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 a64l() has length greater than six, only the first
six bytes are used. If longs have more than 32 bits, then l64a() uses
only the low order 32 bits of value, and a64l() sign-extends its
The 64 digits in the base 64 system are:
'.' represents a 0
'/' represents a 1
0-9 represent 2-11
A-Z represent 12-37
a-z represent 38-63
The value returned by a64l() may be a pointer to a static buffer,
possibly overwritten by later calls.
The behaviour of l64a() is undefined when value is negative. If
value is zero, it returns an empty string.
These functions are broken in glibc before 2.2.5 (puts most significant digit
This is not the encoding used by uuencode(1).