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drivers/MbedCRC.h@165:d1b4690b3f8b, 2018-04-19 (annotated)

Committer:
AnnaBridge
Date:
Thu Apr 19 14:31:27 2018 +0100
Revision:
165:d1b4690b3f8b
Child:
169:a7c7b631e539
mbed library. Release version 161

Who changed what in which revision?

UserRevisionLine numberNew contents of line
AnnaBridge 165:d1b4690b3f8b 1 /* mbed Microcontroller Library
AnnaBridge 165:d1b4690b3f8b 2 * Copyright (c) 2018 ARM Limited
AnnaBridge 165:d1b4690b3f8b 3 *
AnnaBridge 165:d1b4690b3f8b 4 * Licensed under the Apache License, Version 2.0 (the "License");
AnnaBridge 165:d1b4690b3f8b 5 * you may not use this file except in compliance with the License.
AnnaBridge 165:d1b4690b3f8b 6 * You may obtain a copy of the License at
AnnaBridge 165:d1b4690b3f8b 7 *
AnnaBridge 165:d1b4690b3f8b 8 * http://www.apache.org/licenses/LICENSE-2.0
AnnaBridge 165:d1b4690b3f8b 9 *
AnnaBridge 165:d1b4690b3f8b 10 * Unless required by applicable law or agreed to in writing, software
AnnaBridge 165:d1b4690b3f8b 11 * distributed under the License is distributed on an "AS IS" BASIS,
AnnaBridge 165:d1b4690b3f8b 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
AnnaBridge 165:d1b4690b3f8b 13 * See the License for the specific language governing permissions and
AnnaBridge 165:d1b4690b3f8b 14 * limitations under the License.
AnnaBridge 165:d1b4690b3f8b 15 */
AnnaBridge 165:d1b4690b3f8b 16 #ifndef MBED_CRC_API_H
AnnaBridge 165:d1b4690b3f8b 17 #define MBED_CRC_API_H
AnnaBridge 165:d1b4690b3f8b 18
AnnaBridge 165:d1b4690b3f8b 19 #include <stdint.h>
AnnaBridge 165:d1b4690b3f8b 20 #include "drivers/TableCRC.h"
AnnaBridge 165:d1b4690b3f8b 21 #include "platform/mbed_assert.h"
AnnaBridge 165:d1b4690b3f8b 22
AnnaBridge 165:d1b4690b3f8b 23 /* This is invalid warning from the compiler for below section of code
AnnaBridge 165:d1b4690b3f8b 24 if ((width < 8) && (NULL == _crc_table)) {
AnnaBridge 165:d1b4690b3f8b 25 p_crc = (uint32_t)(p_crc << (8 - width));
AnnaBridge 165:d1b4690b3f8b 26 }
AnnaBridge 165:d1b4690b3f8b 27 Compiler warns of the shift operation with width as it is width=(std::uint8_t),
AnnaBridge 165:d1b4690b3f8b 28 but we check for ( width < 8) before performing shift, so it should not be an issue.
AnnaBridge 165:d1b4690b3f8b 29 */
AnnaBridge 165:d1b4690b3f8b 30 #if defined ( __CC_ARM )
AnnaBridge 165:d1b4690b3f8b 31 #pragma diag_suppress 62 // Shift count is negative
AnnaBridge 165:d1b4690b3f8b 32 #elif defined ( __GNUC__ )
AnnaBridge 165:d1b4690b3f8b 33 #pragma GCC diagnostic push
AnnaBridge 165:d1b4690b3f8b 34 #pragma GCC diagnostic ignored "-Wshift-count-negative"
AnnaBridge 165:d1b4690b3f8b 35 #endif
AnnaBridge 165:d1b4690b3f8b 36
AnnaBridge 165:d1b4690b3f8b 37 namespace mbed {
AnnaBridge 165:d1b4690b3f8b 38 /** \addtogroup drivers */
AnnaBridge 165:d1b4690b3f8b 39 /** @{*/
AnnaBridge 165:d1b4690b3f8b 40
AnnaBridge 165:d1b4690b3f8b 41 /** CRC Polynomial value
AnnaBridge 165:d1b4690b3f8b 42 *
AnnaBridge 165:d1b4690b3f8b 43 * Different polynomial values supported
AnnaBridge 165:d1b4690b3f8b 44 */
AnnaBridge 165:d1b4690b3f8b 45 typedef enum crc_polynomial {
AnnaBridge 165:d1b4690b3f8b 46 POLY_OTHER = 0,
AnnaBridge 165:d1b4690b3f8b 47 POLY_8BIT_CCITT = 0x07, // x8+x2+x+1
AnnaBridge 165:d1b4690b3f8b 48 POLY_7BIT_SD = 0x9, // x7+x3+1;
AnnaBridge 165:d1b4690b3f8b 49 POLY_16BIT_CCITT = 0x1021, // x16+x12+x5+1
AnnaBridge 165:d1b4690b3f8b 50 POLY_16BIT_IBM = 0x8005, // x16+x15+x2+1
AnnaBridge 165:d1b4690b3f8b 51 POLY_32BIT_ANSI = 0x04C11DB7, // x32+x26+x23+x22+x16+x12+x11+x10+x8+x7+x5+x4+x2+x+1
AnnaBridge 165:d1b4690b3f8b 52 } crc_polynomial_t;
AnnaBridge 165:d1b4690b3f8b 53
AnnaBridge 165:d1b4690b3f8b 54 /** CRC object provides CRC generation through hardware/software
AnnaBridge 165:d1b4690b3f8b 55 *
AnnaBridge 165:d1b4690b3f8b 56 * ROM polynomial tables for supported polynomials (:: crc_polynomial_t) will be used for
AnnaBridge 165:d1b4690b3f8b 57 * software CRC computation, if ROM tables are not available then CRC is computed runtime
AnnaBridge 165:d1b4690b3f8b 58 * bit by bit for all data input.
