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36 @brief Functions used to compute Reed-Solomon parity and check of byte arrays
43 /** Global definitions for Reed-Solomon encoder/decoder
44 * Phil Karn KA9Q, September 1996
46 * The parameters MM and KK specify the Reed-Solomon code parameters.
48 * Set MM to be the size of each code symbol in bits. The Reed-Solomon
49 * block size will then be NN = 2**M - 1 symbols. Supported values are
52 * Set KK to be the number of data symbols in each block, which must be
53 * less than the block size. The code will then be able to correct up
54 * to NN-KK erasures or (NN-KK)/2 errors, or combinations thereof with
55 * each error counting as two erasures.
57 #define MM 8 /* RS code over GF(2**MM) - change to suit */
61 /*#define KK 239*/ /* KK = number of information symbols */
63 #define NN ((1 << MM) - 1)
66 typedef unsigned char dtype;
68 typedef unsigned int dtype;
71 /** Initialization function */
74 /** These two functions *must* be called in this order (e.g.,
75 * by init_rs()) before any encoding/decoding
77 void generate_gf(void); /* Generate Galois Field */
78 void gen_poly(void); /* Generate generator polynomial */
80 /** Reed-Solomon encoding
81 * data[] is the input block, parity symbols are placed in bb[]
82 * bb[] may lie past the end of the data, e.g., for (255,223):
83 * encode_rs(&data[0],&data[223]);
85 int encode_rs(dtype data[], dtype bb[]);
87 /** Reed-Solomon erasures-and-errors decoding
88 * The received block goes into data[], and a list of zero-origin
89 * erasure positions, if any, goes in eras_pos[] with a count in no_eras.
91 * The decoder corrects the symbols in place, if possible and returns
92 * the number of corrected symbols. If the codeword is illegal or
93 * uncorrectible, the data array is unchanged and -1 is returned
95 int eras_dec_rs(dtype data[], int eras_pos[], int no_eras);
98 Computes the minimum between two integers
99 @param a first integer to compare
100 @param b second integer to compare
101 @return returns the minimum integer between a and b
104 #define min(a,b) (((a) < (b)) ? (a) : (b))
107 #endif /* __RS_HEADER__ */
110 #endif /* USE_JPWL */