Small change of plans, moved stuff around

3 files changed, 28 insertions, 2 deletions

diff --git a/doc/CUBE_INTERNAL.md b/doc/CUBE_INTERNAL.md
new file mode 100644
index 0000000..fd3148a
--- /dev/null
+++ b/doc/CUBE_INTERNAL.md
@@ -0,0 +1,24 @@
+# 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.
diff --git a/utils/FORMAT.txt b/doc/CUBE_TEXT.md
index 5bfb01e..b9234fc 100644
--- a/utils/FORMAT.txt
+++ b/doc/CUBE_TEXT.md
@@ -1,8 +1,10 @@
+# Textual representation of the cube
+
 The functions readcube() and writecube() use different formats to read
 and write a cube to text. Not all formats are supported for both input
 and output.
 
-# H48 - standard format for h48 (read, write)
+## H48 - standard format for h48 (read, write)
 
 Each edge is represented by two letters denoting the sides it belongs to
 and one number denoting its orientation (0 oriented, 1 mis-oriented).
@@ -25,7 +27,7 @@ The cube after the moves R'U'F looks like this:
 FL1 BR0 DB0 UR1 UF0 UB0 DL0 FR0 UL1 DF1 BL0 DR0
 UBL1 DBR1 UFR2 DFR2 DFL2 UBL2 UFL2 DBL0
 
-# SRC - representation of the object in C code for cube_array (write)
+## SRC - representation of the object in C code for cube_array (write)
 
 The exact format depends on the internal cube representation. It is
 guaranteed that, if OUT is the output in this format, the line
diff --git a/utils/TRANSFORMATIONS.txt b/doc/TRANSFORMATIONS.md
index 58446e8..58446e8 100644
--- a/utils/TRANSFORMATIONS.txt
+++ b/doc/TRANSFORMATIONS.md