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src/Source/LibJPEG/install.txt  view on Meta::CPAN

such conversion to all the files EXCEPT those whose names begin with "test".
The test files contain binary data; if you change them in any way then the
self-test will give bad results.

Please check the last section of this file to see if there are hints for the
specific machine or compiler you are using.


CONFIGURING THE SOFTWARE
========================

To configure the IJG code for your system, you need to create two files:
  * jconfig.h: contains values for system-dependent #define symbols.
  * Makefile: controls the compilation process.
(On a non-Unix machine, you may create "project files" or some other
substitute for a Makefile.  jconfig.h is needed in any environment.)

We provide three different ways to generate these files:
  * On a Unix system, you can just run the "configure" script.
  * We provide sample jconfig files and makefiles for popular machines;
    if your machine matches one of the samples, just copy the right sample
    files to jconfig.h and Makefile.
  * If all else fails, read the instructions below and make your own files.


Configuring the software using the automatic "configure" script
---------------------------------------------------------------

If you are on a Unix machine, you can just type
	./configure
and let the configure script construct appropriate configuration files.
If you're using "csh" on an old version of System V, you might need to type
	sh configure
instead to prevent csh from trying to execute configure itself.
Expect configure to run for a few minutes, particularly on slower machines;
it works by compiling a series of test programs.

Configure was created with GNU Autoconf and it follows the usual conventions
for GNU configure scripts.  It makes a few assumptions that you may want to
override.  You can do this by providing optional switches to configure:

* Configure will build both static and shared libraries, if possible.
If you want to build libjpeg only as a static library, say
	./configure --disable-shared
If you want to build libjpeg only as a shared library, say
	./configure --disable-static
Configure uses GNU libtool to take care of system-dependent shared library
building methods.

* Configure will use gcc (GNU C compiler) if it's available, otherwise cc.
To force a particular compiler to be selected, use the CC option, for example
	./configure CC='cc'
The same method can be used to include any unusual compiler switches.
For example, on HP-UX you probably want to say
	./configure CC='cc -Aa'
to get HP's compiler to run in ANSI mode.

* The default CFLAGS setting is "-g" for non-gcc compilers, "-g -O2" for gcc.
You can override this by saying, for example,
	./configure CFLAGS='-O2'
if you want to compile without debugging support.

* Configure will set up the makefile so that "make install" will install files
into /usr/local/bin, /usr/local/man, etc.  You can specify an installation
prefix other than "/usr/local" by giving configure the option "--prefix=PATH".

* If you don't have a lot of swap space, you may need to enable the IJG
software's internal virtual memory mechanism.  To do this, give the option
"--enable-maxmem=N" where N is the default maxmemory limit in megabytes.
This is discussed in more detail under "Selecting a memory manager", below.
You probably don't need to worry about this on reasonably-sized Unix machines,
unless you plan to process very large images.

Configure has some other features that are useful if you are cross-compiling
or working in a network of multiple machine types; but if you need those
features, you probably already know how to use them.


Configuring the software using one of the supplied jconfig and makefile files
-----------------------------------------------------------------------------

If you have one of these systems, you can just use the provided configuration
files:

Makefile	jconfig file	System and/or compiler

makefile.manx	jconfig.manx	Amiga, Manx Aztec C
makefile.sas	jconfig.sas	Amiga, SAS C
makeproj.mac	jconfig.mac	Apple Macintosh, Metrowerks CodeWarrior
mak*jpeg.st	jconfig.st	Atari ST/STE/TT, Pure C or Turbo C
makefile.bcc	jconfig.bcc	MS-DOS or OS/2, Borland C
makefile.dj	jconfig.dj	MS-DOS, DJGPP (Delorie's port of GNU C)
makefile.mc6	jconfig.mc6	MS-DOS, Microsoft C (16-bit only)
makefile.wat	jconfig.wat	MS-DOS, OS/2, or Windows NT, Watcom C
makefile.vc	jconfig.vc	Windows NT/95, MS Visual C++
make*.vc6	jconfig.vc	Windows NT/95, MS Visual C++ 6
make*.v10	jconfig.vc	Windows NT/95, MS Visual C++ 2010 (v10)
makefile.mms	jconfig.vms	Digital VMS, with MMS software
makefile.vms	jconfig.vms	Digital VMS, without MMS software

Copy the proper jconfig file to jconfig.h and the makefile to Makefile (or
whatever your system uses as the standard makefile name).  For more info see
the appropriate system-specific hints section near the end of this file.


Configuring the software by hand
--------------------------------

First, generate a jconfig.h file.  If you are moderately familiar with C,
the comments in jconfig.txt should be enough information to do this; just
copy jconfig.txt to jconfig.h and edit it appropriately.  Otherwise, you may
prefer to use the ckconfig.c program.  You will need to compile and execute
ckconfig.c by hand --- we hope you know at least enough to do that.
ckconfig.c may not compile the first try (in fact, the whole idea is for it
to fail if anything is going to).  If you get compile errors, fix them by
editing ckconfig.c according to the directions given in ckconfig.c.  Once
you get it to run, it will write a suitable jconfig.h file, and will also
print out some advice about which makefile to use.

You may also want to look at the canned jconfig files, if there is one for a
system similar to yours.

src/Source/LibJPEG/install.txt  view on Meta::CPAN

work area to hold the comment text.  If your C library's malloc can't
handle that, reduce MAX_COM_LENGTH as necessary in wrjpgcom.c.

