/**
* Try to find a valid packet in a serial data stream.
*
- * @param serial Previously initialized serial port structure.
- * @param buf Buffer containing the bytes to write.
- * @param buflen Size of the buffer.
+ * @param[in] serial Previously initialized serial port structure.
+ * @param[in] buf Buffer containing the bytes to write.
+ * @param[in] buflen Size of the buffer.
* @param[in] packet_size Size, in bytes, of a valid packet.
- * @param is_valid Callback that assesses whether the packet is valid or not.
+ * @param[in] is_valid Callback that assesses whether the packet is valid or not.
+ * @param[in] is_valid_len Callback which checks a variable length packet.
+ * @param[out] return_size Detected packet size in case of successful match.
* @param[in] timeout_ms The timeout after which, if no packet is detected, to
* abort scanning.
*
+ * Data is received from the serial port and into the caller provided
+ * buffer, until the buffer is exhausted, or the timeout has expired,
+ * or a valid packet was found. Receive data is passed to the caller
+ * provided validity check routine, assuming either fixed size packets
+ * (#is_valid parameter, exact match to the #packet_size length) or
+ * packets of variable length (#is_valid_len parameter, minimum length
+ * #packet_size required for first invocation).
+ *
* @retval SR_OK Valid packet was found within the given timeout.
* @retval SR_ERR Failure.
*
*/
SR_PRIV int serial_stream_detect(struct sr_serial_dev_inst *serial,
uint8_t *buf, size_t *buflen,
- size_t packet_size,
- packet_valid_callback is_valid,
+ size_t packet_size, packet_valid_callback is_valid,
+ packet_valid_len_callback is_valid_len, size_t *return_size,
uint64_t timeout_ms)
{
- uint64_t start, time, byte_delay_us;
- size_t ibuf, i, maxlen;
- ssize_t len;
-
- maxlen = *buflen;
+ uint64_t start_us, elapsed_ms, byte_delay_us;
+ size_t fill_idx, check_idx, max_fill_idx;
+ ssize_t recv_len;
+ const uint8_t *check_ptr;
+ size_t check_len, pkt_len;
+ gboolean do_dump;
+ int ret;
sr_dbg("Detecting packets on %s (timeout = %" PRIu64 "ms).",
serial->port, timeout_ms);
- if (maxlen < (packet_size * 2) ) {
- sr_err("Buffer size must be at least twice the packet size.");
- return SR_ERR;
+ max_fill_idx = *buflen;
+ if (max_fill_idx < 2 * packet_size) {
+ /*
+ * The heuristics in this check is only useful for fixed
+ * packet length scenarios, but for variable length setups
+ * we don't know the packets' sizes up front.
+ */
+ sr_err("Small stream detect RX buffer, want 2x packet size.");
+ return SR_ERR_ARG;
}
- /* Assume 8n1 transmission. That is 10 bits for every byte. */
byte_delay_us = serial_timeout(serial, 1) * 1000;
- start = g_get_monotonic_time();
+ start_us = g_get_monotonic_time();
+
+ check_idx = fill_idx = 0;
+ while (fill_idx < max_fill_idx) {
+ /*
+ * Read bytes individually. Lets callers continue to
+ * successfully process next RX data after first match.
+ * Run full loop bodies for empty or failed reception
+ * in an iteration, to have timeouts checked.
+ */
+ recv_len = serial_read_nonblocking(serial, &buf[fill_idx], 1);
+ if (recv_len > 0)
+ fill_idx += recv_len;
+
+ /* Dump receive data when (a minimum) size is reached. */
+ check_ptr = &buf[check_idx];
+ check_len = fill_idx - check_idx;
+ do_dump = check_len >= packet_size;
+ do_dump &= sr_log_loglevel_get() >= SR_LOG_SPEW;
+ if (do_dump) {
+ GString *text;
- i = ibuf = len = 0;
- while (ibuf < maxlen) {
- len = serial_read_nonblocking(serial, &buf[ibuf], 1);
- if (len > 0) {
- ibuf += len;
- } else if (len == 0) {
- /* No logging, already done in serial_read(). */
- } else {
- /* Error reading byte, but continuing anyway. */
+ text = sr_hexdump_new(check_ptr, check_len);
+ sr_spew("Trying packet: len %zu, bytes %s",
+ check_len, text->str);
+ sr_hexdump_free(text);
}
- time = g_get_monotonic_time() - start;
- time /= 1000;
-
- if ((ibuf - i) >= packet_size) {
- GString *text;
- /* We have at least a packet's worth of data. */
- text = sr_hexdump_new(&buf[i], packet_size);
- sr_spew("Trying packet: %s", text->str);
- sr_hexdump_free(text);
- if (is_valid(&buf[i])) {
- sr_spew("Found valid %zu-byte packet after "
- "%" PRIu64 "ms.", (ibuf - i), time);
- *buflen = ibuf;
+ /* A packet's (minimum) length was received, check its data. */
+ elapsed_ms = g_get_monotonic_time() - start_us;
+ elapsed_ms /= 1000;
+ if (is_valid_len && check_len >= packet_size) {
+ pkt_len = packet_size;
+ ret = is_valid_len(NULL, check_ptr, check_len, &pkt_len);
+ if (ret == SR_PACKET_VALID) {
+ /* Exact match. Terminate with success. */
+ sr_spew("Valid packet after %" PRIu64 "ms.",
+ elapsed_ms);
+ sr_spew("RX count %zu, packet len %zu.",
+ fill_idx, pkt_len);
+ *buflen = fill_idx;
+ if (return_size)
+ *return_size = pkt_len;
return SR_OK;
+ }
+ if (ret == SR_PACKET_NEED_RX) {
+ /* Incomplete, keep accumulating RX data. */
+ sr_spew("Checker needs more RX data.");
} else {
- sr_spew("Got %zu bytes, but not a valid "
- "packet.", (ibuf - i));
+ /* Not a valid packet. Continue searching. */
+ sr_spew("Invalid packet, advancing read pos.");
+ check_idx++;
+ }
+ }
+ if (is_valid && check_len >= packet_size) {
+ if (is_valid(check_ptr)) {
+ /* Exact match. Terminate with success. */
+ sr_spew("Valid packet after %" PRIu64 "ms.",
+ elapsed_ms);
+ sr_spew("RX count %zu, packet len %zu.",
+ fill_idx, packet_size);
+ *buflen = fill_idx;
+ if (return_size)
+ *return_size = packet_size;
+ return SR_OK;
}
/* Not a valid packet. Continue searching. */
- i++;
+ sr_spew("Invalid packet, advancing read pointer.");
+ check_idx++;
}
- if (time >= timeout_ms) {
- /* Timeout */
- sr_dbg("Detection timed out after %" PRIu64 "ms.", time);
+
+ /* Check for packet search timeout. */
+ if (elapsed_ms >= timeout_ms) {
+ sr_dbg("Detection timed out after %" PRIu64 "ms.",
+ elapsed_ms);
break;
}
- if (len < 1)
+ if (recv_len < 1)
g_usleep(byte_delay_us);
}
-
- *buflen = ibuf;
-
- sr_info("Didn't find a valid packet (read %zu bytes).", *buflen);
+ sr_info("Didn't find a valid packet (read %zu bytes).", fill_idx);
+ *buflen = fill_idx;
return SR_ERR;
}
projects / libsigrok.git / blobdiff