Merge the "solver-experiments" branch that I have been working on for

a few weeks. This include mainly three things:

1. Various tweaks for a total performance gain of around 30%.
2. Take into account symmetries and avoid repeated work. This
   required a re-work of the splitting into tasks before the solve.
3. Add a second fallback table (eoesep). This gives huge performance
   gains for particular scrambles (e.g. superflip).

After merging this commit, remove and re-generate all pruning tables.

Squashed commit of the following:

commit 60f0705d2d69050e6a30581a2810f686d6f69b80
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Sat Dec 7 16:06:48 2024 +0100

    Fix indentation

commit cc5d489a251812b6188c0ba264ac6cb2236f1afe
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Sat Dec 7 15:56:19 2024 +0100

    Updated documentation

commit a3f605dd628546e52564f82b139feb473b0725f3
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Sat Dec 7 14:01:11 2024 +0100

    use eoesep table as second fallback

commit c75e43c9116c64f97e92b0fe038be8a032925a72
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Fri Dec 6 16:13:23 2024 +0100

    First commit for gendata_eoesep

commit fea7688ab8bdc5ae0c3480622e2510a3bcd39248
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Tue Dec 3 17:31:00 2024 +0100

    Add scramble to tool

commit 66866cb71dea4ca8278ecb9e90ff4295771feb42
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Tue Dec 3 17:22:59 2024 +0100

    Added tool to check multiple solutions

commit ef65611c772c3996bddca8d181da3538e0af1674
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Tue Dec 3 17:16:20 2024 +0100

    Write all solutions for symmetric positions

commit e3ded26db7d7d4ae7c0e2488151ed14f581f7b8e
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Tue Nov 26 09:14:54 2024 +0100

    Added symmetry filter (TODO: print excluded solutions)

commit 864c437a9751c58d58562650ca9eba4a9e6ad3eb
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Mon Nov 25 14:51:13 2024 +0100

    Improved task split

commit b88926d36d7ab0c64c5fe3bb954fd15d41267fba
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Fri Nov 22 19:06:41 2024 +0100

    Reworked tasks for multi-threading in view of symmetry filter

commit 26fa653f97df8cd601aecb80eaf89f0a00e9ba9f
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Thu Oct 31 15:37:43 2024 +0100

    Added transform move

commit 19f655ef94d658eaa2fefb5cea3c167a3ec58db6
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Thu Oct 31 09:29:15 2024 +0100

    Clarified doc

commit 3b0fe1e5ef8b628854e30f0f0067300e2763c954
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Thu Oct 31 08:36:58 2024 +0100

    Handle solved cube correctly

commit 57705cbc4982e3abe97a36ed64871738d4f721c0
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Thu Oct 31 08:24:30 2024 +0100

    Close file

commit fc7d462b58bcf3d3a3fbf26c1f3bd04c640a4898
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Tue Oct 29 15:05:48 2024 +0100

    Removed stats tool

commit 359bf7cb49ef405ee76ed662207d47cb2abcc5a9
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Tue Oct 29 15:01:51 2024 +0100

    Updated theory doc

commit 39c315af562bc4ce896f41004388a4c34d475d37
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Tue Oct 29 14:51:40 2024 +0100

    Remove unused constants

commit 57a5d24538aa59a4df9221dad2f99e9f0286bd9d
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Tue Oct 29 10:20:38 2024 +0100

    Add tool to solve scrambles from file

commit 07e2918c216636891b1fa6adecc9756086a901e9
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Mon Oct 28 17:00:00 2024 +0100

    Add make table to tool

commit f5e5266c654eb027a5a35c57cc618555246f5e5e
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Mon Oct 28 09:35:49 2024 +0100

    Remove old solver, other small things

commit a1ec78025b7959dbb845213f7f4e6851ecebc204
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Sun Oct 27 02:00:29 2024 +0200

    Improvements

commit 8eea23dbe888d923e662e24ae969130e2c67b999
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Sat Oct 26 12:24:19 2024 +0200

    Makefile fix

commit 3fc3927beacc78971cefeb42da8d71fe6c015fc1
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Fri Oct 25 18:25:09 2024 +0200

    More performance gains

commit 7b4efa1f9af9722de1ab9ccfc27899825a0d12c4
Author: Sebastiano Tronto <sebastiano@tronto.net>
Date:   Fri Oct 25 15:53:20 2024 +0200

