# -*- tcl -*-
# This code is hereby put into the public domain.
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## Overview
# Base32 encoding and decoding of small strings.
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## 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.
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## Requisites
package require base32::core
namespace eval ::base32::hex {}
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## API & Implementation
proc ::base32::hex::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::hex::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 $estring]]]
}
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## Data structures
namespace eval ::base32::hex {
namespace eval core {
namespace import ::base32::core::define
namespace import ::base32::core::valid
}
namespace export encode decode
# Initialize the maps
variable forward
variable backward
variable invalid
core::define {
0 0 9 9 18 I 27 R
1 1 10 A 19 J 28 S
2 2 11 B 20 K 29 T
3 3 12 C 21 L 30 U
4 4 13 D 22 M 31 V
5 5 14 E 23 N
6 6 15 F 24 O
7 7 16 G 25 P
8 8 17 H 26 Q
} forward backward invalid ; # {}
# puts ///$forward///
# puts ///$backward///
}
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## Ok
