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Fork of OmniWheels by Gustav Atmel

mbed-os/drivers/MbedCRC.h@1:9c5af431a1f1, 2018-05-01 (annotated)

Committer:
gustavatmel
Date:
Tue May 01 15:47:08 2018 +0000
Revision:
1:9c5af431a1f1
sdf

Who changed what in which revision?

UserRevisionLine numberNew contents of line
gustavatmel 1:9c5af431a1f1 1 /* mbed Microcontroller Library
gustavatmel 1:9c5af431a1f1 2 * Copyright (c) 2018 ARM Limited
gustavatmel 1:9c5af431a1f1 3 *
gustavatmel 1:9c5af431a1f1 4 * Licensed under the Apache License, Version 2.0 (the "License");
gustavatmel 1:9c5af431a1f1 5 * you may not use this file except in compliance with the License.
gustavatmel 1:9c5af431a1f1 6 * You may obtain a copy of the License at
gustavatmel 1:9c5af431a1f1 7 *
gustavatmel 1:9c5af431a1f1 8 * http://www.apache.org/licenses/LICENSE-2.0
gustavatmel 1:9c5af431a1f1 9 *
gustavatmel 1:9c5af431a1f1 10 * Unless required by applicable law or agreed to in writing, software
gustavatmel 1:9c5af431a1f1 11 * distributed under the License is distributed on an "AS IS" BASIS,
gustavatmel 1:9c5af431a1f1 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
gustavatmel 1:9c5af431a1f1 13 * See the License for the specific language governing permissions and
gustavatmel 1:9c5af431a1f1 14 * limitations under the License.
gustavatmel 1:9c5af431a1f1 15 */
gustavatmel 1:9c5af431a1f1 16 #ifndef MBED_CRC_API_H
gustavatmel 1:9c5af431a1f1 17 #define MBED_CRC_API_H
gustavatmel 1:9c5af431a1f1 18
gustavatmel 1:9c5af431a1f1 19 #include <stdint.h>
gustavatmel 1:9c5af431a1f1 20 #include "drivers/TableCRC.h"
gustavatmel 1:9c5af431a1f1 21 #include "platform/mbed_assert.h"
gustavatmel 1:9c5af431a1f1 22
gustavatmel 1:9c5af431a1f1 23 /* This is invalid warning from the compiler for below section of code
gustavatmel 1:9c5af431a1f1 24 if ((width < 8) && (NULL == _crc_table)) {
gustavatmel 1:9c5af431a1f1 25 p_crc = (uint32_t)(p_crc << (8 - width));
gustavatmel 1:9c5af431a1f1 26 }
gustavatmel 1:9c5af431a1f1 27 Compiler warns of the shift operation with width as it is width=(std::uint8_t),
gustavatmel 1:9c5af431a1f1 28 but we check for ( width < 8) before performing shift, so it should not be an issue.
gustavatmel 1:9c5af431a1f1 29 */
gustavatmel 1:9c5af431a1f1 30 #if defined ( __CC_ARM )
gustavatmel 1:9c5af431a1f1 31 #pragma diag_suppress 62 // Shift count is negative
gustavatmel 1:9c5af431a1f1 32 #elif defined ( __GNUC__ )
gustavatmel 1:9c5af431a1f1 33 #pragma GCC diagnostic push
gustavatmel 1:9c5af431a1f1 34 #pragma GCC diagnostic ignored "-Wshift-count-negative"
gustavatmel 1:9c5af431a1f1 35 #endif
gustavatmel 1:9c5af431a1f1 36
gustavatmel 1:9c5af431a1f1 37 namespace mbed {
gustavatmel 1:9c5af431a1f1 38 /** \addtogroup drivers */
gustavatmel 1:9c5af431a1f1 39 /** @{*/
gustavatmel 1:9c5af431a1f1 40
gustavatmel 1:9c5af431a1f1 41 /** CRC Polynomial value
gustavatmel 1:9c5af431a1f1 42 *
gustavatmel 1:9c5af431a1f1 43 * Different polynomial values supported
gustavatmel 1:9c5af431a1f1 44 */
gustavatmel 1:9c5af431a1f1 45 typedef enum crc_polynomial {
gustavatmel 1:9c5af431a1f1 46 POLY_OTHER = 0,
gustavatmel 1:9c5af431a1f1 47 POLY_8BIT_CCITT = 0x07, // x8+x2+x+1
gustavatmel 1:9c5af431a1f1 48 POLY_7BIT_SD = 0x9, // x7+x3+1;
gustavatmel 1:9c5af431a1f1 49 POLY_16BIT_CCITT = 0x1021, // x16+x12+x5+1
gustavatmel 1:9c5af431a1f1 50 POLY_16BIT_IBM = 0x8005, // x16+x15+x2+1
gustavatmel 1:9c5af431a1f1 51 POLY_32BIT_ANSI = 0x04C11DB7, // x32+x26+x23+x22+x16+x12+x11+x10+x8+x7+x5+x4+x2+x+1
gustavatmel 1:9c5af431a1f1 52 } crc_polynomial_t;
gustavatmel 1:9c5af431a1f1 53
gustavatmel 1:9c5af431a1f1 54 /** CRC object provides CRC generation through hardware/software
gustavatmel 1:9c5af431a1f1 55 *
gustavatmel 1:9c5af431a1f1 56 * ROM polynomial tables for supported polynomials (:: crc_polynomial_t) will be used for
gustavatmel 1:9c5af431a1f1 57 * software CRC computation, if ROM tables are not available then CRC is computed runtime
gustavatmel 1:9c5af431a1f1 58 * bit by bit for all data input.
