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