Most MS-DOS compilers treat stdin/stdout as text files, so you must use
two-file command line style.  But if your compiler has either fdopen() or
setmode(), you can use one-file style if you like.  To do this, define
USE_SETMODE or USE_FDOPEN so that stdin/stdout will be set to binary mode.
(USE_SETMODE seems to work with more DOS compilers than USE_FDOPEN.)  You
should test that I/O through stdin/stdout produces the same results as I/O
to explicitly named files... the "make test" procedures in the supplied
makefiles do NOT use stdin/stdout.


MS-DOS, generic comments for 32-bit compilers:

None of the above comments about memory models apply if you are using a
32-bit flat-memory-space environment, such as DJGPP or Watcom C.  (And you
should use one if you have it, as performance will be much better than
8086-compatible code!)  For flat-memory-space compilers, do NOT define
NEED_FAR_POINTERS, and do NOT use jmemdos.c.  Use jmemnobs.c if the
environment supplies adequate virtual memory, otherwise use jmemansi.c or
jmemname.c.

You'll still need to be careful about binary I/O through stdin/stdout.
See the last paragraph of the previous section.


MS-DOS, Borland C:

Be sure to convert all the source files to DOS text format (CR/LF newlines).
Although Borland C will often work OK with unmodified Unix (LF newlines)
source files, sometimes it will give bogus compile errors.
"Illegal character '#'" is the most common such error.  (This is true with
Borland C 3.1, but perhaps is fixed in newer releases.)

If you want one-file command line style, just undefine TWO_FILE_COMMANDLINE.
jconfig.bcc already includes #define USE_SETMODE to make this work.
(fdopen does not work correctly.)


MS-DOS, Microsoft C:

makefile.mc6 works with Microsoft C, DOS Visual C++, etc.  It should only
be used if you want to build a 16-bit (small or medium memory model) program.

If you want one-file command line style, just undefine TWO_FILE_COMMANDLINE.
jconfig.mc6 already includes #define USE_SETMODE to make this work.
(fdopen does not work correctly.)

Note that this makefile assumes that the working copy of itself is called
"makefile".  If you want to call it something else, say "makefile.mak",
be sure to adjust the dependency line that reads "$(RFILE) : makefile".
Otherwise the make will fail because it doesn't know how to create "makefile".
Worse, some releases of Microsoft's make utilities give an incorrect error
message in this situation.

Old versions of MS C fail with an "out of macro expansion space" error
because they can't cope with the macro TRACEMS8 (defined in jerror.h).
If this happens to you, the easiest solution is to change TRACEMS8 to
expand to nothing.  You'll lose the ability to dump out JPEG coefficient
tables with djpeg -debug -debug, but at least you can compile.

Original MS C 6.0 is very buggy; it compiles incorrect code unless you turn
off optimization entirely (remove -O from CFLAGS).  6.00A is better, but it
still generates bad code if you enable loop optimizations (-Ol or -Ox).

MS C 8.0 crashes when compiling jquant1.c with optimization switch /Oo ...
which is on by default.  To work around this bug, compile that one file
with /Oo-.


Microsoft Windows (all versions), generic comments:

Some Windows system include files define typedef boolean as "unsigned char".
The IJG code also defines typedef boolean, but we make it an "enum" by default.
This doesn't affect the IJG programs because we don't import those Windows
include files.  But if you use the JPEG library in your own program, and some
of your program's files import one definition of boolean while some import the
other, you can get all sorts of mysterious problems.  A good preventive step
is to make the IJG library use "unsigned char" for boolean.  To do that,
add something like this to your jconfig.h file:
	/* Define "boolean" as unsigned char, not enum, per Windows custom */
	#ifndef __RPCNDR_H__	/* don't conflict if rpcndr.h already read */
	typedef unsigned char boolean;
	#endif
	#ifndef FALSE		/* in case these macros already exist */
	#define FALSE	0	/* values of boolean */
	#endif
	#ifndef TRUE
	#define TRUE	1
	#endif
	#define HAVE_BOOLEAN	/* prevent jmorecfg.h from redefining it */
(This is already in jconfig.vc, by the way.)

windef.h contains the declarations
	#define far
	#define FAR far
Since jmorecfg.h tries to define FAR as empty, you may get a compiler
warning if you include both jpeglib.h and windef.h (which windows.h
includes).  To suppress the warning, you can put "#ifndef FAR"/"#endif"
around the line "#define FAR" in jmorecfg.h.
(Something like this is already in jmorecfg.h, by the way.)

When using the library in a Windows application, you will almost certainly
want to modify or replace the error handler module jerror.c, since our
default error handler does a couple of inappropriate things:
  1. it tries to write error and warning messages on stderr;
  2. in event of a fatal error, it exits by calling exit().

A simple stopgap solution for problem 1 is to replace the line
	fprintf(stderr, "%s\n", buffer);
(in output_message in jerror.c) with
	MessageBox(GetActiveWindow(),buffer,"JPEG Error",MB_OK|MB_ICONERROR);
It's highly recommended that you at least do that much, since otherwise
error messages will disappear into nowhere.  (Beginning with IJG v6b, this
code is already present in jerror.c; just define USE_WINDOWS_MESSAGEBOX in
jconfig.h to enable it.)

The proper solution for problem 2 is to return control to your calling
application after a library error.  This can be done with the setjmp/longjmp
technique discussed in libjpeg.txt and illustrated in example.c.  (NOTE: