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1. Change in location (drivers) 2. Non-templated class (soft/fast) 3. Change to enum/defines 4. data/width/top_bit macros are now protected functions And fewer other comments
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Deepika
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Dec 21, 2017
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,184 @@ | ||
| /* mbed Microcontroller Library | ||
| * Copyright (c) 2017 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. | ||
| */ | ||
|
|
||
| #include "platform/mbed_assert.h" | ||
| #include "FastCRC.h" | ||
| #include <stdio.h> | ||
|
|
||
| namespace mbed { | ||
|
|
||
| FastCRC::FastCRC(crc_polynomial_type_t polynomial) : | ||
| _polynomial_type(polynomial), _inital_value(0x0), | ||
| _final_xor(0x0), _reflect_data(false), _reflect_remainder(false) | ||
| { | ||
| // Set the non-default polynomial specific parameters | ||
| if (CRC_16BIT_CCITT == _polynomial_type) { | ||
| _inital_value = ~(0x0); | ||
| } else if (CRC_16BIT_IBM == _polynomial_type) { | ||
| _reflect_data = true; | ||
| _reflect_remainder = true; | ||
| } else if (CRC_32BIT == _polynomial_type) { | ||
| _inital_value = ~(0x0); | ||
| _final_xor = ~(0x0); | ||
| _reflect_data = true; | ||
| _reflect_remainder = true; | ||
| } | ||
| } | ||
|
|
||
| FastCRC::~FastCRC() { | ||
| deinit(); | ||
| } | ||
|
|
||
| int32_t FastCRC::init(void) | ||
| { | ||
| uint32_t crc; | ||
| uint8_t data_size = get_data_size(); | ||
| crc_width_t width = get_width(); | ||
| uint32_t polynomial = get_polynomial(); | ||
|
|
||
| _crc_table = new uint32_t[64*data_size]; | ||
| uint8_t *crc_table = (uint8_t *)_crc_table; | ||
|
|
||
| if (width < 8) { | ||
| polynomial <<= (8 - width); | ||
| } | ||
|
|
||
| for (int32_t dividend = 0; dividend < 256; ++dividend) { | ||
| if (width < 8) { | ||
| crc = dividend; | ||
| } else { | ||
| crc = dividend << (width - 8); | ||
| } | ||
| for (uint8_t bit = 8; bit > 0; --bit) { | ||
| if (crc & get_top_bit()) { | ||
| crc = (crc << 1) ^ polynomial; | ||
| } else { | ||
| crc = (crc << 1); | ||
| } | ||
| } | ||
|
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||
| for (int i = 0; i < data_size; i++) { | ||
| crc_table[(dividend*data_size)+i] = (crc >> (8*i)) & 0xFF; | ||
| } | ||
| } | ||
| return 0; | ||
| } | ||
|
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||
| int32_t FastCRC::deinit(void) | ||
| { | ||
| delete []_crc_table; | ||
| return 0; | ||
| } | ||
|
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||
| crc_polynomial_type_t FastCRC::get_polynomial_type(void) const | ||
| { | ||
| return _polynomial_type; | ||
| } | ||
|
|
||
| int32_t FastCRC::compute_partial(void *buffer, crc_data_size_t size, uint32_t *crc) | ||
| { | ||
| MBED_ASSERT(crc != NULL); | ||
| MBED_ASSERT(buffer != NULL); | ||
|
|
||
| uint8_t *data = static_cast<uint8_t *>(buffer); | ||
| crc_width_t width = this->get_width(); | ||
| uint32_t p_crc = *crc; | ||
| uint8_t data_byte; | ||
|
|
||
| if (width < 8) { | ||
| uint8_t *crc_table = (uint8_t *)_crc_table; | ||
| for (crc_data_size_t byte = 0; byte < size; byte++) { | ||
| p_crc = crc_table[(data[byte] ^ p_crc)]; | ||
| } | ||
| } 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 { | ||
| 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); | ||
| } | ||
| } | ||
| if (width < 8) { | ||
| p_crc >>= (8 - width); | ||
| } | ||
| *crc = p_crc & get_crc_mask(); | ||
| return 0; | ||
| } | ||
|
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||
| int32_t FastCRC::compute(void *buffer, crc_data_size_t size, uint32_t *crc) | ||
| { | ||
| MBED_ASSERT(crc != NULL); | ||
| int32_t status; | ||
| *crc = _inital_value; | ||
| status = compute_partial(buffer, size, crc); | ||
| *crc = (reflect_remainder(*crc) ^ _final_xor) & get_crc_mask(); | ||
| return status; | ||
| } | ||
|
|
||
| int32_t FastCRC::compute_partial_start(uint32_t *crc) | ||
| { | ||
| MBED_ASSERT(crc != NULL); | ||
| *crc = _inital_value; | ||
| return 0; | ||
| } | ||
|
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||
| int32_t FastCRC::compute_partial_stop(uint32_t *crc) | ||
| { | ||
| MBED_ASSERT(crc != NULL); | ||
| *crc = (reflect_remainder(*crc) ^ _final_xor) & get_crc_mask(); | ||
| return 0; | ||
| } | ||
|
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| uint32_t FastCRC::reflect_remainder(uint32_t data) | ||
| { | ||
| crc_width_t width = get_width(); | ||
| if (_reflect_remainder) { | ||
| uint32_t reflection = 0x0; | ||
| uint8_t const nBits = (width < 8 ? 8 : width); | ||
|
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| for (uint8_t bit = 0; bit < nBits; ++bit) { | ||
| if (data & 0x01) { | ||
| reflection |= (1 << ((nBits - 1) - bit)); | ||
| } | ||
| data = (data >> 1); | ||
| } | ||
| return (reflection); | ||
| } else { | ||
| return data; | ||
| } | ||
| } | ||
|
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| uint32_t FastCRC::reflect_bytes(uint32_t data) | ||
| { | ||
| if(_reflect_data) { | ||
| uint32_t reflection = 0x0; | ||
|
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| for (uint8_t bit = 0; bit < 8; ++bit) { | ||
| if (data & 0x01) { | ||
| reflection |= (1 << (7 - bit)); | ||
| } | ||
| data = (data >> 1); | ||
| } | ||
| return (reflection); | ||
| } else { | ||
| return data; | ||
| } | ||
| } | ||
| } |
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