Denislam Valeev / Mbed OS Nucleo_rtos_basic

1

mbed-os/drivers/MbedCRC.h@0:e056ac8fecf8, 2018-03-13 (annotated)

Committer:
valeyev
Date:
Tue Mar 13 07:17:50 2018 +0000
Revision:
0:e056ac8fecf8
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valeyev 0:e056ac8fecf8 1 /* mbed Microcontroller Library
valeyev 0:e056ac8fecf8 2 * Copyright (c) 2018 ARM Limited
valeyev 0:e056ac8fecf8 3 *
valeyev 0:e056ac8fecf8 4 * Licensed under the Apache License, Version 2.0 (the "License");
valeyev 0:e056ac8fecf8 5 * you may not use this file except in compliance with the License.
valeyev 0:e056ac8fecf8 6 * You may obtain a copy of the License at
valeyev 0:e056ac8fecf8 7 *
valeyev 0:e056ac8fecf8 8 * http://www.apache.org/licenses/LICENSE-2.0
valeyev 0:e056ac8fecf8 9 *
valeyev 0:e056ac8fecf8 10 * Unless required by applicable law or agreed to in writing, software
valeyev 0:e056ac8fecf8 11 * distributed under the License is distributed on an "AS IS" BASIS,
valeyev 0:e056ac8fecf8 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
valeyev 0:e056ac8fecf8 13 * See the License for the specific language governing permissions and
valeyev 0:e056ac8fecf8 14 * limitations under the License.
valeyev 0:e056ac8fecf8 15 */
valeyev 0:e056ac8fecf8 16 #ifndef MBED_CRC_API_H
valeyev 0:e056ac8fecf8 17 #define MBED_CRC_API_H
valeyev 0:e056ac8fecf8 18
valeyev 0:e056ac8fecf8 19 #include <stdint.h>
valeyev 0:e056ac8fecf8 20 #include "drivers/TableCRC.h"
valeyev 0:e056ac8fecf8 21 #include "platform/mbed_assert.h"
valeyev 0:e056ac8fecf8 22
valeyev 0:e056ac8fecf8 23 /* This is invalid warning from the compiler for below section of code
valeyev 0:e056ac8fecf8 24 if ((width < 8) && (NULL == _crc_table)) {
valeyev 0:e056ac8fecf8 25 p_crc = (uint32_t)(p_crc << (8 - width));
valeyev 0:e056ac8fecf8 26 }
valeyev 0:e056ac8fecf8 27 Compiler warns of the shift operation with width as it is width=(std::uint8_t),
valeyev 0:e056ac8fecf8 28 but we check for ( width < 8) before performing shift, so it should not be an issue.
valeyev 0:e056ac8fecf8 29 */
valeyev 0:e056ac8fecf8 30 #if defined ( __CC_ARM )
valeyev 0:e056ac8fecf8 31 #pragma diag_suppress 62 // Shift count is negative
valeyev 0:e056ac8fecf8 32 #elif defined ( __GNUC__ )
valeyev 0:e056ac8fecf8 33 #pragma GCC diagnostic push
valeyev 0:e056ac8fecf8 34 #pragma GCC diagnostic ignored "-Wshift-count-negative"
valeyev 0:e056ac8fecf8 35 #endif
valeyev 0:e056ac8fecf8 36
valeyev 0:e056ac8fecf8 37 namespace mbed {
valeyev 0:e056ac8fecf8 38 /** \addtogroup drivers */
valeyev 0:e056ac8fecf8 39 /** @{*/
valeyev 0:e056ac8fecf8 40
valeyev 0:e056ac8fecf8 41 /** CRC Polynomial value
valeyev 0:e056ac8fecf8 42 *
valeyev 0:e056ac8fecf8 43 * Different polynomial values supported
valeyev 0:e056ac8fecf8 44 */
valeyev 0:e056ac8fecf8 45 typedef enum crc_polynomial {
valeyev 0:e056ac8fecf8 46 POLY_OTHER = 0,
valeyev 0:e056ac8fecf8 47 POLY_8BIT_CCITT = 0x07, // x8+x2+x+1
valeyev 0:e056ac8fecf8 48 POLY_7BIT_SD = 0x9, // x7+x3+1;
valeyev 0:e056ac8fecf8 49 POLY_16BIT_CCITT = 0x1021, // x16+x12+x5+1
valeyev 0:e056ac8fecf8 50 POLY_16BIT_IBM = 0x8005, // x16+x15+x2+1
valeyev 0:e056ac8fecf8 51 POLY_32BIT_ANSI = 0x04C11DB7, // x32+x26+x23+x22+x16+x12+x11+x10+x8+x7+x5+x4+x2+x+1
valeyev 0:e056ac8fecf8 52 } crc_polynomial_t;
valeyev 0:e056ac8fecf8 53
valeyev 0:e056ac8fecf8 54 /** CRC object provides CRC generation through hardware/software
valeyev 0:e056ac8fecf8 55 *
valeyev 0:e056ac8fecf8 56 * ROM polynomial tables for supported polynomials (:: crc_polynomial_t) will be used for
valeyev 0:e056ac8fecf8 57 * software CRC computation, if ROM tables are not available then CRC is computed runtime
valeyev 0:e056ac8fecf8 58 * bit by bit for all data input.
