c语言的BCH码的编译码程序doc.doc

BCH码的编译码程序#include #include #include int m, n, length, k, t, d;int p21;int alpha_to1048576, index_of1048576, g548576;int recd1048576, data1048576, bb548576;int seed;int numerr, errpos1024, decerror = 0;void read_p() int i, ninf; printf(nEnter a value of m such that the code length isn); printf(2*(m-1) - 1 length 1) | !(m21) ); for (i=1; i pi = 0; p0 = pm = 1; if (m = 2) p1 = 1; else if (m = 3) p1 = 1; else if (m = 4) p1 = 1; else if (m = 5) p2 = 1; else if (m = 6) p1 = 1; else if (m = 7) p1 = 1; else if (m = 8) p4 = p5 = p6 = 1; else if (m = 9) p4 = 1; else if (m = 10) p3 = 1; else if (m = 11) p2 = 1; else if (m = 12) p3 = p4 = p7 = 1; else if (m = 13) p1 = p3 = p4 = 1; else if (m = 14) p1 = p11 = p12 = 1; else if (m = 15) p1 = 1; else if (m = 16) p2 = p3 = p5 = 1; else if (m = 17) p3 = 1; else if (m = 18) p7 = 1; else if (m = 19) p1 = p5 = p6 = 1; else if (m = 20) p3 = 1; printf(p(x) = ); n = 1; for (i = 0; i = m; i+) n *= 2; printf(%1d, pi); printf(n); n = n / 2 - 1; ninf = (n + 1) / 2 - 1; do printf(Enter code length (%d length = %d): , ninf, n); scanf(%d, &length); while ( !(length ninf) );void generate_gf() register int i, mask; mask = 1; alpha_tom = 0; for (i = 0; i m; i+) alpha_toi = mask; index_ofalpha_toi = i; if (pi != 0) alpha_tom = mask; mask = 1; for (i = m + 1; i = mask) alpha_toi = alpha_tom (alpha_toi - 1 mask) 1); else alpha_toi = alpha_toi - 1 9) printf(Computing cycle sets modulo %dn, n); printf(This may take some time).n); do ii = 0; do ii+; cyclejjii = (cyclejjii - 1 * 2) % n; sizejj+; aux = (cyclejjii * 2) % n; while (aux != cyclejj0); ll = 0; do ll+; test = 0; for (ii = 1; (ii = jj) & (!test); ii+) for (kaux = 0; (kaux sizeii) & (!test); kaux+) if (ll = cycleiikaux) test = 1; while (test) & (ll (n - 1); if (!(test) jj+; cyclejj0 = ll; sizejj = 1; while (ll (n - 1); nocycles = jj; printf(Enter the error correcting capability, t: ); scanf(%d, &t); d = 2 * t + 1; kaux = 0; rdncy = 0; for (ii = 1; ii = nocycles; ii+) minkaux = 0; test = 0; for (jj = 0; (jj sizeii) & (!test); jj+) for (root = 1; (root d) & (!test); root+) if (root = cycleiijj) test = 1; minkaux = ii; if (minkaux) rdncy += sizeminkaux; kaux+; noterms = kaux; kaux = 1; for (ii = 0; ii noterms; ii+) for (jj = 0; jj sizeminii; jj+) zeroskaux = cycleminiijj; kaux+; k = length - rdncy; if (k0) printf(Parameters invalid!n); exit(0); printf(This is a (%d, %d, %d) binary BCH coden, length, k, d); g0 = alpha_tozeros1; g1 = 1; for (ii = 2; ii 0; jj-) if (gjj != 0) gjj = gjj - 1 alpha_to(index_ofgjj + zerosii) % n; else gjj = gjj - 1; g0 = alpha_to(index_ofg0 + zerosii) % n; printf(Generator polynomial:ng(x) = ); for (ii = 0; ii = rdncy; ii+) printf(%d, gii); if (ii & (ii % 50) = 0) printf(n); printf(n);void encode_bch() register int i, j; register int feedback; for (i = 0; i = 0; i-) feedback = datai bblength - k - 1; if (feedback != 0) for (j = length - k - 1; j 0; j-) if (gj != 0) bbj = bbj - 1 feedback; else bbj = bbj - 1; bb0 = g0 & feedback; else for (j = length - k - 1; j 0; j-) bbj = bbj - 1; bb0 = 0; void decode_bch() register int i, j, u, q, t2, count = 0, syn_error = 0; int elp10261024, d1026, l1026, u_lu1026, s1025; int root200, loc200, err1024, reg201; t2 = 2 * t; /* first form the syndromes */ printf(S(x) = ); for (i = 1; i = t2; i+) si = 0; for (j = 0; j length; j+) if (recdj != 0) si = alpha_to(i * j) % n; if (si != 0) syn_error = 1; si = index_ofsi; printf(%3d , si); printf(n); if (syn_error) d0 = 0; d1 = s1; elp00 = 0; elp10 = 1; for (i = 1; i t2; i+) elp0i = -1; elp1i = 0; l0 = 0; l1 = 0; u_lu0 = -1; u_lu1 = 0; u = 0; do u+; if (du = -1) lu + 1 = lu; for (i = 0; i 0) q-; if (q 0) j = q; do j-; if (dj != -1) & (u_luq 0); if (lu lq + u - q) lu + 1 = lu; else lu + 1 = lq + u - q; for (i = 0; i t2; i+) elpu + 1i = 0; for (i = 0; i = lq; i+) if (elpqi != -1) elpu + 1i + u - q = alpha_to(du + n - dq + elpqi) % n; for (i = 0; i = lu; i+) elpu + 1i = elpui; elpui = index_ofelpui; u_luu + 1 = u - lu + 1; if (u t2) if (su + 1 != -1) du + 1 = alpha_tosu + 1; else du + 1 = 0; for (i = 1; i = lu + 1; i+) if (su + 1 - i != -1) & (elpu + 1i != 0) du + 1 = alpha_to(su + 1 - i + index_ofelpu + 1i) % n; du + 1 = index_ofdu + 1; while (u t2) & (lu + 1 = t); u+; if (lu = t) for (i = 0; i = lu; i+) elpui = index_ofelpui; printf(sigma(x) = ); for (i = 0; i = lu; i+) printf(%3d , elpui); printf(n); printf(Roots: ); for (i = 1; i = lu; i+) regi = elpui; count = 0; for (i = 1; i = n; i+) q = 1; for (j = 1; j = lu; j+) if (regj != -1) regj = (regj + j) % n; q = alpha_toregj; if (!q) rootcount = i; loccount = n - i; count+; printf(%3d , n - i); printf(n); if (count = lu) for (i = 0; i lu; i+) recdloci = 1; else printf(Incomplete decoding: errors detectedn); main() int i; read_p(); generate_gf(); gen_poly(); seed = 131073; srandom(seed); for (i = 0; i 16; encode_bch(); for (i = 0; i length - k; i+) recdi = bbi; for (i = 0; i k; i+) recdi + length - k = datai; printf(Code polynomial:nc(x) = ); for (i = 0; i length; i+) printf(%1d, recdi); if (i & (i % 50) = 0) printf(n); printf(n); printf(Enter the number of errors:n); scanf(%d, &numerr); printf(Enter error locations (integers between); printf( 0 and %d): , length-1); for (i = 0; i numerr; i+) scanf(%d, &errposi); if (numerr) for (i = 0; i numerr; i+) recderrposi = 1; printf(r(x) = ); for (i = 0; i length; i+) printf(%1d, recdi); if (i & (i % 50) = 0) printf(n); printf(n); decode_bch(); printf(Results:n); printf(original data = ); for (i = 0; i k; i+) printf(%1d, datai); if (i & (i % 50) = 0) printf(n); printf(nrecovered data = ); for (i = length - k; i