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Replace these with versions built using an older toolset (so as to avoid ABI compatibilities when linking on Ubuntu 14.04 for packaging purposes)
author Chris Cannam
date Fri, 07 Feb 2020 11:51:13 +0000
parents 2cd0e3b3e1fd
children
rev   line source
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Chris@42 3 <!-- This manual is for FFTW
Chris@42 4 (version 3.3.5, 30 July 2016).
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Chris@42 6 Copyright (C) 2003 Matteo Frigo.
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Chris@42 24 <head>
Chris@42 25 <title>FFTW 3.3.5: Wisdom String Export/Import from Fortran</title>
Chris@42 26
Chris@42 27 <meta name="description" content="FFTW 3.3.5: Wisdom String Export/Import from Fortran">
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Chris@42 35 <link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
Chris@42 36 <link href="Accessing-the-wisdom-API-from-Fortran.html#Accessing-the-wisdom-API-from-Fortran" rel="up" title="Accessing the wisdom API from Fortran">
Chris@42 37 <link href="Wisdom-Generic-Export_002fImport-from-Fortran.html#Wisdom-Generic-Export_002fImport-from-Fortran" rel="next" title="Wisdom Generic Export/Import from Fortran">
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Chris@42 71 <body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000">
Chris@42 72 <a name="Wisdom-String-Export_002fImport-from-Fortran"></a>
Chris@42 73 <div class="header">
Chris@42 74 <p>
Chris@42 75 Next: <a href="Wisdom-Generic-Export_002fImport-from-Fortran.html#Wisdom-Generic-Export_002fImport-from-Fortran" accesskey="n" rel="next">Wisdom Generic Export/Import from Fortran</a>, Previous: <a href="Wisdom-File-Export_002fImport-from-Fortran.html#Wisdom-File-Export_002fImport-from-Fortran" accesskey="p" rel="prev">Wisdom File Export/Import from Fortran</a>, Up: <a href="Accessing-the-wisdom-API-from-Fortran.html#Accessing-the-wisdom-API-from-Fortran" accesskey="u" rel="up">Accessing the wisdom API from Fortran</a> &nbsp; [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
Chris@42 76 </div>
Chris@42 77 <hr>
Chris@42 78 <a name="Wisdom-String-Export_002fImport-from-Fortran-1"></a>
Chris@42 79 <h4 class="subsection">7.6.2 Wisdom String Export/Import from Fortran</h4>
Chris@42 80
Chris@42 81 <a name="index-fftw_005fexport_005fwisdom_005fto_005fstring-1"></a>
Chris@42 82 <p>Dealing with FFTW&rsquo;s C string export/import is a bit more painful. In
Chris@42 83 particular, the <code>fftw_export_wisdom_to_string</code> function requires
Chris@42 84 you to deal with a dynamically allocated C string. To get its length,
Chris@42 85 you must define an interface to the C <code>strlen</code> function, and to
Chris@42 86 deallocate it you must define an interface to C <code>free</code>:
Chris@42 87 </p>
Chris@42 88 <div class="example">
Chris@42 89 <pre class="example"> use, intrinsic :: iso_c_binding
Chris@42 90 interface
Chris@42 91 integer(C_INT) function strlen(s) bind(C, name='strlen')
Chris@42 92 import
Chris@42 93 type(C_PTR), value :: s
Chris@42 94 end function strlen
Chris@42 95 subroutine free(p) bind(C, name='free')
Chris@42 96 import
Chris@42 97 type(C_PTR), value :: p
Chris@42 98 end subroutine free
Chris@42 99 end interface
Chris@42 100 </pre></div>
Chris@42 101
Chris@42 102 <p>Given these definitions, you can then export wisdom to a Fortran
Chris@42 103 character array:
Chris@42 104 </p>
Chris@42 105 <div class="example">
Chris@42 106 <pre class="example"> character(C_CHAR), pointer :: s(:)
Chris@42 107 integer(C_SIZE_T) :: slen
Chris@42 108 type(C_PTR) :: p
Chris@42 109 p = fftw_export_wisdom_to_string()
Chris@42 110 if (.not. c_associated(p)) stop 'error exporting wisdom'
Chris@42 111 slen = strlen(p)
Chris@42 112 call c_f_pointer(p, s, [slen+1])
Chris@42 113 ...
Chris@42 114 call free(p)
Chris@42 115 </pre></div>
Chris@42 116 <a name="index-c_005fassociated"></a>
Chris@42 117 <a name="index-c_005ff_005fpointer-3"></a>
Chris@42 118
Chris@42 119 <p>Note that <code>slen</code> is the length of the C string, but the length of
Chris@42 120 the array is <code>slen+1</code> because it includes the terminating null
Chris@42 121 character. (You can omit the &lsquo;<samp>+1</samp>&rsquo; if you don&rsquo;t want Fortran to
Chris@42 122 know about the null character.) The standard <code>c_associated</code> function
Chris@42 123 checks whether <code>p</code> is a null pointer, which is returned by
Chris@42 124 <code>fftw_export_wisdom_to_string</code> if there was an error.
Chris@42 125 </p>
Chris@42 126 <a name="index-fftw_005fimport_005fwisdom_005ffrom_005fstring-1"></a>
Chris@42 127 <p>To import wisdom from a string, use
Chris@42 128 <code>fftw_import_wisdom_from_string</code> as usual; note that the argument
Chris@42 129 of this function must be a <code>character(C_CHAR)</code> that is terminated
Chris@42 130 by the <code>C_NULL_CHAR</code> character, like the <code>s</code> array above.
Chris@42 131 </p>
Chris@42 132
Chris@42 133
Chris@42 134
Chris@42 135 </body>
Chris@42 136 </html>