kingst-la2016: move capture download details out of USB xfer handling

Ideally the USB transfer handling logic and the interpretation of the
downloaded capture data would not be as intertwined. The current
implementation assumes a rather specific capture model ("normal mode"
as it's called in the vendor software), and would not work in streaming
mode.

Move as many details out of the receive_transfer() routine and into the
send_chunk() data processing routine as we can. Which only leaves error
code paths and USB transfer re-submission, which get addressed in a
subsequent commit.

diff --git a/src/hardware/kingst-la2016/protocol.c b/src/hardware/kingst-la2016/protocol.c
index def77ba40128ce11030bf6cda2714e8dbaaaee85..6a133a5fa9c73631c82d6e664c38fc50391ed558 100644 (file)
--- a/src/hardware/kingst-la2016/protocol.c
+++ b/src/hardware/kingst-la2016/protocol.c
@@ -1099,10 +1099,10 @@ static int la2016_start_download(const struct sr_dev_inst *sdi,
  * contain a number of samples (8bit repeat count per 16bit sample data).
  */
 static void send_chunk(struct sr_dev_inst *sdi,
-       const uint8_t *packets, size_t num_xfers)
+       const uint8_t *data_buffer, size_t data_length)
 {
        struct dev_context *devc;
-       size_t num_pkts;
+       size_t num_xfers, num_pkts;
        const uint8_t *rp;
        uint32_t sample_value;
        size_t repetitions;
@@ -1119,8 +1119,20 @@ static void send_chunk(struct sr_dev_inst *sdi,
                devc->trigger_marked = TRUE;
        }
 
+       /*
+        * Adjust the number of remaining bytes to read from the device
+        * before the processing of the currently received chunk affects
+        * the variable which holds the number of received bytes.
+        */
+       if (data_length > devc->n_bytes_to_read)
+               devc->n_bytes_to_read = 0;
+       else
+               devc->n_bytes_to_read -= data_length;
+
+       /* Process the received chunk of capture data. */
        sample_value = 0;
-       rp = packets;
+       rp = data_buffer;
+       num_xfers = data_length / TRANSFER_PACKET_LENGTH;
        while (num_xfers--) {
                num_pkts = devc->packets_per_chunk;
                while (num_pkts--) {
@@ -1153,6 +1165,18 @@ static void send_chunk(struct sr_dev_inst *sdi,
                (void)read_u8_inc(&rp); /* Skip sequence number. */
        }
 
+       /*
+        * Check for several conditions which shall terminate the
+        * capture data download: When the amount of capture data in
+        * the device is exhausted. When the user specified samples
+        * count limit is reached.
+        */
+       if (!devc->n_bytes_to_read) {
+               devc->download_finished = TRUE;
+       } else {
+               sr_dbg("%" PRIu32 " more bytes to download from the device.",
+                       devc->n_bytes_to_read);
+       }
        if (!devc->download_finished && sr_sw_limits_check(&devc->sw_limits)) {
                sr_dbg("Acquisition limit reached.");
                devc->download_finished = TRUE;
@@ -1169,7 +1193,6 @@ static void LIBUSB_CALL receive_transfer(struct libusb_transfer *transfer)
        struct sr_dev_inst *sdi;
        struct dev_context *devc;
        struct sr_usb_dev_inst *usb;
-       size_t num_xfers;
        int ret;
 
        sdi = transfer->user_data;
@@ -1185,17 +1208,17 @@ static void LIBUSB_CALL receive_transfer(struct libusb_transfer *transfer)
         * or exhausting the device's captured data will complete the
         * sample data download.
         */
-       num_xfers = transfer->actual_length / TRANSFER_PACKET_LENGTH;
-       send_chunk(sdi, transfer->buffer, num_xfers);
+       send_chunk(sdi, transfer->buffer, transfer->actual_length);
+
+       if (!devc->download_finished) {
+               uint32_t to_read;
 
-       devc->n_bytes_to_read -= transfer->actual_length;
-       if (devc->n_bytes_to_read) {
-               uint32_t to_read = devc->n_bytes_to_read;
                /*
                 * Determine read size for the next USB transfer. Make
                 * the buffer size a multiple of the endpoint packet
                 * size. Don't exceed a maximum value.
                 */
+               to_read = devc->n_bytes_to_read;
                if (to_read >= LA2016_USB_BUFSZ)
                        to_read = LA2016_USB_BUFSZ;
                to_read += LA2016_EP6_PKTSZ - 1;
@@ -1211,11 +1234,11 @@ static void LIBUSB_CALL receive_transfer(struct libusb_transfer *transfer)
                        return;
                sr_err("Cannot submit another USB transfer: %s.",
                        libusb_error_name(ret));
+               devc->download_finished = TRUE;
        }
 
        g_free(transfer->buffer);
        libusb_free_transfer(transfer);
-       devc->download_finished = TRUE;
 }
 
 SR_PRIV int la2016_receive_data(int fd, int revents, void *cb_data)