source: rtems-graphics-toolkit/jpeg-8d/install.txt @ 86b99f7

Last change on this file since 86b99f7 was 86b99f7, checked in by Alexandru-Sever Horin <alex.sever.h@…>, on Aug 1, 2012 at 10:40:32 PM

Added jpeg-8d version. Made modifications to compile for RTEMS, without man or binaries

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1INSTALLATION INSTRUCTIONS for the Independent JPEG Group's JPEG software
2
3Copyright (C) 1991-2011, Thomas G. Lane, Guido Vollbeding.
4This file is part of the Independent JPEG Group's software.
5For conditions of distribution and use, see the accompanying README file.
6
7
8This file explains how to configure and install the IJG software.  We have
9tried to make this software extremely portable and flexible, so that it can be
10adapted to almost any environment.  The downside of this decision is that the
11installation process is complicated.  We have provided shortcuts to simplify
12the task on common systems.  But in any case, you will need at least a little
13familiarity with C programming and program build procedures for your system.
14
15If you are only using this software as part of a larger program, the larger
16program's installation procedure may take care of configuring the IJG code.
17For example, Ghostscript's installation script will configure the IJG code.
18You don't need to read this file if you just want to compile Ghostscript.
19
20If you are on a Unix machine, you may not need to read this file at all.
21Try doing
22        ./configure
23        make
24        make test
25If that doesn't complain, do
26        make install
27(better do "make -n install" first to see if the makefile will put the files
28where you want them).  Read further if you run into snags or want to customize
29the code for your system.
30
31
32TABLE OF CONTENTS
33-----------------
34
35Before you start
36Configuring the software:
37        using the automatic "configure" script
38        using one of the supplied jconfig and makefile files
39        by hand
40Building the software
41Testing the software
42Installing the software
43Optional stuff
44Optimization
45Hints for specific systems
46
47
48BEFORE YOU START
49================
50
51Before installing the software you must unpack the distributed source code.
52Since you are reading this file, you have probably already succeeded in this
53task.  However, there is a potential for error if you needed to convert the
54files to the local standard text file format (for example, if you are on
55MS-DOS you may have converted LF end-of-line to CR/LF).  You must apply
56such conversion to all the files EXCEPT those whose names begin with "test".
57The test files contain binary data; if you change them in any way then the
58self-test will give bad results.
59
60Please check the last section of this file to see if there are hints for the
61specific machine or compiler you are using.
62
63
64CONFIGURING THE SOFTWARE
65========================
66
67To configure the IJG code for your system, you need to create two files:
68  * jconfig.h: contains values for system-dependent #define symbols.
69  * Makefile: controls the compilation process.
70(On a non-Unix machine, you may create "project files" or some other
71substitute for a Makefile.  jconfig.h is needed in any environment.)
72
73We provide three different ways to generate these files:
74  * On a Unix system, you can just run the "configure" script.
75  * We provide sample jconfig files and makefiles for popular machines;
76    if your machine matches one of the samples, just copy the right sample
77    files to jconfig.h and Makefile.
78  * If all else fails, read the instructions below and make your own files.
79
80
81Configuring the software using the automatic "configure" script
82---------------------------------------------------------------
83
84If you are on a Unix machine, you can just type
85        ./configure
86and let the configure script construct appropriate configuration files.
87If you're using "csh" on an old version of System V, you might need to type
88        sh configure
89instead to prevent csh from trying to execute configure itself.
90Expect configure to run for a few minutes, particularly on slower machines;
91it works by compiling a series of test programs.
92
93Configure was created with GNU Autoconf and it follows the usual conventions
94for GNU configure scripts.  It makes a few assumptions that you may want to
95override.  You can do this by providing optional switches to configure:
96
97* Configure will build both static and shared libraries, if possible.
98If you want to build libjpeg only as a static library, say
99        ./configure --disable-shared
100If you want to build libjpeg only as a shared library, say
101        ./configure --disable-static
102Configure uses GNU libtool to take care of system-dependent shared library
103building methods.
104
105* Configure will use gcc (GNU C compiler) if it's available, otherwise cc.
106To force a particular compiler to be selected, use the CC option, for example
107        ./configure CC='cc'
108The same method can be used to include any unusual compiler switches.
109For example, on HP-UX you probably want to say
110        ./configure CC='cc -Aa'
111to get HP's compiler to run in ANSI mode.
112
113* The default CFLAGS setting is "-g" for non-gcc compilers, "-g -O2" for gcc.
114You can override this by saying, for example,
115        ./configure CFLAGS='-O2'
116if you want to compile without debugging support.
117
118* Configure will set up the makefile so that "make install" will install files
119into /usr/local/bin, /usr/local/man, etc.  You can specify an installation
120prefix other than "/usr/local" by giving configure the option "--prefix=PATH".
121
122* If you don't have a lot of swap space, you may need to enable the IJG
123software's internal virtual memory mechanism.  To do this, give the option
124"--enable-maxmem=N" where N is the default maxmemory limit in megabytes.
125This is discussed in more detail under "Selecting a memory manager", below.
126You probably don't need to worry about this on reasonably-sized Unix machines,
127unless you plan to process very large images.
128
129Configure has some other features that are useful if you are cross-compiling
130or working in a network of multiple machine types; but if you need those
131features, you probably already know how to use them.
132
133
134Configuring the software using one of the supplied jconfig and makefile files
135-----------------------------------------------------------------------------
136
137If you have one of these systems, you can just use the provided configuration
138files:
139
140Makefile        jconfig file    System and/or compiler
141
142makefile.manx   jconfig.manx    Amiga, Manx Aztec C
143makefile.sas    jconfig.sas     Amiga, SAS C
144makeproj.mac    jconfig.mac     Apple Macintosh, Metrowerks CodeWarrior
145mak*jpeg.st     jconfig.st      Atari ST/STE/TT, Pure C or Turbo C
146makefile.bcc    jconfig.bcc     MS-DOS or OS/2, Borland C
147makefile.dj     jconfig.dj      MS-DOS, DJGPP (Delorie's port of GNU C)
148makefile.mc6    jconfig.mc6     MS-DOS, Microsoft C (16-bit only)
149makefile.wat    jconfig.wat     MS-DOS, OS/2, or Windows NT, Watcom C
150makefile.vc     jconfig.vc      Windows NT/95, MS Visual C++
151make*.vc6       jconfig.vc      Windows NT/95, MS Visual C++ 6
152make*.v10       jconfig.vc      Windows NT/95, MS Visual C++ 2010 (v10)
153makefile.mms    jconfig.vms     Digital VMS, with MMS software
154makefile.vms    jconfig.vms     Digital VMS, without MMS software
155
156Copy the proper jconfig file to jconfig.h and the makefile to Makefile (or
157whatever your system uses as the standard makefile name).  For more info see
158the appropriate system-specific hints section near the end of this file.
