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author Chris Cannam
date Wed, 07 Sep 2016 10:40:32 +0100
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Chris@19 49 <a name="Wisdom-File-Export%2fImport-from-Fortran"></a>
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Chris@19 51 <p>
Chris@19 52 Next:&nbsp;<a rel="next" accesskey="n" href="Wisdom-String-Export_002fImport-from-Fortran.html#Wisdom-String-Export_002fImport-from-Fortran">Wisdom String Export/Import from Fortran</a>,
Chris@19 53 Previous:&nbsp;<a rel="previous" accesskey="p" href="Accessing-the-wisdom-API-from-Fortran.html#Accessing-the-wisdom-API-from-Fortran">Accessing the wisdom API from Fortran</a>,
Chris@19 54 Up:&nbsp;<a rel="up" accesskey="u" href="Accessing-the-wisdom-API-from-Fortran.html#Accessing-the-wisdom-API-from-Fortran">Accessing the wisdom API from Fortran</a>
Chris@19 55 <hr>
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Chris@19 57
Chris@19 58 <h4 class="subsection">7.6.1 Wisdom File Export/Import from Fortran</h4>
Chris@19 59
Chris@19 60 <p><a name="index-fftw_005fimport-wisdom_005ffrom_005ffilename-569"></a><a name="index-fftw_005fexport_005fwisdom_005fto_005ffilename-570"></a>The easiest way to export and import wisdom is to do so using
Chris@19 61 <code>fftw_export_wisdom_to_filename</code> and
Chris@19 62 <code>fftw_wisdom_from_filename</code>. The only trick is that these
Chris@19 63 require you to pass a C string, which is an array of type
Chris@19 64 <code>CHARACTER(C_CHAR)</code> that is terminated by <code>C_NULL_CHAR</code>.
Chris@19 65 You can call them like this:
Chris@19 66
Chris@19 67 <pre class="example"> integer(C_INT) :: ret
Chris@19 68 ret = fftw_export_wisdom_to_filename(C_CHAR_'my_wisdom.dat' // C_NULL_CHAR)
Chris@19 69 if (ret .eq. 0) stop 'error exporting wisdom to file'
Chris@19 70 ret = fftw_import_wisdom_from_filename(C_CHAR_'my_wisdom.dat' // C_NULL_CHAR)
Chris@19 71 if (ret .eq. 0) stop 'error importing wisdom from file'
Chris@19 72 </pre>
Chris@19 73 <p>Note that prepending &lsquo;<samp><span class="samp">C_CHAR_</span></samp>&rsquo; is needed to specify that the
Chris@19 74 literal string is of kind <code>C_CHAR</code>, and we null-terminate the
Chris@19 75 string by appending &lsquo;<samp><span class="samp">// C_NULL_CHAR</span></samp>&rsquo;. These functions return an
Chris@19 76 <code>integer(C_INT)</code> (<code>ret</code>) which is <code>0</code> if an error
Chris@19 77 occurred during export/import and nonzero otherwise.
Chris@19 78
Chris@19 79 <p>It is also possible to use the lower-level routines
Chris@19 80 <code>fftw_export_wisdom_to_file</code> and
Chris@19 81 <code>fftw_import_wisdom_from_file</code>, which accept parameters of the C
Chris@19 82 type <code>FILE*</code>, expressed in Fortran as <code>type(C_PTR)</code>.
Chris@19 83 However, you are then responsible for creating the <code>FILE*</code>
Chris@19 84 yourself. You can do this by using <code>iso_c_binding</code> to define
Chris@19 85 Fortran intefaces for the C library functions <code>fopen</code> and
Chris@19 86 <code>fclose</code>, which is a bit strange in Fortran but workable.
Chris@19 87
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