def doubleParityChksum(data):
"""Computes horizontal an vertical parities.
One horizontal parity bit is computed per octet. 8 vertical parity bits
are computed. The checksum is the 8 vertical parity bits plus the
horizontal parity bits, padded by a variable number of 0 bits to align
on an octet boundary. Even parity is used.
The checksum is returned as a string where each character codes a byte
of the checksum.
"""
bitmask = Numeric.array([128,64,32,16,8,4,2,1])
bytes = Numeric.fromstring(data,Numeric.UnsignedInt8)
numBytes = len(bytes)
bits = Numeric.bitwise_and.outer(bytes,bitmask).flat
Numeric.putmask(bits,bits,1)
bits = Numeric.reshape(bits, (numBytes,8))
verParities = Numeric.bitwise_and(Numeric.sum(bits),1)
bits = Numeric.concatenate((bits,[verParities]))
horParities = Numeric.bitwise_and(Numeric.sum(bits,1),1)
if len(horParities)%8:
horParities = Numeric.concatenate((horParities,
[0]*(8-len(horParities)%8)))
bitmask = Numeric.array([128,64,32,16,8,4,2,1])
chksumstring = chr(Numeric.dot(verParities,bitmask))
for i in range(len(horParities)/8):
chksumstring += chr(Numeric.dot(horParities[i*8:(i+1)*8],bitmask))
return chksumstring
def testOperators (self):
"Test the operators +, -, *, /, %, ^, &, |"
x = Numeric.array([1.,2.,3.,4.,5.,6.])
y = Numeric.array([-1.,2.,0.,2.,-1, 3.])
assert_eq(x + y, [0., 4., 3., 6., 4., 9.])
assert_eq(x - y, [2., 0., 3., 2., 6., 3.])
assert_eq(x * y, [-1., 4., 0., 8., -5., 18.])
assert_eq(y / x, [-1, 1., 0., .5, -.2, .5])
assert_eq(x**2, [1., 4., 9., 16., 25., 36.])
xc = Numeric.array([1.,2.,3.,4.,5.,6.])
xc += y
assert_eq(xc, x + y)
xc = Numeric.array([1.,2.,3.,4.,5.,6.])
xc -= y
assert_eq(xc, x - y)
xc = Numeric.array([1.,2.,3.,4.,5.,6.])
xc *= y
assert_eq(xc, x * y)
yc = Numeric.array(y)
yc /= x
assert_eq( yc, y / x)
assert_eq(x + y, Numeric.add(x, y))
assert_eq(x - y, Numeric.subtract(x, y))
assert_eq(x * y, Numeric.multiply(x, y))
assert_eq(y / x, Numeric.divide (y, x))
self.failUnlessRaises(ZeroDivisionError, Numeric.divide,
Numeric.array(1), Numeric.array(0))
assert_eq(x**2, Numeric.power(x,2))
x = Numeric.array([1,2])
y = Numeric.zeros((2,))
assert_eq(x%x, y)
assert_eq(Numeric.remainder(x,x), y)
assert_eq(x <<1, [2,4])
assert_eq(Numeric.left_shift(x,1), [2,4])
assert_eq(x >>1, [0,1])
assert_eq(Numeric.right_shift(x,1), [0,1])
assert_eq(x & 2, [0,2])
assert_eq(Numeric.bitwise_and (x, 2), [0,2])
assert_eq(x | 1, [1,3])
assert_eq(Numeric.bitwise_or (x, 1), [1,3])
assert_eq(x ^ 2, [3,0])
assert_eq(Numeric.bitwise_xor(x,2), [3,0])
x = divmod(Numeric.array([2,1]), Numeric.array([1,2]))
assert_eq(x[0], [2,0])
assert_eq(x[1], [0,1])
assert (4L*Numeric.arange(3)).typecode() == Numeric.PyObject
x = Numeric.array([1,2,3,4,5,6],'u')
y = Numeric.array([1,2,0,2,2,3],'u')
assert_eq(x + y, [2, 4, 3, 6, 7, 9])
assert_eq(x - y, [0, 0, 3, 2, 3, 3])
assert_eq(x * y, [1, 4, 0, 8, 10, 18])
assert_eq(y / x, [1, 1, 0, 0, 0, 0])
assert_eq(y // x, [1, 1, 0, 0, 0, 0])
assert_eq(x**2, [1, 4, 9, 16, 25, 36])