159
160
161Configuring the software by hand
162--------------------------------
163
164First, generate a jconfig.h file.  If you are moderately familiar with C,
165the comments in jconfig.txt should be enough information to do this; just
166copy jconfig.txt to jconfig.h and edit it appropriately.  Otherwise, you may
167prefer to use the ckconfig.c program.  You will need to compile and execute
168ckconfig.c by hand --- we hope you know at least enough to do that.
169ckconfig.c may not compile the first try (in fact, the whole idea is for it
170to fail if anything is going to).  If you get compile errors, fix them by
171editing ckconfig.c according to the directions given in ckconfig.c.  Once
172you get it to run, it will write a suitable jconfig.h file, and will also
173print out some advice about which makefile to use.
174
175You may also want to look at the canned jconfig files, if there is one for a
176system similar to yours.
177
178Second, select a makefile and copy it to Makefile (or whatever your system
179uses as the standard makefile name).  The most generic makefiles we provide
180are
181        makefile.ansi:  if your C compiler supports function prototypes
182        makefile.unix:  if not.
183(You have function prototypes if ckconfig.c put "#define HAVE_PROTOTYPES"
184in jconfig.h.)  You may want to start from one of the other makefiles if
185there is one for a system similar to yours.
186
187Look over the selected Makefile and adjust options as needed.  In particular
188you may want to change the CC and CFLAGS definitions.  For instance, if you
189are using GCC, set CC=gcc.  If you had to use any compiler switches to get
190ckconfig.c to work, make sure the same switches are in CFLAGS.
191
192If you are on a system that doesn't use makefiles, you'll need to set up
193project files (or whatever you do use) to compile all the source files and
194link them into executable files cjpeg, djpeg, jpegtran, rdjpgcom, and wrjpgcom.
195See the file lists in any of the makefiles to find out which files go into
196each program.  Note that the provided makefiles all make a "library" file
197libjpeg first, but you don't have to do that if you don't want to; the file
198lists identify which source files are actually needed for compression,
199decompression, or both.  As a last resort, you can make a batch script that
200just compiles everything and links it all together; makefile.vms is an example
201of this (it's for VMS systems that have no make-like utility).
202
203Here are comments about some specific configuration decisions you'll
204need to make:
205
206Command line style
207------------------
208
209These programs can use a Unix-like command line style which supports
210redirection and piping, like this:
211        cjpeg inputfile >outputfile
212        cjpeg <inputfile >outputfile
213        source program | cjpeg >outputfile
214The simpler "two file" command line style is just
215        cjpeg inputfile outputfile
216You may prefer the two-file style, particularly if you don't have pipes.
217
218You MUST use two-file style on any system that doesn't cope well with binary
219data fed through stdin/stdout; this is true for some MS-DOS compilers, for
220example.  If you're not on a Unix system, it's safest to assume you need
221two-file style.  (But if your compiler provides either the Posix-standard
222fdopen() library routine or a Microsoft-compatible setmode() routine, you
223can safely use the Unix command line style, by defining USE_FDOPEN or
224USE_SETMODE respectively.)
225
226To use the two-file style, make jconfig.h say "#define TWO_FILE_COMMANDLINE".
227
228Selecting a memory manager
229--------------------------
230
231The IJG code is capable of working on images that are too big to fit in main
232memory; data is swapped out to temporary files as necessary.  However, the
233code to do this is rather system-dependent.  We provide five different
234memory managers:
235
236* jmemansi.c    This version uses the ANSI-standard library routine tmpfile(),
237                which not all non-ANSI systems have.  On some systems
238                tmpfile() may put the temporary file in a non-optimal
239                location; if you don't like what it does, use jmemname.c.
240
241* jmemname.c    This version creates named temporary files.  For anything
242                except a Unix machine, you'll need to configure the
243                select_file_name() routine appropriately; see the comments
244                near the head of jmemname.c.  If you use this version, define
245                NEED_SIGNAL_CATCHER in jconfig.h to make sure the temp files
246                are removed if the program is aborted.
247
248* jmemnobs.c    (That stands for No Backing Store :-).)  This will compile on
249                almost any system, but it assumes you have enough main memory
250                or virtual memory to hold the biggest images you work with.
251
252* jmemdos.c     This should be used with most 16-bit MS-DOS compilers.
253                See the system-specific notes about MS-DOS for more info.
254                IMPORTANT: if you use this, define USE_MSDOS_MEMMGR in
255                jconfig.h, and include the assembly file jmemdosa.asm in the
256                programs.  The supplied makefiles and jconfig files for
257                16-bit MS-DOS compilers already do both.
258
259* jmemmac.c     Custom version for Apple Macintosh; see the system-specific
260                notes for Macintosh for more info.
261
262To use a particular memory manager, change the SYSDEPMEM variable in your
263makefile to equal the corresponding object file name (for example, jmemansi.o
264or jmemansi.obj for jmemansi.c).
265
266If you have plenty of (real or virtual) main memory, just use jmemnobs.c.
267"Plenty" means about ten bytes for every pixel in the largest images
268you plan to process, so a lot of systems don't meet this criterion.
269If yours doesn't, try jmemansi.c first.  If that doesn't compile, you'll have
270to use jmemname.c; be sure to adjust select_file_name() for local conditions.
271You may also need to change unlink() to remove() in close_backing_store().
272
273Except with jmemnobs.c or jmemmac.c, you need to adjust the DEFAULT_MAX_MEM
274setting to a reasonable value for your system (either by adding a #define for
275DEFAULT_MAX_MEM to jconfig.h, or by adding a -D switch to the Makefile).
276This value limits the amount of data space the program will attempt to
277allocate.  Code and static data space isn't counted, so the actual memory
278needs for cjpeg or djpeg are typically 100 to 150Kb more than the max-memory
279setting.  Larger max-memory settings reduce the amount of I/O needed to
280process a large image, but too large a value can result in "insufficient
281memory" failures.  On most Unix machines (and other systems with virtual
282memory), just set DEFAULT_MAX_MEM to several million and forget it.  At the
283other end of the spectrum, for MS-DOS machines you probably can't go much
284above 300K to 400K.  (On MS-DOS the value refers to conventional memory only.
285Extended/expanded memory is handled separately by jmemdos.c.)
286
287
288BUILDING THE SOFTWARE
289=====================
290
291Now you should be able to compile the software.  Just say "make" (or
292whatever's necessary to start the compilation).  Have a cup of coffee.
