return temp;
}
-static void process_packet(struct sr_dev_inst *sdi)
+static void process_packet(struct sr_dev_inst *sdi, uint8_t *pkt, size_t len)
{
struct dev_context *devc;
struct sr_datafeed_packet packet;
struct sr_analog_spec spec;
GString *spew;
float temp;
- int i;
gboolean is_valid;
- devc = sdi->priv;
- sr_dbg("Received full 19-byte packet.");
if (sr_log_loglevel_get() >= SR_LOG_SPEW) {
- spew = g_string_sized_new(60);
- for (i = 0; i < devc->packet_len; i++)
- g_string_append_printf(spew, "%.2x ", devc->packet[i]);
- sr_spew("%s", spew->str);
- g_string_free(spew, TRUE);
+ spew = sr_hexdump_new(pkt, len);
+ sr_spew("Got a packet, len %zu, bytes%s", len, spew->str);
+ sr_hexdump_free(spew);
}
+ if (len != PACKET_SIZE)
+ return;
+ if (pkt[17] != SEP[0] || pkt[18] != SEP[1])
+ return;
+ if (pkt[8] != '0' || pkt[16] != '1')
+ return;
+ sr_dbg("Processing 19-byte packet.");
is_valid = TRUE;
- if (devc->packet[1] == NEG && devc->packet[2] == NEG
- && devc->packet[3] == NEG && devc->packet[4] == NEG)
+ if (pkt[1] == NEG && pkt[2] == NEG && pkt[3] == NEG && pkt[4] == NEG)
/* No measurement: missing channel, empty storage location, ... */
is_valid = FALSE;
- temp = parse_temperature(devc->packet + 1);
+ temp = parse_temperature(&pkt[1]);
if (isnan(temp))
is_valid = FALSE;
if (is_valid) {
+ memset(&packet, 0, sizeof(packet));
sr_analog_init(&analog, &encoding, &meaning, &spec, 1);
analog.meaning->mq = SR_MQ_TEMPERATURE;
analog.meaning->mqflags = 0;
- switch (devc->packet[5] - '0') {
+ switch (pkt[5] - '0') {
case 1:
analog.meaning->unit = SR_UNIT_CELSIUS;
break;
break;
default:
/* We can still pass on the measurement, whatever it is. */
- sr_dbg("Unknown unit 0x%.2x.", devc->packet[5]);
+ sr_dbg("Unknown unit 0x%.2x.", pkt[5]);
}
- switch (devc->packet[13] - '0') {
+ switch (pkt[13] - '0') {
case 0:
/* Channel T1. */
analog.meaning->channels = g_slist_append(NULL, g_slist_nth_data(sdi->channels, 0));
analog.meaning->mqflags |= SR_MQFLAG_RELATIVE;
break;
default:
- sr_err("Unknown channel 0x%.2x.", devc->packet[13]);
+ sr_err("Unknown channel 0x%.2x.", pkt[13]);
is_valid = FALSE;
}
if (is_valid) {
* a sample limit on "Memory" data source still works: Unused
* memory slots come through as "----" measurements.
*/
+ devc = sdi->priv;
sr_sw_limits_update_samples_read(&devc->limits, 1);
if (sr_sw_limits_check(&devc->limits))
sr_dev_acquisition_stop(sdi);
}
+static int process_buffer(struct sr_dev_inst *sdi)
+{
+ struct dev_context *devc;
+ uint8_t *pkt;
+ size_t remain, idx;
+
+ /*
+ * Specifically do not insist on finding the packet boundary at
+ * the end of the most recently received data chunk. Serial
+ * ports might involve hardware buffers (FIFO). We want to sync
+ * as fast as possible.
+ *
+ * Handle the synchronized situation first. Process complete
+ * packets that reside at the start of the buffer. Then fallback
+ * to incomplete or unaligned packets if the receive buffer
+ * still contains data bytes. (Depending on the bitrate and the
+ * poll interval, we may always end up in the manual search. But
+ * considering the update rate - two or three packets per second
+ * - this is not an issue.)
+ */
+ devc = sdi->priv;
+ pkt = &devc->packet[0];
+ while (devc->packet_len >= PACKET_SIZE &&
+ pkt[PACKET_SIZE - 2] == SEP[0] &&
+ pkt[PACKET_SIZE - 1] == SEP[1]) {
+ process_packet(sdi, &pkt[0], PACKET_SIZE);
+ remain = devc->packet_len - PACKET_SIZE;
+ if (remain)
+ memmove(&pkt[0], &pkt[PACKET_SIZE], remain);
+ devc->packet_len -= PACKET_SIZE;
+ }
+
+ /*
+ * The 'for' loop and the increment upon re-iteration after
+ * setting the loop var to zero is not an issue. The marker has
+ * two bytes, so effectively starting the search at offset 1 is
+ * fine for the specific packet layout.
+ */
+ for (idx = 0; idx < devc->packet_len; idx++) {
+ if (idx < 1)
+ continue;
+ if (pkt[idx - 1] != SEP[0] || pkt[idx] != SEP[1])
+ continue;
+ /* Found a packet that spans up to and including 'idx'. */
+ idx++;
+ process_packet(sdi, &pkt[0], idx);
+ remain = devc->packet_len - idx;
+ if (remain)
+ memmove(&pkt[0], &pkt[idx], remain);
+ devc->packet_len -= idx;
+ idx = 0;
+ }
+
+ return 0;
+}
+
SR_PRIV void LIBUSB_CALL uni_t_ut32x_receive_transfer(struct libusb_transfer *transfer)
{
struct dev_context *devc;
memcpy(devc->packet + devc->packet_len, transfer->buffer + 1,
hid_payload_len);
devc->packet_len += hid_payload_len;
- if (devc->packet_len >= 2
- && devc->packet[devc->packet_len - 2] == SEP[0]
- && devc->packet[devc->packet_len - 1] == SEP[1]) {
- /* Got end of packet, but do we have a complete packet? */
- if (devc->packet_len == PACKET_SIZE)
- process_packet(sdi);
- /* Either way, done with it. */
- devc->packet_len = 0;
- } else if (devc->packet_len > PACKET_SIZE) {
- /* Guard against garbage from the device overrunning
- * our packet buffer. */
- sr_dbg("Buffer overrun!");
+ /*
+ * Discard receive data when the buffer is exhausted. This shall
+ * allow to (re-)synchronize to the data stream when we find it
+ * in an arbitrary state. Check the receive buffer for packets.
+ */
+ if (devc->packet_len == sizeof(devc->packet)) {
+ process_packet(sdi, &devc->packet[0], devc->packet_len);
devc->packet_len = 0;
}
+ process_buffer(sdi);
}
/* Get the next transfer (unless we're shutting down). */
projects / libsigrok.git / blobdiff