * support for up to 4 codecs; each block can use 1 of the 4

  * new LZMA codec, which tends to do better than zlib overall

  * new FLAC codec, primarily used for CDs (but can be applied

     anywhere)

  * upgraded AVHuff codec now uses FLAC for encoding audio

  * new Huffman codec, used to catch more nearly-uncompressable blocks

  * compressed CHDs now use a compressed map for significant savings

  * CHDs now are aware of a "unit" size; each hunk holds 1 or more

     units (in general units map to sectors for hard disks/CDs)

  * diff'ing against a parent now diffs at the unit level, greatly

    improving compression



 Rewrote and modernized chd.c. CHD versions prior to 3 are

 unsupported, and version 3/4 CHDs are only supported for reading.

 Creating a new CHD now leaves the file open.  Added methods to read

 and write at the unit and byte level, removing the need to handle

 this manually. Added metadata access methods that pass astrings and

 dynamic_buffers to simplify the interfaces. A companion class

 chd_compressor now implements full multithreaded compression,

 analyzing and compressing multiple hunks independently in parallel.

 Split the codec implementations out into a separate file chdcodec.*



 Updated harddisk.c and cdrom.c to rely on the caching/byte-level

 read/ write capabilities of the chd_file class. cdrom.c (and chdman)

 now also pad CDs to 4-frame boundaries instead of hunk boundaries,

 ensuring that the same SHA1 hashes are produced regardless of the

 hunk size.



 Rewrote chdman.exe entirely, switching from positional parameters to

 proper options. Use "chdman help" to get a list of commands, and

 "chdman help <command>" to get help for any particular command. Many

 redundant commands were removed now that additional flexibility is

 available. Some basic mappings:



 Old: chdman -createblankhd <out.chd> <cyls> <heads> <secs> New: chdman

 createhd -o <out.chd> -chs <cyls>,<heads>,<secs>



 Old: chdman -createuncomphd <in.raw> <out.chd> .... New: chdman

 createhd -i <in.raw> -o <out.chd> -c none ....



 Old: chdman -verifyfix <in.chd> New: chdman verify -i <in.chd> -f



 Old: chdman -merge <parent.chd> <diff.chd> <out.chd> New: chdman copy

 -i <diff.chd> -ip <parent.chd> -o <out.chd>



 Old: chdman -diff <parent.chd> <compare.chd> <diff.chd> New: chdman

 copy -i <compare.chd> -o <diff.chd> -op <parent.chd>



 Old: chdman -update <in.chd> <out.chd> New: chdman copy -i <in.chd> 

 -o <out.chd>



 Added new core file coretmpl.h to hold core template classes. For now

 just one class, dynamic_array<> is defined, which acts like an array

 of a given object but which can be appended to and/or resized. Also

 defines dynamic_buffer as dynamic_array<UINT8> for holding an

 arbitrary buffer of bytes. Expect to see these used a lot.



 Added new core helper hashing.c/.h which defines classes for each of

 the common hashing methods and creator classes to wrap the

 computation of these hashes. A future work item is to reimplement the

 core emulator hashing code using these.



 Split bit buffer helpers out into C++ classes and into their own

 public header in bitstream.h.



 Updated huffman.c/.h to C++, and changed the interface to make it

 more flexible to use in nonstandard ways. Also added huffman

 compression of the static tree for slightly better compression rates.



 Created flac.c/.h as simplified C++ wrappers around the FLAC

 interface. A future work item is to convert the samples sound device

 to a modern device and leverage this for reading FLAC files.



 Renamed avcomp.* to avhuff.*, updated to C++, and added support for

 FLAC as the audio encoding mechanism. The old huffman audio is still

 supported for decode only.



 Added a variant of core_fload that loads to a dynamic_buffer.



 Tweaked winwork.c a bit to not limit the maximum number of processors

 unless the work queue was created with the WORK_QUEUE_FLAG_HIGH_FREQ

 option. Further adjustments here are likely going to be necessary.