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/**
* Serial communication module.
*/
#include <stdbool.h>
#include "dataTypes.h"
serial_state_t serial_state = SERIAL_UNKNOWN;
static void handle_recv(int r);
static void handle_ctrl(int r) {
// detect reset procedure
switch (r) {
case RESET1:
// reset request received, ack and wait for RESET2
Serial.write(ACK1);
serial_state = SERIAL_INIT;
return;
case RESET2:
if (serial_state == SERIAL_INIT) {
// Handshake completed!
Serial.write(ACK2);
serial_state = SERIAL_READY;
} else {
// invalid state, reject it
Serial.write(OUTOFSYNC);
serial_state = SERIAL_UNKNOWN;
}
return;
case PONG:
// TODO mark as alive if PING was previously sent
return;
}
// TODO commands for navigation? Use DATA_LEN, etc?
}
void handle_serial(data_t *data, int changedBits) {
// first attempt sync
while (Serial.available()) {
r = Serial.read();
if ((r & 0xC0) == 0x80) {
// handle control packets
handle_ctrl(r);
// TODO if DATA_ESCAPE or DATA_LEN1, react appropriately
} else if (serial_state == SERIAL_READY) {
// handle normal data only when the handshake has completed.
handle_recv(r);
}
}
if (serial_state != SERIAL_READY) {
// Hardware is not ready, do not send data.
return;
}
// then send queued data
}
// writes data of length len
static void serial_write_data(const char *data, unsigned len) {
len--; // length on wire is one smaller (00 means 1 byte, 01 means 2, etc.)
if (len >= 0 && len < 56) {
Serial.write(0x80 + len + 7);
} else if (len >= 0 && len < 256) {
Serial.write(0x88 | (len >> 5));
Serial.write(0xA0 | (len & 0x1F));
} else {
// zero length or too long.
return;
}
// write remainder
for (unsigned i = 0; i < len; i++) {
char c = data[i];
if (c & 0x80) {
Serial.write(DATA_ESCAPE);
Serial.write(c & ~0x80);
} else {
Serial.write(c);
}
}
}
void serial_print_debug(const char *str) {
serial_print_debug(str, strlen(str));
}
static void handle_recv(int r) {
}
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