kingst-la2016: adjust sample memory interpretation for LA5032

The 32-channel model in the Kingst LA series uses a different sample
memory layout than 16-channel models. The previously encoded assumption
of 3x (u32 + u8) to hold 32 channels within the same 15 bytes as other
models was incorrect. User feedback in bug #1805 suggests that the
transfer size and the sequence number size differs as well. Thus the
packet count per transfer differs, too. LA5032 holds 6 packets within
a transfer that spans 32 bytes.

Reported-By: Roman Shishkin <roman-dj-95@yandex.ru>

src/hardware/kingst-la2016/api.c

@@ -1035,7 +1035,7 @@ static int dev_acquisition_start(const struct sr_dev_inst *sdi)
 	struct drv_context *drvc;
 	struct sr_context *ctx;
 	struct dev_context *devc;
-	size_t unitsize;
+	size_t unitsize, xfersize, repsize, seqsize;
 	double voltage;
 	int ret;
 
@@ -1045,21 +1045,35 @@ static int dev_acquisition_start(const struct sr_dev_inst *sdi)
 	devc = sdi->priv;
 
 	if (!devc->feed_queue) {
-		if (devc->model->channel_count == 32)
+		/*
+		 * TODO
+		 * Move this into protocol.c which concentrates the
+		 * wire format. The api.c source should not bother.
+		 */
+		if (devc->model->channel_count == 32) {
 			unitsize = sizeof(uint32_t);
-		else if (devc->model->channel_count == 16)
+			repsize = sizeof(uint8_t);
+			seqsize = 2 * sizeof(uint8_t);
+			xfersize = 32;
+		} else if (devc->model->channel_count == 16) {
 			unitsize = sizeof(uint16_t);
-		else
+			repsize = sizeof(uint8_t);
+			seqsize = 1 * sizeof(uint8_t);
+			xfersize = 16;
+		} else {
 			return SR_ERR_ARG;
+		}
 		devc->feed_queue = feed_queue_logic_alloc(sdi,
 			LA2016_CONVBUFFER_SIZE, unitsize);
 		if (!devc->feed_queue) {
 			sr_err("Cannot allocate buffer for session feed.");
 			return SR_ERR_MALLOC;
 		}
-		devc->packets_per_chunk = TRANSFER_PACKET_LENGTH;
-		devc->packets_per_chunk--;
-		devc->packets_per_chunk /= unitsize + sizeof(uint8_t);
+		devc->transfer_size = xfersize;
+		devc->sequence_size = seqsize;
+		devc->packets_per_chunk = xfersize;
+		devc->packets_per_chunk -= seqsize;
+		devc->packets_per_chunk /= unitsize + repsize;
 	}
 
 	sr_sw_limits_acquisition_start(&devc->sw_limits);

src/hardware/kingst-la2016/protocol.c

@@ -1283,7 +1283,7 @@ static int la2016_start_download(const struct sr_dev_inst *sdi)
 	devc->n_transfer_packets_to_read = devc->info.n_rep_packets;
 	devc->n_transfer_packets_to_read /= devc->packets_per_chunk;
 	devc->n_bytes_to_read = devc->n_transfer_packets_to_read;
-	devc->n_bytes_to_read *= TRANSFER_PACKET_LENGTH;
+	devc->n_bytes_to_read *= devc->transfer_size;
 	devc->read_pos = devc->info.write_pos - devc->n_bytes_to_read;
 	devc->n_reps_until_trigger = devc->info.n_rep_packets_before_trigger;
 
@@ -1341,15 +1341,12 @@ static int la2016_start_download(const struct sr_dev_inst *sdi)
  * - 2x u8 sequence number (inverted, and normal)
  *
  * This implementation silently ignores the (weak) sequence number.
- *
- * TODO Adjust the code paths for the 32-channel models. The version
- * below currently only works correctly for 16-channel models.
  */
 static void send_chunk(struct sr_dev_inst *sdi,
 	const uint8_t *data_buffer, size_t data_length)
 {
 	struct dev_context *devc;
-	size_t num_xfers, num_pkts;
+	size_t num_xfers, num_pkts, num_seqs;
 	const uint8_t *rp;
 	uint32_t sample_value;
 	size_t repetitions;
@@ -1379,12 +1376,11 @@ static void send_chunk(struct sr_dev_inst *sdi,
 	/* Process the received chunk of capture data. */
 	sample_value = 0;
 	rp = data_buffer;
-	num_xfers = data_length / TRANSFER_PACKET_LENGTH;
+	num_xfers = data_length / devc->transfer_size;
 	while (num_xfers--) {
 		num_pkts = devc->packets_per_chunk;
 		while (num_pkts--) {
 
-			/* TODO Verify 32channel layout. */
 			if (devc->model->channel_count == 32)
 				sample_value = read_u32le_inc(&rp);
 			else if (devc->model->channel_count == 16)
@@ -1409,7 +1405,10 @@ static void send_chunk(struct sr_dev_inst *sdi,
 				}
 			}
 		}
-		(void)read_u8_inc(&rp); /* Skip sequence number. */
+		/* Skip the sequence number bytes. */
+		num_seqs = devc->sequence_size;
+		while (num_seqs--)
+			(void)read_u8_inc(&rp);
 	}
 
 	/*

src/hardware/kingst-la2016/protocol.h

@@ -81,8 +81,6 @@
 #define LA2016_THR_VOLTAGE_MIN	0.40
 #define LA2016_THR_VOLTAGE_MAX	4.00
 
-/* Properties related to the layout of capture data downloads. */
-#define TRANSFER_PACKET_LENGTH	16
 #define LA2016_NUM_SAMPLES_MAX	(UINT64_C(10 * 1000 * 1000 * 1000))
 
 /* Maximum device capabilities. May differ between models. */
@@ -143,6 +141,8 @@ struct dev_context {
 	gboolean frame_begin_sent;
 	gboolean completion_seen;
 	gboolean download_finished;
+	size_t transfer_size;
+	size_t sequence_size;
 	uint32_t packets_per_chunk;
 	struct capture_info {
 		uint32_t n_rep_packets;