gustavatmel 1:9c5af431a1f1 59 *
gustavatmel 1:9c5af431a1f1 60 * @tparam polynomial CRC polynomial value in hex
gustavatmel 1:9c5af431a1f1 61 * @tparam width CRC polynomial width
gustavatmel 1:9c5af431a1f1 62 *
gustavatmel 1:9c5af431a1f1 63 * Example: Compute CRC data
gustavatmel 1:9c5af431a1f1 64 * @code
gustavatmel 1:9c5af431a1f1 65 *
gustavatmel 1:9c5af431a1f1 66 * #include "mbed.h"
gustavatmel 1:9c5af431a1f1 67 *
gustavatmel 1:9c5af431a1f1 68 * int main() {
gustavatmel 1:9c5af431a1f1 69 * MbedCRC<POLY_32BIT_ANSI, 32> ct;
gustavatmel 1:9c5af431a1f1 70 *
gustavatmel 1:9c5af431a1f1 71 * char test[] = "123456789";
gustavatmel 1:9c5af431a1f1 72 * uint32_t crc = 0;
gustavatmel 1:9c5af431a1f1 73 *
gustavatmel 1:9c5af431a1f1 74 * printf("\nPolynomial = 0x%lx Width = %d \n", ct.get_polynomial(), ct.get_width());
gustavatmel 1:9c5af431a1f1 75 *
gustavatmel 1:9c5af431a1f1 76 * ct.compute((void *)test, strlen((const char*)test), &crc);
gustavatmel 1:9c5af431a1f1 77 *
gustavatmel 1:9c5af431a1f1 78 * printf("The CRC of data \"123456789\" is : 0x%lx\n", crc);
gustavatmel 1:9c5af431a1f1 79 * return 0;
gustavatmel 1:9c5af431a1f1 80 * }
gustavatmel 1:9c5af431a1f1 81 * @endcode
gustavatmel 1:9c5af431a1f1 82 * Example: Compute CRC with data available in parts
gustavatmel 1:9c5af431a1f1 83 * @code
gustavatmel 1:9c5af431a1f1 84 *
gustavatmel 1:9c5af431a1f1 85 * #include "mbed.h"
gustavatmel 1:9c5af431a1f1 86 * int main() {
gustavatmel 1:9c5af431a1f1 87 * MbedCRC<POLY_32BIT_ANSI, 32> ct;
gustavatmel 1:9c5af431a1f1 88 *
gustavatmel 1:9c5af431a1f1 89 * char test[] = "123456789";
gustavatmel 1:9c5af431a1f1 90 * uint32_t crc = 0;
gustavatmel 1:9c5af431a1f1 91 *
gustavatmel 1:9c5af431a1f1 92 * printf("\nPolynomial = 0x%lx Width = %d \n", ct.get_polynomial(), ct.get_width());
gustavatmel 1:9c5af431a1f1 93 *
gustavatmel 1:9c5af431a1f1 94 * ct.compute_partial_start(&crc);
gustavatmel 1:9c5af431a1f1 95 * ct.compute_partial((void *)&test, 4, &crc);
gustavatmel 1:9c5af431a1f1 96 * ct.compute_partial((void *)&test[4], 5, &crc);
gustavatmel 1:9c5af431a1f1 97 * ct.compute_partial_stop(&crc);
gustavatmel 1:9c5af431a1f1 98 *
gustavatmel 1:9c5af431a1f1 99 * printf("The CRC of data \"123456789\" is : 0x%lx\n", crc);
gustavatmel 1:9c5af431a1f1 100 * return 0;
gustavatmel 1:9c5af431a1f1 101 * }
gustavatmel 1:9c5af431a1f1 102 * @endcode
gustavatmel 1:9c5af431a1f1 103 * @ingroup drivers
gustavatmel 1:9c5af431a1f1 104 */
gustavatmel 1:9c5af431a1f1 105
gustavatmel 1:9c5af431a1f1 106 template <uint32_t polynomial=POLY_32BIT_ANSI, uint8_t width=32>
gustavatmel 1:9c5af431a1f1 107 class MbedCRC
gustavatmel 1:9c5af431a1f1 108 {
gustavatmel 1:9c5af431a1f1 109 public:
gustavatmel 1:9c5af431a1f1 110 typedef uint64_t crc_data_size_t;
gustavatmel 1:9c5af431a1f1 111
gustavatmel 1:9c5af431a1f1 112 /** Lifetime of CRC object
gustavatmel 1:9c5af431a1f1 113 *
