blob: fd3148ac787087ae41a3df3aa7ffe4b868f9fc0d (
plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
|
# Internal representation of the cube
The plan (TODO) is to have multiple implementations: some that
take advantage of advanced CPU instructions (SIMD) and a fallback
"array" representation that works on any architecture.
# Array representation (fallback)
In this implementation of the cube.h interface, the cube is represented
by two arrays of 8-bit unsigned integers, one for centers and one for
corners. The 4 leas-significant digits of each bit determine the piece,
the other 4 are used for orientation or kept to 0.
Edges:
xxxopppp (x = unused, o = orientation, p = piece)
Corners:
xooxpppp (x = unused, o = orientation, p = piece)
The two bits for CO are shifted to make it possible to perform mod 3
operations (sum, inverse) using only addition and bitwise operators.
See below for details.
The third bit is needed because x+y+1 can exceed 4.
|
