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121 lines
5.0 KiB
HTML
121 lines
5.0 KiB
HTML
4 years ago
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<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<!-- Created by GNU Texinfo 6.4, http://www.gnu.org/software/texinfo/ -->
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<title>a64l (The Red Hat newlib C Library)</title>
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<meta name="description" content="a64l (The Red Hat newlib C Library)">
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<link href="Document-Index.html#Document-Index" rel="index" title="Document Index">
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<link href="Document-Index.html#SEC_Contents" rel="contents" title="Table of Contents">
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<link href="Stdlib.html#Stdlib" rel="up" title="Stdlib">
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<link href="abort.html#abort" rel="next" title="abort">
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<body lang="en">
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<a name="a64l"></a>
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<div class="header">
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<p>
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Next: <a href="abort.html#abort" accesskey="n" rel="next">abort</a>, Previous: <a href="_005fExit.html#g_t_005fExit" accesskey="p" rel="prev">_Exit</a>, Up: <a href="Stdlib.html#Stdlib" accesskey="u" rel="up">Stdlib</a> [<a href="Document-Index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Document-Index.html#Document-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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<hr>
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<a name="a64l_002c-l64a_002d_002d_002dconvert-between-radix_002d64-ASCII-string-and-long"></a>
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<h3 class="section">2.2 <code>a64l</code>, <code>l64a</code>—convert between radix-64 ASCII string and long</h3>
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<a name="index-a64l"></a>
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<a name="index-l64a"></a>
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<p><strong>Synopsis</strong>
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</p><div class="example">
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<pre class="example">#include <stdlib.h>
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long a64l(const char *<var>input</var>);
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char *l64a(long <var>input</var>);
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</pre></div>
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<p><strong>Description</strong><br>
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Conversion is performed between long and radix-64 characters. The
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<code>l64a</code> routine transforms up to 32 bits of input value starting from
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least significant bits to the most significant bits. The input value
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is split up into a maximum of 5 groups of 6 bits and possibly one
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group of 2 bits (bits 31 and 30).
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</p>
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<p>Each group of 6 bits forms a value from 0–63 which is translated into
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a character as follows:
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</p>
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<ul>
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<li> 0 = ’.’
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</li><li> 1 = ’/’
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</li><li> 2–11 = ’0’ to ’9’
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</li><li> 12–37 = ’A’ to ’Z’
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</li><li> 38–63 = ’a’ to ’z’
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</li></ul>
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<p>When the remaining bits are zero or all bits have been translated, a
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null terminator is appended to the string. An input value of 0
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results in the empty string.
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</p>
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<p>The <code>a64l</code> function performs the reverse translation. Each
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character is used to generate a 6-bit value for up to 30 bits and then
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a 2-bit value to complete a 32-bit result. The null terminator means
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that the remaining digits are 0. An empty input string or NULL string
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results in 0L. An invalid string results in undefined behavior. If
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the size of a long is greater than 32 bits, the result is sign-extended.
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</p>
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<br>
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<p><strong>Returns</strong><br>
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<code>l64a</code> returns a null-terminated string of 0 to 6 characters.
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<code>a64l</code> returns the 32-bit translated value from the input character string.
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</p>
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<br>
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<p><strong>Portability</strong><br>
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<code>l64a</code> and <code>a64l</code> are non-ANSI and are defined by the Single Unix Specification.
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</p>
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<p>Supporting OS subroutines required: None.
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</p>
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<br>
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<hr>
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<div class="header">
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<p>
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Next: <a href="abort.html#abort" accesskey="n" rel="next">abort</a>, Previous: <a href="_005fExit.html#g_t_005fExit" accesskey="p" rel="prev">_Exit</a>, Up: <a href="Stdlib.html#Stdlib" accesskey="u" rel="up">Stdlib</a> [<a href="Document-Index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Document-Index.html#Document-Index" title="Index" rel="index">Index</a>]</p>
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</div>
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</body>
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</html>
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