NAME
dec64, enc64, dec32, enc32, dec16, enc16, dec64chr, enc64chr, dec32chr, enc32chr, dec16chr, enc16chr, encodefmt – encoding byte arrays as strings

SYNOPSIS
#include <u.h>
#include <libc.h>

int    dec64(uchar *out, int lim, char *in, int n)

int    enc64(char *out, int lim, uchar *in, int n)

int    dec32(uchar *out, int lim, char *in, int n)

int    enc32(char *out, int lim, uchar *in, int n)

int    dec16(uchar *out, int lim, char *in, int n)

int    enc16(char *out, int lim, uchar *in, int n)

int    dec64chr(int c)

int    enc64chr(int o)

int    dec32chr(int c)

int    enc32chr(int o)

int    dec16chr(int c)

int    enc16chr(int o)

int    encodefmt(Fmt*)

DESCRIPTION
The functions described here handle encoding and decoding of bytes to printable ASCII strings as specified by RFC4648.

Enc16, enc32 and enc64 create null terminated strings. They return the size of the encoded string (without the null) or –1 if the encoding fails. The encoding fails if lim, the length of the output buffer (including null), is too small.

Dec16, dec32 and dec64 return the number of bytes decoded or –1 if the decoding fails. The decoding fails if the output buffer is not large enough or, for base 32, if the input buffer length is not a multiple of 8.

Dec16chr, dec32chr and dec64chr return the value for a symbol of the alphabet or –1 when the symbol is not in the alphabet.

Enc16chr, enc32chr and enc64chr encode a symbol of the alphabet given a value. if the value is out of range then zero is returned.

Encodefmt can be used with fmtinstall(2) and print(2) to print encoded representations of byte arrays. The verbs are
H     base 16 (i.e. hexadecimal). The default encoding is in upper case. The l flag forces lower case.
<     base 32. The default is upper case, same as H.
[     base 64 (same as MIME)

The length of the array is specified as f2. For example, to display a 15 byte array as hex:
char x[15];
fmtinstall('H', encodefmt);
print("%.*H\n", sizeof x, x);

SOURCE
/sys/src/libc/port/u16.c
/sys/src/libc/port/u32.c
/sys/src/libc/port/u64.c
/sys/src/libc/port/encodefmt.c

HISTORY
In Jan 2018, base 32 encoding was changed from non–standard to standard RFC4648 alphabet.
old:   23456789abcdefghijkmnpqrstuvwxyz
new:   ABCDEFGHIJKLMNOPQRSTUVWXYZ234567