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#!/usr/bin/env python
#
# Copyright 2015 Free Software Foundation, Inc.
#
# GNU Radio is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3, or (at your option)
# any later version.
#
# GNU Radio is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with GNU Radio; see the file COPYING. If not, write to
# the Free Software Foundation, Inc., 51 Franklin Street,
# Boston, MA 02110-1301, USA.
#
import numpy as np
from common import PolarCommon
class PolarEncoder(PolarCommon):
def __init__(self, n, k, frozen_bit_position, frozenbits=None):
PolarCommon.__init__(self, n, k, frozen_bit_position, frozenbits)
self.G = self._gn(n)
def _gn(self, n):
# this matrix is called generator matrix
if n == 1:
return np.array([1, ])
f = self._fn(n)
return f
def _fn(self, n):
# this matrix defines the actual channel combining.
if n == 1:
return np.array([1, ])
f2 = np.array([[1, 0], [1, 1]], np.int)
nump = int(np.log2(n)) - 1 # number of Kronecker products to calculate
fn = f2
for i in range(nump):
fn = np.kron(fn, f2)
return fn
def get_gn(self):
return self.G
def _prepare_input_data(self, vec):
vec = self._insert_frozen_bits(vec)
vec = self._reverse_bits(vec)
return vec
def _encode_matrix(self, data):
data = np.dot(data, self.G) % 2
data = data.astype(dtype=int)
return data
def _encode_efficient(self, vec):
nstages = int(np.log2(self.N))
pos = np.arange(self.N, dtype=int)
for i in range(nstages):
splitted = np.reshape(pos, (2 ** (i + 1), -1))
upper_branch = splitted[0::2].flatten()
lower_branch = splitted[1::2].flatten()
vec[upper_branch] = (vec[upper_branch] + vec[lower_branch]) % 2
return vec
def encode(self, data, is_packed=False):
if not len(data) == self.K:
raise ValueError("len(data)={0} is not equal to k={1}!".format(len(data), self.K))
if is_packed:
data = np.unpackbits(data)
if np.max(data) > 1 or np.min(data) < 0:
raise ValueError("can only encode bits!")
data = self._prepare_input_data(data)
data = self._encode_efficient(data)
if is_packed:
data = np.packbits(data)
return data
def compare_results(encoder, ntests, k):
for n in range(ntests):
bits = np.random.randint(2, size=k)
preped = encoder._prepare_input_data(bits)
menc = encoder._encode_matrix(preped)
fenc = encoder._encode_efficient(preped)
if (menc == fenc).all() == False:
return False
return True
def test_pseudo_rate_1_encoder(encoder, ntests, k):
for n in range(ntests):
bits = np.random.randint(2, size=k)
u = encoder._prepare_input_data(bits)
fenc = encoder._encode_efficient(u)
u_hat = encoder._encode_efficient(fenc)
if not (u_hat == u).all():
print('rate-1 encoder/decoder failed')
print u
print u_hat
return False
return True
def test_encoder_impls():
print('comparing encoder implementations, matrix vs. efficient')
ntests = 1000
n = 16
k = 8
frozenbits = np.zeros(n - k)
# frozenbitposition8 = np.array((0, 1, 2, 4), dtype=int) # keep it!
frozenbitposition = np.array((0, 1, 2, 3, 4, 5, 8, 9), dtype=int)
encoder = PolarEncoder(n, k, frozenbitposition, frozenbits)
print 'result:', compare_results(encoder, ntests, k)
print('Test rate-1 encoder/decoder chain results')
r1_test = test_pseudo_rate_1_encoder(encoder, ntests, k)
print 'test rate-1 encoder/decoder:', r1_test
def main():
print "main in encoder"
test_encoder_impls()
if __name__ == '__main__':
main()
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