311 lines
21 KiB
HTML
311 lines
21 KiB
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<!DOCTYPE html>
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<!-- Created by GNU Texinfo 7.1, https://www.gnu.org/software/texinfo/ -->
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8">
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<!-- This manual documents Guile version 3.0.10.
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Copyright (C) 1996-1997, 2000-2005, 2009-2023 Free Software Foundation,
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Inc.
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Copyright (C) 2021 Maxime Devos
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Copyright (C) 2024 Tomas Volf
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Permission is granted to copy, distribute and/or modify this document
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under the terms of the GNU Free Documentation License, Version 1.3 or
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any later version published by the Free Software Foundation; with no
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Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
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copy of the license is included in the section entitled "GNU Free
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Documentation License." -->
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<title>Binary I/O (Guile Reference Manual)</title>
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<meta name="description" content="Binary I/O (Guile Reference Manual)">
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<link href="index.html" rel="start" title="Top">
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<link href="Concept-Index.html" rel="index" title="Concept Index">
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<link href="index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Input-and-Output.html" rel="up" title="Input and Output">
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<link href="Encoding.html" rel="next" title="Encoding">
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<link href="Ports.html" rel="prev" title="Ports">
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<link rel="stylesheet" type="text/css" href="https://www.gnu.org/software/gnulib/manual.css">
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</head>
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<body lang="en">
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<div class="subsection-level-extent" id="Binary-I_002fO">
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<div class="nav-panel">
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<p>
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Next: <a href="Encoding.html" accesskey="n" rel="next">Encoding</a>, Previous: <a href="Ports.html" accesskey="p" rel="prev">Ports</a>, Up: <a href="Input-and-Output.html" accesskey="u" rel="up">Input and Output</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<h4 class="subsection" id="Binary-I_002fO-1"><span>6.12.2 Binary I/O<a class="copiable-link" href="#Binary-I_002fO-1"> ¶</a></span></h4>
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<p>Guile’s ports are fundamentally binary in nature: at the lowest level,
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they work on bytes. This section describes Guile’s core binary I/O
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operations. See <a class="xref" href="Textual-I_002fO.html">Textual I/O</a>, for input and output of strings and
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characters.
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</p>
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<p>To use these routines, first include the binary I/O module:
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</p>
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<div class="example">
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<pre class="example-preformatted">(use-modules (ice-9 binary-ports))
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</pre></div>
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<p>Note that although this module’s name suggests that binary ports are
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some different kind of port, that’s not the case: all ports in Guile are
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both binary and textual ports.
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</p>
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<a class="index-entry-id" id="index-binary-input"></a>
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<a class="anchor" id="x_002dget_002du8"></a><dl class="first-deffn">
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<dt class="deffn" id="index-get_002du8"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">get-u8</strong> <var class="def-var-arguments">port</var><a class="copiable-link" href="#index-get_002du8"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fget_005fu8"><span class="category-def">C Function: </span><span><strong class="def-name">scm_get_u8</strong> <var class="def-var-arguments">(port)</var><a class="copiable-link" href="#index-scm_005fget_005fu8"> ¶</a></span></dt>
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<dd><p>Return an octet read from <var class="var">port</var>, an input port, blocking as
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necessary, or the end-of-file object.
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</p></dd></dl>
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<a class="anchor" id="x_002dlookahead_002du8"></a><dl class="first-deffn">
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<dt class="deffn" id="index-lookahead_002du8"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">lookahead-u8</strong> <var class="def-var-arguments">port</var><a class="copiable-link" href="#index-lookahead_002du8"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005flookahead_005fu8"><span class="category-def">C Function: </span><span><strong class="def-name">scm_lookahead_u8</strong> <var class="def-var-arguments">(port)</var><a class="copiable-link" href="#index-scm_005flookahead_005fu8"> ¶</a></span></dt>
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<dd><p>Like <code class="code">get-u8</code> but does not update <var class="var">port</var>’s position to point
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past the octet.
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</p></dd></dl>
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<p>The end-of-file object is unlike any other kind of object: it’s not a
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pair, a symbol, or anything else. To check if a value is the
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end-of-file object, use the <code class="code">eof-object?</code> predicate.