AnnaBridge 165:d1b4690b3f8b 59 *
AnnaBridge 165:d1b4690b3f8b 60 * @tparam polynomial CRC polynomial value in hex
AnnaBridge 165:d1b4690b3f8b 61 * @tparam width CRC polynomial width
AnnaBridge 165:d1b4690b3f8b 62 *
AnnaBridge 165:d1b4690b3f8b 63 * Example: Compute CRC data
AnnaBridge 165:d1b4690b3f8b 64 * @code
AnnaBridge 165:d1b4690b3f8b 65 *
AnnaBridge 165:d1b4690b3f8b 66 * #include "mbed.h"
AnnaBridge 165:d1b4690b3f8b 67 *
AnnaBridge 165:d1b4690b3f8b 68 * int main() {
AnnaBridge 165:d1b4690b3f8b 69 * MbedCRC<POLY_32BIT_ANSI, 32> ct;
AnnaBridge 165:d1b4690b3f8b 70 *
AnnaBridge 165:d1b4690b3f8b 71 * char test[] = "123456789";
AnnaBridge 165:d1b4690b3f8b 72 * uint32_t crc = 0;
AnnaBridge 165:d1b4690b3f8b 73 *
AnnaBridge 165:d1b4690b3f8b 74 * printf("\nPolynomial = 0x%lx Width = %d \n", ct.get_polynomial(), ct.get_width());
AnnaBridge 165:d1b4690b3f8b 75 *
AnnaBridge 165:d1b4690b3f8b 76 * ct.compute((void *)test, strlen((const char*)test), &crc);
AnnaBridge 165:d1b4690b3f8b 77 *
AnnaBridge 165:d1b4690b3f8b 78 * printf("The CRC of data \"123456789\" is : 0x%lx\n", crc);
AnnaBridge 165:d1b4690b3f8b 79 * return 0;
AnnaBridge 165:d1b4690b3f8b 80 * }
AnnaBridge 165:d1b4690b3f8b 81 * @endcode
AnnaBridge 165:d1b4690b3f8b 82 * Example: Compute CRC with data available in parts
AnnaBridge 165:d1b4690b3f8b 83 * @code
AnnaBridge 165:d1b4690b3f8b 84 *
AnnaBridge 165:d1b4690b3f8b 85 * #include "mbed.h"
AnnaBridge 165:d1b4690b3f8b 86 * int main() {
AnnaBridge 165:d1b4690b3f8b 87 * MbedCRC<POLY_32BIT_ANSI, 32> ct;
AnnaBridge 165:d1b4690b3f8b 88 *
AnnaBridge 165:d1b4690b3f8b 89 * char test[] = "123456789";
AnnaBridge 165:d1b4690b3f8b 90 * uint32_t crc = 0;
AnnaBridge 165:d1b4690b3f8b 91 *
AnnaBridge 165:d1b4690b3f8b 92 * printf("\nPolynomial = 0x%lx Width = %d \n", ct.get_polynomial(), ct.get_width());
AnnaBridge 165:d1b4690b3f8b 93 *
AnnaBridge 165:d1b4690b3f8b 94 * ct.compute_partial_start(&crc);
AnnaBridge 165:d1b4690b3f8b 95 * ct.compute_partial((void *)&test, 4, &crc);
AnnaBridge 165:d1b4690b3f8b 96 * ct.compute_partial((void *)&test[4], 5, &crc);
AnnaBridge 165:d1b4690b3f8b 97 * ct.compute_partial_stop(&crc);
AnnaBridge 165:d1b4690b3f8b 98 *
AnnaBridge 165:d1b4690b3f8b 99 * printf("The CRC of data \"123456789\" is : 0x%lx\n", crc);
AnnaBridge 165:d1b4690b3f8b 100 * return 0;
AnnaBridge 165:d1b4690b3f8b 101 * }
AnnaBridge 165:d1b4690b3f8b 102 * @endcode
AnnaBridge 165:d1b4690b3f8b 103 * @ingroup drivers
AnnaBridge 165:d1b4690b3f8b 104 */
AnnaBridge 165:d1b4690b3f8b 105
AnnaBridge 165:d1b4690b3f8b 106 template <uint32_t polynomial=POLY_32BIT_ANSI, uint8_t width=32>
AnnaBridge 165:d1b4690b3f8b 107 class MbedCRC
AnnaBridge 165:d1b4690b3f8b 108 {
AnnaBridge 165:d1b4690b3f8b 109 public:
AnnaBridge 165:d1b4690b3f8b 110 typedef uint64_t crc_data_size_t;
AnnaBridge 165:d1b4690b3f8b 111
AnnaBridge 165:d1b4690b3f8b 112 /** Lifetime of CRC object
AnnaBridge 165:d1b4690b3f8b 113 *
AnnaBridge 165:d1b4690b3f8b 114 * @param initial_xor Inital value/seed to Xor
AnnaBridge 165:d1b4690b3f8b 115 * @param final_xor Final Xor value
