A64L(3)

NAME
a64l, l64a - convert between radix-64 ASCII string and long

SYNOPSIS

#include <stdlib.h>

long a64l(const char *input);

char *l64a(long input);

DESCRIPTION

Conversion is performed between long and radix-64 characters. The l64a routine transforms up to 32 bits of input value starting from least significant bits to the most significant bits. The input value is split up into a maximum of 5 groups of 6 bits and possibly one group of 2 bits (bits 31 and 30).

Each group of 6 bits forms a value from 0--63 which is translated into a character as follows:

    • 0 = '.'

    • 1 = '/'

    • 2--11 = '0' to '9'

    • 12--37 = 'A' to 'Z'

    • 38--63 = 'a' to 'z'

When the remaining bits are zero or all bits have been translated, a null terminator is appended to the string. An input value of 0 results in the empty string.

The a64l function performs the reverse translation. Each character is used to generate a 6-bit value for up to 30 bits and then a 2-bit value to complete a 32-bit result. The null terminator means that the remaining digits are 0. An empty input string or NULL string results in 0L. An invalid string results in undefined behavior. If the size of a long is greater than 32 bits, the result is sign-extended.

RETURNS

l64a returns a null-terminated string of 0 to 6 characters. a64l returns the 32-bit translated value from the input character string.

PORTABILITY

l64a and a64l are non-ANSI and are defined by the Single Unix Specification.

Supporting OS subroutines required: None.

AUTHORS

Steve Chamberlain
    Author.

Roland Pesch
    Author.

Red Hat Support

Jeff Johnston
    Author.

COPYRIGHT

This file documents the ANSI C library.

Copyright (C) 1992, 1993, 1994-2014 Red Hat, Inc.

libc includes software developed by the University of California, Berkeley and its contributors.

libc includes software developed by Martin Jackson, Graham Haley and Steve Chamberlain of Tadpole Technology and released to Cygnus.

libc uses floating-point conversion software developed at AT&T, which includes this copyright information:

The author of this software is David M. Gay.

Copyright (c) 1991 by AT&T.

Permission to use, copy, modify, and distribute this software for any purpose without fee is hereby granted, provided that this entire notice is included in all copies of any software which is or includes a copy or modification of this software and in all copies of the supporting documentation for such software.

THIS SOFTWARE IS BEING PROVIDED "AS IS", WITHOUT ANY EXPRESS OR IMPLIED WARRANTY. IN PARTICULAR, NEITHER THE AUTHOR NOR AT&T MAKES ANY REPRESENTATION OR WARRANTY OF ANY KIND CONCERNING THE MERCHANTABILITY OF THIS SOFTWARE OR ITS FITNESS FOR ANY PARTICULAR PURPOSE.

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Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, subject to the terms of the GNU General Public License, which includes the provision that the entire resulting derived work is distributed under the terms of a permission notice identical to this one.

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