valeyev 0:e056ac8fecf8 59 *
valeyev 0:e056ac8fecf8 60 * @tparam polynomial CRC polynomial value in hex
valeyev 0:e056ac8fecf8 61 * @tparam width CRC polynomial width
valeyev 0:e056ac8fecf8 62 *
valeyev 0:e056ac8fecf8 63 * Example: Compute CRC data
valeyev 0:e056ac8fecf8 64 * @code
valeyev 0:e056ac8fecf8 65 *
valeyev 0:e056ac8fecf8 66 * #include "mbed.h"
valeyev 0:e056ac8fecf8 67 *
valeyev 0:e056ac8fecf8 68 * int main() {
valeyev 0:e056ac8fecf8 69 * MbedCRC<POLY_32BIT_ANSI, 32> ct;
valeyev 0:e056ac8fecf8 70 *
valeyev 0:e056ac8fecf8 71 * char test[] = "123456789";
valeyev 0:e056ac8fecf8 72 * uint32_t crc = 0;
valeyev 0:e056ac8fecf8 73 *
valeyev 0:e056ac8fecf8 74 * printf("\nPolynomial = 0x%lx Width = %d \n", ct.get_polynomial(), ct.get_width());
valeyev 0:e056ac8fecf8 75 *
valeyev 0:e056ac8fecf8 76 * ct.compute((void *)test, strlen((const char*)test), &crc);
valeyev 0:e056ac8fecf8 77 *
valeyev 0:e056ac8fecf8 78 * printf("The CRC of data \"123456789\" is : 0x%lx\n", crc);
valeyev 0:e056ac8fecf8 79 * return 0;
valeyev 0:e056ac8fecf8 80 * }
valeyev 0:e056ac8fecf8 81 * @endcode
valeyev 0:e056ac8fecf8 82 * Example: Compute CRC with data available in parts
valeyev 0:e056ac8fecf8 83 * @code
valeyev 0:e056ac8fecf8 84 *
valeyev 0:e056ac8fecf8 85 * #include "mbed.h"
valeyev 0:e056ac8fecf8 86 * int main() {
valeyev 0:e056ac8fecf8 87 * MbedCRC<POLY_32BIT_ANSI, 32> ct;
valeyev 0:e056ac8fecf8 88 *
valeyev 0:e056ac8fecf8 89 * char test[] = "123456789";
valeyev 0:e056ac8fecf8 90 * uint32_t crc = 0;
valeyev 0:e056ac8fecf8 91 *
valeyev 0:e056ac8fecf8 92 * printf("\nPolynomial = 0x%lx Width = %d \n", ct.get_polynomial(), ct.get_width());
valeyev 0:e056ac8fecf8 93 *
valeyev 0:e056ac8fecf8 94 * ct.compute_partial_start(&crc);
valeyev 0:e056ac8fecf8 95 * ct.compute_partial((void *)&test, 4, &crc);
valeyev 0:e056ac8fecf8 96 * ct.compute_partial((void *)&test[4], 5, &crc);
valeyev 0:e056ac8fecf8 97 * ct.compute_partial_stop(&crc);
valeyev 0:e056ac8fecf8 98 *
valeyev 0:e056ac8fecf8 99 * printf("The CRC of data \"123456789\" is : 0x%lx\n", crc);
valeyev 0:e056ac8fecf8 100 * return 0;
valeyev 0:e056ac8fecf8 101 * }
valeyev 0:e056ac8fecf8 102 * @endcode
valeyev 0:e056ac8fecf8 103 * @ingroup drivers
valeyev 0:e056ac8fecf8 104 */
valeyev 0:e056ac8fecf8 105
valeyev 0:e056ac8fecf8 106 template <uint32_t polynomial=POLY_32BIT_ANSI, uint8_t width=32>
valeyev 0:e056ac8fecf8 107 class MbedCRC
valeyev 0:e056ac8fecf8 108 {
valeyev 0:e056ac8fecf8 109 public:
valeyev 0:e056ac8fecf8 110 typedef uint64_t crc_data_size_t;
valeyev 0:e056ac8fecf8 111
valeyev 0:e056ac8fecf8 112 /** Lifetime of CRC object
valeyev 0:e056ac8fecf8 113 *
