From 0fe3b1699f3ce2cf3ca6f5466fa8f9930563dda0 Mon Sep 17 00:00:00 2001
From: Kistaro Windrider <kistaro@gmail.com>
Date: Thu, 22 Dec 2022 23:15:03 -0800
Subject: [PATCH] packed crate representation

don't bother exploding crates into four bools, and then comparing them all individually to a bunch of conditions. absurd bit manipulation bullshit saves cycles and tokens. leaving a crate's movement rule represented as four bits means we can exploit our previous calculation of dx1 and dy1, which must each either be 0x0001 or 0x8FFF, and violently hammer them down to align with this bit-packed representation, giving this glorious little atrocity.
---
 chameleonic.p8 | 31 ++++++++++++++++---------------
 1 file changed, 16 insertions(+), 15 deletions(-)

diff --git a/chameleonic.p8 b/chameleonic.p8
index d91f9e5..498cf3f 100644
--- a/chameleonic.p8
+++ b/chameleonic.p8
@@ -480,16 +480,18 @@ function _mix(mx,my)
   return mx..","..my
 end
 
+-- crate spec:
+-- "up" == 1
+-- "right" == 2
+-- "down" == 4
+-- "left" == 8
+--
+--    +1+
+--    8 2
+--    +4+
 function level:_get_cratedef(s)
- if (s<64 or s>=80) return nil
- 
- local s2=s-64
- return {
-  up=s2&1!=0,
-  right=s2&2!=0,
-  down=s2&4!=0,
-  left=s2&8!=0
- }
+ if (s<64 or s>=80) return
+ return s & 0x000F
 end
 
 function level:get_latch(dx,dy,px,py)
@@ -500,12 +502,11 @@ function level:get_latch(dx,dy,px,py)
  local dx1,dy1=-sgn0(dx),-sgn0(dy)
 
  if crate then
-  if
-   (crate.def.up and dy>0) or
-   (crate.def.down and dy<0) or 
-   (crate.def.left and dx>0) or
-   (crate.def.right and dx<0)
-  then
+  if crate.def & (
+    dy1 >>> 15 | 
+    (dy1 & 0x1) << 2 |
+    (dx1 & 0x8000) >>> 12 |
+    (dx1 & 0x1) << 1) ~= 0 then
    return {
     el="crate",
     dx=dx1,dy=dy1,