Convert a MAC Address to Motorola S-Records

#!/bin/bash

mac_addr_pattern='^[0-9a-fA-F]{2}[-:]'
mac_addr_pattern+='[0-9a-fA-F]{2}[-:]'
mac_addr_pattern+='[0-9a-fA-F]{2}[-:]'
mac_addr_pattern+='[0-9a-fA-F]{2}[-:]'
mac_addr_pattern+='[0-9a-fA-F]{2}[-:]'
mac_addr_pattern+='[0-9a-fA-F]{2}'

address_pattern='^(0x)?[0-9a-fA-F]{8}$'


######################################################################
function usage()
{
    if [[ "$*" ]]; then echo $* >&2; fi
    cat >&2 <<EOU
Usage: $0 OPTIONS MAC-ADDRESS
  --address ADDRESS              Address in FLASH of serial number or MAC Id.
  --output FILE                  Output file.
EOU
    exit 1
}


######################################################################
trap "rm -f $$-?.tmp" EXIT

output_file=

while [[ "$1" ]]
do
    case "$1" in
    --address)
        shift
        if [[ ! "$1" ]]; then usage "Missing address"; fi
        address=$1
        if ! grep --silent -P "$address_pattern" <<<$address; then
            usage "Invalid address: $address"
        fi
        ;;
    --output)
        shift
        if [[ ! "$1" ]]; then usage "Missing output file name"; fi
        output_file=$1
        ;;
    *)
        mac_addr=$1
        shift
        if [[ "$1" ]]; then usage "Unexpected argument: $1"; fi
        if ! grep --silent -P "$mac_addr_pattern" <<<$mac_addr; then
            usage "Invalid mac address: $mac_addr"
        fi
        ;;
    esac
    shift
done

if [[ ! "$mac_addr" ]]; then usage "Missing mac address"; fi

mac_addr=${mac_addr/:/ }
mac_addr=${mac_addr/-/ }
echo "0000: $mac_addr" | xxd -r >$$-1.tmp
opt=
if [[ "$address" ]]; then opt="--change-addresses $address"; fi
objcopy $opt -I binary -O srec $$-1.tmp $$-2.tmp
if [[ "$output_file" ]]; then
    mv $$-2.tmp $output_file
else
    cat $$-2.tmp
fi

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