AnnaBridge 165:d1b4690b3f8b 116 * @param reflect_data
AnnaBridge 165:d1b4690b3f8b 117 * @param reflect_remainder
AnnaBridge 165:d1b4690b3f8b 118 * @note Default constructor without any arguments is valid only for supported CRC polynomials. :: crc_polynomial_t
AnnaBridge 165:d1b4690b3f8b 119 * MbedCRC <POLY_7BIT_SD, 7> ct; --- Valid POLY_7BIT_SD
AnnaBridge 165:d1b4690b3f8b 120 * MbedCRC <0x1021, 16> ct; --- Valid POLY_16BIT_CCITT
AnnaBridge 165:d1b4690b3f8b 121 * MbedCRC <POLY_16BIT_CCITT, 32> ct; --- Invalid, compilation error
AnnaBridge 165:d1b4690b3f8b 122 * MbedCRC <POLY_16BIT_CCITT, 32> ct (i,f,rd,rr) Consturctor can be used for not supported polynomials
AnnaBridge 165:d1b4690b3f8b 123 * MbedCRC<POLY_16BIT_CCITT, 16> sd(0, 0, false, false); Constructor can also be used for supported
AnnaBridge 165:d1b4690b3f8b 124 * polynomials with different intial/final/reflect values
AnnaBridge 165:d1b4690b3f8b 125 *
AnnaBridge 165:d1b4690b3f8b 126 */
AnnaBridge 165:d1b4690b3f8b 127 MbedCRC(uint32_t initial_xor, uint32_t final_xor, bool reflect_data, bool reflect_remainder) :
AnnaBridge 165:d1b4690b3f8b 128 _initial_value(initial_xor), _final_xor(final_xor), _reflect_data(reflect_data),
AnnaBridge 165:d1b4690b3f8b 129 _reflect_remainder(reflect_remainder), _crc_table(NULL)
AnnaBridge 165:d1b4690b3f8b 130 {
AnnaBridge 165:d1b4690b3f8b 131 mbed_crc_ctor();
AnnaBridge 165:d1b4690b3f8b 132 }
AnnaBridge 165:d1b4690b3f8b 133 MbedCRC();
AnnaBridge 165:d1b4690b3f8b 134 virtual ~MbedCRC()
AnnaBridge 165:d1b4690b3f8b 135 {
AnnaBridge 165:d1b4690b3f8b 136 // Do nothing
AnnaBridge 165:d1b4690b3f8b 137 }
AnnaBridge 165:d1b4690b3f8b 138
AnnaBridge 165:d1b4690b3f8b 139 /** Compute CRC for the data input
AnnaBridge 165:d1b4690b3f8b 140 *
AnnaBridge 165:d1b4690b3f8b 141 * @param buffer Data bytes
AnnaBridge 165:d1b4690b3f8b 142 * @param size Size of data
AnnaBridge 165:d1b4690b3f8b 143 * @param crc CRC is the output value
AnnaBridge 165:d1b4690b3f8b 144 * @return 0 on success, negative error code on failure
AnnaBridge 165:d1b4690b3f8b 145 */
AnnaBridge 165:d1b4690b3f8b 146 int32_t compute(void *buffer, crc_data_size_t size, uint32_t *crc)
AnnaBridge 165:d1b4690b3f8b 147 {
AnnaBridge 165:d1b4690b3f8b 148 MBED_ASSERT(crc != NULL);
AnnaBridge 165:d1b4690b3f8b 149 int32_t status;
AnnaBridge 165:d1b4690b3f8b 150 if (0 != (status = compute_partial_start(crc))) {
AnnaBridge 165:d1b4690b3f8b 151 *crc = 0;
AnnaBridge 165:d1b4690b3f8b 152 return status;
AnnaBridge 165:d1b4690b3f8b 153 }
AnnaBridge 165:d1b4690b3f8b 154 if (0 != (status = compute_partial(buffer, size, crc))) {
AnnaBridge 165:d1b4690b3f8b 155 *crc = 0;
AnnaBridge 165:d1b4690b3f8b 156 return status;
AnnaBridge 165:d1b4690b3f8b 157 }
AnnaBridge 165:d1b4690b3f8b 158 if (0 != (status = compute_partial_stop(crc))) {
AnnaBridge 165:d1b4690b3f8b 159 *crc = 0;
AnnaBridge 165:d1b4690b3f8b 160 return status;
AnnaBridge 165:d1b4690b3f8b 161 }
AnnaBridge 165:d1b4690b3f8b 162 return 0;
AnnaBridge 165:d1b4690b3f8b 163 }
AnnaBridge 165:d1b4690b3f8b 164
AnnaBridge 165:d1b4690b3f8b 165 /** Compute partial CRC for the data input.