293
294Here are some things that could go wrong:
295
296If your compiler complains about undefined structures, you should be able to
297shut it up by putting "#define INCOMPLETE_TYPES_BROKEN" in jconfig.h.
298
299If you have trouble with missing system include files or inclusion of the
300wrong ones, read jinclude.h.  This shouldn't happen if you used configure
301or ckconfig.c to set up jconfig.h.
302
303There are a fair number of routines that do not use all of their parameters;
304some compilers will issue warnings about this, which you can ignore.  There
305are also a few configuration checks that may give "unreachable code" warnings.
306Any other warning deserves investigation.
307
308If you don't have a getenv() library routine, define NO_GETENV.
309
310Also see the system-specific hints, below.
311
312
313TESTING THE SOFTWARE
314====================
315
316As a quick test of functionality we've included a small sample image in
317several forms:
318        testorig.jpg    Starting point for the djpeg tests.
319        testimg.ppm     The output of djpeg testorig.jpg
320        testimg.bmp     The output of djpeg -bmp -colors 256 testorig.jpg
321        testimg.jpg     The output of cjpeg testimg.ppm
322        testprog.jpg    Progressive-mode equivalent of testorig.jpg.
323        testimgp.jpg    The output of cjpeg -progressive -optimize testimg.ppm
324(The first- and second-generation .jpg files aren't identical since the
325default compression parameters are lossy.)  If you can generate duplicates
326of the testimg* files then you probably have working programs.
327
328With most of the makefiles, "make test" will perform the necessary
329comparisons.
330
331If you're using a makefile that doesn't provide the test option, run djpeg
332and cjpeg by hand and compare the output files to testimg* with whatever
333binary file comparison tool you have.  The files should be bit-for-bit
334identical.
335
336If the programs complain "MAX_ALLOC_CHUNK is wrong, please fix", then you
337need to reduce MAX_ALLOC_CHUNK to a value that fits in type size_t.
338Try adding "#define MAX_ALLOC_CHUNK 65520L" to jconfig.h.  A less likely
339configuration error is "ALIGN_TYPE is wrong, please fix": defining ALIGN_TYPE
340as long should take care of that one.
341
342If the cjpeg test run fails with "Missing Huffman code table entry", it's a
343good bet that you needed to define RIGHT_SHIFT_IS_UNSIGNED.  Go back to the
344configuration step and run ckconfig.c.  (This is a good plan for any other
345test failure, too.)
346
347If you are using Unix (one-file) command line style on a non-Unix system,
348it's a good idea to check that binary I/O through stdin/stdout actually
349works.  You should get the same results from "djpeg <testorig.jpg >out.ppm"
350as from "djpeg -outfile out.ppm testorig.jpg".  Note that the makefiles all
351use the latter style and therefore do not exercise stdin/stdout!  If this
352check fails, try recompiling with USE_SETMODE or USE_FDOPEN defined.
353If it still doesn't work, better use two-file style.
354
355If you chose a memory manager other than jmemnobs.c, you should test that
356temporary-file usage works.  Try "djpeg -bmp -colors 256 -max 0 testorig.jpg"
357and make sure its output matches testimg.bmp.  If you have any really large
358images handy, try compressing them with -optimize and/or decompressing with
359-colors 256 to make sure your DEFAULT_MAX_MEM setting is not too large.
360
361NOTE: this is far from an exhaustive test of the JPEG software; some modules,
362such as 1-pass color quantization, are not exercised at all.  It's just a
363quick test to give you some confidence that you haven't missed something
364major.
365
366
367INSTALLING THE SOFTWARE
368=======================
369
370Once you're done with the above steps, you can install the software by
371copying the executable files (cjpeg, djpeg, jpegtran, rdjpgcom, and wrjpgcom)
372to wherever you normally install programs.  On Unix systems, you'll also want
373to put the man pages (cjpeg.1, djpeg.1, jpegtran.1, rdjpgcom.1, wrjpgcom.1)
374in the man-page directory.  The pre-fab makefiles don't support this step
375since there's such a wide variety of installation procedures on different
376systems.
377
378If you generated a Makefile with the "configure" script, you can just say
379        make install
380to install the programs and their man pages into the standard places.
381(You'll probably need to be root to do this.)  We recommend first saying
382        make -n install
383to see where configure thought the files should go.  You may need to edit
384the Makefile, particularly if your system's conventions for man page
385filenames don't match what configure expects.
386
387If you want to install the IJG library itself, for use in compiling other
388programs besides ours, then you need to put the four include files
389        jpeglib.h jerror.h jconfig.h jmorecfg.h
390into your include-file directory, and put the library file libjpeg.a
391(extension may vary depending on system) wherever library files go.
392If you generated a Makefile with "configure", it will do what it thinks
393is the right thing if you say
394        make install-lib
395
396
397OPTIONAL STUFF
398==============
399
400Progress monitor:
401
402If you like, you can #define PROGRESS_REPORT (in jconfig.h) to enable display
403of percent-done progress reports.  The routine provided in cdjpeg.c merely
404prints percentages to stderr, but you can customize it to do something
405fancier.
406
407Utah RLE file format support:
408
409We distribute the software with support for RLE image files (Utah Raster
410Toolkit format) disabled, because the RLE support won't compile without the
411Utah library.  If you have URT version 3.1 or later, you can enable RLE
412support as follows:
413        1.  #define RLE_SUPPORTED in jconfig.h.
414        2.  Add a -I option to CFLAGS in the Makefile for the directory
415            containing the URT .h files (typically the "include"
416            subdirectory of the URT distribution).
417        3.  Add -L... -lrle to LDLIBS in the Makefile, where ... specifies
418            the directory containing the URT "librle.a" file (typically the
419            "lib" subdirectory of the URT distribution).
420
421Support for 12-bit-deep pixel data:
422
423The JPEG standard allows either 8-bit or 12-bit data precision.  (For color,
424this means 8 or 12 bits per channel, of course.)  If you need to work with
425deeper than 8-bit data, you can compile the IJG code for 12-bit operation.
426To do so:
427  1. In jmorecfg.h, define BITS_IN_JSAMPLE as 12 rather than 8.
428  2. In jconfig.h, undefine BMP_SUPPORTED, RLE_SUPPORTED, and TARGA_SUPPORTED,
429     because the code for those formats doesn't handle 12-bit data and won't
430     even compile.  (The PPM code does work, as explained below.  The GIF
431     code works too; it scales 8-bit GIF data to and from 12-bit depth
432     automatically.)
433  3. Compile.  Don't expect "make test" to pass, since the supplied test
434     files are for 8-bit data.
435
436Currently, 12-bit support does not work on 16-bit-int machines.
437
438Note that a 12-bit version will not read 8-bit JPEG files, nor vice versa;
439so you'll want to keep around a regular 8-bit compilation as well.