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</p>
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<a class="index-entry-id" id="index-eof_002dobject_003f-4"></a>
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<a class="index-entry-id" id="index-End-of-file-object"></a>
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<dl class="first-deffn">
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<dt class="deffn" id="index-eof_002dobject_003f"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">eof-object?</strong> <var class="def-var-arguments">x</var><a class="copiable-link" href="#index-eof_002dobject_003f"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005feof_005fobject_005fp"><span class="category-def">C Function: </span><span><strong class="def-name">scm_eof_object_p</strong> <var class="def-var-arguments">(x)</var><a class="copiable-link" href="#index-scm_005feof_005fobject_005fp"> ¶</a></span></dt>
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<dd><p>Return <code class="code">#t</code> if <var class="var">x</var> is an end-of-file object, or <code class="code">#f</code>
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otherwise.
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</p></dd></dl>
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<p>Note that unlike other procedures in this module, <code class="code">eof-object?</code> is
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defined in the default environment.
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</p>
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<dl class="first-deffn">
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<dt class="deffn" id="index-get_002dbytevector_002dn"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">get-bytevector-n</strong> <var class="def-var-arguments">port count</var><a class="copiable-link" href="#index-get_002dbytevector_002dn"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fget_005fbytevector_005fn"><span class="category-def">C Function: </span><span><strong class="def-name">scm_get_bytevector_n</strong> <var class="def-var-arguments">(port, count)</var><a class="copiable-link" href="#index-scm_005fget_005fbytevector_005fn"> ¶</a></span></dt>
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<dd><p>Read <var class="var">count</var> octets from <var class="var">port</var>, blocking as necessary and
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return a bytevector containing the octets read. If fewer bytes are
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available, a bytevector smaller than <var class="var">count</var> is returned.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-get_002dbytevector_002dn_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">get-bytevector-n!</strong> <var class="def-var-arguments">port bv start count</var><a class="copiable-link" href="#index-get_002dbytevector_002dn_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fget_005fbytevector_005fn_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_get_bytevector_n_x</strong> <var class="def-var-arguments">(port, bv, start, count)</var><a class="copiable-link" href="#index-scm_005fget_005fbytevector_005fn_005fx"> ¶</a></span></dt>
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<dd><p>Read <var class="var">count</var> bytes from <var class="var">port</var> and store them in <var class="var">bv</var>
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starting at index <var class="var">start</var>. Return either the number of bytes
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actually read or the end-of-file object.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-get_002dbytevector_002dsome"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">get-bytevector-some</strong> <var class="def-var-arguments">port</var><a class="copiable-link" href="#index-get_002dbytevector_002dsome"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fget_005fbytevector_005fsome"><span class="category-def">C Function: </span><span><strong class="def-name">scm_get_bytevector_some</strong> <var class="def-var-arguments">(port)</var><a class="copiable-link" href="#index-scm_005fget_005fbytevector_005fsome"> ¶</a></span></dt>
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<dd><p>Read from <var class="var">port</var>, blocking as necessary, until bytes are available
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or an end-of-file is reached. Return either the end-of-file object or a
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new bytevector containing some of the available bytes (at least one),
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and update the port position to point just past these bytes.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-get_002dbytevector_002dsome_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">get-bytevector-some!</strong> <var class="def-var-arguments">port bv start count</var><a class="copiable-link" href="#index-get_002dbytevector_002dsome_0021"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fget_005fbytevector_005fsome_005fx"><span class="category-def">C Function: </span><span><strong class="def-name">scm_get_bytevector_some_x</strong> <var class="def-var-arguments">(port, bv, start, count)</var><a class="copiable-link" href="#index-scm_005fget_005fbytevector_005fsome_005fx"> ¶</a></span></dt>
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<dd><p>Read up to <var class="var">count</var> bytes from <var class="var">port</var>, blocking as necessary
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until at least one byte is available or an end-of-file is reached.
