From: Michel Pollet <buserror@gmail.com>
Date: Mon, 28 May 2012 09:18:20 +0000 (+0100)
Subject: reprap: Steppers use proper logic
X-Git-Url: http://git.rot13.org/?a=commitdiff_plain;ds=sidebyside;h=60d62d42dc3bd3e1b9344ab76ed0930afcf88f9b;p=simavr

reprap: Steppers use proper logic

For underflow detection, instead of using a signed value

Signed-off-by: Michel Pollet <buserror@gmail.com>
---

diff --git a/examples/board_reprap/src/stepper.c b/examples/board_reprap/src/stepper.c
index 23f6e7d..81acda6 100644
--- a/examples/board_reprap/src/stepper.c
+++ b/examples/board_reprap/src/stepper.c
@@ -79,9 +79,7 @@ stepper_step_hook(
 		return;
 	if (value)
 		return;
-	p->position += p->dir ? 1 : -1;
-	if (p->position < 0)
-		p->position = 0;
+	p->position += !p->dir && p->position == 0 ? 0 : p->dir ? 1 : -1;
 	if (p->endstop && p->position < p->endstop)
 		p->position = p->endstop;
 	if (p->max_position > 0 && p->position > p->max_position)
diff --git a/examples/board_reprap/src/stepper.h b/examples/board_reprap/src/stepper.h
index 14b0df1..9f450ac 100644
--- a/examples/board_reprap/src/stepper.h
+++ b/examples/board_reprap/src/stepper.h
@@ -40,7 +40,7 @@ typedef struct stepper_t {
 	char name[32];
 	int enable : 1, dir : 1, trace : 1;
 	double steps_per_mm;
-	int64_t	position;	// in steps
+	uint64_t	position;	// in steps
 	uint64_t max_position;
 	uint64_t endstop;
 	avr_cycle_count_t timer_period;