440(Run-time selection of data depth, to allow a single copy that does both,
441is possible but would probably slow things down considerably; it's very low
442on our to-do list.)
443
444The PPM reader (rdppm.c) can read 12-bit data from either text-format or
445binary-format PPM and PGM files.  Binary-format PPM/PGM files which have a
446maxval greater than 255 are assumed to use 2 bytes per sample, MSB first
447(big-endian order).  As of early 1995, 2-byte binary format is not
448officially supported by the PBMPLUS library, but it is expected that a
449future release of PBMPLUS will support it.  Note that the PPM reader will
450read files of any maxval regardless of the BITS_IN_JSAMPLE setting; incoming
451data is automatically rescaled to either maxval=255 or maxval=4095 as
452appropriate for the cjpeg bit depth.
453
454The PPM writer (wrppm.c) will normally write 2-byte binary PPM or PGM
455format, maxval 4095, when compiled with BITS_IN_JSAMPLE=12.  Since this
456format is not yet widely supported, you can disable it by compiling wrppm.c
457with PPM_NORAWWORD defined; then the data is scaled down to 8 bits to make a
458standard 1-byte/sample PPM or PGM file.  (Yes, this means still another copy
459of djpeg to keep around.  But hopefully you won't need it for very long.
460Poskanzer's supposed to get that new PBMPLUS release out Real Soon Now.)
461
462Of course, if you are working with 12-bit data, you probably have it stored
463in some other, nonstandard format.  In that case you'll probably want to
464write your own I/O modules to read and write your format.
465
466Note that a 12-bit version of cjpeg always runs in "-optimize" mode, in
467order to generate valid Huffman tables.  This is necessary because our
468default Huffman tables only cover 8-bit data.
469
470Removing code:
471
472If you need to make a smaller version of the JPEG software, some optional
473functions can be removed at compile time.  See the xxx_SUPPORTED #defines in
474jconfig.h and jmorecfg.h.  If at all possible, we recommend that you leave in
475decoder support for all valid JPEG files, to ensure that you can read anyone's
476output.  Taking out support for image file formats that you don't use is the
477most painless way to make the programs smaller.  Another possibility is to
478remove some of the DCT methods: in particular, the "IFAST" method may not be
479enough faster than the others to be worth keeping on your machine.  (If you
480do remove ISLOW or IFAST, be sure to redefine JDCT_DEFAULT or JDCT_FASTEST
481to a supported method, by adding a #define in jconfig.h.)
482
483
484OPTIMIZATION
485============
486
487Unless you own a Cray, you'll probably be interested in making the JPEG
488software go as fast as possible.  This section covers some machine-dependent
489optimizations you may want to try.  We suggest that before trying any of
490this, you first get the basic installation to pass the self-test step.
491Repeat the self-test after any optimization to make sure that you haven't
492broken anything.
493
494The integer DCT routines perform a lot of multiplications.  These
495multiplications must yield 32-bit results, but none of their input values
496are more than 16 bits wide.  On many machines, notably the 680x0 and 80x86
497CPUs, a 16x16=>32 bit multiply instruction is faster than a full 32x32=>32
498bit multiply.  Unfortunately there is no portable way to specify such a
499multiplication in C, but some compilers can generate one when you use the
500right combination of casts.  See the MULTIPLYxxx macro definitions in
501jdct.h.  If your compiler makes "int" be 32 bits and "short" be 16 bits,
502defining SHORTxSHORT_32 is fairly likely to work.  When experimenting with
503alternate definitions, be sure to test not only whether the code still works
504(use the self-test), but also whether it is actually faster --- on some
505compilers, alternate definitions may compute the right answer, yet be slower
506than the default.  Timing cjpeg on a large PGM (grayscale) input file is the
507best way to check this, as the DCT will be the largest fraction of the runtime
508in that mode.  (Note: some of the distributed compiler-specific jconfig files
509already contain #define switches to select appropriate MULTIPLYxxx
510definitions.)
511
512If your machine has sufficiently fast floating point hardware, you may find
513that the float DCT method is faster than the integer DCT methods, even
514after tweaking the integer multiply macros.  In that case you may want to
515make the float DCT be the default method.  (The only objection to this is
516that float DCT results may vary slightly across machines.)  To do that, add
517"#define JDCT_DEFAULT JDCT_FLOAT" to jconfig.h.  Even if you don't change
518the default, you should redefine JDCT_FASTEST, which is the method selected
519by djpeg's -fast switch.  Don't forget to update the documentation files
520(usage.txt and/or cjpeg.1, djpeg.1) to agree with what you've done.
521
522If access to "short" arrays is slow on your machine, it may be a win to
523define type JCOEF as int rather than short.  This will cost a good deal of
524memory though, particularly in some multi-pass modes, so don't do it unless
525you have memory to burn and short is REALLY slow.
526
527If your compiler can compile function calls in-line, make sure the INLINE
528macro in jmorecfg.h is defined as the keyword that marks a function
529inline-able.  Some compilers have a switch that tells the compiler to inline
530any function it thinks is profitable (e.g., -finline-functions for gcc).
531Enabling such a switch is likely to make the compiled code bigger but faster.
532
533In general, it's worth trying the maximum optimization level of your compiler,
534and experimenting with any optional optimizations such as loop unrolling.
535(Unfortunately, far too many compilers have optimizer bugs ... be prepared to
536back off if the code fails self-test.)  If you do any experimentation along
537these lines, please report the optimal settings to jpeg-info@jpegclub.org so
538we can mention them in future releases.  Be sure to specify your machine and
539compiler version.
540
541
542HINTS FOR SPECIFIC SYSTEMS
543==========================
544
545We welcome reports on changes needed for systems not mentioned here.  Submit
546'em to jpeg-info@jpegclub.org.  Also, if configure or ckconfig.c is wrong
547about how to configure the JPEG software for your system, please let us know.
548
549
550Acorn RISC OS:
551
552(Thanks to Simon Middleton for these hints on compiling with Desktop C.)
553After renaming the files according to Acorn conventions, take a copy of
554makefile.ansi, change all occurrences of 'libjpeg.a' to 'libjpeg.o' and
555change these definitions as indicated:
556
557CFLAGS= -throwback -IC: -Wn
558LDLIBS=C:o.Stubs
559SYSDEPMEM=jmemansi.o
560LN=Link
561AR=LibFile -c -o
562
563Also add a new line '.c.o:; $(cc) $< $(cflags) -c -o $@'.  Remove the
564lines '$(RM) libjpeg.o' and '$(AR2) libjpeg.o' and the 'jconfig.h'
565dependency section.
