1 // SPDX-License-Identifier: GPL-2.0 2 /* 3 * Generic Reed Solomon encoder / decoder library 4 * 5 * Copyright 2002, Phil Karn, KA9Q 6 * May be used under the terms of the GNU General Public License (GPL) 7 * 8 * Adaption to the kernel by Thomas Gleixner (tglx@linutronix.de) 9 * 10 * Generic data width independent code which is included by the wrappers. 11 */ 12 { 13 int i, j, pad; 14 int nn = rs->nn; 15 int nroots = rs->nroots; 16 uint16_t *alpha_to = rs->alpha_to; 17 uint16_t *index_of = rs->index_of; 18 uint16_t *genpoly = rs->genpoly; 19 uint16_t fb; 20 uint16_t msk = (uint16_t) rs->nn; 21 22 /* Check length parameter for validity */ 23 pad = nn - nroots - len; 24 if (pad < 0 || pad >= nn) 25 return -ERANGE; 26 27 for (i = 0; i < len; i++) { 28 fb = index_of[((((uint16_t) data[i])^invmsk) & msk) ^ par[0]]; 29 /* feedback term is non-zero */ 30 if (fb != nn) { 31 for (j = 1; j < nroots; j++) { 32 par[j] ^= alpha_to[rs_modnn(rs, fb + 33 genpoly[nroots - j])]; 34 } 35 } 36 /* Shift */ 37 memmove(&par[0], &par[1], sizeof(uint16_t) * (nroots - 1)); 38 if (fb != nn) { 39 par[nroots - 1] = alpha_to[rs_modnn(rs, 40 fb + genpoly[0])]; 41 } else { 42 par[nroots - 1] = 0; 43 } 44 } 45 return 0; 46 } 47