travail d'un we (j'en ai big marre)

old/spotify-codes-part-2/src/simple_convolutional_code.py

@@ -0,0 +1,35 @@
+from typing import List
+
+
+def encode(bits: List[int], polynomial: List[int], tail_bite=False):
+    """Convolutionally encode the stream of bits using the generator polynomial.
+    If tail_bite == True, prepend the tail of the input. Otherwise use 0s to fill.
+    """
+    if tail_bite:
+        tail = bits[-(len(polynomial) - 1):]
+    else: 
+        tail = [0 for i in range(len(polynomial) - 1)]
+    full = tail + bits
+    polynomial.reverse() # Reverse since we're working the other direction
+    parity_bits = []
+    for i in range(len(bits)):
+        parity = 0
+        for j in range(len(polynomial)):
+            parity ^= full[i + j] * polynomial[j]
+        parity_bits.append(parity)
+    return parity_bits
+
+
+if __name__ == "__main__":
+    g0 = [1, 0, 1, 1, 0, 1, 1]
+    g1 = [1, 1, 1, 1, 0, 0, 1]
+    bits = "010001001110111111110001110101101011011001100"
+    g0_expected = "100011100111110100110011110100000010001001011"
+    g1_expected = "110011100010110110110100101101011100110011011"
+    bits = [int(i) for i in bits]
+
+    p0 = encode(bits, g0, True)
+    p1 = encode(bits, g1, True)
+
+    print(g0_expected == "".join(str(i) for i in p0))
+    print(g1_expected == "".join(str(i) for i in p1))