566
567Copy jconfig.txt to jconfig.h.  Edit jconfig.h to define TWO_FILE_COMMANDLINE
568and CHAR_IS_UNSIGNED.
569
570Run the makefile using !AMU not !Make.  If you want to use the 'clean' and
571'test' makefile entries then you will have to fiddle with the syntax a bit
572and rename the test files.
573
574
575Amiga:
576
577SAS C 6.50 reportedly is too buggy to compile the IJG code properly.
578A patch to update to 6.51 is available from SAS or AmiNet FTP sites.
579
580The supplied config files are set up to use jmemname.c as the memory
581manager, with temporary files being created on the device named by
582"JPEGTMP:".
583
584
585Atari ST/STE/TT:
586
587Copy the project files makcjpeg.st, makdjpeg.st, maktjpeg.st, and makljpeg.st
588to cjpeg.prj, djpeg.prj, jpegtran.prj, and libjpeg.prj respectively.  The
589project files should work as-is with Pure C.  For Turbo C, change library
590filenames "pc..." to "tc..." in each project file.  Note that libjpeg.prj
591selects jmemansi.c as the recommended memory manager.  You'll probably want to
592adjust the DEFAULT_MAX_MEM setting --- you want it to be a couple hundred K
593less than your normal free memory.  Put "#define DEFAULT_MAX_MEM nnnn" into
594jconfig.h to do this.
595
596To use the 68881/68882 coprocessor for the floating point DCT, add the
597compiler option "-8" to the project files and replace pcfltlib.lib with
598pc881lib.lib in cjpeg.prj and djpeg.prj.  Or if you don't have a
599coprocessor, you may prefer to remove the float DCT code by undefining
600DCT_FLOAT_SUPPORTED in jmorecfg.h (since without a coprocessor, the float
601code will be too slow to be useful).  In that case, you can delete
602pcfltlib.lib from the project files.
603
604Note that you must make libjpeg.lib before making cjpeg.ttp, djpeg.ttp,
605or jpegtran.ttp.  You'll have to perform the self-test by hand.
606
607We haven't bothered to include project files for rdjpgcom and wrjpgcom.
608Those source files should just be compiled by themselves; they don't
609depend on the JPEG library.  You can use the default.prj project file
610of the Pure C distribution to make the programs.
611
612There is a bug in some older versions of the Turbo C library which causes the
613space used by temporary files created with "tmpfile()" not to be freed after
614an abnormal program exit.  If you check your disk afterwards, you will find
615cluster chains that are allocated but not used by a file.  This should not
616happen in cjpeg/djpeg/jpegtran, since we enable a signal catcher to explicitly
617close temp files before exiting.  But if you use the JPEG library with your
618own code, be sure to supply a signal catcher, or else use a different
619system-dependent memory manager.
620
621
622Cray:
623
624Should you be so fortunate as to be running JPEG on a Cray YMP, there is a
625compiler bug in old versions of Cray's Standard C (prior to 3.1).  If you
626still have an old compiler, you'll need to insert a line reading
627"#pragma novector" just before the loop
628    for (i = 1; i <= (int) htbl->bits[l]; i++)
629      huffsize[p++] = (char) l;
630in fix_huff_tbl (in V5beta1, line 204 of jchuff.c and line 176 of jdhuff.c).
631[This bug may or may not still occur with the current IJG code, but it's
632probably a dead issue anyway...]
633
634
635HP-UX:
636
637If you have HP-UX 7.05 or later with the "software development" C compiler,
638you should run the compiler in ANSI mode.  If using the configure script,
639say
640        ./configure CC='cc -Aa'
641(or -Ae if you prefer).  If configuring by hand, use makefile.ansi and add
642"-Aa" to the CFLAGS line in the makefile.
643
644If you have a pre-7.05 system, or if you are using the non-ANSI C compiler
645delivered with a minimum HP-UX system, then you must use makefile.unix
646(and do NOT add -Aa); or just run configure without the CC option.
647
648On HP 9000 series 800 machines, the HP C compiler is buggy in revisions prior
649to A.08.07.  If you get complaints about "not a typedef name", you'll have to
650use makefile.unix, or run configure without the CC option.
651
652
653Macintosh, generic comments:
654
655The supplied user-interface files (cjpeg.c, djpeg.c, etc) are set up to
656provide a Unix-style command line interface.  You can use this interface on
657the Mac by means of the ccommand() library routine provided by Metrowerks
658CodeWarrior or Think C.  This is only appropriate for testing the library,
659however; to make a user-friendly equivalent of cjpeg/djpeg you'd really want
660to develop a Mac-style user interface.  There isn't a complete example
661available at the moment, but there are some helpful starting points:
6621. Sam Bushell's free "To JPEG" applet provides drag-and-drop conversion to
663JPEG under System 7 and later.  This only illustrates how to use the
664compression half of the library, but it does a very nice job of that part.
665The CodeWarrior source code is available from http://www.pobox.com/~jsam.
6662. Jim Brunner prepared a Mac-style user interface for both compression and
667decompression.  Unfortunately, it hasn't been updated since IJG v4, and
668the library's API has changed considerably since then.  Still it may be of
669some help, particularly as a guide to compiling the IJG code under Think C.
670Jim's code is available from the Info-Mac archives, at sumex-aim.stanford.edu
671or mirrors thereof; see file /info-mac/dev/src/jpeg-convert-c.hqx.
672
673jmemmac.c is the recommended memory manager back end for Macintosh.  It uses
674NewPtr/DisposePtr instead of malloc/free, and has a Mac-specific
675implementation of jpeg_mem_available().  It also creates temporary files that
676follow Mac conventions.  (That part of the code relies on System-7-or-later OS
677functions.  See the comments in jmemmac.c if you need to run it on System 6.)
678NOTE that USE_MAC_MEMMGR must be defined in jconfig.h to use jmemmac.c.
679
680You can also use jmemnobs.c, if you don't care about handling images larger
681than available memory.  If you use any memory manager back end other than
682jmemmac.c, we recommend replacing "malloc" and "free" by "NewPtr" and
683"DisposePtr", because Mac C libraries often have peculiar implementations of
684malloc/free.  (For instance, free() may not return the freed space to the
685Mac Memory Manager.  This is undesirable for the IJG code because jmemmgr.c
686already clumps space requests.)
687
688
689Macintosh, Metrowerks CodeWarrior:
690
691The Unix-command-line-style interface can be used by defining USE_CCOMMAND.
692You'll also need to define TWO_FILE_COMMANDLINE to avoid stdin/stdout.
693This means that when using the cjpeg/djpeg programs, you'll have to type the
694input and output file names in the "Arguments" text-edit box, rather than
695using the file radio buttons.  (Perhaps USE_FDOPEN or USE_SETMODE would
696eliminate the problem, but I haven't heard from anyone who's tried it.)
