lecroy-xstream: Fix sample rate

We can't use the memory size command because it returns
the *maximum* memory used, not the *actual* memory used.
Hence, we only know the number of samples per div once
sample data actually comes in.

src/hardware/lecroy-xstream/api.c

@@ -204,7 +204,6 @@ static int config_set(uint32_t key, GVariant *data,
 	const struct scope_config *model;
 	struct scope_state *state;
 	double tmp_d;
-	gboolean update_sample_rate;
 
 	if (!sdi)
 		return SR_ERR_ARG;
@@ -213,7 +212,6 @@ static int config_set(uint32_t key, GVariant *data,
 
 	model = devc->model_config;
 	state = devc->model_state;
-	update_sample_rate = FALSE;
 
 	ret = SR_ERR_NA;
 
@@ -249,7 +247,6 @@ static int config_set(uint32_t key, GVariant *data,
 		g_snprintf(command, sizeof(command),
 				"TIME_DIV %E", (float) (*model->timebases)[idx][0] / (*model->timebases)[idx][1]);
 		ret = sr_scpi_send(sdi->conn, command);
-		update_sample_rate = TRUE;
 		break;
 	case SR_CONF_HORIZ_TRIGGERPOS:
 		tmp_d = g_variant_get_double(data);
@@ -296,9 +293,6 @@ static int config_set(uint32_t key, GVariant *data,
 	if (ret == SR_OK)
 		ret = sr_scpi_get_opc(sdi->conn);
 
-	if (ret == SR_OK && update_sample_rate)
-		ret = lecroy_xstream_update_sample_rate(sdi);
-
 	return ret;
 }
 
@@ -378,7 +372,6 @@ SR_PRIV int lecroy_xstream_request_data(const struct sr_dev_inst *sdi)
 static int setup_channels(const struct sr_dev_inst *sdi)
 {
 	GSList *l;
-	gboolean setup_changed;
 	char command[MAX_COMMAND_SIZE];
 	struct scope_state *state;
 	struct sr_channel *ch;
@@ -388,7 +381,6 @@ static int setup_channels(const struct sr_dev_inst *sdi)
 	devc = sdi->priv;
 	scpi = sdi->conn;
 	state = devc->model_state;
-	setup_changed = FALSE;
 
 	for (l = sdi->channels; l; l = l->next) {
 		ch = l->data;
@@ -403,16 +395,12 @@ static int setup_channels(const struct sr_dev_inst *sdi)
 				return SR_ERR;
 
 			state->analog_channels[ch->index].state = ch->enabled;
-			setup_changed = TRUE;
 			break;
 		default:
 			return SR_ERR;
 		}
 	}
 
-	if (setup_changed && lecroy_xstream_update_sample_rate(sdi) != SR_OK)
-		return SR_ERR;
-
 	return SR_OK;
 }
 
@@ -421,6 +409,7 @@ static int dev_acquisition_start(const struct sr_dev_inst *sdi)
 	GSList *l;
 	struct sr_channel *ch;
 	struct dev_context *devc;
+	struct scope_state *state;
 	int ret;
 	struct sr_scpi_dev_inst *scpi;
 
@@ -430,6 +419,8 @@ static int dev_acquisition_start(const struct sr_dev_inst *sdi)
 	/* Preset empty results. */
 	g_slist_free(devc->enabled_channels);
 	devc->enabled_channels = NULL;
+	state = devc->model_state;
+	state->sample_rate = 0;
 
 	/* Contruct the list of enabled channels. */
 	for (l = sdi->channels; l; l = l->next) {

src/hardware/lecroy-xstream/protocol.c

@@ -366,24 +366,22 @@ SR_PRIV int lecroy_xstream_channel_state_set(const struct sr_dev_inst *sdi,
 	return result;
 }
 
-SR_PRIV int lecroy_xstream_update_sample_rate(const struct sr_dev_inst *sdi)
+SR_PRIV int lecroy_xstream_update_sample_rate(const struct sr_dev_inst *sdi,
+		int num_of_samples)
 {
 	struct dev_context *devc;
 	struct scope_state *state;
 	const struct scope_config *config;
-	float memsize, timediv;
+	double time_div;
 
 	devc = sdi->priv;
-	state = devc->model_state;
 	config = devc->model_config;
+	state = devc->model_state;
 
-	if (sr_scpi_get_float(sdi->conn, "MEMORY_SIZE?", &memsize) != SR_OK)
+	if (sr_scpi_get_double(sdi->conn, "TIME_DIV?", &time_div) != SR_OK)
 		return SR_ERR;
 
-	if (sr_scpi_get_float(sdi->conn, "TIME_DIV?", &timediv) != SR_OK)
-		return SR_ERR;
-
-	state->sample_rate = 1 / ((timediv * config->num_xdivs) / memsize);
+	state->sample_rate = num_of_samples / (time_div * config->num_xdivs);
 
 	return SR_OK;
 }
@@ -454,9 +452,6 @@ SR_PRIV int lecroy_xstream_state_get(struct sr_dev_inst *sdi)
 	if (sr_scpi_get_float(sdi->conn, "TRIG_DELAY?", &state->horiz_triggerpos) != SR_OK)
 		return SR_ERR;
 
-	if (lecroy_xstream_update_sample_rate(sdi) != SR_OK)
-		return SR_ERR;
-
 	sr_info("Fetching finished.");
 
 	scope_state_dump(config, state);
@@ -624,6 +619,7 @@ SR_PRIV int lecroy_xstream_receive_data(int fd, int revents, void *cb_data)
 	struct sr_channel *ch;
 	struct sr_dev_inst *sdi;
 	struct dev_context *devc;
+	struct scope_state *state;
 	struct sr_datafeed_packet packet;
 	GByteArray *data;
 	struct sr_datafeed_analog analog;
@@ -644,6 +640,7 @@ SR_PRIV int lecroy_xstream_receive_data(int fd, int revents, void *cb_data)
 		return TRUE;
 
 	ch = devc->current_channel->data;
+	state = devc->model_state;
 
 	if (ch->type != SR_CHANNEL_ANALOG)
 		return SR_ERR;
@@ -671,7 +668,14 @@ SR_PRIV int lecroy_xstream_receive_data(int fd, int revents, void *cb_data)
 		/* No data available, we have to acquire data first. */
 		g_snprintf(command, sizeof(command), "ARM;WAIT;*OPC;C%d:WAVEFORM?", ch->index + 1);
 		sr_scpi_send(sdi->conn, command);
+
+		state->sample_rate = 0;
 		return TRUE;
+	} else {
+		/* Update sample rate if needed. */
+		if (state->sample_rate == 0)
+			if (lecroy_xstream_update_sample_rate(sdi, analog.num_samples) != SR_OK)
+				return SR_ERR;
 	}
 
 	/*

src/hardware/lecroy-xstream/protocol.h

@@ -98,6 +98,7 @@ SR_PRIV void lecroy_xstream_state_free(struct scope_state *state);
 SR_PRIV int lecroy_xstream_state_get(struct sr_dev_inst *sdi);
 SR_PRIV int lecroy_xstream_channel_state_set(const struct sr_dev_inst *sdi,
 		const int ch_index, gboolean ch_state);
-SR_PRIV int lecroy_xstream_update_sample_rate(const struct sr_dev_inst *sdi);
+SR_PRIV int lecroy_xstream_update_sample_rate(const struct sr_dev_inst *sdi,
+		int num_of_samples);
 
 #endif