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DDA: reduce code duplication and simplify. 

There are three locations in the code that repeat a pattern of
"If z=0 then use 2d-approx(dx,dy), else if x==0 && y==0 then use dz,
else use 3d-approx".

Teach approx_distance_3 to detect these conditions for us and apply
the same logic.  Replace the three call locations with a simple call
to approx_distance_3.

Binary size for the LOOKAHEAD case drops by almost 400 bytes:

  old:  FLASH : 21242 bytes          149%       70%        34%       17%
  new:  FLASH : 20844 bytes          146%       68%        33%       17%

The size for non-LOOKAHEAD drops by 40 bytes:

  old:  FLASH : 16592 bytes          116%       55%        27%       13%
  new:  FLASH : 16552 bytes          116%       54%        27%       13%

We can actually do a little better if we consider the zero-ness of all
three axes, but this does make the code a little bit bigger. Another
change will consider that option. This change simply tries to mimic
the existing functionality.
This commit is contained in:
Phil Hord 2013-10-31 12:25:49 -04:00 committed by Markus Hitter
parent ed9f56a9d8
commit 88b6101e9a
1 changed files with 8 additions and 22 deletions
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30
dda_lookahead.c
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@ -183,29 +183,15 @@ void dda_find_crossing_speed(DDA *prev, DDA *current) {
// Find out movement distances.
// TODO: remember these from dda_start();
if (prev->delta_um.Z == 0)
prev_distance = approx_distance(
prev->x_direction ? prev->delta_um.X : - prev->delta_um.X,
prev->y_direction ? prev->delta_um.Y : - prev->delta_um.Y);
else if (prev->delta_um.X == 0 && prev->delta_um.Y == 0)
prev_distance = prev->z_direction ? prev->delta_um.Z : - prev->delta_um.Z;
else
prev_distance = approx_distance_3(
prev->x_direction ? prev->delta_um.X : - prev->delta_um.X,
prev->y_direction ? prev->delta_um.Y : - prev->delta_um.Y,
prev->z_direction ? prev->delta_um.Z : - prev->delta_um.Z);
prev_distance = approx_distance_3(
prev->x_direction ? prev->delta_um.X : - prev->delta_um.X,
prev->y_direction ? prev->delta_um.Y : - prev->delta_um.Y,
prev->z_direction ? prev->delta_um.Z : - prev->delta_um.Z);
if (current->delta_um.Z == 0)
curr_distance = approx_distance(
current->x_direction ? current->delta_um.X : - current->delta_um.X,
current->y_direction ? current->delta_um.Y : - current->delta_um.Y);
else if (current->delta_um.X == 0 && current->delta_um.Y == 0)
curr_distance = current->z_direction ? current->delta_um.Z : - current->delta_um.Z;
else
curr_distance = approx_distance_3(
current->x_direction ? current->delta_um.X : - current->delta_um.X,
current->y_direction ? current->delta_um.Y : - current->delta_um.Y,
current->z_direction ? current->delta_um.Z : - current->delta_um.Z);
curr_distance = approx_distance_3(
current->x_direction ? current->delta_um.X : - current->delta_um.X,
current->y_direction ? current->delta_um.Y : - current->delta_um.Y,
current->z_direction ? current->delta_um.Z : - current->delta_um.Z);
if (DEBUG_DDA && (debug_flags & DEBUG_DDA))
sersendf_P(PSTR("Distance: %lu, then %lu\n"), prev_distance, curr_distance);