697
698On 680x0 Macs, Metrowerks defines type "double" as a 10-byte IEEE extended
699float.  jmemmgr.c won't like this: it wants sizeof(ALIGN_TYPE) to be a power
700of 2.  Add "#define ALIGN_TYPE long" to jconfig.h to eliminate the complaint.
701
702The supplied configuration file jconfig.mac can be used for your jconfig.h;
703it includes all the recommended symbol definitions.  If you have AppleScript
704installed, you can run the supplied script makeproj.mac to create CodeWarrior
705project files for the library and the testbed applications, then build the
706library and applications.  (Thanks to Dan Sears and Don Agro for this nifty
707hack, which saves us from trying to maintain CodeWarrior project files as part
708of the IJG distribution...)
709
710
711Macintosh, Think C:
712
713The documentation in Jim Brunner's "JPEG Convert" source code (see above)
714includes detailed build instructions for Think C; it's probably somewhat
715out of date for the current release, but may be helpful.
716
717If you want to build the minimal command line version, proceed as follows.
718You'll have to prepare project files for the programs; we don't include any
719in the distribution since they are not text files.  Use the file lists in
720any of the supplied makefiles as a guide.  Also add the ANSI and Unix C
721libraries in a separate segment.  You may need to divide the JPEG files into
722more than one segment; we recommend dividing compression and decompression
723modules.  Define USE_CCOMMAND in jconfig.h so that the ccommand() routine is
724called.  You must also define TWO_FILE_COMMANDLINE because stdin/stdout
725don't handle binary data correctly.
726
727On 680x0 Macs, Think C defines type "double" as a 12-byte IEEE extended float.
728jmemmgr.c won't like this: it wants sizeof(ALIGN_TYPE) to be a power of 2.
729Add "#define ALIGN_TYPE long" to jconfig.h to eliminate the complaint.
730
731jconfig.mac should work as a jconfig.h configuration file for Think C,
732but the makeproj.mac AppleScript script is specific to CodeWarrior.  Sorry.
733
734
735MIPS R3000:
736
737MIPS's cc version 1.31 has a rather nasty optimization bug.  Don't use -O
738if you have that compiler version.  (Use "cc -V" to check the version.)
739Note that the R3000 chip is found in workstations from DEC and others.
740
741
742MS-DOS, generic comments for 16-bit compilers:
743
744The IJG code is designed to work well in 80x86 "small" or "medium" memory
745models (i.e., data pointers are 16 bits unless explicitly declared "far";
746code pointers can be either size).  You may be able to use small model to
747compile cjpeg or djpeg by itself, but you will probably have to use medium
748model for any larger application.  This won't make much difference in
749performance.  You *will* take a noticeable performance hit if you use a
750large-data memory model, and you should avoid "huge" model if at all
751possible.  Be sure that NEED_FAR_POINTERS is defined in jconfig.h if you use
752a small-data memory model; be sure it is NOT defined if you use a large-data
753model.  (The supplied makefiles and jconfig files for Borland and Microsoft C
754compile in medium model and define NEED_FAR_POINTERS.)
755
756The DOS-specific memory manager, jmemdos.c, should be used if possible.
757It needs some assembly-code routines which are in jmemdosa.asm; make sure
758your makefile assembles that file and includes it in the library.  If you
759don't have a suitable assembler, you can get pre-assembled object files for
760jmemdosa by FTP from ftp.uu.net:/graphics/jpeg/jdosaobj.zip.  (DOS-oriented
761distributions of the IJG source code often include these object files.)
762
763When using jmemdos.c, jconfig.h must define USE_MSDOS_MEMMGR and must set
764MAX_ALLOC_CHUNK to less than 64K (65520L is a typical value).  If your
765C library's far-heap malloc() can't allocate blocks that large, reduce
766MAX_ALLOC_CHUNK to whatever it can handle.
767
768If you can't use jmemdos.c for some reason --- for example, because you
769don't have an assembler to assemble jmemdosa.asm --- you'll have to fall
770back to jmemansi.c or jmemname.c.  You'll probably still need to set
771MAX_ALLOC_CHUNK in jconfig.h, because most DOS C libraries won't malloc()
772more than 64K at a time.  IMPORTANT: if you use jmemansi.c or jmemname.c,
773you will have to compile in a large-data memory model in order to get the
774right stdio library.  Too bad.
775
776wrjpgcom needs to be compiled in large model, because it malloc()s a 64KB
777work area to hold the comment text.  If your C library's malloc can't
778handle that, reduce MAX_COM_LENGTH as necessary in wrjpgcom.c.
779
780Most MS-DOS compilers treat stdin/stdout as text files, so you must use
781two-file command line style.  But if your compiler has either fdopen() or
782setmode(), you can use one-file style if you like.  To do this, define
783USE_SETMODE or USE_FDOPEN so that stdin/stdout will be set to binary mode.
784(USE_SETMODE seems to work with more DOS compilers than USE_FDOPEN.)  You
785should test that I/O through stdin/stdout produces the same results as I/O
786to explicitly named files... the "make test" procedures in the supplied
787makefiles do NOT use stdin/stdout.
788
789
790MS-DOS, generic comments for 32-bit compilers:
791
792None of the above comments about memory models apply if you are using a
79332-bit flat-memory-space environment, such as DJGPP or Watcom C.  (And you
794should use one if you have it, as performance will be much better than
7958086-compatible code!)  For flat-memory-space compilers, do NOT define
796NEED_FAR_POINTERS, and do NOT use jmemdos.c.  Use jmemnobs.c if the
797environment supplies adequate virtual memory, otherwise use jmemansi.c or
798jmemname.c.
799
800You'll still need to be careful about binary I/O through stdin/stdout.
801See the last paragraph of the previous section.
802
803
804MS-DOS, Borland C:
805
806Be sure to convert all the source files to DOS text format (CR/LF newlines).
807Although Borland C will often work OK with unmodified Unix (LF newlines)
808source files, sometimes it will give bogus compile errors.
809"Illegal character '#'" is the most common such error.  (This is true with
810Borland C 3.1, but perhaps is fixed in newer releases.)
811
812If you want one-file command line style, just undefine TWO_FILE_COMMANDLINE.
813jconfig.bcc already includes #define USE_SETMODE to make this work.
814(fdopen does not work correctly.)
815
816
817MS-DOS, Microsoft C:
818
819makefile.mc6 works with Microsoft C, DOS Visual C++, etc.  It should only
820be used if you want to build a 16-bit (small or medium memory model) program.
821
822If you want one-file command line style, just undefine TWO_FILE_COMMANDLINE.
823jconfig.mc6 already includes #define USE_SETMODE to make this work.
