error correction coding

ecc.py

@@ -0,0 +1,47 @@
+# -*- coding: utf-8 -*-
+
+#GP: Generator Polynomial, MP: Message Polynomial
+# test:
+GP = [0, 251, 67, 46, 61, 118, 70, 64, 94, 32, 45]
+
+#DC: Data Codewords, ECC: Error Correction Codewords
+def get_ECC(DC, ECC_num):
+    po2 = get_power_of_2_list()
+    log = get_log_list(po2)
+    
+    # ..... get the correct GP according to ECC_num
+    
+    remainder = DC
+    for i in range(len(DC)):
+        remainder = divide(remainder, GP)
+    return remainder
+    
+def divide(MP, GP):
+    a = len(MP) - len(GP)
+    if a < 0:
+        MP += [0] * (-a)
+    elif a > 0:
+        GP += [0] * a
+    
+    log(MP[0])
+    
+def XOR():
+    pass
+    
+def get_power_of_2_list():
+    po2 = [1]
+    for i in range(255):
+        a = po2[i] * 2
+        if a > 255:
+            a ^= 285
+        po2.append(a)
+    return po2
+    
+def get_log_list(po2):
+    log = [None]*256
+    for i in range(255):
+        log[po2[i]] = i
+    return log
+    
+# test:
+dc = '32, 91, 11, 120, 209, 114, 220, 77, 67, 64, 236, 17, 236, 17, 236, 17'