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drivers/MbedCRC.h
- Committer:
- kevman
- Date:
- 2018-11-28
- Revision:
- 0:38ceb79fef03
File content as of revision 0:38ceb79fef03:
/* mbed Microcontroller Library * Copyright (c) 2018 ARM Limited * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ #ifndef MBED_CRC_API_H #define MBED_CRC_API_H #include "drivers/TableCRC.h" #include "hal/crc_api.h" #include "platform/mbed_assert.h" #include "platform/SingletonPtr.h" #include "platform/PlatformMutex.h" /* This is invalid warning from the compiler for below section of code if ((width < 8) && (NULL == _crc_table)) { p_crc = (uint32_t)(p_crc << (8 - width)); } Compiler warns of the shift operation with width as it is width=(std::uint8_t), but we check for ( width < 8) before performing shift, so it should not be an issue. */ #if defined ( __CC_ARM ) #pragma diag_suppress 62 // Shift count is negative #elif defined ( __GNUC__ ) #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wshift-count-negative" #elif defined (__ICCARM__) #pragma diag_suppress=Pe062 // Shift count is negative #endif namespace mbed { /** \addtogroup drivers */ /** @{*/ /** CRC object provides CRC generation through hardware/software * * ROM polynomial tables for supported polynomials (:: crc_polynomial_t) will be used for * software CRC computation, if ROM tables are not available then CRC is computed runtime * bit by bit for all data input. * @note Synchronization level: Thread safe * * @tparam polynomial CRC polynomial value in hex * @tparam width CRC polynomial width * * Example: Compute CRC data * @code * * #include "mbed.h" * * int main() { * MbedCRC<POLY_32BIT_ANSI, 32> ct; * * char test[] = "123456789"; * uint32_t crc = 0; * * printf("\nPolynomial = 0x%lx Width = %d \n", ct.get_polynomial(), ct.get_width()); * * ct.compute((void *)test, strlen((const char*)test), &crc); * * printf("The CRC of data \"123456789\" is : 0x%lx\n", crc); * return 0; * } * @endcode * Example: Compute CRC with data available in parts * @code * * #include "mbed.h" * int main() { * MbedCRC<POLY_32BIT_ANSI, 32> ct; * * char test[] = "123456789"; * uint32_t crc = 0; * * printf("\nPolynomial = 0x%lx Width = %d \n", ct.get_polynomial(), ct.get_width()); * ct.compute_partial_start(&crc); * ct.compute_partial((void *)&test, 4, &crc); * ct.compute_partial((void *)&test[4], 5, &crc); * ct.compute_partial_stop(&crc); * printf("The CRC of data \"123456789\" is : 0x%lx\n", crc); * return 0; * } * @endcode * @ingroup drivers */ extern SingletonPtr<PlatformMutex> mbed_crc_mutex; template <uint32_t polynomial = POLY_32BIT_ANSI, uint8_t width = 32> class MbedCRC { public: enum CrcMode { #ifdef DEVICE_CRC HARDWARE = 0, #endif TABLE = 1, BITWISE }; typedef uint64_t crc_data_size_t; /** Lifetime of CRC object * * @param initial_xor Inital value/seed to Xor * @param final_xor Final Xor value * @param reflect_data * @param reflect_remainder * @note Default constructor without any arguments is valid only for supported CRC polynomials. :: crc_polynomial_t * MbedCRC <POLY_7BIT_SD, 7> ct; --- Valid POLY_7BIT_SD * MbedCRC <0x1021, 16> ct; --- Valid POLY_16BIT_CCITT * MbedCRC <POLY_16BIT_CCITT, 32> ct; --- Invalid, compilation error * MbedCRC <POLY_16BIT_CCITT, 32> ct (i,f,rd,rr) Constructor can be used for not supported polynomials * MbedCRC<POLY_16BIT_CCITT, 16> sd(0, 0, false, false); Constructor can also be used for supported * polynomials with different intial/final/reflect values * */ MbedCRC(uint32_t initial_xor, uint32_t final_xor, bool reflect_data, bool reflect_remainder) : _initial_value(initial_xor), _final_xor(final_xor), _reflect_data(reflect_data), _reflect_remainder(reflect_remainder) { mbed_crc_ctor(); } MbedCRC(); virtual ~MbedCRC() { // Do nothing } /** Compute CRC for the data input * Compute CRC performs the initialization, computation and collection of * final CRC. * * @param buffer Data bytes * @param size Size of data * @param crc CRC is the output value * @return 0 on success, negative error code on failure */ int32_t compute(void *buffer, crc_data_size_t size, uint32_t *crc) { MBED_ASSERT(crc != NULL); int32_t status = 0; status = compute_partial_start(crc); if (0 != status) { unlock(); return status; } status = compute_partial(buffer, size, crc); if (0 != status) { unlock(); return status; } status = compute_partial_stop(crc); if (0 != status) { *crc = 0; } return status; } /** Compute partial CRC for the data input. * * CRC data if not available fully, CRC