gustavatmel 1:9c5af431a1f1 114 * @param initial_xor Inital value/seed to Xor
gustavatmel 1:9c5af431a1f1 115 * @param final_xor Final Xor value
gustavatmel 1:9c5af431a1f1 116 * @param reflect_data
gustavatmel 1:9c5af431a1f1 117 * @param reflect_remainder
gustavatmel 1:9c5af431a1f1 118 * @note Default constructor without any arguments is valid only for supported CRC polynomials. :: crc_polynomial_t
gustavatmel 1:9c5af431a1f1 119 * MbedCRC <POLY_7BIT_SD, 7> ct; --- Valid POLY_7BIT_SD
gustavatmel 1:9c5af431a1f1 120 * MbedCRC <0x1021, 16> ct; --- Valid POLY_16BIT_CCITT
gustavatmel 1:9c5af431a1f1 121 * MbedCRC <POLY_16BIT_CCITT, 32> ct; --- Invalid, compilation error
gustavatmel 1:9c5af431a1f1 122 * MbedCRC <POLY_16BIT_CCITT, 32> ct (i,f,rd,rr) Consturctor can be used for not supported polynomials
gustavatmel 1:9c5af431a1f1 123 * MbedCRC<POLY_16BIT_CCITT, 16> sd(0, 0, false, false); Constructor can also be used for supported
gustavatmel 1:9c5af431a1f1 124 * polynomials with different intial/final/reflect values
gustavatmel 1:9c5af431a1f1 125 *
gustavatmel 1:9c5af431a1f1 126 */
gustavatmel 1:9c5af431a1f1 127 MbedCRC(uint32_t initial_xor, uint32_t final_xor, bool reflect_data, bool reflect_remainder);
gustavatmel 1:9c5af431a1f1 128 MbedCRC();
gustavatmel 1:9c5af431a1f1 129 virtual ~MbedCRC()
gustavatmel 1:9c5af431a1f1 130 {
gustavatmel 1:9c5af431a1f1 131 // Do nothing
gustavatmel 1:9c5af431a1f1 132 }
gustavatmel 1:9c5af431a1f1 133
gustavatmel 1:9c5af431a1f1 134 /** Compute CRC for the data input
gustavatmel 1:9c5af431a1f1 135 *
gustavatmel 1:9c5af431a1f1 136 * @param buffer Data bytes
gustavatmel 1:9c5af431a1f1 137 * @param size Size of data
gustavatmel 1:9c5af431a1f1 138 * @param crc CRC is the output value
gustavatmel 1:9c5af431a1f1 139 * @return 0 on success, negative error code on failure
gustavatmel 1:9c5af431a1f1 140 */
gustavatmel 1:9c5af431a1f1 141 int32_t compute(void *buffer, crc_data_size_t size, uint32_t *crc)
gustavatmel 1:9c5af431a1f1 142 {
gustavatmel 1:9c5af431a1f1 143 MBED_ASSERT(crc != NULL);
gustavatmel 1:9c5af431a1f1 144 int32_t status;
gustavatmel 1:9c5af431a1f1 145 if (0 != (status = compute_partial_start(crc))) {
gustavatmel 1:9c5af431a1f1 146 *crc = 0;
gustavatmel 1:9c5af431a1f1 147 return status;
gustavatmel 1:9c5af431a1f1 148 }
gustavatmel 1:9c5af431a1f1 149 if (0 != (status = compute_partial(buffer, size, crc))) {
gustavatmel 1:9c5af431a1f1 150 *crc = 0;
gustavatmel 1:9c5af431a1f1 151 return status;
gustavatmel 1:9c5af431a1f1 152 }
gustavatmel 1:9c5af431a1f1 153 if (0 != (status = compute_partial_stop(crc))) {
gustavatmel 1:9c5af431a1f1 154 *crc = 0;
gustavatmel 1:9c5af431a1f1 155 return status;
gustavatmel 1:9c5af431a1f1 156 }
gustavatmel 1:9c5af431a1f1 157 return 0;
gustavatmel 1:9c5af431a1f1 158 }
gustavatmel 1:9c5af431a1f1 159
gustavatmel 1:9c5af431a1f1 160 /** Compute partial CRC for the data input.
gustavatmel 1:9c5af431a1f1 161 *
gustavatmel 1:9c5af431a1f1 162 * CRC data if not available fully, CRC can be computed in parts with available data.
gustavatmel 1:9c5af431a1f1 163 * Previous CRC output should be passed as argument to the current compute_partial call.
gustavatmel 1:9c5af431a1f1 164 * @pre: Call \ref compute_partial_start to start the partial CRC calculation.
gustavatmel 1:9c5af431a1f1 165 * @post: Call \ref compute_partial_stop to get the final CRC value.
gustavatmel 1:9c5af431a1f1 166 *
gustavatmel 1:9c5af431a1f1 167 * @param buffer Data bytes
gustavatmel 1:9c5af431a1f1 168 * @param size Size of data
gustavatmel 1:9c5af431a1f1 169 * @param crc CRC value is intermediate CRC value filled by API.
gustavatmel 1:9c5af431a1f1 170 * @return 0 on success or a negative error code on failure
gustavatmel 1:9c5af431a1f1 171 * @note: CRC as output in compute_partial is not final CRC value, call @ref compute_partial_stop
gustavatmel 1:9c5af431a1f1 172 * to get final correct CRC value.
gustavatmel 1:9c5af431a1f1 173 */
gustavatmel 1:9c5af431a1f1 174 int32_t compute_partial(void *buffer, crc_data_size_t size, uint32_t *crc)
gustavatmel 1:9c5af431a1f1 175 {
gustavatmel 1:9c5af431a1f1 176 if (NULL == _crc_table) {
gustavatmel 1:9c5af431a1f1 177 // Compute bitwise CRC
gustavatmel 1:9c5af431a1f1 178 return bitwise_compute_partial(buffer, size, crc);
gustavatmel 1:9c5af431a1f1 179 } else {
gustavatmel 1:9c5af431a1f1 180 // Table CRC
gustavatmel 1:9c5af431a1f1 181 return table_compute_partial(buffer, size, crc);
gustavatmel 1:9c5af431a1f1 182 }
gustavatmel 1:9c5af431a1f1 183 }
gustavatmel 1:9c5af431a1f1 184
gustavatmel 1:9c5af431a1f1 185 /** Compute partial start, indicate start of partial computation
gustavatmel 1:9c5af431a1f1 186 *
gustavatmel 1:9c5af431a1f1 187 * This API should be called before performing any partial computation
gustavatmel 1:9c5af431a1f1 188 * with compute_partial API.
gustavatmel 1:9c5af431a1f1 189 *
gustavatmel 1:9c5af431a1f1 190 * @param crc Initial CRC value set by the API
gustavatmel 1:9c5af431a1f1 191 * @return 0 on success or a negative in case of failure
gustavatmel 1:9c5af431a1f1 192 * @note: CRC is an out parameter and must be reused with compute_partial
gustavatmel 1:9c5af431a1f1 193 * and compute_partial_stop without any modifications in application.
gustavatmel 1:9c5af431a1f1 194 */
gustavatmel 1:9c5af431a1f1 195 int32_t compute_partial_start(uint32_t *crc)
gustavatmel 1:9c5af431a1f1 196 {
gustavatmel 1:9c5af431a1f1 197 MBED_ASSERT(crc != NULL);
gustavatmel 1:9c5af431a1f1 198 *crc = _initial_value;
gustavatmel 1:9c5af431a1f1 199 return 0;
gustavatmel 1:9c5af431a1f1 200 }
gustavatmel 1:9c5af431a1f1 201
gustavatmel 1:9c5af431a1f1 202 /** Get the final CRC value of partial computation.
gustavatmel 1:9c5af431a1f1 203 *
gustavatmel 1:9c5af431a1f1 204 * CRC value available in partial computation is not correct CRC, as some
gustavatmel 1:9c5af431a1f1 205 * algorithms require remainder to be reflected and final value to be XORed
gustavatmel 1:9c5af431a1f1 206 * This API is used to perform final computation to get correct CRC value.
gustavatmel 1:9c5af431a1f1 207 *
gustavatmel 1:9c5af431a1f1 208 * @param crc CRC result
gustavatmel 1:9c5af431a1f1 209 */
gustavatmel 1:9c5af431a1f1 210 int32_t compute_partial_stop(uint32_t *crc)
gustavatmel 1:9c5af431a1f1 211 {
gustavatmel 1:9c5af431a1f1 212 MBED_ASSERT(crc != NULL);
gustavatmel 1:9c5af431a1f1 213 uint32_t p_crc = *crc;
gustavatmel 1:9c5af431a1f1 214 if ((width < 8) && (NULL == _crc_table)) {
gustavatmel 1:9c5af431a1f1 215 p_crc = (uint32_t)(p_crc << (8 - width));
gustavatmel 1:9c5af431a1f1 216 }
gustavatmel 1:9c5af431a1f1 217 *crc = (reflect_remainder(p_crc) ^ _final_xor) & get_crc_mask();
gustavatmel 1:9c5af431a1f1 218 return 0;
gustavatmel 1:9c5af431a1f1 219 }
gustavatmel 1:9c5af431a1f1 220
gustavatmel 1:9c5af431a1f1 221 /** Get the current CRC polynomial
gustavatmel 1:9c5af431a1f1 222 *
gustavatmel 1:9c5af431a1f1 223 * @return Polynomial value
gustavatmel 1:9c5af431a1f1 224 */
gustavatmel 1:9c5af431a1f1 225 uint32_t get_polynomial(void) const
gustavatmel 1:9c5af431a1f1 226 {
gustavatmel 1:9c5af431a1f1 227 return polynomial;
gustavatmel 1:9c5af431a1f1 228 }
gustavatmel 1:9c5af431a1f1 229
gustavatmel 1:9c5af431a1f1 230 /** Get the current CRC width
gustavatmel 1:9c5af431a1f1 231 *
gustavatmel 1:9c5af431a1f1 232 * @return CRC width
gustavatmel 1:9c5af431a1f1 233 */
gustavatmel 1:9c5af431a1f1 234 uint8_t get_width(void) const
gustavatmel 1:9c5af431a1f1 235 {
gustavatmel 1:9c5af431a1f1 236 return width;
gustavatmel 1:9c5af431a1f1 237 }
gustavatmel 1:9c5af431a1f1 238
gustavatmel 1:9c5af431a1f1 239 private:
gustavatmel 1:9c5af431a1f1 240 uint32_t _initial_value;
gustavatmel 1:9c5af431a1f1 241 uint32_t _final_xor;
gustavatmel 1:9c5af431a1f1 242 bool _reflect_data;
gustavatmel 1:9c5af431a1f1 243 bool _reflect_remainder;
gustavatmel 1:9c5af431a1f1 244 uint32_t *_crc_table;
gustavatmel 1:9c5af431a1f1 245
gustavatmel 1:9c5af431a1f1 246 /** Get the current CRC data size
gustavatmel 1:9c5af431a1f1 247 *
gustavatmel 1:9c5af431a1f1 248 * @return CRC data size in bytes
gustavatmel 1:9c5af431a1f1 249 */
gustavatmel 1:9c5af431a1f1 250 uint8_t get_data_size(void) const
gustavatmel 1:9c5af431a1f1 251 {
gustavatmel 1:9c5af431a1f1 252 return (width <= 8 ? 1 : (width <= 16 ? 2 : 4));
gustavatmel 1:9c5af431a1f1 253 }
gustavatmel 1:9c5af431a1f1 254
gustavatmel 1:9c5af431a1f1 255 /** Get the top bit of current CRC
gustavatmel 1:9c5af431a1f1 256 *
gustavatmel 1:9c5af431a1f1 257 * @return Top bit is set high for respective data width of current CRC
gustavatmel 1:9c5af431a1f1 258 * Top bit for CRC width less then 8 bits will be set as 8th bit.
gustavatmel 1:9c5af431a1f1 259 */
gustavatmel 1:9c5af431a1f1 260 uint32_t get_top_bit(void) const
gustavatmel 1:9c5af431a1f1 261 {
gustavatmel 1:9c5af431a1f1 262 return (width < 8 ? (1u << 7) : (uint32_t)(1ul << (width - 1)));
gustavatmel 1:9c5af431a1f1 263 }
gustavatmel 1:9c5af431a1f1 264
gustavatmel 1:9c5af431a1f1 265 /** Get the CRC data mask
gustavatmel 1:9c5af431a1f1 266 *
gustavatmel 1:9c5af431a1f1 267 * @return CRC data mask is generated based on current CRC width
gustavatmel 1:9c5af431a1f1 268 */
gustavatmel 1:9c5af431a1f1 269 uint32_t get_crc_mask(void) const
gustavatmel 1:9c5af431a1f1 270 {
gustavatmel 1:9c5af431a1f1 271 return (width < 8 ? ((1u << 8) - 1) : (uint32_t)((uint64_t)(1ull << width) - 1));
gustavatmel 1:9c5af431a1f1 272 }
gustavatmel 1:9c5af431a1f1 273
gustavatmel 1:9c5af431a1f1 274 /** Final value of CRC is reflected
gustavatmel 1:9c5af431a1f1 275 *
gustavatmel 1:9c5af431a1f1 276 * @param data final crc value, which should be reflected
gustavatmel 1:9c5af431a1f1 277 * @return Reflected CRC value
gustavatmel 1:9c5af431a1f1 278 */
gustavatmel 1:9c5af431a1f1 279 uint32_t reflect_remainder(uint32_t data) const
gustavatmel 1:9c5af431a1f1 280 {
gustavatmel 1:9c5af431a1f1 281 if (_reflect_remainder) {
gustavatmel 1:9c5af431a1f1 282 uint32_t reflection = 0x0;
gustavatmel 1:9c5af431a1f1 283 uint8_t const nBits = (width < 8 ? 8 : width);
gustavatmel 1:9c5af431a1f1 284
gustavatmel 1:9c5af431a1f1 285 for (uint8_t bit = 0; bit < nBits; ++bit) {
gustavatmel 1:9c5af431a1f1 286 if (data & 0x01) {
gustavatmel 1:9c5af431a1f1 287 reflection |= (1 << ((nBits - 1) - bit));
gustavatmel 1:9c5af431a1f1 288 }
gustavatmel 1:9c5af431a1f1 289 data = (data >> 1);
gustavatmel 1:9c5af431a1f1 290 }
gustavatmel 1:9c5af431a1f1 291 return (reflection);
gustavatmel 1:9c5af431a1f1 292 } else {
gustavatmel 1:9c5af431a1f1 293 return data;
gustavatmel 1:9c5af431a1f1 294 }
gustavatmel 1:9c5af431a1f1 295 }
gustavatmel 1:9c5af431a1f1 296
gustavatmel 1:9c5af431a1f1 297 /** Data bytes are reflected
gustavatmel 1:9c5af431a1f1 298 *
gustavatmel 1:9c5af431a1f1 299 * @param data value to be reflected
gustavatmel 1:9c5af431a1f1 300 * @return Reflected data value
gustavatmel 1:9c5af431a1f1 301 */
gustavatmel 1:9c5af431a1f1 302 uint32_t reflect_bytes(uint32_t data) const
gustavatmel 1:9c5af431a1f1 303 {
gustavatmel 1:9c5af431a1f1 304 if(_reflect_data) {
gustavatmel 1:9c5af431a1f1 305 uint32_t reflection = 0x0;
gustavatmel 1:9c5af431a1f1 306
gustavatmel 1:9c5af431a1f1 307 for (uint8_t bit = 0; bit < 8; ++bit) {
gustavatmel 1:9c5af431a1f1 308 if (data & 0x01) {
gustavatmel 1:9c5af431a1f1 309 reflection |= (1 << (7 - bit));
gustavatmel 1:9c5af431a1f1 310 }
gustavatmel 1:9c5af431a1f1 311 data = (data >> 1);
gustavatmel 1:9c5af431a1f1 312 }
gustavatmel 1:9c5af431a1f1 313 return (reflection);
gustavatmel 1:9c5af431a1f1 314 } else {
gustavatmel 1:9c5af431a1f1 315 return data;
gustavatmel 1:9c5af431a1f1 316 }
