NAME
a64l, l64a - convert between a 32-bit integer and a radix-64 ASCII
string
SYNOPSIS
#include <stdlib.h>
long a64l(const char *s);
char *l64a(long value);
DESCRIPTION
These functions maintain numbers stored in radix-64 ASCII characters.
This is a notation by which 32-bit integers can be represented by up to
six characters; each character represents a digit in radix-64 notation.
If the type long contains more than 32 bits, only the low-order 32 bits
shall be used for these operations.
The characters used to represent digits are ’.’ (dot) for 0, ’/’ for 1,
’0’ through ’9’ for [2,11], ’A’ through ’Z’ for [12,37], and ’a’
through ’z’ for [38,63].
The a64l() function shall take a pointer to a radix-64 representation,
in which the first digit is the least significant, and return the
corresponding long value. If the string pointed to by s contains more
than six characters, a64l() shall use the first six. If the first six
characters of the string contain a null terminator, a64l() shall use
only characters preceding the null terminator. The a64l() function
shall scan the character string from left to right with the least
significant digit on the left, decoding each character as a 6-bit
radix-64 number. If the type long contains more than 32 bits, the
resulting value is sign-extended. The behavior of a64l() is unspecified
if s is a null pointer or the string pointed to by s was not generated
by a previous call to l64a().
The l64a() function shall take a long argument and return a pointer to
the corresponding radix-64 representation. The behavior of l64a() is
unspecified if value is negative.
The value returned by l64a() may be a pointer into a static buffer.
Subsequent calls to l64a() may overwrite the buffer.
The l64a() function need not be reentrant. A function that is not
required to be reentrant is not required to be thread-safe.
RETURN VALUE
Upon successful completion, a64l() shall return the long value
resulting from conversion of the input string. If a string pointed to
by s is an empty string, a64l() shall return 0L.
The l64a() function shall return a pointer to the radix-64
representation. If value is 0L, l64a() shall return a pointer to an
empty string.
ERRORS
No errors are defined.
The following sections are informative.
EXAMPLES
None.
APPLICATION USAGE
If the type long contains more than 32 bits, the result of
a64l(l64a(x)) is x in the low-order 32 bits.
RATIONALE
This is not the same encoding as used by either encoding variant of the
uuencode utility.
FUTURE DIRECTIONS
None.
SEE ALSO
strtoul() , the Base Definitions volume of IEEE Std 1003.1-2001,
<stdlib.h>, the Shell and Utilities volume of IEEE Std 1003.1-2001,
uuencode
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .