/* * lib/reed_solomon/encode_rs.c * * Overview: * Generic Reed Solomon encoder / decoder library * * Copyright 2002, Phil Karn, KA9Q * May be used under the terms of the GNU General Public License (GPL) * * Adaption to the kernel by Thomas Gleixner (tglx@linutronix.de) * * $Id: encode_rs.c,v 1.5 2005/11/07 11:14:59 gleixner Exp $ * */ /* Generic data width independent code which is included by the * wrappers. * int encode_rsX (struct rs_control *rs, uintX_t *data, int len, uintY_t *par) */ { int i, j, pad; int nn = rs->nn; int nroots = rs->nroots; uint16_t *alpha_to = rs->alpha_to; uint16_t *index_of = rs->index_of; uint16_t *genpoly = rs->genpoly; uint16_t fb; uint16_t msk = (uint16_t) rs->nn; /* Check length parameter for validity */ pad = nn - nroots - len; if (pad < 0 || pad >= nn) return -ERANGE; for (i = 0; i < len; i++) { fb = index_of[((((uint16_t) data[i])^invmsk) & msk) ^ par[0]]; /* feedback term is non-zero */ if (fb != nn) { for (j = 1; j < nroots; j++) { par[j] ^= alpha_to[rs_modnn(rs, fb + genpoly[nroots - j])]; } } /* Shift */ memmove(&par[0], &par[1], sizeof(uint16_t) * (nroots - 1)); if (fb != nn) { par[nroots - 1] = alpha_to[rs_modnn(rs, fb + genpoly[0])]; } else { par[nroots - 1] = 0; } } return 0; } lauser

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