valeyev 0:e056ac8fecf8 114 * @param initial_xor Inital value/seed to Xor
valeyev 0:e056ac8fecf8 115 * @param final_xor Final Xor value
valeyev 0:e056ac8fecf8 116 * @param reflect_data
valeyev 0:e056ac8fecf8 117 * @param reflect_remainder
valeyev 0:e056ac8fecf8 118 * @note Default constructor without any arguments is valid only for supported CRC polynomials. :: crc_polynomial_t
valeyev 0:e056ac8fecf8 119 * MbedCRC <POLY_7BIT_SD, 7> ct; --- Valid POLY_7BIT_SD
valeyev 0:e056ac8fecf8 120 * MbedCRC <0x1021, 16> ct; --- Valid POLY_16BIT_CCITT
valeyev 0:e056ac8fecf8 121 * MbedCRC <POLY_16BIT_CCITT, 32> ct; --- Invalid, compilation error
valeyev 0:e056ac8fecf8 122 * MbedCRC <POLY_16BIT_CCITT, 32> ct (i,f,rd,rr) Consturctor can be used for not supported polynomials
valeyev 0:e056ac8fecf8 123 * MbedCRC<POLY_16BIT_CCITT, 16> sd(0, 0, false, false); Constructor can also be used for supported
valeyev 0:e056ac8fecf8 124 * polynomials with different intial/final/reflect values
valeyev 0:e056ac8fecf8 125 *
valeyev 0:e056ac8fecf8 126 */
valeyev 0:e056ac8fecf8 127 MbedCRC(uint32_t initial_xor, uint32_t final_xor, bool reflect_data, bool reflect_remainder);
valeyev 0:e056ac8fecf8 128 MbedCRC();
valeyev 0:e056ac8fecf8 129 virtual ~MbedCRC()
valeyev 0:e056ac8fecf8 130 {
valeyev 0:e056ac8fecf8 131 // Do nothing
valeyev 0:e056ac8fecf8 132 }
valeyev 0:e056ac8fecf8 133
valeyev 0:e056ac8fecf8 134 /** Compute CRC for the data input
valeyev 0:e056ac8fecf8 135 *
valeyev 0:e056ac8fecf8 136 * @param buffer Data bytes
valeyev 0:e056ac8fecf8 137 * @param size Size of data
valeyev 0:e056ac8fecf8 138 * @param crc CRC is the output value
valeyev 0:e056ac8fecf8 139 * @return 0 on success, negative error code on failure
valeyev 0:e056ac8fecf8 140 */
valeyev 0:e056ac8fecf8 141 int32_t compute(void *buffer, crc_data_size_t size, uint32_t *crc)
valeyev 0:e056ac8fecf8 142 {
valeyev 0:e056ac8fecf8 143 MBED_ASSERT(crc != NULL);
valeyev 0:e056ac8fecf8 144 int32_t status;
valeyev 0:e056ac8fecf8 145 if (0 != (status = compute_partial_start(crc))) {
valeyev 0:e056ac8fecf8 146 *crc = 0;
valeyev 0:e056ac8fecf8 147 return status;
valeyev 0:e056ac8fecf8 148 }
valeyev 0:e056ac8fecf8 149 if (0 != (status = compute_partial(buffer, size, crc))) {
valeyev 0:e056ac8fecf8 150 *crc = 0;
valeyev 0:e056ac8fecf8 151 return status;
valeyev 0:e056ac8fecf8 152 }
valeyev 0:e056ac8fecf8 153 if (0 != (status = compute_partial_stop(crc))) {
valeyev 0:e056ac8fecf8 154 *crc = 0;
valeyev 0:e056ac8fecf8 155 return status;
valeyev 0:e056ac8fecf8 156 }
valeyev 0:e056ac8fecf8 157 return 0;
valeyev 0:e056ac8fecf8 158 }
valeyev 0:e056ac8fecf8 159
valeyev 0:e056ac8fecf8 160 /** Compute partial CRC for the data input.
