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
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.
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.
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