rdtech-tc: grab receive data in larger chunks

[libsigrok.git] / src / hardware / rdtech-tc / protocol.c

diff --git a/src/hardware/rdtech-tc/protocol.c b/src/hardware/rdtech-tc/protocol.c
index 9b5270db5dd0201737f71f1a2fabca38ea64e1af..f2a439e4dacbcbbe0c1975ea562d1f6cdf9496ee 100644 (file)
--- a/src/hardware/rdtech-tc/protocol.c
+++ b/src/hardware/rdtech-tc/protocol.c
@@ -163,12 +163,26 @@ SR_PRIV int rdtech_tc_poll(const struct sr_dev_inst *sdi, gboolean force)
        struct sr_serial_dev_inst *serial;
        int len;
 
+       /*
+        * Don't send the request while receive data is being accumulated.
+        */
        devc = sdi->priv;
+       if (!force && devc->buflen)
+               return SR_OK;
+
+       /*
+        * Send the request when the transmit interval was reached. Or
+        * when the caller forced the transmission.
+        */
        now = g_get_monotonic_time() / 1000;
        elapsed = now - devc->cmd_sent_at;
        if (!force && elapsed < POLL_PERIOD_MS)
                return SR_OK;
 
+       /*
+        * Transmit another measurement request. Only advance the
+        * interval after successful transmission.
+        */
        serial = sdi->conn;
        len = serial_write_blocking(serial,
                poll_cmd, strlen(poll_cmd), WRITE_TO_MS);
@@ -191,8 +205,8 @@ static int handle_poll_data(struct sr_dev_inst *sdi)
 
        devc = sdi->priv;
        sr_spew("Received poll packet (len: %zu).", devc->buflen);
-       if (devc->buflen != TC_POLL_LEN) {
-               sr_err("Unexpected poll packet length: %zu", devc->buflen);
+       if (devc->buflen < TC_POLL_LEN) {
+               sr_err("Insufficient poll packet length: %zu", devc->buflen);
                return SR_ERR_DATA;
        }
 
@@ -220,13 +234,16 @@ static int handle_poll_data(struct sr_dev_inst *sdi)
 static int recv_poll_data(struct sr_dev_inst *sdi, struct sr_serial_dev_inst *serial)
 {
        struct dev_context *devc;
+       size_t space;
        int len;
        int ret;
 
-       /* Serial data arrived. */
+       /* Receive data became available. Drain the transport layer. */
        devc = sdi->priv;
        while (devc->buflen < TC_POLL_LEN) {
-               len = serial_read_nonblocking(serial, devc->buf + devc->buflen, 1);
+               space = sizeof(devc->buf) - devc->buflen;
+               len = serial_read_nonblocking(serial,
+                       &devc->buf[devc->buflen], space);
                if (len < 0)
                        return SR_ERR_IO;
                if (len == 0)
@@ -234,12 +251,20 @@ static int recv_poll_data(struct sr_dev_inst *sdi, struct sr_serial_dev_inst *se
                devc->buflen += len;
        }
 
-       if (devc->buflen == TC_POLL_LEN) {
+       /*
+        * TODO Want to (re-)synchronize to the packet stream? The
+        * 'pac1' string literal would be a perfect match for that.
+        */
+
+       /* Process packets when their reception has completed. */
+       while (devc->buflen >= TC_POLL_LEN) {
                ret = handle_poll_data(sdi);
                if (ret != SR_OK)
                        return ret;
+               devc->buflen -= TC_POLL_LEN;
+               if (devc->buflen)
+                       memmove(&devc->buf[0], &devc->buf[TC_POLL_LEN], devc->buflen);
        }
-       devc->buflen = 0;
 
        return SR_OK;
 }