valeyev 0:e056ac8fecf8 161 *
valeyev 0:e056ac8fecf8 162 * CRC data if not available fully, CRC can be computed in parts with available data.
valeyev 0:e056ac8fecf8 163 * Previous CRC output should be passed as argument to the current compute_partial call.
valeyev 0:e056ac8fecf8 164 * @pre: Call \ref compute_partial_start to start the partial CRC calculation.
valeyev 0:e056ac8fecf8 165 * @post: Call \ref compute_partial_stop to get the final CRC value.
valeyev 0:e056ac8fecf8 166 *
valeyev 0:e056ac8fecf8 167 * @param buffer Data bytes
valeyev 0:e056ac8fecf8 168 * @param size Size of data
valeyev 0:e056ac8fecf8 169 * @param crc CRC value is intermediate CRC value filled by API.
valeyev 0:e056ac8fecf8 170 * @return 0 on success or a negative error code on failure
valeyev 0:e056ac8fecf8 171 * @note: CRC as output in compute_partial is not final CRC value, call @ref compute_partial_stop
valeyev 0:e056ac8fecf8 172 * to get final correct CRC value.
valeyev 0:e056ac8fecf8 173 */
valeyev 0:e056ac8fecf8 174 int32_t compute_partial(void *buffer, crc_data_size_t size, uint32_t *crc)
valeyev 0:e056ac8fecf8 175 {
valeyev 0:e056ac8fecf8 176 if (NULL == _crc_table) {
valeyev 0:e056ac8fecf8 177 // Compute bitwise CRC
valeyev 0:e056ac8fecf8 178 return bitwise_compute_partial(buffer, size, crc);
valeyev 0:e056ac8fecf8 179 } else {
valeyev 0:e056ac8fecf8 180 // Table CRC
valeyev 0:e056ac8fecf8 181 return table_compute_partial(buffer, size, crc);
valeyev 0:e056ac8fecf8 182 }
valeyev 0:e056ac8fecf8 183 }
valeyev 0:e056ac8fecf8 184
valeyev 0:e056ac8fecf8 185 /** Compute partial start, indicate start of partial computation
valeyev 0:e056ac8fecf8 186 *
valeyev 0:e056ac8fecf8 187 * This API should be called before performing any partial computation
valeyev 0:e056ac8fecf8 188 * with compute_partial API.
valeyev 0:e056ac8fecf8 189 *
valeyev 0:e056ac8fecf8 190 * @param crc Initial CRC value set by the API
valeyev 0:e056ac8fecf8 191 * @return 0 on success or a negative in case of failure
valeyev 0:e056ac8fecf8 192 * @note: CRC is an out parameter and must be reused with compute_partial
valeyev 0:e056ac8fecf8 193 * and compute_partial_stop without any modifications in application.
valeyev 0:e056ac8fecf8 194 */
valeyev 0:e056ac8fecf8 195 int32_t compute_partial_start(uint32_t *crc)
valeyev 0:e056ac8fecf8 196 {
valeyev 0:e056ac8fecf8 197 MBED_ASSERT(crc != NULL);
valeyev 0:e056ac8fecf8 198 *crc = _initial_value;
valeyev 0:e056ac8fecf8 199 return 0;
valeyev 0:e056ac8fecf8 200 }
valeyev 0:e056ac8fecf8 201
valeyev 0:e056ac8fecf8 202 /** Get the final CRC value of partial computation.
