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diff --git a/share/doc/gfortran/GFORTRAN_005fCONVERT_005fUNIT.html b/share/doc/gfortran/GFORTRAN_005fCONVERT_005fUNIT.html new file mode 100644 index 0000000..7b109fc --- /dev/null +++ b/share/doc/gfortran/GFORTRAN_005fCONVERT_005fUNIT.html @@ -0,0 +1,166 @@ +<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd"> +<html> +<!-- Copyright (C) 1999-2023 Free Software Foundation, Inc. + +Permission is granted to copy, distribute and/or modify this document +under the terms of the GNU Free Documentation License, Version 1.3 or +any later version published by the Free Software Foundation; with the +Invariant Sections being "Funding Free Software", the Front-Cover +Texts being (a) (see below), and with the Back-Cover Texts being (b) +(see below). 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Copies published by the Free Software Foundation raise + funds for GNU development. --> +<!-- Created by GNU Texinfo 5.1, http://www.gnu.org/software/texinfo/ --> +<head> +<title>The GNU Fortran Compiler: GFORTRAN_CONVERT_UNIT</title> + +<meta name="description" content="The GNU Fortran Compiler: GFORTRAN_CONVERT_UNIT"> +<meta name="keywords" content="The GNU Fortran Compiler: GFORTRAN_CONVERT_UNIT"> +<meta name="resource-type" content="document"> +<meta name="distribution" content="global"> +<meta name="Generator" content="makeinfo"> +<meta http-equiv="Content-Type" content="text/html; charset=utf-8"> +<link href="index.html#Top" rel="start" title="Top"> +<link href="Option-Index.html#Option-Index" rel="index" title="Option Index"> +<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents"> +<link href="Runtime.html#Runtime" rel="up" title="Runtime"> +<link href="GFORTRAN_005fERROR_005fBACKTRACE.html#GFORTRAN_005fERROR_005fBACKTRACE" rel="next" title="GFORTRAN_ERROR_BACKTRACE"> +<link href="GFORTRAN_005fLIST_005fSEPARATOR.html#GFORTRAN_005fLIST_005fSEPARATOR" rel="previous" title="GFORTRAN_LIST_SEPARATOR"> +<style type="text/css"> +<!-- +a.summary-letter {text-decoration: none} +blockquote.smallquotation {font-size: smaller} +div.display {margin-left: 3.2em} +div.example {margin-left: 3.2em} +div.indentedblock {margin-left: 3.2em} +div.lisp {margin-left: 3.2em} +div.smalldisplay {margin-left: 3.2em} +div.smallexample {margin-left: 3.2em} +div.smallindentedblock {margin-left: 3.2em; font-size: smaller} +div.smalllisp {margin-left: 3.2em} +kbd {font-style:oblique} +pre.display {font-family: inherit} +pre.format {font-family: inherit} +pre.menu-comment {font-family: serif} +pre.menu-preformatted {font-family: serif} +pre.smalldisplay {font-family: inherit; font-size: smaller} +pre.smallexample {font-size: smaller} +pre.smallformat {font-family: inherit; font-size: smaller} +pre.smalllisp {font-size: smaller} +span.nocodebreak {white-space:nowrap} +span.nolinebreak {white-space:nowrap} +span.roman {font-family:serif; font-weight:normal} +span.sansserif {font-family:sans-serif; font-weight:normal} +ul.no-bullet {list-style: none} +--> +</style> + + +</head> + +<body lang="en" bgcolor="#FFFFFF" text="#000000" link="#0000FF" vlink="#800080" alink="#FF0000"> +<a name="GFORTRAN_005fCONVERT_005fUNIT"></a> +<div class="header"> +<p> +Next: <a href="GFORTRAN_005fERROR_005fBACKTRACE.html#GFORTRAN_005fERROR_005fBACKTRACE" accesskey="n" rel="next">GFORTRAN_ERROR_BACKTRACE</a>, Previous: <a href="GFORTRAN_005fLIST_005fSEPARATOR.html#GFORTRAN_005fLIST_005fSEPARATOR" accesskey="p" rel="previous">GFORTRAN_LIST_SEPARATOR</a>, Up: <a href="Runtime.html#Runtime" accesskey="u" rel="up">Runtime</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> +</div> +<hr> +<a name="GFORTRAN_005fCONVERT_005fUNIT_002d_002d_002dSet-conversion-for-unformatted-I_002fO"></a> +<h3 class="section">3.10 <code>GFORTRAN_CONVERT_UNIT</code>—Set conversion for unformatted I/O</h3> + +<p>By setting the <code>GFORTRAN_CONVERT_UNIT</code> variable, it is possible +to change the representation of data for unformatted files. +The syntax for the <code>GFORTRAN_CONVERT_UNIT</code> variable for +most systems is: +</p><div class="smallexample"> +<pre class="smallexample">GFORTRAN_CONVERT_UNIT: mode | mode ';' exception | exception ; +mode: 'native' | 'swap' | 'big_endian' | 'little_endian' ; +exception: mode ':' unit_list | unit_list ; +unit_list: unit_spec | unit_list unit_spec ; +unit_spec: INTEGER | INTEGER '-' INTEGER ; +</pre></div> +<p>The variable consists of an optional default mode, followed by +a list of optional exceptions, which are separated by semicolons +from the preceding default and each other. Each exception consists +of a format and a comma-separated list of units. Valid values for +the modes are the same as for the <code>CONVERT</code> specifier: +</p> +<ul class="no-bullet"> +<li><!