FreeCalypso > hg > sipout-test-utils
view libutil/crc8gen.c @ 5:e80b0051cd92
libutil: add G.711 decoding tables from themwi-mgw
author | Mychaela Falconia <falcon@freecalypso.org> |
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date | Mon, 04 Mar 2024 22:25:53 -0800 |
parents | 35c0d9f03c0a |
children |
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/*! \file crc8gen.c * Osmocom generic CRC routines (for max 8 bits poly). */ /* * Copyright (C) 2011 Sylvain Munaut <tnt@246tNt.com> * * All Rights Reserved * * SPDX-License-Identifier: GPL-2.0+ * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation; either version 2 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License along * with this program; if not, write to the Free Software Foundation, Inc., * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA. */ /*! \addtogroup crc * @{ * Osmocom generic CRC routines (for max 8 bits poly). * * \file crc8gen.c.tpl */ #include <stdint.h> #include "osmo_bits.h" /*! Compute the CRC value of a given array of hard-bits * \param[in] code The CRC code description to apply * \param[in] in Array of hard bits * \param[in] len Length of the array of hard bits * \returns The CRC value */ uint8_t osmo_crc8gen_compute_bits(const struct osmo_crc8gen_code *code, const ubit_t *in, int len) { const uint8_t poly = code->poly; uint8_t crc = code->init; int i, n = code->bits-1; for (i=0; i<len; i++) { uint8_t bit = in[i] & 1; crc ^= (bit << n); if (crc & ((uint8_t)1 << n)) { crc <<= 1; crc ^= poly; } else { crc <<= 1; } crc &= ((uint8_t)1 << code->bits) - 1; } crc ^= code->remainder; return crc; } /*! Checks the CRC value of a given array of hard-bits * \param[in] code The CRC code description to apply * \param[in] in Array of hard bits * \param[in] len Length of the array of hard bits * \param[in] crc_bits Array of hard bits with the alleged CRC * \returns 0 if CRC matches. 1 in case of error. * * The crc_bits array must have a length of code->len */ int osmo_crc8gen_check_bits(const struct osmo_crc8gen_code *code, const ubit_t *in, int len, const ubit_t *crc_bits) { uint8_t crc; int i; crc = osmo_crc8gen_compute_bits(code, in, len); for (i=0; i<code->bits; i++) if (crc_bits[i] ^ ((crc >> (code->bits-i-1)) & 1)) return 1; return 0; } /*! Computes and writes the CRC value of a given array of bits * \param[in] code The CRC code description to apply * \param[in] in Array of hard bits * \param[in] len Length of the array of hard bits * \param[in] crc_bits Array of hard bits to write the computed CRC to * * The crc_bits array must have a length of code->len */ void osmo_crc8gen_set_bits(const struct osmo_crc8gen_code *code, const ubit_t *in, int len, ubit_t *crc_bits) { uint8_t crc; int i; crc = osmo_crc8gen_compute_bits(code, in, len); for (i=0; i<code->bits; i++) crc_bits[i] = ((crc >> (code->bits-i-1)) & 1); } /*! @} */ /* vim: set syntax=c: */