can be computed in parts with available data. * * In case of hardware, intermediate values and states are saved by hardware. Mutex * locking is used to serialize access to hardware CRC. * * In case of software CRC, previous CRC output should be passed as argument to the * current compute_partial call. Please note the intermediate CRC value is maintained by * application and not the driver. * * @pre: Call `compute_partial_start` to start the partial CRC calculation. * @post: Call `compute_partial_stop` to get the final CRC value. * * @param buffer Data bytes * @param size Size of data * @param crc CRC value is intermediate CRC value filled by API. * @return 0 on success or a negative error code on failure * @note: CRC as output in compute_partial is not final CRC value, call `compute_partial_stop` * to get final correct CRC value. */ int32_t compute_partial(void *buffer, crc_data_size_t size, uint32_t *crc) { int32_t status = 0; switch (_mode) { #ifdef DEVICE_CRC case HARDWARE: hal_crc_compute_partial((uint8_t *)buffer, size); *crc = 0; break; #endif case TABLE: status = table_compute_partial(buffer, size, crc); break; case BITWISE: status = bitwise_compute_partial(buffer, size, crc); break; default: status = -1; break; } return status; } /** Compute partial start, indicate start of partial computation. * * This API should be called before performing any partial computation * with compute_partial API. * * @param crc Initial CRC value set by the API * @return 0 on success or a negative in case of failure * @note: CRC is an out parameter and must be reused with compute_partial * and `compute_partial_stop` without any modifications in application. */ int32_t compute_partial_start(uint32_t *crc) { MBED_ASSERT(crc != NULL); #ifdef DEVICE_CRC if (_mode == HARDWARE) { lock(); crc_mbed_config_t config; config.polynomial = polynomial; config.width = width; config.initial_xor = _initial_value; config.final_xor = _final_xor; config.reflect_in = _reflect_data; config.reflect_out = _reflect_remainder; hal_crc_compute_partial_start(&config); } #endif *crc = _initial_value; return 0; } /** Get the final CRC value of partial computation. * * CRC value available in partial computation is not correct CRC, as some * algorithms require remainder to be reflected and final value to be XORed * This API is used to perform final computation to get correct CRC value. * * @param crc CRC result * @return 0 on success or a negative in case of failure. */ int32_t compute_partial_stop(uint32_t *crc) { MBED_ASSERT(crc != NULL); #ifdef DEVICE_CRC if (_mode == HARDWARE) { *crc = hal_crc_get_result(); unlock(); return 0; } #endif uint32_t p_crc = *crc; if ((width < 8) && (NULL == _crc_table)) { p_crc = (uint32_t)(p_crc << (8 - width)); } // Optimized algorithm for 32BitANSI does not need additional reflect_remainder if ((TABLE == _mode) && (POLY_32BIT_REV_ANSI == polynomial)) { *crc = (p_crc ^ _final_xor) & get_crc_mask(); } else { *crc = (reflect_remainder(p_crc) ^ _final_xor) & get_crc_mask(); } unlock(); return 0; } /** Get the current CRC polynomial. * * @return Polynomial value */ uint32_t get_polynomial(void) const { return polynomial; } /** Get the current CRC width * * @return CRC width */ uint8_t get_width(void) const { return width; } private: uint32_t _initial_value; uint32_t _final_xor; bool _reflect_data; bool _reflect_remainder; uint32_t *_crc_table; CrcMode _mode; /** Acquire exclusive access to CRC hardware/software. */ void lock() { #ifdef DEVICE_CRC if (_mode == HARDWARE) { mbed_crc_mutex->lock(); } #endif } /** Release exclusive access to CRC hardware/software. */ virtual void unlock() { #ifdef DEVICE_CRC if (_mode == HARDWARE) { mbed_crc_mutex->unlock(); } #endif } /** Get the current CRC data size. * * @return CRC data size in bytes */ uint8_t get_data_size(void) const { return (width <= 8 ? 1 : (width <= 16 ? 2 : 4)); } /** Get the top bit of current CRC. * * @return Top bit is set high for respective data width of current CRC * Top bit for CRC width less then 8 bits will be set as 8th bit. */ uint32_t get_top_bit(void) const { return (width < 8 ? (1u << 7) : (uint32_t)(1ul << (width - 1))); } /** Get the CRC data mask. * * @return CRC data mask is generated based on current CRC width */ uint32_t get_crc_mask(void) const { return (width < 8 ? ((1u << 8) - 1) : (uint32_t)((uint64_t)(1ull << width) - 1)); } /** Final value of CRC is reflected. * * @param data final crc value, which should be reflected * @return Reflected CRC value */ uint32_t reflect_remainder(uint32_t data) const { if (_reflect_remainder) { uint32_t reflection = 0x0; uint8_t const nBits = (width < 8 ? 