def cyclic_code_genpoly(n, k):
if n%2 == 0:
raise ValueError, "n cannot be an even number"
for m in arange(1, 18):
if (2**m-1)%n == 0:
break
x_gf = GF(arange(1, 2**m), m)
coset_fields = x_gf.cosets()
coset_leaders = array([])
minpol_degrees = array([])
for field in coset_fields:
coset_leaders = concatenate((coset_leaders, array([field.elements[0]])))
minpol_degrees = concatenate((minpol_degrees, array([len(field.elements)])))
y_gf = GF(coset_leaders, m)
minpol_list = y_gf.minpolys()
idx_list = arange(1, len(minpol_list))
poly_list = array([])
for i in xrange(1, 2**len(minpol_list)):
i_array = dec2bitarray(i, len(minpol_list))
subset_array = minpol_degrees[i_array == 1]
if int(subset_array.sum()) == (n-k):
poly_set = minpol_list[i_array == 1]
gpoly = 1
for poly in poly_set:
gpoly_array = dec2bitarray(gpoly, 2**m)
poly_array = dec2bitarray(poly, 2**m)
gpoly = bitarray2dec(convolve(gpoly_array, poly_array) % 2)
poly_list = concatenate((poly_list, array([gpoly])))
return poly_list.astype(int)
def cyclic_code_genpoly(n, k):
"""
Generate all possible generator polynomials for a (n, k)-cyclic code.
Parameters
----------
n : int
Code blocklength of the cyclic code.
k : int
Information blocklength of the cyclic code.
Returns
-------
poly_list : 1D ndarray of ints
A list of generator polynomials (represented as integers) for the (n, k)-cyclic code.
"""
if n%2 == 0:
raise ValueError, "n cannot be an even number"
for m in arange(1, 18):
if (2**m-1)%n == 0:
break
x_gf = GF(arange(1, 2**m), m)
coset_fields = x_gf.cosets()
coset_leaders = array([])
minpol_degrees = array([])
for field in coset_fields:
coset_leaders = concatenate((coset_leaders, array([field.elements[0]])))
minpol_degrees = concatenate((minpol_degrees, array([len(field.elements)])))
y_gf = GF(coset_leaders, m)
minpol_list = y_gf.minpolys()
idx_list = arange(1, len(minpol_list))
poly_list = array([])
for i in xrange(1, 2**len(minpol_list)):
i_array = dec2bitarray(i, len(minpol_list))
subset_array = minpol_degrees[i_array == 1]
if int(subset_array.sum()) == (n-k):
poly_set = minpol_list[i_array == 1]
gpoly = 1
for poly in poly_set:
gpoly_array = dec2bitarray(gpoly, 2**m)
poly_array = dec2bitarray(poly, 2**m)
gpoly = bitarray2dec(convolve(gpoly_array, poly_array) % 2)
poly_list = concatenate((poly_list, array([gpoly])))
return poly_list.astype(int)
def cyclic_code_genpoly(n, k):
if n % 2 == 0:
raise ValueError, "n cannot be an even number"
for m in arange(1, 18):
if (2**m - 1) % n == 0:
break
x_gf = GF(arange(1, 2**m), m)
coset_fields = x_gf.cosets()
coset_leaders = array([])
minpol_degrees = array([])
for field in coset_fields:
coset_leaders = concatenate(
(coset_leaders, array([field.elements[0]])))
minpol_degrees = concatenate(
(minpol_degrees, array([len(field.elements)])))
y_gf = GF(coset_leaders, m)
minpol_list = y_gf.minpolys()
idx_list = arange(1, len(minpol_list))
poly_list = array([])
for i in xrange(1, 2**len(minpol_list)):
i_array = dec2bitarray(i, len(minpol_list))
subset_array = minpol_degrees[i_array == 1]
if int(subset_array.sum()) == (n - k):
poly_set = minpol_list[i_array == 1]
gpoly = 1
for poly in poly_set:
gpoly_array = dec2bitarray(gpoly, 2**m)
poly_array = dec2bitarray(poly, 2**m)
gpoly = bitarray2dec(convolve(gpoly_array, poly_array) % 2)
poly_list = concatenate((poly_list, array([gpoly])))
return poly_list.astype(int)
