Bugfix: bad math for long distance moves.

1 files changed, 5 insertions, 1 deletions

diff --git a/Sprinter/Sprinter.pde b/Sprinter/Sprinter.pde
index 1aa91f7..b31a629 100644
--- a/Sprinter/Sprinter.pde
+++ b/Sprinter/Sprinter.pde
@@ -1010,7 +1010,11 @@ void linear_move(unsigned long axis_steps_remaining[]) // make linear move with
       }
     for(int i = 0; i < NUM_AXIS; i++)
       if(axis_steps_remaining[i] >0) {
-        new_axis_max_intervals[i] = slowest_start_axis_max_interval * axis_steps_remaining[slowest_start_axis] / axis_steps_remaining[i];
+        // multiplying slowest_start_axis_max_interval by axis_steps_remaining[slowest_start_axis]
+        // could lead to overflows when we have long distance moves (say, 390625*390625 > sizeof(unsigned long))
+        float steps_remaining_ratio = axis_steps_remaining[slowest_start_axis] / axis_steps_remaining[i];
+        new_axis_max_intervals[i] = slowest_start_axis_max_interval * steps_remaining_ratio;
+        
         if(i == primary_axis) {
           max_interval = new_axis_max_intervals[i];
           min_speed_steps_per_second = 100000000 / max_interval;