AnnaBridge 165:d1b4690b3f8b 166 *
AnnaBridge 165:d1b4690b3f8b 167 * CRC data if not available fully, CRC can be computed in parts with available data.
AnnaBridge 165:d1b4690b3f8b 168 * Previous CRC output should be passed as argument to the current compute_partial call.
AnnaBridge 165:d1b4690b3f8b 169 * @pre: Call \ref compute_partial_start to start the partial CRC calculation.
AnnaBridge 165:d1b4690b3f8b 170 * @post: Call \ref compute_partial_stop to get the final CRC value.
AnnaBridge 165:d1b4690b3f8b 171 *
AnnaBridge 165:d1b4690b3f8b 172 * @param buffer Data bytes
AnnaBridge 165:d1b4690b3f8b 173 * @param size Size of data
AnnaBridge 165:d1b4690b3f8b 174 * @param crc CRC value is intermediate CRC value filled by API.
AnnaBridge 165:d1b4690b3f8b 175 * @return 0 on success or a negative error code on failure
AnnaBridge 165:d1b4690b3f8b 176 * @note: CRC as output in compute_partial is not final CRC value, call @ref compute_partial_stop
AnnaBridge 165:d1b4690b3f8b 177 * to get final correct CRC value.
AnnaBridge 165:d1b4690b3f8b 178 */
AnnaBridge 165:d1b4690b3f8b 179 int32_t compute_partial(void *buffer, crc_data_size_t size, uint32_t *crc)
AnnaBridge 165:d1b4690b3f8b 180 {
AnnaBridge 165:d1b4690b3f8b 181 if (NULL == _crc_table) {
AnnaBridge 165:d1b4690b3f8b 182 // Compute bitwise CRC
AnnaBridge 165:d1b4690b3f8b 183 return bitwise_compute_partial(buffer, size, crc);
AnnaBridge 165:d1b4690b3f8b 184 } else {
AnnaBridge 165:d1b4690b3f8b 185 // Table CRC
AnnaBridge 165:d1b4690b3f8b 186 return table_compute_partial(buffer, size, crc);
AnnaBridge 165:d1b4690b3f8b 187 }
AnnaBridge 165:d1b4690b3f8b 188 }
AnnaBridge 165:d1b4690b3f8b 189
AnnaBridge 165:d1b4690b3f8b 190 /** Compute partial start, indicate start of partial computation
AnnaBridge 165:d1b4690b3f8b 191 *
AnnaBridge 165:d1b4690b3f8b 192 * This API should be called before performing any partial computation
AnnaBridge 165:d1b4690b3f8b 193 * with compute_partial API.
AnnaBridge 165:d1b4690b3f8b 194 *
AnnaBridge 165:d1b4690b3f8b 195 * @param crc Initial CRC value set by the API
AnnaBridge 165:d1b4690b3f8b 196 * @return 0 on success or a negative in case of failure
AnnaBridge 165:d1b4690b3f8b 197 * @note: CRC is an out parameter and must be reused with compute_partial
AnnaBridge 165:d1b4690b3f8b 198 * and compute_partial_stop without any modifications in application.
