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Add FFTW3
| author | Chris Cannam |
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| date | Wed, 20 Mar 2013 15:35:50 +0000 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/src/fftw-3.3.3/doc/html/Wisdom-String-Export_002fImport-from-Fortran.html Wed Mar 20 15:35:50 2013 +0000 @@ -0,0 +1,106 @@ +<html lang="en"> +<head> +<title>Wisdom String Export/Import from Fortran - FFTW 3.3.3</title> +<meta http-equiv="Content-Type" content="text/html"> +<meta name="description" content="FFTW 3.3.3"> +<meta name="generator" content="makeinfo 4.13"> +<link title="Top" rel="start" href="index.html#Top"> +<link rel="up" href="Accessing-the-wisdom-API-from-Fortran.html#Accessing-the-wisdom-API-from-Fortran" title="Accessing the wisdom API from Fortran"> +<link rel="prev" href="Wisdom-File-Export_002fImport-from-Fortran.html#Wisdom-File-Export_002fImport-from-Fortran" title="Wisdom File Export/Import from Fortran"> +<link rel="next" href="Wisdom-Generic-Export_002fImport-from-Fortran.html#Wisdom-Generic-Export_002fImport-from-Fortran" title="Wisdom Generic Export/Import from Fortran"> +<link href="http://www.gnu.org/software/texinfo/" rel="generator-home" title="Texinfo Homepage"> +<!-- +This manual is for FFTW +(version 3.3.3, 25 November 2012). + +Copyright (C) 2003 Matteo Frigo. + +Copyright (C) 2003 Massachusetts Institute of Technology. + + Permission is granted to make and distribute verbatim copies of + this manual provided the copyright notice and this permission + notice are preserved on all copies. + + Permission is granted to copy and distribute modified versions of + this manual under the conditions for verbatim copying, provided + that the entire resulting derived work is distributed under the + terms of a permission notice identical to this one. + + Permission is granted to copy and distribute translations of this + manual into another language, under the above conditions for + modified versions, except that this permission notice may be + stated in a translation approved by the Free Software Foundation. + --> +<meta http-equiv="Content-Style-Type" content="text/css"> +<style type="text/css"><!-- + pre.display { font-family:inherit } + pre.format { font-family:inherit } + pre.smalldisplay { font-family:inherit; font-size:smaller } + pre.smallformat { font-family:inherit; font-size:smaller } + pre.smallexample { font-size:smaller } + pre.smalllisp { font-size:smaller } + span.sc { font-variant:small-caps } + span.roman { font-family:serif; font-weight:normal; } + span.sansserif { font-family:sans-serif; font-weight:normal; } +--></style> +</head> +<body> +<div class="node"> +<a name="Wisdom-String-Export%2fImport-from-Fortran"></a> +<a name="Wisdom-String-Export_002fImport-from-Fortran"></a> +<p> +Next: <a rel="next" accesskey="n" href="Wisdom-Generic-Export_002fImport-from-Fortran.html#Wisdom-Generic-Export_002fImport-from-Fortran">Wisdom Generic Export/Import from Fortran</a>, +Previous: <a rel="previous" accesskey="p" href="Wisdom-File-Export_002fImport-from-Fortran.html#Wisdom-File-Export_002fImport-from-Fortran">Wisdom File Export/Import from Fortran</a>, +Up: <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> +<hr> +</div> + +<h4 class="subsection">7.6.2 Wisdom String Export/Import from Fortran</h4> + +<p><a name="index-fftw_005fexport_005fwisdom_005fto_005fstring-568"></a>Dealing with FFTW's C string export/import is a bit more painful. In +particular, the <code>fftw_export_wisdom_to_string</code> function requires +you to deal with a dynamically allocated C string. To get its length, +you must define an interface to the C <code>strlen</code> function, and to +deallocate it you must define an interface to C <code>free</code>: + +<pre class="example"> use, intrinsic :: iso_c_binding + interface + integer(C_INT) function strlen(s) bind(C, name='strlen') + import + type(C_PTR), value :: s + end function strlen + subroutine free(p) bind(C, name='free') + import + type(C_PTR), value :: p + end subroutine free + end interface +</pre> + <p>Given these definitions, you can then export wisdom to a Fortran +character array: + +<pre class="example"> character(C_CHAR), pointer :: s(:) + integer(C_SIZE_T) :: slen + type(C_PTR) :: p + p = fftw_export_wisdom_to_string() + if (.not. c_associated(p)) stop 'error exporting wisdom' + slen = strlen(p) + call c_f_pointer(p, s, [slen+1]) + ... + call free(p) +</pre> + <p><a name="index-c_005fassociated-569"></a><a name="index-c_005ff_005fpointer-570"></a> +Note that <code>slen</code> is the length of the C string, but the length of +the array is <code>slen+1</code> because it includes the terminating null +character. (You can omit the ‘<samp><span class="samp">+1</span></samp>’ if you don't want Fortran to +know about the null character.) The standard <code>c_associated</code> function +checks whether <code>p</code> is a null pointer, which is returned by +<code>fftw_export_wisdom_to_string</code> if there was an error. + + <p><a name="index-fftw_005fimport_005fwisdom_005ffrom_005fstring-571"></a>To import wisdom from a string, use +<code>fftw_import_wisdom_from_string</code> as usual; note that the argument +of this function must be a <code>character(C_CHAR)</code> that is terminated +by the <code>C_NULL_CHAR</code> character, like the <code>s</code> array above. + +<!-- =========> --> + </body></html> +