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dda.c: describe all lookahead cases in a comment.

This commit is contained in:
Markus Hitter 2013-11-29 19:31:13 +01:00
parent d10c0f3041
commit 1b5682c01a
1 changed files with 20 additions and 2 deletions
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22
dda.c
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@ -82,7 +82,24 @@ void dda_new_startpoint(void) {
It also pre-fills any data that the selected accleration algorithm needs, and can be pre-computed for the whole move. It also pre-fills any data that the selected accleration algorithm needs, and can be pre-computed for the whole move.
This algorithm is probably the main limiting factor to print speed in terms of firmware limitations This algorithm is probably the main limiting factor to print speed in terms of firmware limitations
*/ *
* Regarding lookahead, we can distinguish everything into these cases:
*
* 1. Standard movement. To be joined with the previous move.
* 2. Movement after a pause. This interrupts lookahead, and invalidates
* prev_dda and prev_distance.
* 3. Non-move, e.g. a wait for temp. This also interrupts lookahead and makes
* prev_dda and prev_distance invalid. There might be more such cases in the
* future, e.g. when heater or fan changes are queued up, too.
* 4. Nullmove due to no movement expected, e.g. a pure speed change. This
* shouldn't interrupt lookahead and be handled af if the change would come
* with the next movement.
* 5. Nullmove due to movement smaller than a single step. Shouldn't interrupt
* lookahead either, but this small distance should be added to the next
* movement.
* 6. Lookahead calculation too slow. This is handled in dda_join_moves()
* already.
*/
void dda_create(DDA *dda, TARGET *target) { void dda_create(DDA *dda, TARGET *target) {
uint32_t steps, x_delta_um, y_delta_um, z_delta_um, e_delta_um; uint32_t steps, x_delta_um, y_delta_um, z_delta_um, e_delta_um;
uint32_t distance, c_limit, c_limit_calc; uint32_t distance, c_limit, c_limit_calc;
@ -98,7 +115,8 @@ void dda_create(DDA *dda, TARGET *target) {
if (dda->waitfor_temp) if (dda->waitfor_temp)
return; return;
// initialise DDA to a known state // Initialise DDA to a known state. This also clears flags like
// dda->live, dda->done and dda->wait_for_temp.
dda->allflags = 0; dda->allflags = 0;
if (DEBUG_DDA && (debug_flags & DEBUG_DDA)) if (DEBUG_DDA && (debug_flags & DEBUG_DDA))