AnnaBridge 165:d1b4690b3f8b 199 */
AnnaBridge 165:d1b4690b3f8b 200 int32_t compute_partial_start(uint32_t *crc)
AnnaBridge 165:d1b4690b3f8b 201 {
AnnaBridge 165:d1b4690b3f8b 202 MBED_ASSERT(crc != NULL);
AnnaBridge 165:d1b4690b3f8b 203 *crc = _initial_value;
AnnaBridge 165:d1b4690b3f8b 204 return 0;
AnnaBridge 165:d1b4690b3f8b 205 }
AnnaBridge 165:d1b4690b3f8b 206
AnnaBridge 165:d1b4690b3f8b 207 /** Get the final CRC value of partial computation.
AnnaBridge 165:d1b4690b3f8b 208 *
AnnaBridge 165:d1b4690b3f8b 209 * CRC value available in partial computation is not correct CRC, as some
AnnaBridge 165:d1b4690b3f8b 210 * algorithms require remainder to be reflected and final value to be XORed
AnnaBridge 165:d1b4690b3f8b 211 * This API is used to perform final computation to get correct CRC value.
AnnaBridge 165:d1b4690b3f8b 212 *
AnnaBridge 165:d1b4690b3f8b 213 * @param crc CRC result
AnnaBridge 165:d1b4690b3f8b 214 */
AnnaBridge 165:d1b4690b3f8b 215 int32_t compute_partial_stop(uint32_t *crc)
AnnaBridge 165:d1b4690b3f8b 216 {
AnnaBridge 165:d1b4690b3f8b 217 MBED_ASSERT(crc != NULL);
AnnaBridge 165:d1b4690b3f8b 218 uint32_t p_crc = *crc;
AnnaBridge 165:d1b4690b3f8b 219 if ((width < 8) && (NULL == _crc_table)) {
AnnaBridge 165:d1b4690b3f8b 220 p_crc = (uint32_t)(p_crc << (8 - width));
AnnaBridge 165:d1b4690b3f8b 221 }
AnnaBridge 165:d1b4690b3f8b 222 *crc = (reflect_remainder(p_crc) ^ _final_xor) & get_crc_mask();
AnnaBridge 165:d1b4690b3f8b 223 return 0;
AnnaBridge 165:d1b4690b3f8b 224 }
AnnaBridge 165:d1b4690b3f8b 225
AnnaBridge 165:d1b4690b3f8b 226 /** Get the current CRC polynomial
AnnaBridge 165:d1b4690b3f8b 227 *
AnnaBridge 165:d1b4690b3f8b 228 * @return Polynomial value
AnnaBridge 165:d1b4690b3f8b 229 */
AnnaBridge 165:d1b4690b3f8b 230 uint32_t get_polynomial(void) const
AnnaBridge 165:d1b4690b3f8b 231 {
AnnaBridge 165:d1b4690b3f8b 232 return polynomial;
AnnaBridge 165:d1b4690b3f8b 233 }
AnnaBridge 165:d1b4690b3f8b 234
AnnaBridge 165:d1b4690b3f8b 235 /** Get the current CRC width
AnnaBridge 165:d1b4690b3f8b 236 *
AnnaBridge 165:d1b4690b3f8b 237 * @return CRC width
AnnaBridge 165:d1b4690b3f8b 238 */
AnnaBridge 165:d1b4690b3f8b 239 uint8_t get_width(void) const
AnnaBridge 165:d1b4690b3f8b 240 {
AnnaBridge 165:d1b4690b3f8b 241 return width;
AnnaBridge 165:d1b4690b3f8b 242 }
AnnaBridge 165:d1b4690b3f8b 243
AnnaBridge 165:d1b4690b3f8b 244 private:
AnnaBridge 165:d1b4690b3f8b 245 uint32_t _initial_value;
AnnaBridge 165:d1b4690b3f8b 246 uint32_t _final_xor;
AnnaBridge 165:d1b4690b3f8b 247 bool _reflect_data;
AnnaBridge 165:d1b4690b3f8b 248 bool _reflect_remainder;
AnnaBridge 165:d1b4690b3f8b 249 uint32_t *_crc_table;
AnnaBridge 165:d1b4690b3f8b 250
AnnaBridge 165:d1b4690b3f8b 251 /** Get the current CRC data size
AnnaBridge 165:d1b4690b3f8b 252 *
AnnaBridge 165:d1b4690b3f8b 253 * @return CRC data size in bytes
AnnaBridge 165:d1b4690b3f8b 254 */
AnnaBridge 165:d1b4690b3f8b 255 uint8_t get_data_size(void) const
AnnaBridge 165:d1b4690b3f8b 256 {
AnnaBridge 165:d1b4690b3f8b 257 return (width <= 8 ? 1 : (width <= 16 ? 2 : 4));
AnnaBridge 165:d1b4690b3f8b 258 }
AnnaBridge 165:d1b4690b3f8b 259
AnnaBridge 165:d1b4690b3f8b 260 /** Get the top bit of current CRC
AnnaBridge 165:d1b4690b3f8b 261 *
AnnaBridge 165:d1b4690b3f8b 262 * @return Top bit is set high for respective data width of current CRC
AnnaBridge 165:d1b4690b3f8b 263 * Top bit for CRC width less then 8 bits will be set as 8th bit.