valeyev 0:e056ac8fecf8 203 *
valeyev 0:e056ac8fecf8 204 * CRC value available in partial computation is not correct CRC, as some
valeyev 0:e056ac8fecf8 205 * algorithms require remainder to be reflected and final value to be XORed
valeyev 0:e056ac8fecf8 206 * This API is used to perform final computation to get correct CRC value.
valeyev 0:e056ac8fecf8 207 *
valeyev 0:e056ac8fecf8 208 * @param crc CRC result
valeyev 0:e056ac8fecf8 209 */
valeyev 0:e056ac8fecf8 210 int32_t compute_partial_stop(uint32_t *crc)
valeyev 0:e056ac8fecf8 211 {
valeyev 0:e056ac8fecf8 212 MBED_ASSERT(crc != NULL);
valeyev 0:e056ac8fecf8 213 uint32_t p_crc = *crc;
valeyev 0:e056ac8fecf8 214 if ((width < 8) && (NULL == _crc_table)) {
valeyev 0:e056ac8fecf8 215 p_crc = (uint32_t)(p_crc << (8 - width));
valeyev 0:e056ac8fecf8 216 }
valeyev 0:e056ac8fecf8 217 *crc = (reflect_remainder(p_crc) ^ _final_xor) & get_crc_mask();
valeyev 0:e056ac8fecf8 218 return 0;
valeyev 0:e056ac8fecf8 219 }
valeyev 0:e056ac8fecf8 220
valeyev 0:e056ac8fecf8 221 /** Get the current CRC polynomial
valeyev 0:e056ac8fecf8 222 *
valeyev 0:e056ac8fecf8 223 * @return Polynomial value
valeyev 0:e056ac8fecf8 224 */
valeyev 0:e056ac8fecf8 225 uint32_t get_polynomial(void) const
valeyev 0:e056ac8fecf8 226 {
valeyev 0:e056ac8fecf8 227 return polynomial;
valeyev 0:e056ac8fecf8 228 }
valeyev 0:e056ac8fecf8 229
valeyev 0:e056ac8fecf8 230 /** Get the current CRC width
valeyev 0:e056ac8fecf8 231 *
valeyev 0:e056ac8fecf8 232 * @return CRC width
valeyev 0:e056ac8fecf8 233 */
valeyev 0:e056ac8fecf8 234 uint8_t get_width(void) const
valeyev 0:e056ac8fecf8 235 {
valeyev 0:e056ac8fecf8 236 return width;
valeyev 0:e056ac8fecf8 237 }
valeyev 0:e056ac8fecf8 238
valeyev 0:e056ac8fecf8 239 private:
valeyev 0:e056ac8fecf8 240 uint32_t _initial_value;
valeyev 0:e056ac8fecf8 241 uint32_t _final_xor;
valeyev 0:e056ac8fecf8 242 bool _reflect_data;
valeyev 0:e056ac8fecf8 243 bool _reflect_remainder;
valeyev 0:e056ac8fecf8 244 uint32_t *_crc_table;
valeyev 0:e056ac8fecf8 245
valeyev 0:e056ac8fecf8 246 /** Get the current CRC data size
valeyev 0:e056ac8fecf8 247 *
valeyev 0:e056ac8fecf8 248 * @return CRC data size in bytes
valeyev 0:e056ac8fecf8 249 */
valeyev 0:e056ac8fecf8 250 uint8_t get_data_size(void) const
valeyev 0:e056ac8fecf8 251 {
valeyev 0:e056ac8fecf8 252 return (width <= 8 ? 1 : (width <= 16 ? 2 : 4));
valeyev 0:e056ac8fecf8 253 }
valeyev 0:e056ac8fecf8 254
valeyev 0:e056ac8fecf8 255 /** Get the top bit of current CRC
valeyev 0:e056ac8fecf8 256 *
valeyev 0:e056ac8fecf8 257 * @return Top bit is set high for respective data width of current CRC
valeyev 0:e056ac8fecf8 258 * Top bit for CRC width less then 8 bits will be set as 8th bit.
