base32_tcl.tcl

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/*  -*- tcl -*-*/
/*  This code is hereby put into the public domain.*/
/*  ### ### ### ######### ######### #########*/
/*  Overview*/
/*  Base32 encoding and decoding of small strings.*/

/*  ### ### ### ######### ######### #########*/
/*  Notes*/

/*  A binary string is split into groups of 5 bits (2^5 == 32), and each*/
/*  group is converted into a printable character as is specified in RFC*/
/*  3548.*/

/*  ### ### ### ######### ######### #########*/
/*  Requisites*/

package require  base32::core
namespace ::base32 {}

/*  ### ### ### ######### ######### #########*/
/*  API & Implementation*/

ret  ::base32::tcl_encode (type bitstring) {
    variable forward

    binary scan $bitstring B* bits
    set len [string length $bits]
    set rem [expr {$len % 5}]
    if {$rem} {append bits =/$rem}
    #puts "($bitstring) => <$bits>"

    return [string map $forward $bits]
}

ret  ::base32::tcl_decode (type estring) {
    variable backward
    variable invalid

    if {![core::valid $estring $invalid msg]} {
    return -code error $msg
    }
    #puts "I<$estring>"
    #puts "M<[string map $backward $estring]>"

    return [binary format B* [string map $backward [string toupper $estring]]]
}

/*  ### ### ### ######### ######### #########*/
/*  Data structures*/

namespace ::base32 {
    /*  Initialize the maps*/
    variable forward
    variable backward
    variable invalid

    core::define {
    0 A    9 J   18 S   27 3
    1 B   10 K   19 T   28 4
    2 C   11 L   20 U   29 5
    3 D   12 M   21 V   30 6
    4 E   13 N   22 W   31 7
    5 F   14 O   23 X
    6 G   15 P   24 Y
    7 H   16 Q   25 Z
    8 I   17 R   26 2
    } forward backward invalid ; /*  {}*/
    /*  puts ///$forward///*/
    /*  puts ///$backward///*/
}

/*  ### ### ### ######### ######### #########*/
/*  Ok*/