hameg-hmo: Send exactly one sigrok frame per scope frame

The previous implementation used to put FRAME_BEGIN and FRAME_END
markers around each received chunk of samples, while those chunks
correspond to a single channel (analog) or a group of eight channels
(digital) each. In other words, the hameg-hmo driver had provided a
multiple of the requested frames, and those frames were incomplete.

Make sure to only send FRAME_BEGIN before the first channel's data,
and FRAME_END after the last channel's data of a frame. Thus make
sigrok frames exactly match the scope's frames.

Add some comments on the frame marker and the acquisition stop logic
while we are here.

diff --git a/src/hardware/hameg-hmo/protocol.c b/src/hardware/hameg-hmo/protocol.c
index 97eb77aaac5ddce714e3d43ec1db41ad2767a790..978708c46c2aaca5ebe8948ff1750ca0f0482add 100644 (file)
--- a/src/hardware/hameg-hmo/protocol.c
+++ b/src/hardware/hameg-hmo/protocol.c
@@ -799,6 +799,18 @@ SR_PRIV int hmo_receive_data(int fd, int revents, void *cb_data)
        ch = devc->current_channel->data;
        state = devc->model_state;
 
+       /*
+        * Send "frame begin" packet upon reception of data for the
+        * first enabled channel.
+        */
+       if (devc->current_channel == devc->enabled_channels) {
+               packet.type = SR_DF_FRAME_BEGIN;
+               sr_session_send(sdi, &packet);
+       }
+
+       /*
+        * Pass on the received data of the channel(s).
+        */
        switch (ch->type) {
        case SR_CHANNEL_ANALOG:
                if (sr_scpi_get_block(sdi->conn, NULL, &data) != SR_OK) {
@@ -808,9 +820,6 @@ SR_PRIV int hmo_receive_data(int fd, int revents, void *cb_data)
                        return TRUE;
                }
 
-               packet.type = SR_DF_FRAME_BEGIN;
-               sr_session_send(sdi, &packet);
-
                packet.type = SR_DF_ANALOG;
 
                analog.data = data->data;
@@ -857,8 +866,6 @@ SR_PRIV int hmo_receive_data(int fd, int revents, void *cb_data)
                        return TRUE;
                }
 
-               packet.type = SR_DF_FRAME_BEGIN;
-               sr_session_send(sdi, &packet);
 
                logic.length = data->len;
                logic.unitsize = 1;
@@ -874,13 +881,24 @@ SR_PRIV int hmo_receive_data(int fd, int revents, void *cb_data)
                break;
        }
 
-       packet.type = SR_DF_FRAME_END;
-       sr_session_send(sdi, &packet);
-
+       /*
+        * Advance to the next enabled channel. When data for all enabled
+        * channels was received, then send the "frame end" packet.
+        */
        if (devc->current_channel->next) {
                devc->current_channel = devc->current_channel->next;
                hmo_request_data(sdi);
-       } else if (++devc->num_frames == devc->frame_limit) {
+               return TRUE;
+       }
+       packet.type = SR_DF_FRAME_END;
+       sr_session_send(sdi, &packet);
+
+       /*
+        * End of frame was reached. Stop acquisition after the specified
+        * number of frames, or continue reception by starting over at
+        * the first enabled channel.
+        */
+       if (++devc->num_frames == devc->frame_limit) {
                sdi->driver->dev_acquisition_stop(sdi);
        } else {
                devc->current_channel = devc->enabled_channels;