valeyev 0:e056ac8fecf8 259 */
valeyev 0:e056ac8fecf8 260 uint32_t get_top_bit(void) const
valeyev 0:e056ac8fecf8 261 {
valeyev 0:e056ac8fecf8 262 return (width < 8 ? (1u << 7) : (uint32_t)(1ul << (width - 1)));
valeyev 0:e056ac8fecf8 263 }
valeyev 0:e056ac8fecf8 264
valeyev 0:e056ac8fecf8 265 /** Get the CRC data mask
valeyev 0:e056ac8fecf8 266 *
valeyev 0:e056ac8fecf8 267 * @return CRC data mask is generated based on current CRC width
valeyev 0:e056ac8fecf8 268 */
valeyev 0:e056ac8fecf8 269 uint32_t get_crc_mask(void) const
valeyev 0:e056ac8fecf8 270 {
valeyev 0:e056ac8fecf8 271 return (width < 8 ? ((1u << 8) - 1) : (uint32_t)((uint64_t)(1ull << width) - 1));
valeyev 0:e056ac8fecf8 272 }
valeyev 0:e056ac8fecf8 273
valeyev 0:e056ac8fecf8 274 /** Final value of CRC is reflected
valeyev 0:e056ac8fecf8 275 *
valeyev 0:e056ac8fecf8 276 * @param data final crc value, which should be reflected
valeyev 0:e056ac8fecf8 277 * @return Reflected CRC value
valeyev 0:e056ac8fecf8 278 */
valeyev 0:e056ac8fecf8 279 uint32_t reflect_remainder(uint32_t data) const
valeyev 0:e056ac8fecf8 280 {
valeyev 0:e056ac8fecf8 281 if (_reflect_remainder) {
valeyev 0:e056ac8fecf8 282 uint32_t reflection = 0x0;
valeyev 0:e056ac8fecf8 283 uint8_t const nBits = (width < 8 ? 8 : width);
valeyev 0:e056ac8fecf8 284
valeyev 0:e056ac8fecf8 285 for (uint8_t bit = 0; bit < nBits; ++bit) {
valeyev 0:e056ac8fecf8 286 if (data & 0x01) {
valeyev 0:e056ac8fecf8 287 reflection |= (1 << ((nBits - 1) - bit));
valeyev 0:e056ac8fecf8 288 }
valeyev 0:e056ac8fecf8 289 data = (data >> 1);
valeyev 0:e056ac8fecf8 290 }
valeyev 0:e056ac8fecf8 291 return (reflection);
valeyev 0:e056ac8fecf8 292 } else {
valeyev 0:e056ac8fecf8 293 return data;
valeyev 0:e056ac8fecf8 294 }
valeyev 0:e056ac8fecf8 295 }
valeyev 0:e056ac8fecf8 296
valeyev 0:e056ac8fecf8 297 /** Data bytes are reflected
valeyev 0:e056ac8fecf8 298 *
valeyev 0:e056ac8fecf8 299 * @param data value to be reflected
valeyev 0:e056ac8fecf8 300 * @return Reflected data value
valeyev 0:e056ac8fecf8 301 */
valeyev 0:e056ac8fecf8 302 uint32_t reflect_bytes(uint32_t data) const
valeyev 0:e056ac8fecf8 303 {
valeyev 0:e056ac8fecf8 304 if(_reflect_data) {
valeyev 0:e056ac8fecf8 305 uint32_t reflection = 0x0;
valeyev 0:e056ac8fecf8 306
valeyev 0:e056ac8fecf8 307 for (uint8_t bit = 0; bit < 8; ++bit) {
valeyev 0:e056ac8fecf8 308 if (data & 0x01) {
valeyev 0:e056ac8fecf8 309 reflection |= (1 << (7 - bit));
valeyev 0:e056ac8fecf8 310 }
valeyev 0:e056ac8fecf8 311 data = (data >> 1);
valeyev 0:e056ac8fecf8 312 }
valeyev 0:e056ac8fecf8 313 return (reflection);
valeyev 0:e056ac8fecf8 314 } else {
valeyev 0:e056ac8fecf8 315 return data;
valeyev 0:e056ac8fecf8 316 }