824(fdopen does not work correctly.)
825
826Note that this makefile assumes that the working copy of itself is called
827"makefile".  If you want to call it something else, say "makefile.mak",
828be sure to adjust the dependency line that reads "$(RFILE) : makefile".
829Otherwise the make will fail because it doesn't know how to create "makefile".
830Worse, some releases of Microsoft's make utilities give an incorrect error
831message in this situation.
832
833Old versions of MS C fail with an "out of macro expansion space" error
834because they can't cope with the macro TRACEMS8 (defined in jerror.h).
835If this happens to you, the easiest solution is to change TRACEMS8 to
836expand to nothing.  You'll lose the ability to dump out JPEG coefficient
837tables with djpeg -debug -debug, but at least you can compile.
838
839Original MS C 6.0 is very buggy; it compiles incorrect code unless you turn
840off optimization entirely (remove -O from CFLAGS).  6.00A is better, but it
841still generates bad code if you enable loop optimizations (-Ol or -Ox).
842
843MS C 8.0 crashes when compiling jquant1.c with optimization switch /Oo ...
844which is on by default.  To work around this bug, compile that one file
845with /Oo-.
846
847
848Microsoft Windows (all versions), generic comments:
849
850Some Windows system include files define typedef boolean as "unsigned char".
851The IJG code also defines typedef boolean, but we make it "int" by default.
852This doesn't affect the IJG programs because we don't import those Windows
853include files.  But if you use the JPEG library in your own program, and some
854of your program's files import one definition of boolean while some import the
855other, you can get all sorts of mysterious problems.  A good preventive step
856is to make the IJG library use "unsigned char" for boolean.  To do that,
857add something like this to your jconfig.h file:
858        /* Define "boolean" as unsigned char, not int, per Windows custom */
859        #ifndef __RPCNDR_H__    /* don't conflict if rpcndr.h already read */
860        typedef unsigned char boolean;
861        #endif
862        #define HAVE_BOOLEAN    /* prevent jmorecfg.h from redefining it */
863(This is already in jconfig.vc, by the way.)
864
865windef.h contains the declarations
866        #define far
867        #define FAR far
868Since jmorecfg.h tries to define FAR as empty, you may get a compiler
869warning if you include both jpeglib.h and windef.h (which windows.h
870includes).  To suppress the warning, you can put "#ifndef FAR"/"#endif"
871around the line "#define FAR" in jmorecfg.h.
872(Something like this is already in jmorecfg.h, by the way.)
873
874When using the library in a Windows application, you will almost certainly
875want to modify or replace the error handler module jerror.c, since our
876default error handler does a couple of inappropriate things:
877  1. it tries to write error and warning messages on stderr;
878  2. in event of a fatal error, it exits by calling exit().
879
880A simple stopgap solution for problem 1 is to replace the line
881        fprintf(stderr, "%s\n", buffer);
882(in output_message in jerror.c) with
883        MessageBox(GetActiveWindow(),buffer,"JPEG Error",MB_OK|MB_ICONERROR);
884It's highly recommended that you at least do that much, since otherwise
885error messages will disappear into nowhere.  (Beginning with IJG v6b, this
886code is already present in jerror.c; just define USE_WINDOWS_MESSAGEBOX in
887jconfig.h to enable it.)
888
889The proper solution for problem 2 is to return control to your calling
890application after a library error.  This can be done with the setjmp/longjmp
891technique discussed in libjpeg.txt and illustrated in example.c.  (NOTE:
892some older Windows C compilers provide versions of setjmp/longjmp that
893don't actually work under Windows.  You may need to use the Windows system
894functions Catch and Throw instead.)
895
896The recommended memory manager under Windows is jmemnobs.c; in other words,
897let Windows do any virtual memory management needed.  You should NOT use
898jmemdos.c nor jmemdosa.asm under Windows.
899
900For Windows 3.1, we recommend compiling in medium or large memory model;
901for newer Windows versions, use a 32-bit flat memory model.  (See the MS-DOS
902sections above for more info about memory models.)  In the 16-bit memory
903models only, you'll need to put
904        #define MAX_ALLOC_CHUNK 65520L  /* Maximum request to malloc() */
905into jconfig.h to limit allocation chunks to 64Kb.  (Without that, you'd
906have to use huge memory model, which slows things down unnecessarily.)
907jmemnobs.c works without modification in large or flat memory models, but to
908use medium model, you need to modify its jpeg_get_large and jpeg_free_large
909routines to allocate far memory.  In any case, you might like to replace
910its calls to malloc and free with direct calls on Windows memory allocation
911functions.
912
913You may also want to modify jdatasrc.c and jdatadst.c to use Windows file
914operations rather than fread/fwrite.  This is only necessary if your C
915compiler doesn't provide a competent implementation of C stdio functions.
916
917You might want to tweak the RGB_xxx macros in jmorecfg.h so that the library
918will accept or deliver color pixels in BGR sample order, not RGB; BGR order
919is usually more convenient under Windows.  Note that this change will break
920the sample applications cjpeg/djpeg, but the library itself works fine.
921
922
923Many people want to convert the IJG library into a DLL.  This is reasonably
924straightforward, but watch out for the following:
925
926  1. Don't try to compile as a DLL in small or medium memory model; use
927large model, or even better, 32-bit flat model.  Many places in the IJG code
928assume the address of a local variable is an ordinary (not FAR) pointer;
929that isn't true in a medium-model DLL.
930
931  2. Microsoft C cannot pass file pointers between applications and DLLs.
932(See Microsoft Knowledge Base, PSS ID Number Q50336.)  So jdatasrc.c and
933jdatadst.c don't work if you open a file in your application and then pass
934the pointer to the DLL.  One workaround is to make jdatasrc.c/jdatadst.c
935part of your main application rather than part of the DLL.
936
937  3. You'll probably need to modify the macros GLOBAL() and EXTERN() to
938attach suitable linkage keywords to the exported routine names.  Similarly,
939you'll want to modify METHODDEF() and JMETHOD() to ensure function pointers
940are declared in a way that lets application routines be called back through
941the function pointers.  These macros are in jmorecfg.h.  Typical definitions
942for a 16-bit DLL are:
943        #define GLOBAL(type)            type _far _pascal _loadds _export
944        #define EXTERN(type)            extern type _far _pascal _loadds
945        #define METHODDEF(type)         static type _far _pascal
946        #define JMETHOD(type,methodname,arglist)  \
947                type (_far _pascal *methodname) arglist
948For a 32-bit DLL you may want something like
949        #define GLOBAL(type)            __declspec(dllexport) type
950        #define EXTERN(type)            extern __declspec(dllexport) type
951Although not all the GLOBAL routines are actually intended to be called by
952the application, the performance cost of making them all DLL entry points is
953negligible.
