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Fix an acceleration anomaly by making block->steps unsigned #3614

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Fix an acceleration anomaly by making block->steps unsigned #3614

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2 changes: 1 addition & 1 deletion Marlin/planner.h
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Original file line number Diff line number Diff line change
Expand Up @@ -52,7 +52,7 @@
// the source g-code and may never actually be reached if acceleration management is active.
typedef struct {
// Fields used by the bresenham algorithm for tracing the line
long steps[NUM_AXIS]; // Step count along each axis
unsigned long steps[NUM_AXIS]; // Step count along each axis
unsigned long step_event_count; // The number of step events required to complete this block
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I see that steps and step_event_count are treated as though they cannot go over 0x7FFFFFFF in the Bresenham algorithm. The negative of the value is assigned to a counter. Then the algorithm looks for the counter to go over zero. If steps or step_event_count are ever 0x80000000 or higher, the code will fail. But surely there could never be more than 2.14 billion steps in a single move, right?

long accelerate_until; // The index of the step event on which to stop acceleration
long decelerate_after; // The index of the step event on which to start decelerating
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