This is a port of FFTW 3.1 to MSDOS/DJGPP.

1.:     DJGPP specific changes.
        =======================

      - This port will look for configuration files in /dev/env/DJDIR/etc/fftw
        instead of /etc/fftw. This is the only djgpp specific change to the code.
        Please note that this package **needs** long filename support to compile.
        It also needs nemeric tails for 8+3 aliases of long file names enabled.
        This is an issue on Windows 9X where this feature can be enabled and
        disabled. If you are not familiar with this issue, please read the FAQ
        chapter 22.19: "How to Set Up a Dual DOS/Windows Installation".
        With other words, this package can not be compiled on plain DOS.
      - Due to the 8.3 file name length restriction the libraries file names
        have been changed from:
          libfftw3X.a  to  libfftwX.a
        where X stands for the character ``f'' or for nothing. This shoud be
        remembered when reading the info docs or man pages and when linking.
      - The package provides two versions of the library:
          fftwf.a (float precision version)
          fftw.a  (double precision version, default)
        The two libraries use the same header: fftw3.h. In your application
        you will have to replace function calls that starts with "fftw_" with
        "fftwf_" in the case of float. You can use both libraries at the same
        time in your appliction. This means that you can performe certain
        computation with single precision in some function and perform another
        computation with double precision in another or in the same function of
        your application. Please read the info docs to become familiar with
        this library. The package offers a third version of the library, this
        is one with long double precision. This version can not be compiled
        with djgpp because it needs versions of trigonometric functions with
        long double precision.
     -  Also the package can be configured to take advantage of processor
        specific instruction set. The options are:
          --enable-3dnow (fallback for non AMD K7 compatible processor)
          --enable-k7 (enables K7 *and* 3dnow instruction set)
          --enable-sse
          --enable-sse2
        Enabling one of the above options produces SIMD code. 3dnow and sse
        only work with --enable-float and k7 and sse2 only work with double
        precision (the default). To make the package good for all djgpp
        installations, I have disable all processor specific instruction set
        optimizations. This may make the library a little bit slower on modern
        processors but this produces smallest libraries and the programms
        linked against the library will work on all processors platforms. If
        you do not like this and you want to take advantage of your processor
        features, you will have to reconfigure and recompile the package.
        Please read the docs carefully to check if the options you may have
        choosen to recompile the package make sense.
        To compile your application you must add the following linker commands
        to the gcc command line:
         -lfftwX -lm
        The letter X must be replaced by either f for the single precision
        library, or omitted in the case of (default) double precision library.
        If you have an application that needs both libraries the above line
        will look like this:
         -lfftwf -lfftw -lm
        The order of the fftw libraries do not matter but the math library (-lm)
        must always be the last or the link process will fail.
        As usual, all djgpp specific files (config.bat, diffs, readme files, etc.)
        are located in the djgpp/ subdir.


2.:     Installing the binary package.
        ==============================

2.1.:   Copy the binary distribution into the top DJGPP installation directory
        and unzip it running *ONE* of the following commands:
          unzip32 fftw31b.zip      or
          djtarx fftw31b.zip       or
          pkunzip -d fftw31b.zip

2.2.:   If there is no entry for the sed info docs in your dir file, located
        info directory, create one running the command:
          install-info --info-dir=/dev/env/DJDIR/info /dev/env/DJDIR/info/fftw.info

        For futher information about FFTW please read the info docs. The info docs,
        html-, dvi-,  ps-formated docs and the man pages have been updated to reflect
        minor djgpp specific issues. This is not the case for pdf formated docs because
        a needed file to recreate it is missing.


3.:     Building the binaries from sources.
        ===================================

3.1.:   To build the binaries you will need the following binary packages:
          djdev203.zip (patch level 2, see the djdev203.dsm)
          bsh204b.zip, gcc341b.zip, bnu215b.zip, mak3791b.zip,
          fil41b.zip, shl2011b.zip, txt20b.zip, txi47b.zip,
          grep24b.zip, sed411b.zip, dif28b.zip and perl561b.zip.

        All this packages can be found in the v2gnu directory of ftp.delorie.com
        and any mirror. The above cited packages are those ones I have used to
        build the binaries from this sources. Previuos versions of those packages
        may do the job as well but I have not tested this.

3.2.:   Create a temporary directory. Copy the source package: fftw31s.zip
        into the directory and unzip it runnig ONE of the following commands:
          unzip32 fftw31s.zip      or
          djtarx fftw31s.zip       or
          pkunzip -d fftw31s.zip

3.3.:   If for some reason you want to reconfigure the package cd into the top
        srcdir (fftw3.1) and run the following commands:
          del djgpp\config.cache
          make distclean
          djgpp\config

        Please note that you *MUST* delete the config.cache file in the djgpp/
        subdir or you will not really reconfigure the sources because the
        configuration informations will be read from the cache file instead
        of being newly computed.
        You can configure and compile three different libraries. One for single
        precision (float), one for double precision (default) and one for
        long double precision. If you give no option at all you will configure
        and compile the double precision library. With the command:
          djgpp\config --enable-float
        you will create a single/float precision library and running the
        command:
          djgpp\config
        you will create the double library (no option at all produces the double
        precision/default library).
        If you have compiled a library with certain precision and you want to
        compile another version with a different precision you *MUST* run the
        the commands:
          del djgpp\config.cache
          make distclean
        or the new build will fail.

        To build the programs in a directory other than where the sources are,
        you must add the parameter that specifies the source directory,
        e.g:
          x:\src\gnu\fftw3.1\djgpp\config x:/src/gnu/fftw3.1

        Lets assume you want to build the binaries in a directory placed on a
        different drive (z:\build in this case) from where the sources are,
        then you will run the following commands:
          z:
          md \build
          cd \build
          x:\src\gnu\fftw3.1\djgpp\config x:/src/gnu/fftw3.1

        The order of the options and the srcdir option does not matter. You
        *MUST* use forward slashes to specify the source directory.

        The batch file will set same environment variables, make MSDOS specific
        modifications to the Makefile.ins and supply all other needed options
        to the configure script.


3.4.:   To compile the package run from the top srcdir the command:
          make

3.5.:   Now you can run the tests if you like. From the top srcdir run the
        command:
          make check

        Non test should fail.
        You may run more exhaustive tests by changing into the tests/ subdir und
        running the command:
          make bigcheck
        or 
          make paranoid-check
        Both tests takes a lot of time (may be hours) to finish.

3.6.:   To install the binary, info docs and man pages run the following command
        from the top srcdir:
          make install

        This will install the products into your DJGPP installation tree given
        by the default prefix "/dev/env/DJDIR". If you prefer to install them
        into some other directory you will have to set prefix to the appropiate
        value.
        Example:
          make install prefix=z:/some/other/dir




        Send sed specific bug reports to <fftw@fftw.org>.
        Send suggestions and bug reports concerning the DJGPP port
        to comp.os.msdos.djgpp or <djgpp@delorie.com>.

Enjoy.

          Guerrero, Juan Manuel <juan.guerrero@gmx.de>
