/* Include file to configure the RS codec for character symbols
 *
 * Copyright 2002, Phil Karn, KA9Q
 * May be used under the terms of the GNU General Public License (GPL)
 */

#define DTYPE unsigned char

#include <gnuradio/fec/api.h>

/* Reed-Solomon codec control block */
struct rs {
    unsigned int mm;         /* Bits per symbol */
    unsigned int nn;         /* Symbols per block (= (1<<mm)-1) */
    unsigned char* alpha_to; /* log lookup table */
    unsigned char* index_of; /* Antilog lookup table */
    unsigned char* genpoly;  /* Generator polynomial */
    unsigned int nroots;     /* Number of generator roots = number of parity symbols */
    unsigned char fcr;       /* First consecutive root, index form */
    unsigned char prim;      /* Primitive element, index form */
    unsigned char iprim;     /* prim-th root of 1, index form */
    int* modnn_table;        /* modnn lookup table, 512 entries */
};

static inline unsigned int modnn(struct rs* rs, unsigned int x)
{
    while (x >= rs->nn) {
        x -= rs->nn;
        x = (x >> rs->mm) + (x & rs->nn);
    }
    return x;
}
#define MODNN(x) modnn(rs, x)

#define MM (rs->mm)
#define NN (rs->nn)
#define ALPHA_TO (rs->alpha_to)
#define INDEX_OF (rs->index_of)
#define GENPOLY (rs->genpoly)
#define NROOTS (rs->nroots)
#define FCR (rs->fcr)
#define PRIM (rs->prim)
#define IPRIM (rs->iprim)
#define A0 (NN)

#define ENCODE_RS encode_rs_char
#define DECODE_RS decode_rs_char
#define INIT_RS init_rs_char
#define FREE_RS free_rs_char

FEC_API void ENCODE_RS(void* p, DTYPE* data, DTYPE* parity);
FEC_API int DECODE_RS(void* p, DTYPE* data, int* eras_pos, int no_eras);
FEC_API void* INIT_RS(unsigned int symsize,
                      unsigned int gfpoly,
                      unsigned int fcr,
                      unsigned int prim,
                      unsigned int nroots);
FEC_API void FREE_RS(void* p);