From: Mikko Rasa <tdb@tdb.fi>
Date: Sun, 3 Nov 2013 09:20:42 +0000 (+0200)
Subject: Support chaining packets to create a larger packet
X-Git-Url: http://git.tdb.fi/?p=model-railway-devices.git;a=commitdiff_plain;h=285513c401954c5ad012ae4ae5411f72b7f73ffc

Support chaining packets to create a larger packet

MFX packets with response windows won't fit into the 256 bits available
in a single packet structure.  I'd rather keep the length field 8-bit to
preserve atomicity, and this also allows certain tricks later that would
be harder to do with a single packet.
---

diff --git a/arducontrol/output.c b/arducontrol/output.c
index 673f232..e017560 100644
--- a/arducontrol/output.c
+++ b/arducontrol/output.c
@@ -14,7 +14,9 @@ enum State
 	SENDING
 };
 
-OutputPacket packet;
+OutputPacket packets[4];
+uint8_t chain_length;
+uint8_t current_packet;
 volatile uint8_t packet_state = IDLE;
 static uint8_t out_bit;
 static uint8_t out_time;
@@ -32,7 +34,14 @@ void output_init(void)
 OutputPacket *output_create_packet(void)
 {
 	while(packet_state!=IDLE) ;
-	return &packet;
+	chain_length = 1;
+	return &packets[0];
+}
+
+OutputPacket *output_create_chained_packet(void)
+{
+	++chain_length;
+	return &packets[chain_length-1];
 }
 
 void output_send_packet(void)
@@ -40,6 +49,7 @@ void output_send_packet(void)
 	if(packet_state!=IDLE)
 		return;
 
+	current_packet = 0;
 	packet_state = READY;
 }
 
@@ -88,27 +98,29 @@ static inline void output_tick(void)
 
 	if(out_time && !--out_time)
 	{
+		OutputPacket *packet = &packets[current_packet];
 		++out_bit;
-		if(out_bit>=packet.length)
+		if(out_bit>=packet->length)
 		{
 			PORTD &= ~BIT(POLARITY);
-			if(packet.repeat_count>1)
+			if(--packet->repeat_count)
 			{
-				if(packet.repeat_count<0xFF)
-					--packet.repeat_count;
-				delay_time = packet.repeat_delay;
+				delay_time = packet->repeat_delay;
 				packet_state = READY;
 			}
 			else
 			{
-				delay_time = packet.final_delay;
-				packet_state = IDLE;
+				delay_time = packet->final_delay;
+				if(++current_packet<chain_length)
+					packet_state = READY;
+				else
+					packet_state = IDLE;
 			}
 		}
 		else
 		{
 			if((out_bit&7)==0)
-				out_data = packet.data[out_bit>>3];
+				out_data = packet->data[out_bit>>3];
 			else
 				out_data >>= 1;
 
@@ -117,7 +129,7 @@ static inline void output_tick(void)
 			else
 				PORTD &= ~BIT(POLARITY);
 
-			out_time = packet.bit_duration;
+			out_time = packet->bit_duration;
 		}
 
 		return;
@@ -125,10 +137,11 @@ static inline void output_tick(void)
 
 	if(packet_state==READY)
 	{
+		OutputPacket *packet = &packets[current_packet];
 		packet_state = SENDING;
 		out_bit = 0;
-		out_time = packet.bit_duration;
-		out_data = packet.data[0];
+		out_time = packet->bit_duration;
+		out_data = packet->data[0];
 		if(out_data&1)
 			PORTD |= BIT(POLARITY);
 		else
diff --git a/arducontrol/output.h b/arducontrol/output.h
index 162e1e0..2fde262 100644
--- a/arducontrol/output.h
+++ b/arducontrol/output.h
@@ -15,6 +15,7 @@ typedef struct
 
 void output_init(void);
 OutputPacket *output_create_packet(void);
+OutputPacket *output_create_chained_packet(void);
 void output_send_packet(void);
 void output_set_power(uint8_t);
 uint8_t output_is_power_on();