1 /* 2 * lib/reed_solomon/encode_rs.c 3 * 4 * Overview: 5 * Generic Reed Solomon encoder / decoder library 6 * 7 * Copyright 2002, Phil Karn, KA9Q 8 * May be used under the terms of the GNU General Public License (GPL) 9 * 10 * Adaption to the kernel by Thomas Gleixner (tglx@linutronix.de) 11 * 12 * $Id: encode_rs.c,v 1.5 2005/11/07 11:14:59 gleixner Exp $ 13 * 14 */ 15 16 /* Generic data width independent code which is included by the 17 * wrappers. 18 * int encode_rsX (struct rs_control *rs, uintX_t *data, int len, uintY_t *par) 19 */ 20 { 21 int i, j, pad; 22 int nn = rs->nn; 23 int nroots = rs->nroots; 24 uint16_t *alpha_to = rs->alpha_to; 25 uint16_t *index_of = rs->index_of; 26 uint16_t *genpoly = rs->genpoly; 27 uint16_t fb; 28 uint16_t msk = (uint16_t) rs->nn; 29 30 /* Check length parameter for validity */ 31 pad = nn - nroots - len; 32 if (pad < 0 || pad >= nn) 33 return -ERANGE; 34 35 for (i = 0; i < len; i++) { 36 fb = index_of[((((uint16_t) data[i])^invmsk) & msk) ^ par[0]]; 37 /* feedback term is non-zero */ 38 if (fb != nn) { 39 for (j = 1; j < nroots; j++) { 40 par[j] ^= alpha_to[rs_modnn(rs, fb + 41 genpoly[nroots - j])]; 42 } 43 } 44 /* Shift */ 45 memmove(&par[0], &par[1], sizeof(uint16_t) * (nroots - 1)); 46 if (fb != nn) { 47 par[nroots - 1] = alpha_to[rs_modnn(rs, 48 fb + genpoly[0])]; 49 } else { 50 par[nroots - 1] = 0; 51 } 52 } 53 return 0; 54 } 55