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Store them in <var class="var">bv</var> starting at index <var class="var">start</var>. Return the number
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of bytes actually read, or an end-of-file object.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-get_002dbytevector_002dall"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">get-bytevector-all</strong> <var class="def-var-arguments">port</var><a class="copiable-link" href="#index-get_002dbytevector_002dall"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fget_005fbytevector_005fall"><span class="category-def">C Function: </span><span><strong class="def-name">scm_get_bytevector_all</strong> <var class="def-var-arguments">(port)</var><a class="copiable-link" href="#index-scm_005fget_005fbytevector_005fall"> ¶</a></span></dt>
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<dd><p>Read from <var class="var">port</var>, blocking as necessary, until the end-of-file is
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reached. Return either a new bytevector containing the data read or the
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end-of-file object (if no data were available).
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-unget_002dbytevector"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">unget-bytevector</strong> <var class="def-var-arguments">port bv [start [count]]</var><a class="copiable-link" href="#index-unget_002dbytevector"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005funget_005fbytevector"><span class="category-def">C Function: </span><span><strong class="def-name">scm_unget_bytevector</strong> <var class="def-var-arguments">(port, bv, start, count)</var><a class="copiable-link" href="#index-scm_005funget_005fbytevector"> ¶</a></span></dt>
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<dd><p>Place the contents of <var class="var">bv</var> in <var class="var">port</var>, optionally starting at
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index <var class="var">start</var> and limiting to <var class="var">count</var> octets, so that its bytes
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will be read from left-to-right as the next bytes from <var class="var">port</var> during
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subsequent read operations. If called multiple times, the unread bytes
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will be read again in last-in first-out order.
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</p></dd></dl>
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<a class="index-entry-id" id="index-binary-output"></a>
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<p>To perform binary output on a port, use <code class="code">put-u8</code> or
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<code class="code">put-bytevector</code>.
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</p>
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<a class="anchor" id="x_002dput_002du8"></a><dl class="first-deffn">
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<dt class="deffn" id="index-put_002du8"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">put-u8</strong> <var class="def-var-arguments">port octet</var><a class="copiable-link" href="#index-put_002du8"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fput_005fu8"><span class="category-def">C Function: </span><span><strong class="def-name">scm_put_u8</strong> <var class="def-var-arguments">(port, octet)</var><a class="copiable-link" href="#index-scm_005fput_005fu8"> ¶</a></span></dt>
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<dd><p>Write <var class="var">octet</var>, an integer in the 0–255 range, to <var class="var">port</var>, a
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binary output port.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-put_002dbytevector"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">put-bytevector</strong> <var class="def-var-arguments">port bv [start [count]]</var><a class="copiable-link" href="#index-put_002dbytevector"> ¶</a></span></dt>
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<dt class="deffnx def-cmd-deffn" id="index-scm_005fput_005fbytevector"><span class="category-def">C Function: </span><span><strong class="def-name">scm_put_bytevector</strong> <var class="def-var-arguments">(port, bv, start, count)</var><a class="copiable-link" href="#index-scm_005fput_005fbytevector"> ¶</a></span></dt>
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<dd><p>Write the contents of <var class="var">bv</var> to <var class="var">port</var>, optionally starting at
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index <var class="var">start</var> and limiting to <var class="var">count</var> octets.
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</p></dd></dl>
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<h4 class="subsubheading" id="Binary-I_002fO-in-R7RS"><span>Binary I/O in R7RS<a class="copiable-link" href="#Binary-I_002fO-in-R7RS"> ¶</a></span></h4>
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<p><a class="ref" href="R7RS-Standard-Libraries.html">R7RS</a> defines the following binary I/O
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procedures. Access them with
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</p>
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<div class="example">
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<pre class="example-preformatted">(use-modules (scheme base))
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</pre></div>
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<a class="anchor" id="x_002dopen_002doutput_002dbytevector"></a><dl class="first-deffn">
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<dt class="deffn" id="index-open_002doutput_002dbytevector"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">open-output-bytevector</strong><a class="copiable-link" href="#index-open_002doutput_002dbytevector"> ¶</a></span></dt>
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<dd><p>Returns a binary output port that will accumulate bytes
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for retrieval by <a class="ref" href="#x_002dget_002doutput_002dbytevector"><code class="code">get-output-bytevector</code></a>.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-write_002du8"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">write-u8</strong> <var class="def-var-arguments">byte [out]</var><a class="copiable-link" href="#index-write_002du8"> ¶</a></span></dt>
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<dd><p>Writes <var class="var">byte</var> to the given binary output port <var class="var">out</var> and returns
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an unspecified value. <var class="var">out</var> defaults to <code class="code">(current-output-port)</code>.
