Posted to tcl by kbk at Thu Oct 22 16:48:24 GMT 2009view pretty

proc inet_cksum32_kbk2 {data} {
    binary scan $data Iu*cu* x extra
    lappend extra 0 0 0 0
    lassign $extra p q r s
    set sum [expr {($p << 24) + ($q << 16) + ($r << 8) + $s}]
    foreach w $x {
	incr sum $w
    }
    set sum [expr {($sum & 0xffffffff) + ($sum >> 32)}]
    set sum [expr {($sum & 0xffff) + ($sum >> 16)}]
    set sum [expr {($sum & 0xffff) + ($sum >> 16)}]
    return [expr {(-1-$sum) & 0xffff}]
}