/*
* Returns: 0 on failure
* 1 on success
*/
unsigned char send_packet(unsigned char to_addr, unsigned char *data, unsigned char data_len) {
// TODO: Wait for timeout to tick down (in multi-station mode)
// Too much data
if (data_len > PACKET_DATA_MAX) {
return 0;
}
unsigned char crc;
crc8_init(0xFF);
rfm12_EnableTx(); // TODO: turn on transmitter
rfm12_Tx_Byte(0xAA); // Preamble for RFM12
rfm12_Tx_Byte(0xAA);
rfm12_Tx_Byte(0xAA);
rfm12_Tx_Byte(0x2D); // RFM12 sync pattern
rfm12_Tx_Byte(0xD4);
rfm12_Tx_Byte(HEADER_LENGTH + data_len); // Total packet length
crc = crc8_byte(HEADER_LENGTH + data_len);
rfm12_Tx_Byte(PACKET_MAGIC); // Magic identification bytes
crc = crc8_byte(PACKET_MAGIC);
rfm12_Tx_Byte(NODE_ADDRESS); // Sender ID
crc = crc8_byte(NODE_ADDRESS);
rfm12_Tx_Byte(to_addr); // Destination ID
crc = crc8_byte(to_addr);
rfm12_Tx_Byte(sequence_number); // Packet sequence number
crc = crc8_byte(sequence_number);
sequence_number++;
rfm12_Tx_Byte(0); // Reserved for future use
crc = crc8_byte(0);
rfm12_Tx_Byte(0); // Reserved for future use
crc = crc8_byte(0);
for (int n = 0; n < data_len; n++) {
rfm12_Tx_Byte(data[n]);
crc = crc8_byte(data[n]);
}
rfm12_Tx_Byte(crc); // CRC
rfm12_Tx_Byte(0xAA); // Trailer
rfm12_Tx_Byte(0xAA);
rfm12_DisableTx(); // Turn off Tx
return 1;
}
/*
* Given offset in flash area, fill in rest of the fcb_entry, and crc8 over
* the data.
*/
int
fcb_elem_crc8(struct fcb *fcb, struct fcb_entry *loc, uint8_t *c8p)
{
uint8_t tmp_str[FCB_TMP_BUF_SZ];
int cnt;
int blk_sz;
uint8_t crc8;
uint16_t len;
uint32_t off;
uint32_t end;
int rc;
if (loc->fe_elem_off + 2 > loc->fe_area->fa_size) {
return FCB_ERR_NOVAR;
}
rc = flash_area_read(loc->fe_area, loc->fe_elem_off, tmp_str, 2);
if (rc) {
return FCB_ERR_FLASH;
}
cnt = fcb_get_len(tmp_str, &len);
if (cnt < 0) {
return cnt;
}
loc->fe_data_off = loc->fe_elem_off + fcb_len_in_flash(fcb, cnt);
loc->fe_data_len = len;
crc8 = crc8_init();
crc8 = crc8_calc(crc8, tmp_str, cnt);
off = loc->fe_data_off;
end = loc->fe_data_off + len;
for (; off < end; off += blk_sz) {
blk_sz = end - off;
if (blk_sz > sizeof(tmp_str)) {
blk_sz = sizeof(tmp_str);
}
rc = flash_area_read(loc->fe_area, off, tmp_str, blk_sz);
if (rc) {
return FCB_ERR_FLASH;
}
crc8 = crc8_calc(crc8, tmp_str, blk_sz);
}
*c8p = crc8;
return 0;
}
unsigned char
_process_packet(unsigned char bytes_received) {
unsigned char length = 0;
unsigned char crc = 0;
receive_count++;
// Check for the start-of-packet byte
if (packet_buffer[0] != PACKET_MAGIC) {
return 0;
}
// Check that the packet is for us (or, in multicast mode, is for
// the multicast address)
#ifdef PACKET_MULTICAST
if (packet_buffer[2] != NODE_ADDRESS && packet_buffer[2] != MULTICAST_ADDRESS) {
#else
if (packet_buffer[2] != NODE_ADDRESS) {
#endif
return 0;
}
// Extract the length
length = packet_buffer[3];
// Calculate the CRC for the whole packet, minus the CRC
// which is at the end
crc8_init(0xff);
for (int n = 0; n < length - 1; n++) {
crc = crc8_byte(packet_buffer[n]);
}
// Check the CRC against the packet
if (crc != packet_buffer[length - 1]) {
return 0;
}
// Copy the data to the buffer
for (int n = 0; n < length - HEADER_LENGTH; n++) {
data_buffer[n] = packet_buffer[7 + n];
}
data_arrived = length - HEADER_LENGTH;
return 1;
}
