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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 eval ::base32 {}
# ### ### ### ######### ######### #########
## API & Implementation
proc ::base32::tcl_encode {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]
}
proc ::base32::tcl_decode {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 $estring]]]
}
# ### ### ### ######### ######### #########
## Data structures
namespace eval ::base32 {
# Initialize the maps
variable forward
variable backward
variable invalid
core::define {
0 A 9 J 18 S 27 3
1 B 10 K 19 T 28 4
2 C 11 L 20 U 29 5
3 D 12 M 21 V 30 6
4 E 13 N 22 W 31 7
5 F 14 O 23 X
6 G 15 P 24 Y
7 H 16 Q 25 Z
8 I 17 R 26 2
} forward backward invalid ; # {}
# puts ///$forward///
# puts ///$backward///
}
# ### ### ### ######### ######### #########
## Ok
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