AnnaBridge 165:d1b4690b3f8b 264 */
AnnaBridge 165:d1b4690b3f8b 265 uint32_t get_top_bit(void) const
AnnaBridge 165:d1b4690b3f8b 266 {
AnnaBridge 165:d1b4690b3f8b 267 return (width < 8 ? (1u << 7) : (uint32_t)(1ul << (width - 1)));
AnnaBridge 165:d1b4690b3f8b 268 }
AnnaBridge 165:d1b4690b3f8b 269
AnnaBridge 165:d1b4690b3f8b 270 /** Get the CRC data mask
AnnaBridge 165:d1b4690b3f8b 271 *
AnnaBridge 165:d1b4690b3f8b 272 * @return CRC data mask is generated based on current CRC width
AnnaBridge 165:d1b4690b3f8b 273 */
AnnaBridge 165:d1b4690b3f8b 274 uint32_t get_crc_mask(void) const
AnnaBridge 165:d1b4690b3f8b 275 {
AnnaBridge 165:d1b4690b3f8b 276 return (width < 8 ? ((1u << 8) - 1) : (uint32_t)((uint64_t)(1ull << width) - 1));
AnnaBridge 165:d1b4690b3f8b 277 }
AnnaBridge 165:d1b4690b3f8b 278
AnnaBridge 165:d1b4690b3f8b 279 /** Final value of CRC is reflected
AnnaBridge 165:d1b4690b3f8b 280 *
AnnaBridge 165:d1b4690b3f8b 281 * @param data final crc value, which should be reflected
AnnaBridge 165:d1b4690b3f8b 282 * @return Reflected CRC value
AnnaBridge 165:d1b4690b3f8b 283 */
AnnaBridge 165:d1b4690b3f8b 284 uint32_t reflect_remainder(uint32_t data) const
AnnaBridge 165:d1b4690b3f8b 285 {
AnnaBridge 165:d1b4690b3f8b 286 if (_reflect_remainder) {
AnnaBridge 165:d1b4690b3f8b 287 uint32_t reflection = 0x0;
AnnaBridge 165:d1b4690b3f8b 288 uint8_t const nBits = (width < 8 ? 8 : width);
AnnaBridge 165:d1b4690b3f8b 289
AnnaBridge 165:d1b4690b3f8b 290 for (uint8_t bit = 0; bit < nBits; ++bit) {
AnnaBridge 165:d1b4690b3f8b 291 if (data & 0x01) {
AnnaBridge 165:d1b4690b3f8b 292 reflection |= (1 << ((nBits - 1) - bit));
AnnaBridge 165:d1b4690b3f8b 293 }
AnnaBridge 165:d1b4690b3f8b 294 data = (data >> 1);
AnnaBridge 165:d1b4690b3f8b 295 }
AnnaBridge 165:d1b4690b3f8b 296 return (reflection);
AnnaBridge 165:d1b4690b3f8b 297 } else {
AnnaBridge 165:d1b4690b3f8b 298 return data;
AnnaBridge 165:d1b4690b3f8b 299 }
AnnaBridge 165:d1b4690b3f8b 300 }
AnnaBridge 165:d1b4690b3f8b 301
AnnaBridge 165:d1b4690b3f8b 302 /** Data bytes are reflected
AnnaBridge 165:d1b4690b3f8b 303 *
AnnaBridge 165:d1b4690b3f8b 304 * @param data value to be reflected
AnnaBridge 165:d1b4690b3f8b 305 * @return Reflected data value
AnnaBridge 165:d1b4690b3f8b 306 */
AnnaBridge 165:d1b4690b3f8b 307 uint32_t reflect_bytes(uint32_t data) const
AnnaBridge 165:d1b4690b3f8b 308 {
AnnaBridge 165:d1b4690b3f8b 309 if(_reflect_data) {
AnnaBridge 165:d1b4690b3f8b 310 uint32_t reflection = 0x0;
AnnaBridge 165:d1b4690b3f8b 311
AnnaBridge 165:d1b4690b3f8b 312 for (uint8_t bit = 0; bit < 8; ++bit) {
AnnaBridge 165:d1b4690b3f8b 313 if (data & 0x01) {
AnnaBridge 165:d1b4690b3f8b 314 reflection |= (1 << (7 - bit));
AnnaBridge 165:d1b4690b3f8b 315 }
AnnaBridge 165:d1b4690b3f8b 316 data = (data >> 1);
AnnaBridge 165:d1b4690b3f8b 317 }
AnnaBridge 165:d1b4690b3f8b 318 return (reflection);
AnnaBridge 165:d1b4690b3f8b 319 } else {
AnnaBridge 165:d1b4690b3f8b 320 return data;
AnnaBridge 165:d1b4690b3f8b 321 }
