Subversion Repositories yahamm

#!/bin/sh

#

# Print out the minimum number of parity bits needed for the Hamming

# code for a given message length.

#

# For usage call it --help.

help="Usage: $0 [-n] <message_length>\n-n: no extra parity bit"

if [ $1 = "--help" ] || [ $1 = "-h" ]; then

    echo -e $help

    exit

fi

if [ $1 = "-n" ]; then

    if [ -z ${2+x} ]; then

        echo -e $help

        exit

    fi

    EXTRA_PARITY_BIT=0

    MESSAGE_LENGTH=$2

else

    if [ -z ${1+x} ]; then

        echo -e $help

        exit

    fi

    EXTRA_PARITY_BIT=1

    MESSAGE_LENGTH=$1

fi

r=0

while [ true ]; do

    if [ $((2**r - r - 1)) -ge $MESSAGE_LENGTH ]; then

        echo $((r+EXTRA_PARITY_BIT))

        exit

    fi

    r=$((r+1))

done