Release Notes

Open Source Used In AsyncOS 8.8 for Cisco Web Security Appliances

jpeg_abort_decompress() or jpeg_abort() if you want to reuse the object.

The previous discussion of aborting compression cycles applies here too.

Mechanics of usage: include files, linking, etc

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Applications using the JPEG library should include the header file jpeglib.h

to obtain declarations of data types and routines. Before including

jpeglib.h, include system headers that define at least the typedefs FILE and

size_t. On ANSI-conforming systems, including <stdio.h> is sufficient; on

older Unix systems, you may need <sys/types.h> to define size_t.

If the application needs to refer to individual JPEG library error codes, also

include jerror.h to define those symbols.

jpeglib.h indirectly includes the files jconfig.h and jmorecfg.h. If you are

installing the JPEG header files in a system directory, you will want to

install all four files: jpeglib.h, jerror.h, jconfig.h, jmorecfg.h.

The most convenient way to include the JPEG code into your executable program

is to prepare a library file ("libjpeg.a", or a corresponding name on non-Unix

machines) and reference it at your link step. If you use only half of the

library (only compression or only decompression), only that much code will be

included from the library, unless your linker is hopelessly brain-damaged.

The supplied makefiles build libjpeg.a automatically (see install.txt).

While you can build the JPEG library as a shared library if the whim strikes

you, we don't really recommend it. The trouble with shared libraries is that

at some point you'll probably try to substitute a new version of the library

without recompiling the calling applications. That generally doesn't work

because the parameter struct declarations usually change with each new

version. In other words, the library's API is *not* guaranteed binary

compatible across versions; we only try to ensure source-code compatibility.

(In hindsight, it might have been smarter to hide the parameter structs from

applications and introduce a ton of access functions instead. Too late now,

however.)

On some systems your application may need to set up a signal handler to ensure

that temporary files are deleted if the program is interrupted. This is most

critical if you are on MS-DOS and use the jmemdos.c memory manager back end;

it will try to grab extended memory for temp files, and that space will NOT be

freed automatically. See cjpeg.c or djpeg.c for an example signal handler.

It may be worth pointing out that the core JPEG library does not actually

require the stdio library: only the default source/destination managers and

error handler need it. You can use the library in a stdio-less environment

if you replace those modules and use jmemnobs.c (or another memory manager of