From 16fea8acf4fae8f7239f810e392e924725dbfdf5 Mon Sep 17 00:00:00 2001
From: Martin Mares <mj@ucw.cz>
Date: Fri, 17 Aug 2018 09:38:03 +0200
Subject: [PATCH] SSR host: Cleanup, avoid non-changes

---
 ssr/host/burrow-ssrd.c | 36 +++++++++++++++++++-----------------
 1 file changed, 19 insertions(+), 17 deletions(-)

diff --git a/ssr/host/burrow-ssrd.c b/ssr/host/burrow-ssrd.c
index d999bc5..1b3c4ff 100644
--- a/ssr/host/burrow-ssrd.c
+++ b/ssr/host/burrow-ssrd.c
@@ -25,7 +25,7 @@ static struct libusb_device_handle *devh;
 
 static struct mosquitto *mosq;
 
-static u32 ssr_state;
+static u32 ssr_state = ~0U;
 
 void open_device(void)
 {
@@ -84,12 +84,16 @@ static int transaction(uint req_len, uint resp_len)
 	return received;
 }
 
-static void set_relays(void)
+static void set_relays(u32 mask, u32 data)
 {
-	msg(L_INFO, "Setting relays to %02x", ssr_state);
-	put_u32_be(req, 1);
-	put_u32_be(req+4, ssr_state);
-	transaction(8, 4);
+	u32 new = (ssr_state & mask) | data;
+	if (new != ssr_state) {
+		msg(L_INFO, "Setting relays to %02x", new);
+		put_u32_be(req, 1);
+		put_u32_be(req+4, new);
+		transaction(8, 4);
+		ssr_state = new;
+	}
 }
 
 static void mqtt_publish(const char *topic, const char *fmt, ...)
@@ -135,19 +139,20 @@ static void mqtt_msg_callback(struct mosquitto *mosq UNUSED, void *obj UNUSED, c
 			x = 0;
 		}
 		msg(L_INFO, "Setting fan level to %u", x);
-		ssr_state &= ~7U;
 		switch (x) {
+			case 0:
+				set_relays(~7U, 0);
+				break;
 			case 1:
-				ssr_state |= 4;
+				set_relays(~7U, 4);
 				break;
 			case 2:
-				ssr_state |= 2;
+				set_relays(~7U, 2);
 				break;
 			case 3:
-				ssr_state |= 1;
+				set_relays(~7U, 1);
 				break;
 		}
-		set_relays();
 	} else if (!strcmp(m->topic, "burrow/loft/circulation")) {
 		uint x;
 		const char *err;
@@ -156,10 +161,7 @@ static void mqtt_msg_callback(struct mosquitto *mosq UNUSED, void *obj UNUSED, c
 			x = 0;
 		}
 		msg(L_INFO, "Setting circulation to %u", x);
-		ssr_state &= ~8U;
-		if (x)
-			ssr_state |= 8;
-		set_relays();
+		set_relays(~8U, (x ? 8 : 0));
 	}
 }
 
@@ -197,7 +199,7 @@ int main(int argc UNUSED, char **argv)
 	if (use_debug)
 		libusb_set_debug(usb_ctxt, 3);
 	open_device();
-	set_relays();
+	set_relays(0, 0);
 
 	mosquitto_lib_init();
 	mosq = mosquitto_new("ssrd", 1, NULL);
@@ -231,7 +233,7 @@ int main(int argc UNUSED, char **argv)
 			continue;
 		}
 
-		next_run = now + 5;
+		next_run = now + 10;
 
 		put_u32_be(req, 2);
 		transaction(8, 8);
-- 
2.39.2