#!/bin/sh

ABC="0123456789ABCDEF"

dec2any () {
  z=$1
  b=$2
  a=""
  while [ $z -ne 0 ]
  do
    t="`expr $z % $b`"
    a="`expr substr $ABC $(expr $t + 1) 1`$a"
    z="`expr $z / $b`"
  done
  echo "${a:-0}"
}

any2dec() {
  b=$2
  a=0
  for digit in `echo "$1" | sed 's/./& /g'`
  do
    digit=`expr $(expr index $ABC $digit) - 1`
    a=`expr $a \* $b + $digit`
  done
  echo "${a:-0}"
}


while [ -n "$1" ]
do
  out=""
  case "$1" in
    -h | --help | help)
    cat << EOF
ABOUT

  digish - small digit converter for small systems

USAGE

  digish [-h] mode number [number number ...]

MODES

 - sourceTOdestination (eg: 2TO10 | 7TO3 etc)
 - sbase2dbase (eg b2d | h2o etc)

BASES

 -  2 | b - binary
 -  8 | o - octal
 - 10 | d - decimal
 - 16 | h - hexadezimal

EXAMPLES

 - digish h2d FF -> 255
 - digish h2b FF -> 11111111
 - digish b2o

AUTHOR

 - tobias gruetzmacher < >
 - mathias gumz <gumz at cs dot uni-magdeburg dot de>

EOF
    exit 0;;
    -a | --alphabet )
      [ -n "$2" ] && ABC="$2"
    ;;

    *)
    if [ -n "$2" ]; then
      case "$1" in
        b2d)out=`any2dec "$2" 2`;;
        b2o)out=`dec2any $(any2dec "$2" 2) 8`;;
        b2h)out=`dec2any $(any2dec "$2" 2) 16`;;

        o2b)out=`dec2any $(any2dec "$2" 8) 2`;;
        o2d)out=`any2dec "$2" 8`;;
        o2h)out=`dec2any $(any2dec "$2" 8) 16`;;

        d2b)out=`dec2any "$2" 2`;;
        d2o)out=`dec2any "$2" 8`;;
        d2h)out=`dec2any "$2" 16`;;

        h2b)out=`dec2any $(any2dec "$2" 16) 2`;;
        h2o)out=`dec2any $(any2dec "$2" 16) 8`;;
        h2d)out=`any2dec "$2" 16`;;

        *[Tt][Oo]*)
          s=`echo $1 | sed -e 's/[Tt][Oo].\+$//g'`
          d=`echo $1 | sed -e 's/^.\+[Tt][Oo]//g'`
          out=`dec2any $(any2dec "$2" $s) $d`
          ;;
     esac
   else
     echo "error, missing value"
     exit 1
   fi
  esac
  echo "${out:-0}"
  out=""
  shift 2
done