gustavatmel 1:9c5af431a1f1 317 }
gustavatmel 1:9c5af431a1f1 318
gustavatmel 1:9c5af431a1f1 319 /** Bitwise CRC computation
gustavatmel 1:9c5af431a1f1 320 *
gustavatmel 1:9c5af431a1f1 321 * @param buffer data buffer
gustavatmel 1:9c5af431a1f1 322 * @param size size of the data
gustavatmel 1:9c5af431a1f1 323 * @param crc CRC value is filled in, but the value is not the final
gustavatmel 1:9c5af431a1f1 324 * @return 0 on success or a negative error code on failure
gustavatmel 1:9c5af431a1f1 325 */
gustavatmel 1:9c5af431a1f1 326 int32_t bitwise_compute_partial(const void *buffer, crc_data_size_t size, uint32_t *crc) const
gustavatmel 1:9c5af431a1f1 327 {
gustavatmel 1:9c5af431a1f1 328 MBED_ASSERT(crc != NULL);
gustavatmel 1:9c5af431a1f1 329 MBED_ASSERT(buffer != NULL);
gustavatmel 1:9c5af431a1f1 330
gustavatmel 1:9c5af431a1f1 331 const uint8_t *data = static_cast<const uint8_t *>(buffer);
gustavatmel 1:9c5af431a1f1 332 uint32_t p_crc = *crc;
gustavatmel 1:9c5af431a1f1 333
gustavatmel 1:9c5af431a1f1 334 if (width < 8) {
gustavatmel 1:9c5af431a1f1 335 uint8_t data_byte;
gustavatmel 1:9c5af431a1f1 336 for (crc_data_size_t byte = 0; byte < size; byte++) {
gustavatmel 1:9c5af431a1f1 337 data_byte = reflect_bytes(data[byte]);
gustavatmel 1:9c5af431a1f1 338 for (uint8_t bit = 8; bit > 0; --bit) {
gustavatmel 1:9c5af431a1f1 339 p_crc <<= 1;
gustavatmel 1:9c5af431a1f1 340 if (( data_byte ^ p_crc) & get_top_bit()) {
gustavatmel 1:9c5af431a1f1 341 p_crc ^= polynomial;
gustavatmel 1:9c5af431a1f1 342 }
gustavatmel 1:9c5af431a1f1 343 data_byte <<= 1;
gustavatmel 1:9c5af431a1f1 344 }
gustavatmel 1:9c5af431a1f1 345 }
gustavatmel 1:9c5af431a1f1 346 } else {
gustavatmel 1:9c5af431a1f1 347 for (crc_data_size_t byte = 0; byte < size; byte++) {
gustavatmel 1:9c5af431a1f1 348 p_crc ^= (reflect_bytes(data[byte]) << (width - 8));
gustavatmel 1:9c5af431a1f1 349
gustavatmel 1:9c5af431a1f1 350 // Perform modulo-2 division, a bit at a time
gustavatmel 1:9c5af431a1f1 351 for (uint8_t bit = 8; bit > 0; --bit) {
gustavatmel 1:9c5af431a1f1 352 if (p_crc & get_top_bit()) {
gustavatmel 1:9c5af431a1f1 353 p_crc = (p_crc << 1) ^ polynomial;
gustavatmel 1:9c5af431a1f1 354 } else {
gustavatmel 1:9c5af431a1f1 355 p_crc = (p_crc << 1);
gustavatmel 1:9c5af431a1f1 356 }
gustavatmel 1:9c5af431a1f1 357 }
gustavatmel 1:9c5af431a1f1 358 }
gustavatmel 1:9c5af431a1f1 359 }
gustavatmel 1:9c5af431a1f1 360 *crc = p_crc & get_crc_mask();
gustavatmel 1:9c5af431a1f1 361 return 0;
gustavatmel 1:9c5af431a1f1 362 }
gustavatmel 1:9c5af431a1f1 363
gustavatmel 1:9c5af431a1f1 364 /** CRC computation using ROM tables
gustavatmel 1:9c5af431a1f1 365 *
gustavatmel 1:9c5af431a1f1 366 * @param buffer data buffer
gustavatmel 1:9c5af431a1f1 367 * @param size size of the data
gustavatmel 1:9c5af431a1f1 368 * @param crc CRC value is filled in, but the value is not the final
gustavatmel 1:9c5af431a1f1 369 * @return 0 on success or a negative error code on failure
