scpi-pps: Optimize channel selection.
This avoids sending a channel selection command to the device if
the channel we're working on is already on the same underlying
output channel.
diff --git a/src/hardware/scpi-pps/protocol.c b/src/hardware/scpi-pps/protocol.c
index 667ce46..13133b5 100644
--- a/src/hardware/scpi-pps/protocol.c
+++ b/src/hardware/scpi-pps/protocol.c
@@ -103,7 +103,7 @@
SR_PRIV int select_channel(const struct sr_dev_inst *sdi, struct sr_channel *ch)
{
struct dev_context *devc;
- struct pps_channel *pch;
+ struct pps_channel *cur_pch, *new_pch;
int ret;
if (g_slist_length(sdi->channels) == 1)
@@ -113,13 +113,40 @@
if (ch == devc->cur_channel)
return SR_OK;
- pch = ch->priv;
- if ((ret = scpi_cmd(sdi, SCPI_CMD_SELECT_CHANNEL, pch->hwname)) == SR_OK)
+ new_pch = ch->priv;
+ if (devc->cur_channel) {
+ cur_pch = devc->cur_channel->priv;
+ if (cur_pch->hw_output_idx == new_pch->hw_output_idx) {
+ /* Same underlying output channel. */
+ devc->cur_channel = ch;
+ return SR_OK;
+ }
+ }
+
+ if ((ret = scpi_cmd(sdi, SCPI_CMD_SELECT_CHANNEL, new_pch->hwname)) == SR_OK)
devc->cur_channel = ch;
return ret;
}
+SR_PRIV struct sr_channel *next_enabled_channel(const struct sr_dev_inst *sdi,
+ struct sr_channel *cur_channel)
+{
+ struct sr_channel *next_channel;
+ GSList *l;
+
+ next_channel = cur_channel;
+ do {
+ l = g_slist_find(sdi->channels, next_channel);
+ if (l && l->next)
+ next_channel = l->next->data;
+ else
+ next_channel = sdi->channels->data;
+ } while (!next_channel->enabled);
+
+ return next_channel;
+}
+
SR_PRIV int scpi_pps_receive_data(int fd, int revents, void *cb_data)
{
struct dev_context *devc;
@@ -129,7 +156,6 @@
struct sr_channel *next_channel;
struct sr_scpi_dev_inst *scpi;
struct pps_channel *pch;
- GSList *l;
float f;
int cmd;
@@ -165,17 +191,8 @@
}
if (g_slist_length(sdi->channels) > 1) {
- /* Find next enabled channel. */
- next_channel = devc->cur_channel;
- do {
- l = g_slist_find(sdi->channels, next_channel);
- if (l->next)
- next_channel = l->next->data;
- else
- next_channel = sdi->channels->data;
- } while (!next_channel->enabled);
- select_channel(sdi, next_channel);
- if (devc->cur_channel != next_channel) {
+ next_channel = next_enabled_channel(sdi, devc->cur_channel);
+ if (select_channel(sdi, next_channel) != SR_OK) {
sr_err("Failed to select channel %s", next_channel->name);
return FALSE;
}
@@ -190,7 +207,7 @@
cmd = SCPI_CMD_GET_MEAS_POWER;
else
return SR_ERR;
- scpi_cmd(sdi, cmd, pch->hwname);
+ scpi_cmd(sdi, cmd);
return TRUE;
}
diff --git a/src/hardware/scpi-pps/protocol.h b/src/hardware/scpi-pps/protocol.h
index 8a810af..189f1ed 100644
--- a/src/hardware/scpi-pps/protocol.h
+++ b/src/hardware/scpi-pps/protocol.h
@@ -153,6 +153,8 @@
SR_PRIV int scpi_cmd_resp(const struct sr_dev_inst *sdi, GVariant **gvar,
const GVariantType *gvtype, int command, ...);
SR_PRIV int select_channel(const struct sr_dev_inst *sdi, struct sr_channel *ch);
+SR_PRIV struct sr_channel *next_enabled_channel(const struct sr_dev_inst *sdi,
+ struct sr_channel *cur_channel);
SR_PRIV int scpi_pps_receive_data(int fd, int revents, void *cb_data);
#endif