TROUBLESHOOTING

=========================================================================
 Troubleshooting
=========================================================================

Here is a list of common problems and potential solutions.

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 Q1     When I try to compile I get an error like
        "internal compiler error: in gimplify_expr, at gimplify.c:7153"

 A1(a)  This is a bug with gcc v4.5.1 and v4.5.2 dealing with complex
        data type, e.g. "float complex"
        (see: http://gcc.gnu.org/bugzilla/show_bug.cgi?id=47150).
        The best option is to update your compiler to a more recent
        version, revert to an older version, or apply a patch.
      
 A1(b)  Alternatively, if you are observing this error with ellip.c you
        can probably comment out the offending lines; however this will
        render the elliptic filter generator in liquid-dsp useless. This
        is probably the fastest solution if you aren't concerned with
        generating elliptic filters.

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 Q2     When compiling I get linker errors:
        /liquid-dsp/src/fec/src/fec_conv.c:210: undefined reference to `create_viterbi27'
        /liquid-dsp/src/fec/src/fec_conv.c:210: undefined reference to `init_viterbi27'
        /liquid-dsp/src/fec/src/fec_conv.c:210: undefined reference to `update_viterbi27_blk'
        ...

 NOTE   Issue should be resolved after version 1.2.0 (commit 2f6ed1c9d39f4)

 A2     This is because the linker cannot find the libfec library.
        The 'configure' script checks to make sure that the fec library
        is available before compiling. If found the additional forward
        error-correction codecs (e.g. convolutional) will be built and
        used. If the headers and library are not found, then the
        liquid-dsp build environment will ignore these. However if, for
        example, the fec headers are found but the libfec is not, the
        build script it will try to build the additional forward error-
        correction codecs without linking to the proper libraries. This
        is a bug with the current version of liquid-dsp. The quick fix
        is to run "./configure" and then edit "config.h" to ignore the
        fec headers.

        Open "config.h" and change the line (approx. 13) from
          #define HAVE_FEC_H 1
        to
          /* #undef HAVE_FEC_H */
        This will disable building the additional FEC codecs (such as
        convolutional) but will still build the internal codes (such as
        the Hamming codes). Now run "make" as normal.

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Q3      When I try compiling on OS 10.9 I get the following error when trying
        to run "./configure":

        configure: error: Need standard c library!

        or 

        configure: error: Could not use standard c library!

A3      This is likely a result of using Apple's default build of gcc (LLVM
        version 5.0) which by default uses extremely strict checking for
        compiling. Because the script generated by configure is pretty sloppy,
        LLVM coughs when trying to build it. The simple fix is to update the
        repository and specify a different compiler by setting your
        environment variable CC, viz

        $ export CC="/usr/local/bin/gcc-4.8"

        I know this is a work-around; I'm working on a permanent fix.