8 : width); for (uint8_t bit = 0; bit < nBits; ++bit) { if (data & 0x01) { reflection |= (1 << ((nBits - 1) - bit)); } data = (data >> 1); } return (reflection); } else { return data; } } /** Data bytes are reflected. * * @param data value to be reflected * @return Reflected data value */ uint32_t reflect_bytes(uint32_t data) const { if (_reflect_data) { uint32_t reflection = 0x0; for (uint8_t bit = 0; bit < 8; ++bit) { if (data & 0x01) { reflection |= (1 << (7 - bit)); } data = (data >> 1); } return (reflection); } else { return data; } } /** Bitwise CRC computation. * * @param buffer data buffer * @param size size of the data * @param crc CRC value is filled in, but the value is not the final * @return 0 on success or a negative error code on failure */ int32_t bitwise_compute_partial(const void *buffer, crc_data_size_t size, uint32_t *crc) const { MBED_ASSERT(crc != NULL); const uint8_t *data = static_cast<const uint8_t *>(buffer); uint32_t p_crc = *crc; if (width < 8) { uint8_t data_byte; for (crc_data_size_t byte = 0; byte < size; byte++) { data_byte = reflect_bytes(data[byte]); for (uint8_t bit = 8; bit > 0; --bit) { p_crc <<= 1; if ((data_byte ^ p_crc) & get_top_bit()) { p_crc ^= polynomial; } data_byte <<= 1; } } } else { for (crc_data_size_t byte = 0; byte < size; byte++) { p_crc ^= (reflect_bytes(data[byte]) << (width - 8)); // Perform modulo-2 division, a bit at a time for (uint8_t bit = 8; bit > 0; --bit) { if (p_crc & get_top_bit()) { p_crc = (p_crc << 1) ^ polynomial; } else { p_crc = (p_crc << 1); } } } } *crc = p_crc & get_crc_mask(); return 0; } /** CRC computation using ROM tables. * * @param buffer data buffer * @param size size of the data * @param crc CRC value is filled in, but the value is not the final * @return 0 on success or a negative error code on failure */ int32_t table_compute_partial(const void *buffer, crc_data_size_t size, uint32_t *crc) const { MBED_ASSERT(crc != NULL); const uint8_t *data = static_cast<const uint8_t *>(buffer); uint32_t p_crc = *crc; uint8_t data_byte = 0; if (width <= 8) { uint8_t *crc_table = (uint8_t *)_crc_table; for (crc_data_size_t byte = 0; byte < size; byte++) { data_byte = reflect_bytes(data[byte]) ^ p_crc; p_crc = crc_table[data_byte]; } } else if (width <= 16) { uint16_t *crc_table = (uint16_t *)_crc_table; for (crc_data_size_t byte = 0; byte < size; byte++) { data_byte = reflect_bytes(data[byte]) ^ (p_crc >> (width - 8)); p_crc = crc_table[data_byte] ^ (p_crc << 8); } } else { uint32_t *crc_table = (uint32_t *)_crc_table; if (POLY_32BIT_REV_ANSI == polynomial) { for (crc_data_size_t i = 0; i < size; i++) { p_crc = (p_crc >> 4) ^ crc_table[(p_crc ^ (data[i] >> 0)) & 0xf]; p_crc = (p_crc >> 4) ^ crc_table[(p_crc ^ (data[i] >> 4)) & 0xf]; } } else { for (crc_data_size_t byte = 0; byte < size; byte++) { data_byte = reflect_bytes(data[byte]) ^ (p_crc >> (width - 8)); p_crc = crc_table[data_byte] ^ (p_crc << 8); } } } *crc = p_crc & get_crc_mask(); return 0; } /** Constructor init called from all specialized cases of constructor. * Note: All construtor common code should be in this function. */ void mbed_crc_ctor(void) { MBED_STATIC_ASSERT(width <= 32, "Max 32-bit CRC supported"); #ifdef DEVICE_CRC if (POLY_32BIT_REV_ANSI == polynomial) { _crc_table = (uint32_t *)Table_CRC_32bit_Rev_ANSI; _mode = TABLE; return; } crc_mbed_config_t config; config.polynomial = polynomial; config.width = width; config.initial_xor = _initial_value; config.final_xor = _final_xor; config.reflect_in = _reflect_data; config.reflect_out = _reflect_remainder; if (hal_crc_is_supported(&config)) { _mode = HARDWARE; return; } #endif switch (polynomial) { case POLY_32BIT_ANSI: _crc_table = (uint32_t *)Table_CRC_32bit_ANSI; break; case POLY_32BIT_REV_ANSI: _crc_table = (uint32_t *)Table_CRC_32bit_Rev_ANSI; break; case POLY_8BIT_CCITT: _crc_table = (uint32_t *)Table_CRC_8bit_CCITT; break; case POLY_7BIT_SD: _crc_table = (uint32_t *)Table_CRC_7Bit_SD; break; case POLY_16BIT_CCITT: _crc_table = (uint32_t *)Table_CRC_16bit_CCITT; break; case POLY_16BIT_IBM: _crc_table = (uint32_t *)Table_CRC_16bit_IBM; break; default: _crc_table = NULL; break; } _mode = (_crc_table != NULL) ? TABLE : BITWISE; } }; #if defined ( __CC_ARM ) #elif defined ( __GNUC__ ) #pragma GCC diagnostic pop #elif defined (__ICCARM__) #endif /** @}*/ } // namespace mbed #endif