gustavatmel 1:9c5af431a1f1 370 */
gustavatmel 1:9c5af431a1f1 371 int32_t table_compute_partial(const void *buffer, crc_data_size_t size, uint32_t *crc) const
gustavatmel 1:9c5af431a1f1 372 {
gustavatmel 1:9c5af431a1f1 373 MBED_ASSERT(crc != NULL);
gustavatmel 1:9c5af431a1f1 374 MBED_ASSERT(buffer != NULL);
gustavatmel 1:9c5af431a1f1 375
gustavatmel 1:9c5af431a1f1 376 const uint8_t *data = static_cast<const uint8_t *>(buffer);
gustavatmel 1:9c5af431a1f1 377 uint32_t p_crc = *crc;
gustavatmel 1:9c5af431a1f1 378 uint8_t data_byte = 0;
gustavatmel 1:9c5af431a1f1 379
gustavatmel 1:9c5af431a1f1 380 if (width <= 8) {
gustavatmel 1:9c5af431a1f1 381 uint8_t *crc_table = (uint8_t *)_crc_table;
gustavatmel 1:9c5af431a1f1 382 for (crc_data_size_t byte = 0; byte < size; byte++) {
gustavatmel 1:9c5af431a1f1 383 data_byte = reflect_bytes(data[byte]) ^ p_crc;
gustavatmel 1:9c5af431a1f1 384 p_crc = crc_table[data_byte];
gustavatmel 1:9c5af431a1f1 385 }
gustavatmel 1:9c5af431a1f1 386 } else if (width <= 16) {
gustavatmel 1:9c5af431a1f1 387 uint16_t *crc_table = (uint16_t *)_crc_table;
gustavatmel 1:9c5af431a1f1 388 for (crc_data_size_t byte = 0; byte < size; byte++) {
gustavatmel 1:9c5af431a1f1 389 data_byte = reflect_bytes(data[byte]) ^ (p_crc >> (width - 8));
gustavatmel 1:9c5af431a1f1 390 p_crc = crc_table[data_byte] ^ (p_crc << 8);
gustavatmel 1:9c5af431a1f1 391 }
gustavatmel 1:9c5af431a1f1 392 } else {
gustavatmel 1:9c5af431a1f1 393 uint32_t *crc_table = (uint32_t *)_crc_table;
gustavatmel 1:9c5af431a1f1 394 for (crc_data_size_t byte = 0; byte < size; byte++) {
gustavatmel 1:9c5af431a1f1 395 data_byte = reflect_bytes(data[byte]) ^ (p_crc >> (width - 8));
gustavatmel 1:9c5af431a1f1 396 p_crc = crc_table[data_byte] ^ (p_crc << 8);
gustavatmel 1:9c5af431a1f1 397 }
gustavatmel 1:9c5af431a1f1 398 }
gustavatmel 1:9c5af431a1f1 399 *crc = p_crc & get_crc_mask();
gustavatmel 1:9c5af431a1f1 400 return 0;
gustavatmel 1:9c5af431a1f1 401 }
gustavatmel 1:9c5af431a1f1 402
gustavatmel 1:9c5af431a1f1 403 /** Constructor init called from all specialized cases of constructor
gustavatmel 1:9c5af431a1f1 404 * Note: All construtor common code should be in this function.
gustavatmel 1:9c5af431a1f1 405 */
gustavatmel 1:9c5af431a1f1 406 void mbed_crc_ctor(void) const
gustavatmel 1:9c5af431a1f1 407 {
gustavatmel 1:9c5af431a1f1 408 MBED_STATIC_ASSERT(width <= 32, "Max 32-bit CRC supported");
gustavatmel 1:9c5af431a1f1 409 }
gustavatmel 1:9c5af431a1f1 410 };
gustavatmel 1:9c5af431a1f1 411
gustavatmel 1:9c5af431a1f1 412 #if defined ( __CC_ARM )
gustavatmel 1:9c5af431a1f1 413 #elif defined ( __GNUC__ )
gustavatmel 1:9c5af431a1f1 414 #pragma GCC diagnostic pop
gustavatmel 1:9c5af431a1f1 415 #endif
gustavatmel 1:9c5af431a1f1 416
gustavatmel 1:9c5af431a1f1 417 /** @}*/
gustavatmel 1:9c5af431a1f1 418 } // namespace mbed
gustavatmel 1:9c5af431a1f1 419
gustavatmel 1:9c5af431a1f1 420 #endif