144 lines
2.8 KiB
C
144 lines
2.8 KiB
C
#include "sss7.h"
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#include <avr/interrupt.h>
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#include <util/crc16.h>
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#include <string.h>
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volatile enum sss7State sss7_state;
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uint8_t sss7_rx_buffer[2][SSS7_PAYLOAD_SIZE];
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uint8_t sss7_rx_active_buffer;
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uint8_t sss7_rx_pos;
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uint8_t sss7_tx_buffer[SSS7_PAYLOAD_SIZE];
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uint8_t sss7_tx_pos;
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uint8_t sss7_tx_crc;
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uint8_t sss7_tx_failed;
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uint8_t sss7_tx_last_byte = 0;
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void sss7_init() {
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sss7_state = SSS7_IDLE;
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sss7_rx_pos = 0;
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sss7_rx_oldest_buffer = 0;
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sss7_rx_active_buffer = 0;
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sss7_tx_pos = 0;
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sss7_tx_crc = 0;
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sss7_tx_failed = 0;
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}
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inline uint8_t sss7_payload_crc(uint8_t buffer[SSS7_PAYLOAD_SIZE]) {
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uint8_t crc = 0;
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for(uint8_t i = 0; i < SSS7_PAYLOAD_SIZE; i++) {
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crc = _crc_ibutton_update(crc, buffer[i]);
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}
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return crc;
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}
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void sss7_send(uint8_t msg[SSS7_PAYLOAD_SIZE]) {
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// Check that we can send, because we will overwritte the buffer
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if(sss7_state != SSS7_IDLE) {
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sss7_tx_failed = 1;
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return;
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}
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memcpy(sss7_tx_buffer, msg, SSS7_PAYLOAD_SIZE);
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sss7_tx_pos = 0;
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sss7_tx_crc = sss7_payload_crc(sss7_tx_buffer);
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// Commit to send state
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sss7_state = SSS7_TX_HEADER;
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uart_sent_byte(SSS7_HEADER[0]);
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}
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void sss7_receive_byte() {
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uint8_t byte = uart_get_byte();
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uint8_t crc = 0;
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switch(sss7_state) {
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case SSS7_IDLE:
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if(byte == SSS7_HEADER[0]) {
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sss7_state = SSS7_RX_HEADER;
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}
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else {
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sss7_state = SSS7_IDLE;
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}
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break;
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case SSS7_RX_HEADER:
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if(byte == SSS7_HEADER[1]) {
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sss7_state = SSS7_RX_PAYLOAD;
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sss7_rx_pos = 0;
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}
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else {
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sss7_state = SSS7_IDLE;
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}
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break;
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case SSS7_RX_PAYLOAD:
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sss7_rx_buffer[sss7_rx_active_buffer][sss7_rx_pos] = byte;
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sss7_rx_pos++;
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if(sss7_rx_pos >= SSS7_PAYLOAD_SIZE) {
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sss7_state = SSS7_RX_CRC;
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}
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break;
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case SSS7_RX_CRC:
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crc = sss7_payload_crc(sss7_rx_buffer[sss7_rx_active_buffer]);
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if(byte == crc) {
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sss7_rx_active_buffer = (sss7_rx_active_buffer + 1);
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}
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sss7_state = SSS7_IDLE;
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break;
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// all the TX states
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default:
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if(byte != sss7_tx_last_byte) {
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sss7_state = SSS7_IDLE;
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sss7_tx_failed = 1;
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}
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break;
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}
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}
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void sss7_transmit_byte() {
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uint8_t byte;
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switch(sss7_state) {
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case SSS7_TX_HEADER:
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uart_sent_byte(SSS7_HEADER[1]);
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sss7_state = SSS7_TX_PAYLOAD;
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sss7_tx_pos = 0;
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break;
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case SSS7_TX_PAYLOAD:
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byte = sss7_tx_buffer[sss7_tx_pos];
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uart_sent_byte(byte);
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sss7_tx_last_byte = byte;
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sss7_tx_pos++;
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if(sss7_tx_pos >= SSS7_PAYLOAD_SIZE) {
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sss7_state = SSS7_TX_CRC;
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}
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break;
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case SSS7_TX_CRC:
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uart_sent_byte(sss7_tx_crc);
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sss7_tx_last_byte = sss7_tx_crc;
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sss7_state = SSS7_IDLE;
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break;
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//All the RX states
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default:
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break;
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}
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}
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void sss7_get_received(uint8_t msg[SSS7_PAYLOAD_SIZE]) {
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if(sss7_has_received()) {
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memcpy(msg, sss7_rx_buffer[sss7_rx_oldest_buffer], SSS7_PAYLOAD_SIZE);
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sss7_rx_oldest_buffer++;
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};
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}
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