#!/bin/ksh
#
# Low ASCII Base64 converter in Kornshell
#
# (c) Peter van Eerten november 2007 - GPL.
#
#----------------------------------------------------------------------------------------------

# Data needed for ASCII value of character
set -A CHAR " " "!" "\"" "#" "$" "%" "&" "'" "(" ")" "*" "+" "," "-" "." "/" "0" "1" "2" \
	    "3" "4" "5" "6" "7" "8" "9" ":" ";" "<" "=" ">" "?" "@" "A" "B" "C" "D" "E" "F" \
	    "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q" "R" "S" "T" "U" "V" "W" "X" "Y" "Z" \
	    "[" "\"" "]" "^" "_" "\`" "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" \
	    "n" "o" "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z" "{" "|" "}" "~"

# This is the Base64 string
set -A BASE64 "A" "B" "C" "D" "E" "F" "G" "H" "I" "J" "K" "L" "M" "N" "O" "P" "Q" "R" "S" "T" \
	    "U" "V" "W" "X" "Y" "Z" "a" "b" "c" "d" "e" "f" "g" "h" "i" "j" "k" "l" "m" "n" \
	    "o" "p" "q" "r" "s" "t" "u" "v" "w" "x" "y" "z" "0" "1" "2" "3" "4" "5" "6" "7" \
	    "8" "9" "+" "/"

# Convert character to ASCII value
function asc
{
typeset i=0

if [[ $1 = "¤" ]]
then
    ASC=32
else
    while [[ $i -lt 95 ]]
    do
        if [[ $1 = "${CHAR[$i]}" ]]
        then
	    break
        fi
        ((i+=1))
    done
    if [[ $i -eq 95 ]]
    then
        ASC=128
    else
        let ASC=$i+32
    fi
fi
}

# This is the main program
if [[ $# -eq 0 ]]
then
    read TOTAL?"Enter text to convert... "
else
    TOTAL=$1
fi

# First convert spaces to "¤"
VAR=""
for t in $TOTAL
do
    VAR=$VAR$t"¤"
done
let NUM=${#VAR}-1
typeset -L${NUM} VAR="$VAR"

# This variable will contain the result
result=""

# Start encoding
while [[ ${#VAR} -gt 0 ]]
do
    # Specify byte values
    if [[ ${#VAR} -eq 1 ]]; then
	typeset -L1 byte="$VAR"
	asc $byte
	byte1=$ASC
	byte2=0
	byte3=0
    fi
    if [[ ${#VAR} -eq 2 ]]; then
	typeset -L1 byte="$VAR"
	asc $byte
	byte1=$ASC
	let NUM=${#VAR}-1
	typeset -R${NUM} TMP="$VAR"
	typeset -L1 byte="$TMP"
	asc $byte
	byte2=$ASC
	byte3=0
    fi
    if [[ ${#VAR} -ge 3 ]]; then
	typeset -L1 byte="$VAR"
	asc $byte
	byte1=$ASC
	let LEN="${#VAR}"-1
	typeset -R$LEN TMP="$VAR"
	typeset -L1 byte=$TMP
	asc $byte
	byte2=$ASC
	let LEN=${#TMP}-1
	typeset -R$LEN TMP="$TMP"
	typeset -L1 byte=$TMP
	asc $byte
	byte3=$ASC
    fi
    # Create BASE64 values
    let base1=$((byte1>>2))
    let base2=$(($((byte1&3))<<4))+$(($((byte2&240))>>4))
    let base3=$(($((byte2&15))<<2))+$(($((byte3&192))>>6))
    let base4=$((byte3&63))
    # Compose BASE64 string
    if [[ ${#VAR} -eq 1 ]]; then
	result=$result${BASE64[$base1]}
	result=$result${BASE64[$base2]}
	result=$result"=="
	unset VAR
    fi
    if [[ ${#VAR} -eq 2 ]]; then
	result=$result${BASE64[$base1]}
	result=$result${BASE64[$base2]}
	result=$result${BASE64[$base3]}
	result=$result"="
	unset VAR
    fi
    if [[ ${#VAR} -ge 3 ]]; then
	result=$result${BASE64[$base1]}
	result=$result${BASE64[$base2]}
	result=$result${BASE64[$base3]}
	result=$result${BASE64[$base4]}
	if [[ ${#VAR} -gt 3 ]]
	then
	    let NUM=${#VAR}-3
	    typeset -R${NUM} VAR="${VAR}"
	else
	    unset VAR
	fi
    fi
done

echo $result

exit

#----------------------------------------------------------------------------------------------