encode_rs.c (1199B)
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 struct rs_codec *rs = rsc->codec; 14 int i, j, pad; 15 int nn = rs->nn; 16 int nroots = rs->nroots; 17 uint16_t *alpha_to = rs->alpha_to; 18 uint16_t *index_of = rs->index_of; 19 uint16_t *genpoly = rs->genpoly; 20 uint16_t fb; 21 uint16_t msk = (uint16_t) rs->nn; 22 23 /* Check length parameter for validity */ 24 pad = nn - nroots - len; 25 if (pad < 0 || pad >= nn) 26 return -ERANGE; 27 28 for (i = 0; i < len; i++) { 29 fb = index_of[((((uint16_t) data[i])^invmsk) & msk) ^ par[0]]; 30 /* feedback term is non-zero */ 31 if (fb != nn) { 32 for (j = 1; j < nroots; j++) { 33 par[j] ^= alpha_to[rs_modnn(rs, fb + 34 genpoly[nroots - j])]; 35 } 36 } 37 /* Shift */ 38 memmove(&par[0], &par[1], sizeof(uint16_t) * (nroots - 1)); 39 if (fb != nn) { 40 par[nroots - 1] = alpha_to[rs_modnn(rs, 41 fb + genpoly[0])]; 42 } else { 43 par[nroots - 1] = 0; 44 } 45 } 46 return 0; 47}