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</p>
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<p>See also <a class="ref" href="#x_002dput_002du8"><code class="code">put-u8</code></a>.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-read_002du8"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">read-u8</strong> <var class="def-var-arguments">[in]</var><a class="copiable-link" href="#index-read_002du8"> ¶</a></span></dt>
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<dd><p>Returns the next byte available from the binary input port <var class="var">in</var>,
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updating the port to point to the following byte. If no more bytes are
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available, an end-of-file object is returned. <var class="var">in</var> defaults to
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<code class="code">(current-input-port)</code>.
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</p>
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<p>See also <a class="ref" href="#x_002dget_002du8"><code class="code">get-u8</code></a>.
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</p></dd></dl>
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<dl class="first-deffn">
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<dt class="deffn" id="index-peek_002du8"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">peek-u8</strong> <var class="def-var-arguments">[in]</var><a class="copiable-link" href="#index-peek_002du8"> ¶</a></span></dt>
|
||
|
|
<dd><p>Returns the next byte available from the binary input port <var class="var">in</var>,
|
||
|
|
but without updating the port to point to the following
|
||
|
|
byte. If no more bytes are available, an end-of-file object
|
||
|
|
is returned. <var class="var">in</var> defaults to <code class="code">(current-input-port)</code>.
|
||
|
|
</p>
|
||
|
|
<p>See also <a class="ref" href="#x_002dlookahead_002du8"><code class="code">lookahead-u8</code></a>.
|
||
|
|
</p></dd></dl>
|
||
|
|
|
||
|
|
<a class="anchor" id="x_002dget_002doutput_002dbytevector"></a><dl class="first-deffn">
|
||
|
|
<dt class="deffn" id="index-get_002doutput_002dbytevector"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">get-output-bytevector</strong> <var class="def-var-arguments">port</var><a class="copiable-link" href="#index-get_002doutput_002dbytevector"> ¶</a></span></dt>
|
||
|
|
<dd><p>Returns a bytevector consisting of the bytes that have been output to
|
||
|
|
<var class="var">port</var> so far in the order they were output. It is an error if
|
||
|
|
<var class="var">port</var> was not created with
|
||
|
|
<a class="ref" href="#x_002dopen_002doutput_002dbytevector"><code class="code">open-output-bytevector</code></a>.
|
||
|
|
</p>
|
||
|
|
<div class="example">
|
||
|
|
<pre class="example-preformatted">(define out (open-output-bytevector))
|
||
|
|
(write-u8 1 out)
|
||
|
|
(write-u8 2 out)
|
||
|
|
(write-u8 3 out)
|
||
|
|
(get-output-bytevector out) ⇒ #vu8(1 2 3)
|
||
|
|
</pre></div>
|
||
|
|
</dd></dl>
|
||
|
|
|
||
|
|
<dl class="first-deffn">
|
||
|
|
<dt class="deffn" id="index-open_002dinput_002dbytevector"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">open-input-bytevector</strong> <var class="def-var-arguments">bv</var><a class="copiable-link" href="#index-open_002dinput_002dbytevector"> ¶</a></span></dt>
|
||
|
|
<dd><p>Takes a bytevector <var class="var">bv</var> and returns a binary input port that
|
||
|
|
delivers bytes from <var class="var">bv</var>.
|
||
|
|
</p>
|
||
|
|
<div class="example">
|
||
|
|
<pre class="example-preformatted">(define in (open-input-bytevector #vu8(1 2 3)))
|
||
|
|
(read-u8 in) ⇒ 1
|
||
|
|
(peek-u8 in) ⇒ 2
|
||
|
|
(read-u8 in) ⇒ 2
|
||
|
|
(read-u8 in) ⇒ 3
|
||
|
|
(read-u8 in) ⇒ #<eof>
|
||
|
|
</pre></div>
|
||
|
|
</dd></dl>
|
||
|
|
|
||
|
|
<dl class="first-deffn">
|
||
|
|
<dt class="deffn" id="index-read_002dbytevector_0021"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">read-bytevector!</strong> <var class="def-var-arguments">bv [port [start [end]]]</var><a class="copiable-link" href="#index-read_002dbytevector_0021"> ¶</a></span></dt>
|
||
|
|
<dd><p>Reads the next <var class="var">end</var> - <var class="var">start</var> bytes, or as many as are
|
||
|
|
available before the end of file, from the binary input port into the
|
||
|
|
bytevector <var class="var">bv</var> in left-to-right order beginning at the <var class="var">start</var>
|
||
|
|
position. If <var class="var">end</var> is not supplied, reads until the end of <var class="var">bv</var>
|
||
|
|
has been reached. If <var class="var">start</var> is not supplied, reads beginning at
|
||
|
|
position 0.
