Update current_position only as needed.

This saves almost 200 bytes and 100 runs of
update_current_position() per second.

clock.c

@@ -42,6 +42,7 @@ void clock_250ms() {
 	ifclock(clock_flag_1s) {
 		if (DEBUG_POSITION && (debug_flags & DEBUG_POSITION)) {
 			// current position
+			update_current_position();
 			sersendf_P(PSTR("Pos: %ld,%ld,%ld,%ld,%lu\n"), current_position.X, current_position.Y, current_position.Z, current_position.E, current_position.F);
 
 			// target position
@@ -75,7 +76,5 @@ void clock_10ms() {
 	ifclock(clock_flag_250ms) {
 		clock_250ms();
 	}
-
-	update_position();
 }
 

dda.c

@@ -169,7 +169,7 @@ const uint8_t	msbloc (uint32_t v) {
 */
 void dda_init(void) {
 	// set up default feedrate
-	current_position.F = startpoint.F = next_target.target.F = SEARCH_FEEDRATE_Z;
+	startpoint.F = next_target.target.F = SEARCH_FEEDRATE_Z;
 
 	#ifdef ACCELERATION_RAMPING
 		move_state.n = 1;
@@ -392,12 +392,7 @@ void dda_create(DDA *dda, TARGET *target) {
 */
 void dda_start(DDA *dda) {
 	// called from interrupt context: keep it simple!
-	if (dda->nullmove) {
+	if ( ! dda->nullmove) {
-		// just change speed?
-		current_position.F = dda->endpoint.F;
-		// keep dda->live = 0
-	}
-	else {
 		// get ready to go
 		steptimeout = 0;
 		if (dda->z_delta)
@@ -435,6 +430,9 @@ void dda_start(DDA *dda) {
 		setTimer(dda->c >> 8);
 		#endif
 	}
+	// else just a speed change, keep dda->live = 0
+
+	current_position.F = dda->endpoint.F;
 }
 
 /*! STEP
@@ -648,13 +646,6 @@ void dda_step(DDA *dda) {
 	}
 	else if (move_state.x_steps == 0 && move_state.y_steps == 0 && move_state.z_steps == 0 && move_state.e_steps == 0) {
 		dda->live = 0;
-		// if E is relative reset it
-		#ifndef E_ABSOLUTE
-			current_position.E = 0;
-		#endif
-		// linear acceleration code doesn't alter F during a move, so we must update it here
-		// in theory, we *could* update F every step, but that would require a divide in interrupt context which should be avoided if at all possible
-		current_position.F = dda->endpoint.F;
 		#ifdef	DC_EXTRUDER
 			heater_set(DC_EXTRUDER, 0);
 		#endif
@@ -683,7 +674,7 @@ void dda_step(DDA *dda) {
 }
 
 /// update global current_position struct
-void update_position() {
+void update_current_position() {
 	DDA *dda = &movebuffer[mb_tail];
 
 	if (dda->live == 0)
@@ -712,4 +703,6 @@ void update_position() {
 		else
 			current_position.E = dda->endpoint.E + move_state.e_steps;
 	#endif
+
+	// current_position.F is updated in dda_start()
 }

dda.h

@@ -165,6 +165,6 @@ void dda_start(DDA *dda)																						__attribute__ ((hot));
 void dda_step(DDA *dda)																							__attribute__ ((hot));
 
 // update current_position
-void update_position(void);
+void update_current_position(void);
 
 #endif	/* _DDA_H */

dda_queue.c

@@ -191,7 +191,7 @@ void print_queue() {
 }
 
 /// dump queue for emergency stop.
-/// \todo effect on startpoint/current_position is undefined!
+/// \todo effect on startpoint is undefined!
 void queue_flush() {
 	// Since the timer interrupt is disabled before this function
 	// is called it is not strictly necessary to write the variables

gcode_process.c

@@ -278,28 +278,28 @@ void process_gcode_command() {
 				queue_wait();
 
 				if (next_target.seen_X) {
-					startpoint.X = current_position.X = next_target.target.X;
+					startpoint.X = next_target.target.X;
 					axisSelected = 1;
 				}
 				if (next_target.seen_Y) {
-					startpoint.Y = current_position.Y = next_target.target.Y;
+					startpoint.Y = next_target.target.Y;
 					axisSelected = 1;
 				}
 				if (next_target.seen_Z) {
-					startpoint.Z = current_position.Z = next_target.target.Z;
+					startpoint.Z = next_target.target.Z;
 					axisSelected = 1;
 				}
 				if (next_target.seen_E) {
 					#ifdef	E_ABSOLUTE
-						startpoint.E = current_position.E = next_target.target.E;
+						startpoint.E = next_target.target.E;
 					#endif
 					axisSelected = 1;
 				}
 
 				if (axisSelected == 0) {
-					startpoint.X = current_position.X = next_target.target.X =
+					startpoint.X = next_target.target.X =
-					startpoint.Y = current_position.Y = next_target.target.Y =
+					startpoint.Y = next_target.target.Y =
-					startpoint.Z = current_position.Z = next_target.target.Z = 0;
+					startpoint.Z = next_target.target.Z = 0;
 				}
 				break;
 