-- /@w --> <code>NATIVE</code> Use the native format. This is the default. +</li><li><!-- /@w --> <code>SWAP</code> Swap between little- and big-endian. +</li><li><!-- /@w --> <code>LITTLE_ENDIAN</code> Use the little-endian format +for unformatted files. +</li><li><!-- /@w --> <code>BIG_ENDIAN</code> Use the big-endian format for unformatted files. +</li></ul> +<p>For POWER systems which support <samp>-mabi=ieeelongdouble</samp>, +there are additional options, which can be combined with the +others with commas. Those are +</p><ul class="no-bullet"> +<li><!-- /@w --> <code>R16_IEEE</code> Use IEEE 128-bit format for <code>REAL(KIND=16)</code>. +</li><li><!-- /@w --> <code>R16_IBM</code> Use IBM <code>long double</code> format for +<code>REAL(KIND=16)</code>. +</li></ul> +<p>A missing mode for an exception is taken to mean <code>BIG_ENDIAN</code>. +Examples of values for <code>GFORTRAN_CONVERT_UNIT</code> are: +</p><ul class="no-bullet"> +<li><!-- /@w --> <code>'big_endian'</code> Do all unformatted I/O in big_endian mode. +</li><li><!-- /@w --> <code>'little_endian;native:10-20,25'</code> Do all unformatted I/O +in little_endian mode, except for units 10 to 20 and 25, which are in +native format. +</li><li><!-- /@w --> <code>'10-20'</code> Units 10 to 20 are big-endian, the rest is native. +</li><li><!-- /@w --> <code>'big_endian,r16_ibm'</code> Do all unformatted I/O in big-endian +mode and use IBM long double for output of <code>REAL(KIND=16)</code> values. +</li></ul> + +<p>Setting the environment variables should be done on the command +line or via the <code>export</code> +command for <code>sh</code>-compatible shells and via <code>setenv</code> +for <code>csh</code>-compatible shells. +</p> +<p>Example for <code>sh</code>: +</p><div class="smallexample"> +<pre class="smallexample">$ gfortran foo.f90 +$ GFORTRAN_CONVERT_UNIT='big_endian;native:10-20' ./a.out +</pre></div> + +<p>Example code for <code>csh</code>: +</p><div class="smallexample"> +<pre class="smallexample">% gfortran foo.f90 +% setenv GFORTRAN_CONVERT_UNIT 'big_endian;native:10-20' +% ./a.out +</pre></div> + +<p>Using anything but the native representation for unformatted data +carries a significant speed overhead. If speed in this area matters +to you, it is best if you use this only for data that needs to be +portable. +</p> +<p>See <a href="CONVERT-specifier.html#CONVERT-specifier">CONVERT specifier</a>, for an alternative way to specify the +data representation for unformatted files. See <a href="Runtime-Options.html#Runtime-Options">Runtime Options</a>, for +setting a default data representation for the whole program. The +<code>CONVERT</code> specifier overrides the <samp>-fconvert</samp> compile options. +</p> +<p><em>Note that the values specified via the GFORTRAN_CONVERT_UNIT +environment variable will override the CONVERT specifier in the +open statement</em>. This is to give control over data formats to +users who do not have the source code of their program available. +</p> +<hr> +<div class="header"> +<p> +Next: <a href="GFORTRAN_005fERROR_005fBACKTRACE.html#GFORTRAN_005fERROR_005fBACKTRACE" accesskey="n" rel="next">GFORTRAN_ERROR_BACKTRACE</a>, Previous: <a href="GFORTRAN_005fLIST_005fSEPARATOR.html#GFORTRAN_005fLIST_005fSEPARATOR" accesskey="p" rel="previous">GFORTRAN_LIST_SEPARATOR</a>, Up: <a href="Runtime.html#Runtime" accesskey="u" rel="up">Runtime</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Option-Index.html#Option-Index" title="Index" rel="index">Index</a>]</p> +</div> + + + +</body> +</html> |