1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
|
'\" t
\t
.\" Copyright 2002 walter harms (walter.harms@informatik.uni-oldenburg.de)
.\"
.\" SPDX-License-Identifier: GPL-1.0-or-later
.\"
.\" Corrected, aeb, 2002-05-30
.\"
.TH a64l 3 2023-07-20 "Linux man-pages 6.05.01"
.SH NAME
a64l, l64a \- convert between long and base-64
.SH LIBRARY
Standard C library
.RI ( libc ", " \-lc )
.SH SYNOPSIS
.nf
.B #include <stdlib.h>
.PP
.BI "long a64l(const char *" str64 );
.BI "char *l64a(long " value );
.fi
.PP
.RS -4
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.RE
.PP
.BR a64l (),
.BR l64a ():
.nf
_XOPEN_SOURCE >= 500
.\" || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED
|| /* glibc >= 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _SVID_SOURCE
.fi
.SH DESCRIPTION
These functions provide a conversion between 32-bit long integers
and little-endian base-64 ASCII strings (of length zero to six).
If the string used as argument for
.BR a64l ()
has length greater than six, only the first six bytes are used.
If the type
.I long
has more than 32 bits, then
.BR l64a ()
uses only the low order 32 bits of
.IR value ,
and
.BR a64l ()
sign-extends its 32-bit result.
.PP
The 64 digits in the base-64 system are:
.PP
.RS
.nf
\&\[aq].\[aq] represents a 0
\&\[aq]/\[aq] represents a 1
0-9 represent 2-11
A-Z represent 12-37
a-z represent 38-63
.fi
.RE
.PP
So 123 = 59*64\[ha]0 + 1*64\[ha]1 = "v/".
.SH ATTRIBUTES
For an explanation of the terms used in this section, see
.BR attributes (7).
.TS
allbox;
lbx lb lb
l l l.
Interface Attribute Value
T{
.na
.nh
.BR l64a ()
T} Thread safety MT-Unsafe race:l64a
T{
.na
.nh
.BR a64l ()
T} Thread safety MT-Safe
.TE
.sp 1
.SH STANDARDS
POSIX.1-2008.
.SH HISTORY
POSIX.1-2001.
.SH NOTES
The value returned by
.BR l64a ()
may be a pointer to a static buffer, possibly overwritten
by later calls.
.PP
The behavior of
.BR l64a ()
is undefined when
.I value
is negative.
If
.I value
is zero, it returns an empty string.
.PP
These functions are broken before glibc 2.2.5
(puts most significant digit first).
.PP
This is not the encoding used by
.BR uuencode (1).
.SH SEE ALSO
.BR uuencode (1),
.\" .BR itoa (3),
.BR strtoul (3)
|