@@ -574,6 +574,7 @@ void process_gcode_command() {
 					// wait for all moves to complete
 					queue_wait();
 				#endif
+				update_current_position();
 				sersendf_P(PSTR("X:%lq,Y:%lq,Z:%lq,E:%lq,F:%ld"), current_position.X * ((int32_t) UM_PER_STEP_X), current_position.Y * ((int32_t) UM_PER_STEP_Y), current_position.Z * ((int32_t) UM_PER_STEP_Z), current_position.E * ((int32_t) UM_PER_STEP_E), current_position.F);
 				// newline is sent from gcode_parse after we return
 				break;
@@ -740,6 +741,7 @@ void process_gcode_command() {
 				//? --- M250: return current position, end position, queue ---
 				//? Undocumented
 				//? This command is only available in DEBUG builds.
+				update_current_position();
 				sersendf_P(PSTR("{X:%ld,Y:%ld,Z:%ld,E:%ld,F:%lu,c:%lu}\t{X:%ld,Y:%ld,Z:%ld,E:%ld,F:%lu,c:%lu}\t"), current_position.X, current_position.Y, current_position.Z, current_position.E, current_position.F, movebuffer[mb_tail].c, movebuffer[mb_tail].endpoint.X, movebuffer[mb_tail].endpoint.Y, movebuffer[mb_tail].endpoint.Z, movebuffer[mb_tail].endpoint.E, movebuffer[mb_tail].endpoint.F,
 					#ifdef ACCELERATION_REPRAP
 						movebuffer[mb_tail].end_c

home.c

@@ -56,10 +56,9 @@ void home_x_negative() {
 		// set X home
 		queue_wait(); // we have to wait here, see G92
 		#ifdef X_MIN
-			startpoint.X = current_position.X = next_target.target.X =
+			startpoint.X = next_target.target.X = (int32_t)(X_MIN * STEPS_PER_MM_X);
-			               (int32_t)(X_MIN * STEPS_PER_MM_X);
 		#else
-			startpoint.X = current_position.X = next_target.target.X = 0;
+			startpoint.X = next_target.target.X = 0;
 		#endif
 	#endif
 }
@@ -92,8 +91,7 @@ void home_x_positive() {
 		// set X home
 		queue_wait();
 		// set position to MAX
-		startpoint.X = current_position.X = next_target.target.X =
+		startpoint.X = next_target.target.X = (int32_t)(X_MAX * STEPS_PER_MM_X);
-		               (int32_t)(X_MAX * STEPS_PER_MM_X);
 		// go to zero
 		t.X = 0;
 		t.F = MAXIMUM_FEEDRATE_X;
@@ -126,10 +124,9 @@ void home_y_negative() {
 		// set Y home
 		queue_wait();
 		#ifdef	Y_MIN
-			startpoint.Y = current_position.Y = next_target.target.Y =
+			startpoint.Y = next_target.target.Y = (int32_t)(Y_MIN * STEPS_PER_MM_Y);
-			               (int32_t)(Y_MIN * STEPS_PER_MM_Y);
 		#else
-			startpoint.Y = current_position.Y = next_target.target.Y = 0;
+			startpoint.Y = next_target.target.Y = 0;
 		#endif
 	#endif
 }
@@ -162,8 +159,7 @@ void home_y_positive() {
 		// set Y home
 		queue_wait();
 		// set position to MAX
-		startpoint.Y = current_position.Y = next_target.target.Y =
+		startpoint.Y = next_target.target.Y = (int32_t)(Y_MAX * STEPS_PER_MM_Y);
-		               (int32_t)(Y_MAX * STEPS_PER_MM_Y);
 		// go to zero
 		t.Y = 0;
 		t.F = MAXIMUM_FEEDRATE_Y;
@@ -196,10 +192,9 @@ void home_z_negative() {
 		// set Z home
 		queue_wait();
 		#ifdef Z_MIN
-			startpoint.Z = current_position.Z = next_target.target.Z =
+			startpoint.Z = next_target.target.Z = (int32_t)(Z_MIN * STEPS_PER_MM_Z);
-			               (int32_t)(Z_MIN * STEPS_PER_MM_Z);
 		#else
-			startpoint.Z = current_position.Z = next_target.target.Z = 0;
+			startpoint.Z = next_target.target.Z = 0;
 		#endif
 		z_disable();
 	#endif
@@ -233,8 +228,7 @@ void home_z_positive() {
 		// set Z home
 		queue_wait();
 		// set position to MAX
-		startpoint.Z = current_position.Z = next_target.target.Z =
+		startpoint.Z = next_target.target.Z = (int32_t)(Z_MAX * STEPS_PER_MM_Z);
-		               (int32_t)(Z_MAX * STEPS_PER_MM_Z);
 		// go to zero
 		t.Z = 0;
 		t.F = MAXIMUM_FEEDRATE_Z;