base32hex_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 for the extended hex encoding.*/

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

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

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

ret  ::base32::hex::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::hex::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::hex {
    namespace core {
    namespace import ::base32::core::define
    namespace import ::base32::core::valid
    }

    namespace export encode decode
    /*  Initialize the maps*/
    variable forward
    variable backward
    variable invalid

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

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