1 /* Include file to configure the RS codec for character symbols
2 *
3 * Copyright 2002, Phil Karn, KA9Q
4 * May be used under the terms of the GNU General Public License (GPL)
5 */
6
7 #define DTYPE unsigned char
8
9 #include <gnuradio/fec/api.h>
10
11 /* Reed-Solomon codec control block */
12 struct rs {
13 unsigned int mm; /* Bits per symbol */
14 unsigned int nn; /* Symbols per block (= (1<<mm)-1) */
15 unsigned char* alpha_to; /* log lookup table */
16 unsigned char* index_of; /* Antilog lookup table */
17 unsigned char* genpoly; /* Generator polynomial */
18 unsigned int nroots; /* Number of generator roots = number of parity symbols */
19 unsigned char fcr; /* First consecutive root, index form */
20 unsigned char prim; /* Primitive element, index form */
21 unsigned char iprim; /* prim-th root of 1, index form */
22 int* modnn_table; /* modnn lookup table, 512 entries */
23 };
24
modnn(struct rs * rs,unsigned int x)25 static inline unsigned int modnn(struct rs* rs, unsigned int x)
26 {
27 while (x >= rs->nn) {
28 x -= rs->nn;
29 x = (x >> rs->mm) + (x & rs->nn);
30 }
31 return x;
32 }
33 #define MODNN(x) modnn(rs, x)
34
35 #define MM (rs->mm)
36 #define NN (rs->nn)
37 #define ALPHA_TO (rs->alpha_to)
38 #define INDEX_OF (rs->index_of)
39 #define GENPOLY (rs->genpoly)
40 #define NROOTS (rs->nroots)
41 #define FCR (rs->fcr)
42 #define PRIM (rs->prim)
43 #define IPRIM (rs->iprim)
44 #define A0 (NN)
45
46 #define ENCODE_RS encode_rs_char
47 #define DECODE_RS decode_rs_char
48 #define INIT_RS init_rs_char
49 #define FREE_RS free_rs_char
50
51 FEC_API void ENCODE_RS(void* p, DTYPE* data, DTYPE* parity);
52 FEC_API int DECODE_RS(void* p, DTYPE* data, int* eras_pos, int no_eras);
53 FEC_API void* INIT_RS(unsigned int symsize,
54 unsigned int gfpoly,
55 unsigned int fcr,
56 unsigned int prim,
57 unsigned int nroots);
58 FEC_API void FREE_RS(void* p);
59