AnnaBridge 165:d1b4690b3f8b 322 }
AnnaBridge 165:d1b4690b3f8b 323
AnnaBridge 165:d1b4690b3f8b 324 /** Bitwise CRC computation
AnnaBridge 165:d1b4690b3f8b 325 *
AnnaBridge 165:d1b4690b3f8b 326 * @param buffer data buffer
AnnaBridge 165:d1b4690b3f8b 327 * @param size size of the data
AnnaBridge 165:d1b4690b3f8b 328 * @param crc CRC value is filled in, but the value is not the final
AnnaBridge 165:d1b4690b3f8b 329 * @return 0 on success or a negative error code on failure
AnnaBridge 165:d1b4690b3f8b 330 */
AnnaBridge 165:d1b4690b3f8b 331 int32_t bitwise_compute_partial(const void *buffer, crc_data_size_t size, uint32_t *crc) const
AnnaBridge 165:d1b4690b3f8b 332 {
AnnaBridge 165:d1b4690b3f8b 333 MBED_ASSERT(crc != NULL);
AnnaBridge 165:d1b4690b3f8b 334 MBED_ASSERT(buffer != NULL);
AnnaBridge 165:d1b4690b3f8b 335
AnnaBridge 165:d1b4690b3f8b 336 const uint8_t *data = static_cast<const uint8_t *>(buffer);
AnnaBridge 165:d1b4690b3f8b 337 uint32_t p_crc = *crc;
AnnaBridge 165:d1b4690b3f8b 338
AnnaBridge 165:d1b4690b3f8b 339 if (width < 8) {
AnnaBridge 165:d1b4690b3f8b 340 uint8_t data_byte;
AnnaBridge 165:d1b4690b3f8b 341 for (crc_data_size_t byte = 0; byte < size; byte++) {
AnnaBridge 165:d1b4690b3f8b 342 data_byte = reflect_bytes(data[byte]);
AnnaBridge 165:d1b4690b3f8b 343 for (uint8_t bit = 8; bit > 0; --bit) {
AnnaBridge 165:d1b4690b3f8b 344 p_crc <<= 1;
AnnaBridge 165:d1b4690b3f8b 345 if (( data_byte ^ p_crc) & get_top_bit()) {
AnnaBridge 165:d1b4690b3f8b 346 p_crc ^= polynomial;
AnnaBridge 165:d1b4690b3f8b 347 }
AnnaBridge 165:d1b4690b3f8b 348 data_byte <<= 1;
AnnaBridge 165:d1b4690b3f8b 349 }
AnnaBridge 165:d1b4690b3f8b 350 }
AnnaBridge 165:d1b4690b3f8b 351 } else {
AnnaBridge 165:d1b4690b3f8b 352 for (crc_data_size_t byte = 0; byte < size; byte++) {
AnnaBridge 165:d1b4690b3f8b 353 p_crc ^= (reflect_bytes(data[byte]) << (width - 8));
AnnaBridge 165:d1b4690b3f8b 354
AnnaBridge 165:d1b4690b3f8b 355 // Perform modulo-2 division, a bit at a time
AnnaBridge 165:d1b4690b3f8b 356 for (uint8_t bit = 8; bit > 0; --bit) {
AnnaBridge 165:d1b4690b3f8b 357 if (p_crc & get_top_bit()) {
AnnaBridge 165:d1b4690b3f8b 358 p_crc = (p_crc << 1) ^ polynomial;
AnnaBridge 165:d1b4690b3f8b 359 } else {
AnnaBridge 165:d1b4690b3f8b 360 p_crc = (p_crc << 1);
AnnaBridge 165:d1b4690b3f8b 361 }
AnnaBridge 165:d1b4690b3f8b 362 }
AnnaBridge 165:d1b4690b3f8b 363 }
AnnaBridge 165:d1b4690b3f8b 364 }
AnnaBridge 165:d1b4690b3f8b 365 *crc = p_crc & get_crc_mask();
AnnaBridge 165:d1b4690b3f8b 366 return 0;
AnnaBridge 165:d1b4690b3f8b 367 }
AnnaBridge 165:d1b4690b3f8b 368
AnnaBridge 165:d1b4690b3f8b 369 /** CRC computation using ROM tables
AnnaBridge 165:d1b4690b3f8b 370 *
AnnaBridge 165:d1b4690b3f8b 371 * @param buffer data buffer
AnnaBridge 165:d1b4690b3f8b 372 * @param size size of the data
AnnaBridge 165:d1b4690b3f8b 373 * @param crc CRC value is filled in, but the value is not the final
AnnaBridge 165:d1b4690b3f8b 374 * @return 0 on success or a negative error code on failure
