jedi-outcast/utils/roq2/libim/imschemes.c
2013-04-22 15:25:59 +10:00

408 lines
6 KiB
C

/**
** $Header: /roq/libim/imschemes.c 1 11/02/99 4:38p Zaphod $
** Copyright (c) 1989-1995 San Diego Supercomputer Center (SDSC)
** a division of General Atomics, San Diego, California, USA
**
** Users and possessors of this source code are hereby granted a
** nonexclusive, royalty-free copyright and design patent license to
** use this code in individual software. License is not granted for
** commercial resale, in whole or in part, without prior written
** permission from SDSC. This source is provided "AS IS" without express
** or implied warranty of any kind.
**
** For further information contact:
** E-Mail: info@sds.sdsc.edu
**
** Surface Mail: Information Center
** San Diego Supercomputer Center
** P.O. Box 85608
** San Diego, CA 92138-5608
** (619) 534-5000
**/
#define HEADER " $Header: /roq/libim/imschemes.c 1 11/02/99 4:38p Zaphod $"
/**
** FILE
** imschemes.c - compression scheme structure declaration
**
** PROJECT
** libim - SDSC image manipulation library
**
** DESCRIPTION
** imschemes.c contains the structure that holds routines/ info for
** reading/ writing encoded files.
**
** PUBLIC CONTENTS
** d =defined constant
** f =function
** m =defined macro
** t =typedef/struct/union
** v =variable
** ? =other
**
** ImGetCompressSchemes f get the list of compression/encoding schemes
**
** PRIVATE CONTENTS
**
** imCompressSchemes v list of compression/encoding schemes
**
**
** HISTORY
** $Log: /roq/libim/imschemes.c $
*
* 1 11/02/99 4:38p Zaphod
* Revision 1.3 1995/06/29 00:28:04 bduggan
* updated copyright year
*
* Revision 1.2 1995/06/16 08:45:42 bduggan
* Took out declarations of schemes. Moved 'em into
* immiscschemes.c
*
* Revision 1.1 1995/05/24 17:05:59 bduggan
* Initial revision
*
**/
//#include <unistd.h>
//#include <sys/wait.h>
#include "im.h"
#include "iminternal.h"
/**
** CODE CREDITS
** Custom development, Brian Duggan, San Diego Supercomputer Center, 1995.
**/
/*
* VARIABLE
* imCompressSchemes
*
* DESCRIPTION
* A list of compression schemes that are supported.
*
* ADDING A NEW SCHEME
*
* Note that here and throughout the library, we try to refer to a file
* compression 'scheme' and an image 'format', and not a compression
* 'format', in order to keep things clear.
*
* Schemes may be added to this list quite easily.
* Here's how to do it:
*
* 1. Add the declaration 'extern ImCompressScheme myscheme'
* 2. Add &myscheme to the list 'imCompressSchemes'.
* 3. Fill up the structure 'myscheme' with the following
* elements:
* - Suffixes of the compressed files
* - The name of the scheme
* - Magic number(s) for the scheme
* - a subroutine that will encode a file
* - a subroutine that will decode a file
*
* Here's an explanation of these structure elements for
* Lempel-Ziv Encoding (.Z files).
*
* 1. Suffix list.
* First we declare imCompressZNames as...
* extern char* imCompressZNames[] = { "Z", NULL };
* Then imCompressZNames is the first element of the ImCompressScheme
* structure.
*
* 2. Scheme name.
* "Lempel-Ziv Encoding" is the second element of the ImCompressScheme
* structure.
*
* 3. Magic numbers
* We make the following declarations:
* static unsigned char imZMagic1[] = { 0x1f, 0x9d };
* static unsigned char imZMagic2[] = { 0x9d, 0x1f };
* static ImFileMagic imZMagic[] =
* {
* { 0, 2, imZMagic1},
* { 0, 2, imZMagic2},
* { 0, 0, NULL}
* };
* This signifies that out files may have one of the following two
* magic numbers: 1) a magic number of length 2 at location 0 (1f9d)
* or 2) a magic number of length 2 at location 0 (9d1f)
*
* 4. Decoding subroutine
* The subroutine 'imZDecode' has the responsibility of decoding the
* the file passed to it, and destroying that file. It must also name
* the new file that it creates, and return that name.
*
* 5. Encoding subroutine.
* The subroutine 'imZEncode' has the responsibility of encoding the
* file passed to it, and destroying that file. It must also name the
* new file that it creates, and return that name.
*
* IMPORTANT:
* The decoding and encoding subroutines will receive a file
* such as /usr/tmp/tmpfile. When creating a new file, the new file name
* should be as close to the old file name as possible. More
* specifically, the file should be in the temp directory. Thus, creating
* a file such as /usr/tmp/tmpfile.z is fine, but creating a file like
* 'tmpfile.z' (in the working directory) is not.
*
* The reason we don't want to create a file in the working
* directory is that the file that is created by these routines will later
* be destroyed.
*
* Many of these routines assume that it's okay to destroy a file
* that has a name similar to the incoming file. e.g. if the incoming
* file is '/usr/tmp/im.zzyxxy', then it's okay to destroy anything named
* '/usr/tmp/im.zzyxxy.Z'.
*
*
* The routines in this file are all simple calls to external programs.
* If you wish to do something more elaborate, then you may want to make a
* seperate file for your structure, and function declarations, and simply
* declare the structure as an 'extern' in this file.
*
*/
#ifndef WIN32
extern ImCompressScheme imCompressuu;
extern ImCompressScheme imCompressGZ;
extern ImCompressScheme imCompressz;
extern ImCompressScheme imCompressZ;
static ImCompressScheme *imCompressSchemes[] =
{
&imCompressuu,
&imCompressGZ,
&imCompressz,
&imCompressZ,
NULL
};
#else
static ImCompressScheme *imCompressSchemes[] =
{
NULL
};
#endif
/*
* FUNCTION
* ImGetCompressSchemes
*
* DESCRIPTION
* Get the list of schemes.
*/
ImCompressScheme**
#ifdef __STDC__
ImGetCompressSchemes( void )
#else
ImGetCompressSchemes( )
#endif
{
return imCompressSchemes;
}