valeyev 0:e056ac8fecf8 317 }
valeyev 0:e056ac8fecf8 318
valeyev 0:e056ac8fecf8 319 /** Bitwise CRC computation
valeyev 0:e056ac8fecf8 320 *
valeyev 0:e056ac8fecf8 321 * @param buffer data buffer
valeyev 0:e056ac8fecf8 322 * @param size size of the data
valeyev 0:e056ac8fecf8 323 * @param crc CRC value is filled in, but the value is not the final
valeyev 0:e056ac8fecf8 324 * @return 0 on success or a negative error code on failure
valeyev 0:e056ac8fecf8 325 */
valeyev 0:e056ac8fecf8 326 int32_t bitwise_compute_partial(const void *buffer, crc_data_size_t size, uint32_t *crc) const
valeyev 0:e056ac8fecf8 327 {
valeyev 0:e056ac8fecf8 328 MBED_ASSERT(crc != NULL);
valeyev 0:e056ac8fecf8 329 MBED_ASSERT(buffer != NULL);
valeyev 0:e056ac8fecf8 330
valeyev 0:e056ac8fecf8 331 const uint8_t *data = static_cast<const uint8_t *>(buffer);
valeyev 0:e056ac8fecf8 332 uint32_t p_crc = *crc;
valeyev 0:e056ac8fecf8 333
valeyev 0:e056ac8fecf8 334 if (width < 8) {
valeyev 0:e056ac8fecf8 335 uint8_t data_byte;
valeyev 0:e056ac8fecf8 336 for (crc_data_size_t byte = 0; byte < size; byte++) {
valeyev 0:e056ac8fecf8 337 data_byte = reflect_bytes(data[byte]);
valeyev 0:e056ac8fecf8 338 for (uint8_t bit = 8; bit > 0; --bit) {
valeyev 0:e056ac8fecf8 339 p_crc <<= 1;
valeyev 0:e056ac8fecf8 340 if (( data_byte ^ p_crc) & get_top_bit()) {
valeyev 0:e056ac8fecf8 341 p_crc ^= polynomial;
valeyev 0:e056ac8fecf8 342 }
valeyev 0:e056ac8fecf8 343 data_byte <<= 1;
valeyev 0:e056ac8fecf8 344 }
valeyev 0:e056ac8fecf8 345 }
valeyev 0:e056ac8fecf8 346 } else {
valeyev 0:e056ac8fecf8 347 for (crc_data_size_t byte = 0; byte < size; byte++) {
valeyev 0:e056ac8fecf8 348 p_crc ^= (reflect_bytes(data[byte]) << (width - 8));
valeyev 0:e056ac8fecf8 349
valeyev 0:e056ac8fecf8 350 // Perform modulo-2 division, a bit at a time
valeyev 0:e056ac8fecf8 351 for (uint8_t bit = 8; bit > 0; --bit) {
valeyev 0:e056ac8fecf8 352 if (p_crc & get_top_bit()) {
valeyev 0:e056ac8fecf8 353 p_crc = (p_crc << 1) ^ polynomial;
valeyev 0:e056ac8fecf8 354 } else {
valeyev 0:e056ac8fecf8 355 p_crc = (p_crc << 1);
valeyev 0:e056ac8fecf8 356 }
valeyev 0:e056ac8fecf8 357 }
valeyev 0:e056ac8fecf8 358 }
valeyev 0:e056ac8fecf8 359 }
valeyev 0:e056ac8fecf8 360 *crc = p_crc & get_crc_mask();
valeyev 0:e056ac8fecf8 361 return 0;
valeyev 0:e056ac8fecf8 362 }
valeyev 0:e056ac8fecf8 363
valeyev 0:e056ac8fecf8 364 /** CRC computation using ROM tables
valeyev 0:e056ac8fecf8 365 *
valeyev 0:e056ac8fecf8 366 * @param buffer data buffer
valeyev 0:e056ac8fecf8 367 * @param size size of the data
valeyev 0:e056ac8fecf8 368 * @param crc CRC value is filled in, but the value is not the final
valeyev 0:e056ac8fecf8 369 * @return 0 on success or a negative error code on failure
