Move dda->c out of DDA into move_state as well.

This also required to get rid of the usage of this variable
when waiting for temperature in dda_queue.*. Hope I got this
later part right.

dda.c

@@ -173,6 +173,7 @@ void dda_init(void) {
 
 	#ifdef ACCELERATION_RAMPING
 		move_state.n = 1;
+		move_state.c = ((uint32_t)((double)F_CPU / sqrt((double)(STEPS_PER_MM_X * ACCELERATION)))) << 8;
 	#endif
 }
 
@@ -356,8 +357,6 @@ void dda_create(DDA *dda, TARGET *target) {
 #endif
 			// c is initial step time in IOclk ticks (currently, IOclk ticks = F_CPU)
 			// yes, this assumes always the x axis as the critical one regarding acceleration. If we want to implement per-axis acceleration, things get tricky ...
-			// TODO: as this number ends exactly where it starts, move it out into a state variable
-			dda->c = ((uint32_t)((double)F_CPU / sqrt((double)(STEPS_PER_MM_X * ACCELERATION)))) << 8;
 			dda->c_min = (move_duration / target->F) << 8;
 			if (dda->c_min < c_limit)
 				dda->c_min = c_limit;
@@ -431,7 +430,14 @@ void dda_start(DDA *dda) {
 		dda->live = 1;
 
 		// set timeout for first step
+		#ifdef ACCELERATION_RAMPING
+		if (dda->c_min > move_state.c) // can be true when look-ahead removed all deceleration steps
+			setTimer(dda->c_min >> 8);
+		else
+			setTimer(move_state.c >> 8);
+		#else
 		setTimer(dda->c >> 8);
+		#endif
 	}
 }
 
@@ -553,7 +559,7 @@ void dda_step(DDA *dda) {
 		if (recalc_speed) {
 			move_state.n += 4;
 			// be careful of signedness!
-			dda->c = (int32_t)dda->c - ((int32_t)(dda->c * 2) / move_state.n);
+			move_state.c = (int32_t)move_state.c - ((int32_t)(move_state.c * 2) / move_state.n);
 		}
 		dda->step_no++;
 
@@ -593,10 +599,10 @@ void dda_step(DDA *dda) {
 		// we don't hit maximum speed exactly with acceleration calculation, so limit it here
 		// the nice thing about _not_ setting dda->c to dda->c_min is, the move stops at the exact same c as it started, so we have to calculate c only once for the time being
 		// TODO: set timer only if dda->c has changed
-		if (dda->c_min > dda->c)
+		if (dda->c_min > move_state.c)
 			setTimer(dda->c_min >> 8);
 		else
-			setTimer(dda->c >> 8);
+			setTimer(move_state.c >> 8);
 	#else
 		setTimer(dda->c >> 8);
 	#endif

dda.h

@@ -54,10 +54,10 @@ typedef struct {
 //	uint32_t					e_steps; ///< number of steps on E axis
 
 	#ifdef ACCELERATION_RAMPING
-//	/// time until next step
-//	uint32_t					c;
 //	/// counts actual steps done
 //	uint32_t					step_no;
+	/// time until next step
+	uint32_t					c;
 	/// tracking variable
 	int32_t						n;
 	#endif
@@ -117,7 +117,9 @@ typedef struct {
 	uint32_t					total_steps;
 
 	// linear acceleration variables: c and end_c are 24.8 fixed point timer values, n is the tracking variable
+	#ifndef ACCELERATION_RAMPING
 	uint32_t					c; ///< time until next step
+	#endif
 	#ifdef ACCELERATION_REPRAP
 	uint32_t					end_c; ///< time between 2nd last step and last step
 	int32_t						n; ///< precalculated step time offset variable. At every step we calculate \f$c = c - (2 c / n)\f$; \f$n+=4\f$. See http://www.embedded.com/columns/technicalinsights/56800129?printable=true for full description

dda_queue.c

@@ -64,7 +64,7 @@ void queue_step() {
 	DDA* current_movebuffer = &movebuffer[mb_tail];
 	if (current_movebuffer->live) {
 		if (current_movebuffer->waitfor_temp) {
-			setTimer(current_movebuffer->c >> 8);
+			setTimer(HEATER_WAIT_TIMEOUT);
 			if (temp_achieved()) {
 				current_movebuffer->live = current_movebuffer->waitfor_temp = 0;
 				serial_writestr_P(PSTR("Temp achieved\n"));
@@ -106,13 +106,6 @@ void enqueue(TARGET *t) {
 		// it's a wait for temp
 		new_movebuffer->waitfor_temp = 1;
 		new_movebuffer->nullmove = 0;
-		#if (F_CPU & 0xFF000000) == 0
-			// set "step" timeout to 1 second
-			new_movebuffer->c = F_CPU << 8;
-		#else
-			// set "step" timeout to maximum
-			new_movebuffer->c = 0xFFFFFF00;
-		#endif
 	}
 
 	// make certain all writes to global memory
@@ -163,13 +156,13 @@ void next_move() {
 		// tail must be set before setTimer call as setTimer
 		// reenables the timer interrupt, potentially exposing
 		// mb_tail to the timer interrupt routine. 
-		mb_tail = t;	
+		mb_tail = t;
 		if (current_movebuffer->waitfor_temp) {
 			#ifndef	REPRAP_HOST_COMPATIBILITY
 				serial_writestr_P(PSTR("Waiting for target temp\n"));
 			#endif
 			current_movebuffer->live = 1;
-			setTimer(current_movebuffer->c >> 8);
+			setTimer(HEATER_WAIT_TIMEOUT);
 		}
 		else {
 			dda_start(current_movebuffer);
@@ -177,7 +170,7 @@ void next_move() {
 	} 
 	if (queue_empty())
 		setTimer(0);
-		
+
 }
 
 /// DEBUG - print queue.

dda_queue.h

@@ -3,6 +3,14 @@
 
 #include	"dda.h"
 
+#if (F_CPU & 0xFF000000) == 0
+	// set timeout to 1 second
+	#define HEATER_WAIT_TIMEOUT (F_CPU << 8)
+#else
+	// set timeout to maximum
+	#define HEATER_WAIT_TIMEOUT 0xFFFFFF00
+#endif
+
 /*
 	variables
 */