AnnaBridge 165:d1b4690b3f8b 375 */
AnnaBridge 165:d1b4690b3f8b 376 int32_t table_compute_partial(const void *buffer, crc_data_size_t size, uint32_t *crc) const
AnnaBridge 165:d1b4690b3f8b 377 {
AnnaBridge 165:d1b4690b3f8b 378 MBED_ASSERT(crc != NULL);
AnnaBridge 165:d1b4690b3f8b 379 MBED_ASSERT(buffer != NULL);
AnnaBridge 165:d1b4690b3f8b 380
AnnaBridge 165:d1b4690b3f8b 381 const uint8_t *data = static_cast<const uint8_t *>(buffer);
AnnaBridge 165:d1b4690b3f8b 382 uint32_t p_crc = *crc;
AnnaBridge 165:d1b4690b3f8b 383 uint8_t data_byte = 0;
AnnaBridge 165:d1b4690b3f8b 384
AnnaBridge 165:d1b4690b3f8b 385 if (width <= 8) {
AnnaBridge 165:d1b4690b3f8b 386 uint8_t *crc_table = (uint8_t *)_crc_table;
AnnaBridge 165:d1b4690b3f8b 387 for (crc_data_size_t byte = 0; byte < size; byte++) {
AnnaBridge 165:d1b4690b3f8b 388 data_byte = reflect_bytes(data[byte]) ^ p_crc;
AnnaBridge 165:d1b4690b3f8b 389 p_crc = crc_table[data_byte];
AnnaBridge 165:d1b4690b3f8b 390 }
AnnaBridge 165:d1b4690b3f8b 391 } else if (width <= 16) {
AnnaBridge 165:d1b4690b3f8b 392 uint16_t *crc_table = (uint16_t *)_crc_table;
AnnaBridge 165:d1b4690b3f8b 393 for (crc_data_size_t byte = 0; byte < size; byte++) {
AnnaBridge 165:d1b4690b3f8b 394 data_byte = reflect_bytes(data[byte]) ^ (p_crc >> (width - 8));
AnnaBridge 165:d1b4690b3f8b 395 p_crc = crc_table[data_byte] ^ (p_crc << 8);
AnnaBridge 165:d1b4690b3f8b 396 }
AnnaBridge 165:d1b4690b3f8b 397 } else {
AnnaBridge 165:d1b4690b3f8b 398 uint32_t *crc_table = (uint32_t *)_crc_table;
AnnaBridge 165:d1b4690b3f8b 399 for (crc_data_size_t byte = 0; byte < size; byte++) {
AnnaBridge 165:d1b4690b3f8b 400 data_byte = reflect_bytes(data[byte]) ^ (p_crc >> (width - 8));
AnnaBridge 165:d1b4690b3f8b 401 p_crc = crc_table[data_byte] ^ (p_crc << 8);
AnnaBridge 165:d1b4690b3f8b 402 }
AnnaBridge 165:d1b4690b3f8b 403 }
AnnaBridge 165:d1b4690b3f8b 404 *crc = p_crc & get_crc_mask();
AnnaBridge 165:d1b4690b3f8b 405 return 0;
AnnaBridge 165:d1b4690b3f8b 406 }
AnnaBridge 165:d1b4690b3f8b 407
AnnaBridge 165:d1b4690b3f8b 408 /** Constructor init called from all specialized cases of constructor
AnnaBridge 165:d1b4690b3f8b 409 * Note: All construtor common code should be in this function.
AnnaBridge 165:d1b4690b3f8b 410 */
AnnaBridge 165:d1b4690b3f8b 411 void mbed_crc_ctor(void) const
AnnaBridge 165:d1b4690b3f8b 412 {
AnnaBridge 165:d1b4690b3f8b 413 MBED_STATIC_ASSERT(width <= 32, "Max 32-bit CRC supported");
AnnaBridge 165:d1b4690b3f8b 414 }
AnnaBridge 165:d1b4690b3f8b 415 };
AnnaBridge 165:d1b4690b3f8b 416
AnnaBridge 165:d1b4690b3f8b 417 #if defined ( __CC_ARM )
AnnaBridge 165:d1b4690b3f8b 418 #elif defined ( __GNUC__ )
AnnaBridge 165:d1b4690b3f8b 419 #pragma GCC diagnostic pop
AnnaBridge 165:d1b4690b3f8b 420 #endif
AnnaBridge 165:d1b4690b3f8b 421
AnnaBridge 165:d1b4690b3f8b 422 /** @}*/
AnnaBridge 165:d1b4690b3f8b 423 } // namespace mbed
AnnaBridge 165:d1b4690b3f8b 424
AnnaBridge 165:d1b4690b3f8b 425 #endif