man3/a64l.3

   1 \t
   2 .\" Copyright 2002 walter harms (walter.harms@informatik.uni-oldenburg.de)
   3 .\"
   4 .\" SPDX-License-Identifier: GPL-1.0-or-later
   5 .\"
   6 .\" Corrected, aeb, 2002-05-30
   7 .\"
   8 .TH A64L 3 2021-03-22 "Linux man-pages (unreleased)"
   9 .SH NAME
  10 a64l, l64a \- convert between long and base-64
  11 .SH LIBRARY
  12 Standard C library
  13 .RI ( libc ", " \-lc )
  14 .SH SYNOPSIS
  15 .nf
  16 .B #include <stdlib.h>
  17 .PP
  18 .BI "long a64l(const char *" str64 );
  19 .BI "char *l64a(long " value );
  20 .fi
  21 .PP
  22 .RS -4
  23 Feature Test Macro Requirements for glibc (see
  24 .BR feature_test_macros (7)):
  25 .RE
  26 .PP
  27 .BR a64l (),
  28 .BR l64a ():
  29 .nf
  30     _XOPEN_SOURCE >= 500
  31 .\"    || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
  32         || /* Glibc since 2.19: */ _DEFAULT_SOURCE
  33         || /* Glibc <= 2.19: */ _SVID_SOURCE
  34 .fi
  35 .SH DESCRIPTION
  36 These functions provide a conversion between 32-bit long integers
  37 and little-endian base-64 ASCII strings (of length zero to six).
  38 If the string used as argument for
  39 .BR a64l ()
  40 has length greater than six, only the first six bytes are used.
  41 If the type
  42 .I long
  43 has more than 32 bits, then
  44 .BR l64a ()
  45 uses only the low order 32 bits of
  46 .IR value ,
  47 and
  48 .BR a64l ()
  49 sign-extends its 32-bit result.
  50 .PP
  51 The 64 digits in the base-64 system are:
  52 .PP
  53 .RS
  54 .nf
  55 \&\(aq.\(aq     represents a 0
  56 \&\(aq/\(aq     represents a 1
  57 0-9     represent  2-11
  58 A-Z     represent 12-37
  59 a-z     represent 38-63
  60 .fi
  61 .RE
  62 .PP
  63 So 123 = 59*64\(ha0 + 1*64\(ha1 = "v/".
  64 .SH ATTRIBUTES
  65 For an explanation of the terms used in this section, see
  66 .BR attributes (7).
  67 .ad l
  68 .nh
  69 .TS
  70 allbox;
  71 lbx lb lb
  72 l l l.
  73 Interface       Attribute       Value
  74 T{
  75 .BR l64a ()
  76 T}      Thread safety   MT-Unsafe race:l64a
  77 T{
  78 .BR a64l ()
  79 T}      Thread safety   MT-Safe
  80 .TE
  81 .hy
  82 .ad
  83 .sp 1
  84 .SH STANDARDS
  85 POSIX.1-2001, POSIX.1-2008.
  86 .SH NOTES
  87 The value returned by
  88 .BR l64a ()
  89 may be a pointer to a static buffer, possibly overwritten
  90 by later calls.
  91 .PP
  92 The behavior of
  93 .BR l64a ()
  94 is undefined when
  95 .I value
  96 is negative.
  97 If
  98 .I value
  99 is zero, it returns an empty string.
 100 .PP
 101 These functions are broken in glibc before 2.2.5
 102 (puts most significant digit first).
 103 .PP
 104 This is not the encoding used by
 105 .BR uuencode (1).
 106 .SH SEE ALSO
 107 .BR uuencode (1),
 108 .\" .BR itoa (3),
 109 .BR strtoul (3)