59 lines
1.4 KiB
C++
59 lines
1.4 KiB
C++
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#include "encoder-emmarine.h"
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#include <furi.h>
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void EncoderEM::init(const uint8_t* data, const uint8_t data_size) {
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furi_check(data_size == 5);
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// header
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card_data = 0b111111111;
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// data
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for(uint8_t i = 0; i < 5; i++) {
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write_nibble(false, data[i]);
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write_nibble(true, data[i]);
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}
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// column parity and stop bit
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uint8_t parity_sum;
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for(uint8_t c = 0; c < 4; c++) {
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parity_sum = 0;
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for(uint8_t i = 1; i <= 10; i++) {
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uint8_t parity_bit = (card_data >> (i * 5 - 1)) & 1;
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parity_sum += parity_bit;
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}
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card_data = (card_data << 1) | ((parity_sum % 2) & 1);
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}
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// stop bit
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card_data = (card_data << 1) | 0;
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card_data_index = 0;
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}
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void EncoderEM::write_nibble(bool low_nibble, uint8_t data) {
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uint8_t parity_sum = 0;
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uint8_t start = 0;
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if(!low_nibble) start = 4;
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for(int8_t i = (start + 3); i >= start; i--) {
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parity_sum += (data >> i) & 1;
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card_data = (card_data << 1) | ((data >> i) & 1);
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}
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card_data = (card_data << 1) | ((parity_sum % 2) & 1);
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}
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// data transmitted as manchester encoding
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// 0 - high2low
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// 1 - low2high
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void EncoderEM::get_next(bool* polarity, uint16_t* period, uint16_t* pulse) {
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*period = clocks_per_bit;
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*pulse = clocks_per_bit / 2;
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*polarity = (card_data >> (63 - card_data_index)) & 1;
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card_data_index++;
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if(card_data_index >= 64) {
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card_data_index = 0;
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}
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}
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