1 /* Stuff common to all the general-purpose Reed-Solomon codecs
2 * Copyright 2004 Phil Karn, KA9Q
3 * May be used under the terms of the GNU Lesser General Public License (LGPL)
4 */
5
6 /* Reed-Solomon codec control block */
7 struct rs {
8 int mm; /* Bits per symbol */
9 int nn; /* Symbols per block (= (1<<mm)-1) */
10 data_t *alpha_to; /* log lookup table */
11 data_t *index_of; /* Antilog lookup table */
12 data_t *genpoly; /* Generator polynomial */
13 int nroots; /* Number of generator roots = number of parity symbols */
14 int fcr; /* First consecutive root, index form */
15 int prim; /* Primitive element, index form */
16 int iprim; /* prim-th root of 1, index form */
17 int pad; /* Padding bytes in shortened block */
18 };
19
modnn(struct rs * rs,int x)20 static inline int modnn(struct rs *rs,int x){
21 while (x >= rs->nn) {
22 x -= rs->nn;
23 x = (x >> rs->mm) + (x & rs->nn);
24 }
25 return x;
26 }
27