mirror of
https://github.com/DarkFlippers/unleashed-firmware
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d92b0a82cc
"A long time ago in a galaxy far, far away...." we started NFC subsystem refactoring. Starring: - @gornekich - NFC refactoring project lead, architect, senior developer - @gsurkov - architect, senior developer - @RebornedBrain - senior developer Supporting roles: - @skotopes, @DrZlo13, @hedger - general architecture advisors, code review - @Astrrra, @doomwastaken, @Hellitron, @ImagineVagon333 - quality assurance Special thanks: @bettse, @pcunning, @nxv, @noproto, @AloneLiberty and everyone else who has been helping us all this time and contributing valuable knowledges, ideas and source code.
62 lines
1.9 KiB
C
62 lines
1.9 KiB
C
#include "iso13239_crc.h"
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#include <core/check.h>
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#define ISO13239_CRC_INIT_DEFAULT (0xFFFFU)
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#define ISO13239_CRC_INIT_PICOPASS (0xE012U)
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#define ISO13239_CRC_POLY (0x8408U)
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static uint16_t
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iso13239_crc_calculate(Iso13239CrcType type, const uint8_t* data, size_t data_size) {
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uint16_t crc;
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if(type == Iso13239CrcTypeDefault) {
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crc = ISO13239_CRC_INIT_DEFAULT;
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} else if(type == Iso13239CrcTypePicopass) {
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crc = ISO13239_CRC_INIT_PICOPASS;
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} else {
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furi_crash("Wrong ISO13239 CRC type");
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}
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for(size_t i = 0; i < data_size; ++i) {
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crc ^= (uint16_t)data[i];
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for(size_t j = 0; j < 8; ++j) {
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if(crc & 1U) {
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crc = (crc >> 1) ^ ISO13239_CRC_POLY;
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} else {
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crc >>= 1;
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}
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}
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}
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return type == Iso13239CrcTypePicopass ? crc : ~crc;
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}
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void iso13239_crc_append(Iso13239CrcType type, BitBuffer* buf) {
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const uint8_t* data = bit_buffer_get_data(buf);
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const size_t data_size = bit_buffer_get_size_bytes(buf);
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const uint16_t crc = iso13239_crc_calculate(type, data, data_size);
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bit_buffer_append_bytes(buf, (const uint8_t*)&crc, ISO13239_CRC_SIZE);
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}
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bool iso13239_crc_check(Iso13239CrcType type, const BitBuffer* buf) {
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const size_t data_size = bit_buffer_get_size_bytes(buf);
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if(data_size <= ISO13239_CRC_SIZE) return false;
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uint16_t crc_received;
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bit_buffer_write_bytes_mid(
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buf, &crc_received, data_size - ISO13239_CRC_SIZE, ISO13239_CRC_SIZE);
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const uint8_t* data = bit_buffer_get_data(buf);
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const uint16_t crc_calc = iso13239_crc_calculate(type, data, data_size - ISO13239_CRC_SIZE);
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return (crc_calc == crc_received);
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}
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void iso13239_crc_trim(BitBuffer* buf) {
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const size_t data_size = bit_buffer_get_size_bytes(buf);
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furi_assert(data_size > ISO13239_CRC_SIZE);
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bit_buffer_set_size_bytes(buf, data_size - ISO13239_CRC_SIZE);
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}
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