valeyev 0:e056ac8fecf8 370 */
valeyev 0:e056ac8fecf8 371 int32_t table_compute_partial(const void *buffer, crc_data_size_t size, uint32_t *crc) const
valeyev 0:e056ac8fecf8 372 {
valeyev 0:e056ac8fecf8 373 MBED_ASSERT(crc != NULL);
valeyev 0:e056ac8fecf8 374 MBED_ASSERT(buffer != NULL);
valeyev 0:e056ac8fecf8 375
valeyev 0:e056ac8fecf8 376 const uint8_t *data = static_cast<const uint8_t *>(buffer);
valeyev 0:e056ac8fecf8 377 uint32_t p_crc = *crc;
valeyev 0:e056ac8fecf8 378 uint8_t data_byte = 0;
valeyev 0:e056ac8fecf8 379
valeyev 0:e056ac8fecf8 380 if (width <= 8) {
valeyev 0:e056ac8fecf8 381 uint8_t *crc_table = (uint8_t *)_crc_table;
valeyev 0:e056ac8fecf8 382 for (crc_data_size_t byte = 0; byte < size; byte++) {
valeyev 0:e056ac8fecf8 383 data_byte = reflect_bytes(data[byte]) ^ p_crc;
valeyev 0:e056ac8fecf8 384 p_crc = crc_table[data_byte];
valeyev 0:e056ac8fecf8 385 }
valeyev 0:e056ac8fecf8 386 } else if (width <= 16) {
valeyev 0:e056ac8fecf8 387 uint16_t *crc_table = (uint16_t *)_crc_table;
valeyev 0:e056ac8fecf8 388 for (crc_data_size_t byte = 0; byte < size; byte++) {
valeyev 0:e056ac8fecf8 389 data_byte = reflect_bytes(data[byte]) ^ (p_crc >> (width - 8));
valeyev 0:e056ac8fecf8 390 p_crc = crc_table[data_byte] ^ (p_crc << 8);
valeyev 0:e056ac8fecf8 391 }
valeyev 0:e056ac8fecf8 392 } else {
valeyev 0:e056ac8fecf8 393 uint32_t *crc_table = (uint32_t *)_crc_table;
valeyev 0:e056ac8fecf8 394 for (crc_data_size_t byte = 0; byte < size; byte++) {
valeyev 0:e056ac8fecf8 395 data_byte = reflect_bytes(data[byte]) ^ (p_crc >> (width - 8));
valeyev 0:e056ac8fecf8 396 p_crc = crc_table[data_byte] ^ (p_crc << 8);
valeyev 0:e056ac8fecf8 397 }
valeyev 0:e056ac8fecf8 398 }
valeyev 0:e056ac8fecf8 399 *crc = p_crc & get_crc_mask();
valeyev 0:e056ac8fecf8 400 return 0;
valeyev 0:e056ac8fecf8 401 }
valeyev 0:e056ac8fecf8 402
valeyev 0:e056ac8fecf8 403 /** Constructor init called from all specialized cases of constructor
valeyev 0:e056ac8fecf8 404 * Note: All construtor common code should be in this function.
valeyev 0:e056ac8fecf8 405 */
valeyev 0:e056ac8fecf8 406 void mbed_crc_ctor(void) const
valeyev 0:e056ac8fecf8 407 {
valeyev 0:e056ac8fecf8 408 MBED_STATIC_ASSERT(width <= 32, "Max 32-bit CRC supported");
valeyev 0:e056ac8fecf8 409 }
valeyev 0:e056ac8fecf8 410 };
valeyev 0:e056ac8fecf8 411
valeyev 0:e056ac8fecf8 412 #if defined ( __CC_ARM )
valeyev 0:e056ac8fecf8 413 #elif defined ( __GNUC__ )
valeyev 0:e056ac8fecf8 414 #pragma GCC diagnostic pop
valeyev 0:e056ac8fecf8 415 #endif
valeyev 0:e056ac8fecf8 416
valeyev 0:e056ac8fecf8 417 /** @}*/
valeyev 0:e056ac8fecf8 418 } // namespace mbed
valeyev 0:e056ac8fecf8 419
valeyev 0:e056ac8fecf8 420 #endif