On 10/04/12 15:30, Mark Cave-Ayland wrote:
So by reducing s_ofmem_data, the main component is now the size of the Forth dictionary. Hmmm I've had an idea though - we could compress the dictionary, and then decompress/relocate into another set of OFMEM-allocated memory in a similar way so that the entire dictionary doesn't have to be part of the image.
For example:
$ ls -l obj-sparc64/openbios-sparc64.dict -rw-r--r-- 1 build build 181560 Apr 10 15:08 obj-sparc64/openbios-sparc64.dict
Now we need to allocate 512K in total within the image in order to allow for new entries created by bootloaders etc. If we compress the image aswell, e.g. using gzip:
$ ls -l obj-sparc64/openbios-sparc64.dict.gz -rw-r--r-- 1 build build 37933 Apr 10 15:08 obj-sparc64/openbios-sparc64.dict.gz
Then we can dramatically reduce the dictionary usage within the file too. I wonder if we could incorporate a simple decompressor based upon something like pdlzip (http://lzip.nongnu.org/pdlzip.html) to perform LZMA decompression/relocation on the dictionary early within the startup process?
Actually, it seems as if zlib contains a miniature inflator called puff which seems license-friendly and designed for embedded applications:
/* puff.h Copyright (C) 2002-2010 Mark Adler, all rights reserved version 2.2, 25 Apr 2010
This software is provided 'as-is', without any express or implied warranty. In no event will the author be held liable for any damages arising from the use of this software.
Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions:
1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgment in the product documentation would be appreciated but is not required. 2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software. 3. This notice may not be removed or altered from any source distribution.
Mark Adler madler@alumni.caltech.edu */
Does anyone see any reason why we couldn't use this code within OpenBIOS to decompress the Forth dictionary in OFMEM-allocated memory at runtime? I think with a little bit of extra work we could simply use gzip on the command line in order to compress the dictionary at build time.
ATB,
Mark.