|
||
|
|
</p>
|
||
|
|
<p>Returns the number of bytes read. If no bytes are available, an
|
||
|
|
end-of-file object is returned.
|
||
|
|
</p>
|
||
|
|
<div class="example">
|
||
|
|
<pre class="example-preformatted">(define in (open-input-bytevector #vu8(1 2 3)))
|
||
|
|
(define bv (make-bytevector 5 0))
|
||
|
|
(read-bytevector! bv in 1 3) ⇒ 2
|
||
|
|
bv ⇒ #vu8(0 1 2 0 0 0)
|
||
|
|
</pre></div>
|
||
|
|
|
||
|
|
</dd></dl>
|
||
|
|
|
||
|
|
<dl class="first-deffn">
|
||
|
|
<dt class="deffn" id="index-read_002dbytevector"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">read-bytevector</strong> <var class="def-var-arguments">k in</var><a class="copiable-link" href="#index-read_002dbytevector"> ¶</a></span></dt>
|
||
|
|
<dd><p>Reads the next <var class="var">k</var> bytes, or as many as are available before the end
|
||
|
|
of file if that is less than <var class="var">k</var>, from the binary input port
|
||
|
|
<var class="var">in</var> into a newly allocated bytevector in left-to-right order, and
|
||
|
|
returns the bytevector. If no bytes are available before the end of
|
||
|
|
file, an end-of-file object is returned.
|
||
|
|
</p>
|
||
|
|
<div class="example">
|
||
|
|
<pre class="example-preformatted">(define bv #vu8(1 2 3))
|
||
|
|
(read-bytevector 2 (open-input-bytevector bv)) ⇒ #vu8(1 2)
|
||
|
|
(read-bytevector 10 (open-input-bytevector bv)) ⇒ #vu8(1 2 3)
|
||
|
|
</pre></div>
|
||
|
|
|
||
|
|
</dd></dl>
|
||
|
|
|
||
|
|
<dl class="first-deffn">
|
||
|
|
<dt class="deffn" id="index-write_002dbytevector"><span class="category-def">Scheme Procedure: </span><span><strong class="def-name">write-bytevector</strong> <var class="def-var-arguments">bv [port [start [end]]]</var><a class="copiable-link" href="#index-write_002dbytevector"> ¶</a></span></dt>
|
||
|
|
<dd><p>Writes the bytes of bytevector <var class="var">bv</var> from <var class="var">start</var> to <var class="var">end</var> in
|
||
|
|
left-to-right order to the binary output <var class="var">port</var>. <var class="var">start</var>
|
||
|
|
defaults to 0 and <var class="var">end</var> defaults to the length of <var class="var">bv</var>.
|
||
|
|
</p>
|
||
|
|
<div class="example">
|
||
|
|
<pre class="example-preformatted">(define out (open-output-bytevector))
|
||
|
|
(write-bytevector #vu8(0 1 2 3 4) out 2 4)
|
||
|
|
(get-output-bytevector out) ⇒ #vu8(2 3)
|
||
|
|
</pre></div>
|
||
|
|
|
||
|
|
</dd></dl>
|
||
|
|
|
||
|
|
</div>
|
||
|
|
<hr>
|
||
|
|
<div class="nav-panel">
|
||
|
|
<p>
|
||
|
|
Next: <a href="Encoding.html">Encoding</a>, Previous: <a href="Ports.html">Ports</a>, Up: <a href="Input-and-Output.html">Input and Output</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html" title="Index" rel="index">Index</a>]</p>
|
||
|
|
</div>
|
||
|
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|
||
|
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|
||
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|
||
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</body>
|
||
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</html>
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