50 lines
1.9 KiB
Diff
50 lines
1.9 KiB
Diff
From c8e28f3ff9b72eace20cce851d77a6de5e995c69 Mon Sep 17 00:00:00 2001
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From: Markus Hitter <mah@jump-ing.de>
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Date: Sun, 12 Oct 2014 23:17:48 +0200
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Subject: [PATCH] dda.c: attempts to use sign of dda->delta_um[] to set
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direction.
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At that point we stored movement distance in steps signed in
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dda->delta_um[] as well as unsigned in dda->delta[] plus its
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sign in dda->{xyze}_direction. That's obvously redundant, so
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the try was to get rid of the redundancy.
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However, dda_start() is the most time critical part when using
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look-ahead, so this attemt was dropped. Next attempt will be to
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use dda->{xyze}_direction in dda_find_crossing_speed(), the only
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usage of the dda->delta_um[].
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---
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dda.c | 16 +++++++++++++++-
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1 file changed, 15 insertions(+), 1 deletion(-)
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diff --git a/dda.c b/dda.c
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index 8d53256..195e472 100644
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--- a/dda.c
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+++ b/dda.c
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@@ -468,7 +468,21 @@ void dda_start(DDA *dda) {
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endstops_on();
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// set direction outputs
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- x_direction(dda->x_direction);
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+ // This is the fastest one.
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+ x_direction(dda->x_direction); // 20164 bytes
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+ // Costs 14 additional CPU clock cycles.
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+ //x_direction(dda->delta_um[X] < 0 ? 1 : 0); // 20184 bytes
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+ // Costs 12 additional CPU clock cycles.
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+ //x_direction(dda->delta_um[X] >> (sizeof(int32_t) * 8 - 1)); // 20178 bytes
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+ // Costs 14 additional CPU clock cycles.
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+ //x_direction(dda->delta_um[X] > 0); // 20184 bytes
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+ // Costs 12 additional CPU clock cycles.
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+ //x_direction(dda->delta_um[X] < 0); // 20178 bytes
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+ // Costs 5 additional CPU clock cycles.
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+ //x_direction( ! ((*((uint8_t *)(&dda->delta_um[X]) + 3)) & 0x80)); // 20172 bytes
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+ // Check just the last byte, that's smaller and faster.
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+ // Costs 6 additional CPU clock cycles.
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+ //x_direction((*((uint8_t *)(&dda->delta_um[X]) + 3)) > 0); // 20172 bytes
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y_direction(dda->y_direction);
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z_direction(dda->z_direction);
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e_direction(dda->e_direction);
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--
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2.1.0
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