#
# bitfield manipulation
# http://code.activestate.com/recipes/113799/
# Author: Sebastien Keim
#

class bf(object):
    def __init__(self,value=0):
        self._d = value

    def __getitem__(self, index):
        return (self._d >> index) & 1 

    def __setitem__(self,index,value):
        value    = (value&1L)<<index
        mask     = (1L)<<index
        self._d  = (self._d & ~mask) | value

    def __getslice__(self, start, end):
        mask = 2L**(end - start) -1
        return (self._d >> start) & mask

    def __setslice__(self, start, end, value):
        mask = 2L**(end - start) -1
        value = (value & mask) << start
        mask = mask << start
        self._d = (self._d & ~mask) | value
        return (self._d >> start) & mask

    def __int__(self):
        return self._d

def pack16(v1,v2):
    f = bf()
    f[0:8] = v1
    f[9:16] = v2
    return int(f)

def unpack16(v):
    f = bf(v)
    return (f[0:8], f[9:16])

def pack24(v1,v2,v3):
    f = bf()
    f[0:8] = v1
    f[9:16] = v2
    f[17:24] = v3
    return int(f)

def unpack24(v):
    f = bf(v)
    return (f[0:8], f[9:16], f[17:24])