NAME
a64l, l64a
— convert between 32-bit integer
and radix-64 ASCII string
SYNOPSIS
#include
<stdlib.h>
long
a64l(const
char *s);
char *
l64a(long
l);
DESCRIPTION
The
a64l()
and l64a() functions are used to 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 a radix-64 notation.
The characters used to represent digits are
‘.’ 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 takes a pointer to a NUL-terminated radix-64 representation and
returns a corresponding 32-bit value. If the string pointed to by
s contains more than six characters,
a64l() will use the first six.
a64l() scans the character string from left to
right, decoding each character as a 6-bit radix-64 number. If a long integer
is larger than 32 bits, the return value will be sign-extended.
l64a()
takes a long integer argument l and returns a pointer
to the corresponding radix-64 representation.
RETURN VALUES
On success, a64l() returns a 32-bit
representation of s. If s is a
null pointer or if it contains digits other than those described above,
a64l() returns -1 and sets the global variable
errno to EINVAL.
On success, l64a() returns a pointer to a
string containing the radix-64 representation of l. If
l is 0, l64a() returns a
pointer to the empty string. If l is negative,
l64a() returns a null pointer and sets the global
variable errno to EINVAL.
STANDARDS
The a64l() and
l64a() functions conform to X/Open
Portability Guide Issue 4, Version 2
(“XPG4.2”).
CAVEATS
The value returned by l64a() is a pointer
into a static buffer, the contents of which will be overwritten by
subsequent calls.
The value returned by a64l() may be
incorrect if the value is too large; for that reason, only strings that
resulted from a call to l64a() should be used to
call a64l().
If a long integer is larger than 32 bits, only the low-order 32 bits are used.