From 9c489911b6a3549b982d9ad24665a740259b504c Mon Sep 17 00:00:00 2001
From: Markus Hitter <mah@jump-ing.de>
Date: Thu, 17 Nov 2011 13:33:31 +0100
Subject: [PATCH] timer.c: get rid of explicitely disabling the step timer.

This is no longer neccessary, as the step timer is not designed to
fire always exactly once.

Saves 54 bytes binary size.
---
 dda_queue.c |  3 --
 timer.c     | 82 +++++++++++++++++++++++------------------------------
 2 files changed, 36 insertions(+), 49 deletions(-)

diff --git a/dda_queue.c b/dda_queue.c
index 854ee5e..784b54f 100644
--- a/dda_queue.c
+++ b/dda_queue.c
@@ -167,9 +167,6 @@ void next_move() {
 			dda_start(current_movebuffer);
 		}
 	} 
-	if (queue_empty())
-		setTimer(0);
-
 }
 
 /// DEBUG - print queue.
diff --git a/timer.c b/timer.c
index 7c9b991..9aa3a3a 100644
--- a/timer.c
+++ b/timer.c
@@ -138,56 +138,46 @@ void setTimer(uint32_t delay)
 	// re-enable clock interrupt in case we're recovering from emergency stop
 	TIMSK1 |= MASK(OCIE1B);
 
-	if (delay > 0) {
+	// if the delay is too small use a minimum delay so that there is time
+	// to set everything up before the timer expires.
 
-		// if the delay is too small use a minimum delay so that there is time
-		// to set everything up before the timer expires.
+	if (delay < 17 )
+		delay = 17;
 
-		if (delay < 17 )
-			delay = 17;
-		
-		// Assume all steps belong to one move. Within one move the delay is
-		// from one step to the next one, which should be more or less the same
-		// as from one step interrupt to the next one. The last step interrupt happend
-		// at OCR1A, so start delay from there.
-		step_start = OCR1A;
-		if (next_step_time == 0) {
-			// new move, take current time as start value
-			step_start = TCNT1;
-		}
-
-		next_step_time = delay;
-		if (next_step_time < 65536) {
-			// set the comparator directly to the next real step
-			OCR1A = (next_step_time + step_start) & 0xFFFF;
-		}
-		else if (next_step_time < 75536) {
-			// Next comparator interrupt would have to trigger another
-			// interrupt within a short time (possibly within 1 cycle).
-			// Avoid the impossible by firing the interrupt earlier.
-			OCR1A = (step_start - 10000) & 0xFFFF;
-			next_step_time += 10000;
-		}
-		else {
-			OCR1A = step_start;
-		}
-
-		// Enable this interrupt, but only do it after disabling
-		// global interrupts. This will cause push any possible
-		// timer1a interrupt to the far side of the return, protecting the 
-		// stack from recursively clobbering memory.
-		cli();
-		CLI_SEI_BUG_MEMORY_BARRIER();
-		TIMSK1 |= MASK(OCIE1A);
-
-	} else {
-		// TODO: as the interrupt is designed to fire only once,
-		//       doing a setTimer(0) should be obsolete.
-		// flag: move has ended
-		next_step_time = 0;
-		TIMSK1 &= ~MASK(OCIE1A);
+	// Assume all steps belong to one move. Within one move the delay is
+	// from one step to the next one, which should be more or less the same
+	// as from one step interrupt to the next one. The last step interrupt happend
+	// at OCR1A, so start delay from there.
+	step_start = OCR1A;
+	if (next_step_time == 0) {
+		// new move, take current time as start value
+		step_start = TCNT1;
 	}
 
+	next_step_time = delay;
+	if (next_step_time < 65536) {
+		// set the comparator directly to the next real step
+		OCR1A = (next_step_time + step_start) & 0xFFFF;
+	}
+	else if (next_step_time < 75536) {
+		// Next comparator interrupt would have to trigger another
+		// interrupt within a short time (possibly within 1 cycle).
+		// Avoid the impossible by firing the interrupt earlier.
+		OCR1A = (step_start - 10000) & 0xFFFF;
+		next_step_time += 10000;
+	}
+	else {
+		OCR1A = step_start;
+	}
+
+	// Enable this interrupt, but only do it after disabling
+	// global interrupts. This will cause push any possible
+	// timer1a interrupt to the far side of the return, protecting the 
+	// stack from recursively clobbering memory.
+	cli();
+	CLI_SEI_BUG_MEMORY_BARRIER();
+	TIMSK1 |= MASK(OCIE1A);
+
 	// restore interrupt flag
 	MEMORY_BARRIER();
 	SREG = sreg;