954
955The unmodified IJG library presents a very C-specific application interface,
956so the resulting DLL is only usable from C or C++ applications.  There has
957been some talk of writing wrapper code that would present a simpler interface
958usable from other languages, such as Visual Basic.  This is on our to-do list
959but hasn't been very high priority --- any volunteers out there?
960
961
962Microsoft Windows, Borland C:
963
964The provided jconfig.bcc should work OK in a 32-bit Windows environment,
965but you'll need to tweak it in a 16-bit environment (you'd need to define
966NEED_FAR_POINTERS and MAX_ALLOC_CHUNK).  Beware that makefile.bcc will need
967alteration if you want to use it for Windows --- in particular, you should
968use jmemnobs.c not jmemdos.c under Windows.
969
970Borland C++ 4.5 fails with an internal compiler error when trying to compile
971jdmerge.c in 32-bit mode.  If enough people complain, perhaps Borland will fix
972it.  In the meantime, the simplest known workaround is to add a redundant
973definition of the variable range_limit in h2v1_merged_upsample(), at the head
974of the block that handles odd image width (about line 268 in v6 jdmerge.c):
975  /* If image width is odd, do the last output column separately */
976  if (cinfo->output_width & 1) {
977    register JSAMPLE * range_limit = cinfo->sample_range_limit; /* ADD THIS */
978    cb = GETJSAMPLE(*inptr1);
979Pretty bizarre, especially since the very similar routine h2v2_merged_upsample
980doesn't trigger the bug.
981Recent reports suggest that this bug does not occur with "bcc32a" (the
982Pentium-optimized version of the compiler).
983
984Another report from a user of Borland C 4.5 was that incorrect code (leading
985to a color shift in processed images) was produced if any of the following
986optimization switch combinations were used:
987        -Ot -Og
988        -Ot -Op
989        -Ot -Om
990So try backing off on optimization if you see such a problem.  (Are there
991several different releases all numbered "4.5"??)
992
993
994Microsoft Windows, Microsoft Visual C++:
995
996jconfig.vc should work OK with any Microsoft compiler for a 32-bit memory
997model.  makefile.vc is intended for command-line use.  (If you are using
998the Developer Studio environment, you may prefer the DevStudio project
999files; see below.)
1000
1001IJG JPEG 7 adds extern "C" to jpeglib.h.  This avoids the need to put
1002extern "C" { ... } around #include "jpeglib.h" in your C++ application.
1003You can also force VC++ to treat the library as C++ code by renaming
1004all the *.c files to *.cpp (and adjusting the makefile to match).
1005In this case you also need to define the symbol DONT_USE_EXTERN_C in
1006the configuration to prevent jpeglib.h from using extern "C".
1007
1008
1009Microsoft Windows, Microsoft Visual C++ 6 Developer Studio:
1010
1011We include makefiles that should work as project files in DevStudio 6.0 or
1012later.  There is a library makefile that builds the IJG library as a static
1013Win32 library, and application makefiles that build the sample applications
1014as Win32 console applications.  (Even if you only want the library, we
1015recommend building the applications so that you can run the self-test.)
1016
1017To use:
10181. Open the command prompt, change to the main directory and execute the
1019   command line
1020        NMAKE /f makefile.vc  setup-vc6
1021   This will move jconfig.vc to jconfig.h and makefiles to project files.
1022   (Note that the renaming is critical!)
10232. Open the workspace file jpeg.dsw, build the library project.
1024   (If you are using DevStudio more recent than 6.0, you'll probably
1025   get a message saying that the project files are being updated.)
10263. Open the workspace file apps.dsw, build the application projects.
10274. To perform the self-test, execute the command line
1028        NMAKE /f makefile.vc  test-build
10295. Move the application .exe files from `app`\Release to an
1030   appropriate location on your path.
1031
1032
1033Microsoft Windows, Microsoft Visual C++ 2010 Developer Studio (v10):
1034
1035We include makefiles that should work as project files in Visual Studio
10362010 or later.  There is a library makefile that builds the IJG library
1037as a static Win32 library, and application makefiles that build the sample
1038applications as Win32 console applications.  (Even if you only want the
1039library, we recommend building the applications so that you can run the
1040self-test.)
1041
1042To use:
10431. Open the command prompt, change to the main directory and execute the
1044   command line
1045        NMAKE /f makefile.vc  setup-v10
1046   This will move jconfig.vc to jconfig.h and makefiles to project files.
1047   (Note that the renaming is critical!)
10482. Open the solution file jpeg.sln, build the library project.
1049   (If you are using Visual Studio more recent than 2010 (v10), you'll
1050   probably get a message saying that the project files are being updated.)
10513. Open the solution file apps.sln, build the application projects.
10524. To perform the self-test, execute the command line
1053        NMAKE /f makefile.vc  test-build
10545. Move the application .exe files from `app`\Release to an
1055   appropriate location on your path.
1056
1057Note:
1058There seems to be an optimization bug in the compiler which causes the
1059self-test to fail with the color quantization option.
1060We have disabled optimization for the file jquant2.c in the library
1061project file which causes the self-test to pass properly.
1062
1063
1064OS/2, Borland C++:
1065
1066Watch out for optimization bugs in older Borland compilers; you may need
1067to back off the optimization switch settings.  See the comments in
1068makefile.bcc.
1069
1070
1071SGI:
1072
1073On some SGI systems, you may need to set "AR2= ar -ts" in the Makefile.
1074If you are using configure, you can do this by saying
1075        ./configure RANLIB='ar -ts'
1076This change is not needed on all SGIs.  Use it only if the make fails at the
1077stage of linking the completed programs.
1078
1079On the MIPS R4000 architecture (Indy, etc.), the compiler option "-mips2"
1080reportedly speeds up the float DCT method substantially, enough to make it
1081faster than the default int method (but still slower than the fast int
1082method).  If you use -mips2, you may want to alter the default DCT method to
1083be float.  To do this, put "#define JDCT_DEFAULT JDCT_FLOAT" in jconfig.h.
1084
1085
1086VMS:
1087
1088On an Alpha/VMS system with MMS, be sure to use the "/Marco=Alpha=1"
1089qualifier with MMS when building the JPEG package.
1090
1091VAX/VMS v5.5-1 may have problems with the test step of the build procedure
1092reporting differences when it compares the original and test images.  If the
1093error points to the last block of the files, it is most likely bogus and may
1094be safely ignored.  It seems to be because the files are Stream_LF and
1095Backup/Compare has difficulty with the (presumably) null padded files.
1096This problem was not observed on VAX/VMS v6.1 or AXP/VMS v6.1.
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