    Alternative solver implementation, small performance gain

2 files changed, 73 insertions, 21 deletions

diff --git a/src/core/moves.h b/src/core/moves.h
index e3a9bc1..7d4972e 100644
--- a/src/core/moves.h
+++ b/src/core/moves.h
@@ -2,8 +2,8 @@
 #define PREMOVE(M, c) compose(MOVE_CUBE_ ## M, c)
 
 STATIC_INLINE bool allowednextmove(uint8_t *, uint8_t);
+STATIC_INLINE uint32_t allowednextmove_mask(uint8_t *, uint8_t);
 
-STATIC_INLINE uint8_t inverse_trans(uint8_t);
 STATIC_INLINE uint8_t movebase(uint8_t);
 STATIC_INLINE uint8_t moveaxis(uint8_t);
 STATIC_INLINE uint32_t disable_moves(uint32_t, uint8_t);
@@ -38,26 +38,38 @@ STATIC cube_t applymoves(cube_t, const char *);
 STATIC bool
 allowednextmove(uint8_t *moves, uint8_t n)
 {
-        uint8_t base[3], axis[3];
+        return n == 0 ? true :
+            allowednextmove_mask(moves, n-1) & (1 << moves[n-1]);
+}
+
+STATIC uint32_t
+allowednextmove_mask(uint8_t *moves, uint8_t n)
+{
+        uint32_t result;
+        uint8_t base1, base2, axis1, axis2;
+
+        result = MM_ALLMOVES;
 
-        if (n < 2)
-                return true;
+        if (n == 0)
+                return result;
 
-        base[0] = movebase(moves[n-1]);
-        axis[0] = moveaxis(moves[n-1]);
-        base[1] = movebase(moves[n-2]);
-        axis[1] = moveaxis(moves[n-2]);
+        base1 = movebase(moves[n-1]);
+        axis1 = moveaxis(moves[n-1]);
+        result = disable_moves(result, base1 * 3);
 
-        if (base[0] == base[1] || (axis[0] == axis[1] && base[0] < base[1]))
-                return false;
+        if (base1 % 2)
+                result = disable_moves(result, (base1 - 1) * 3);
 
-        if (n == 2)
-                return true;
+        if (n == 1)
+        return result;
 
-        base[2] = movebase(moves[n-3]);
-        axis[2] = moveaxis(moves[n-3]);
+        base2 = movebase(moves[n-2]);
+        axis2 = moveaxis(moves[n-2]);
 
-        return axis[1] != axis[2] || base[0] != base[2];
+        if(axis1 == axis2)
+                result = disable_moves(result, base2 * 3);
+
+        return result;
 }
 
 STATIC_INLINE uint32_t 
@@ -67,12 +79,6 @@ disable_moves(uint32_t current_result, uint8_t base_index)
 }
 
 STATIC_INLINE uint8_t
-inverse_trans(uint8_t t)
-{
-        return inverse_trans_table[t];
-}
-
-STATIC_INLINE uint8_t
 movebase(uint8_t move)
 {
         return move / 3;
@@ -84,6 +90,12 @@ moveaxis(uint8_t move)
         return move / 6;
 }
 
+STATIC_INLINE uint8_t
+moveopposite(uint8_t move)
+{
+        return movebase(move) == 2 * moveaxis(move) ? move + 3 : move - 3;
+}
+
 STATIC cube_t
 move(cube_t c, uint8_t m)
 {
diff --git a/src/core/transform.h b/src/core/transform.h
index 73636fe..f956718 100644
--- a/src/core/transform.h
+++ b/src/core/transform.h
@@ -21,6 +21,9 @@ STATIC cube_t transform_edges(cube_t, uint8_t);
 STATIC cube_t transform_corners(cube_t, uint8_t);
 STATIC cube_t transform(cube_t, uint8_t);
 STATIC cube_t applytrans(cube_t, const char *);
+STATIC_INLINE uint8_t inverse_trans(uint8_t);
+STATIC uint8_t transform_move(uint8_t, uint8_t);
+STATIC uint64_t symmetry_mask(cube_t);
 
 STATIC cube_t
 transform_edges(cube_t c, uint8_t t)
@@ -354,3 +357,40 @@ applytrans(cube_t cube, const char *buf)
 
         return transform(cube, t);
 }
+
+STATIC_INLINE uint8_t
+inverse_trans(uint8_t t)
+{
+        return inverse_trans_table[t];
+}
+
+STATIC uint8_t
+transform_move(uint8_t m, uint8_t t)
+{
+        uint8_t a, base, modifier;
+
+        a = moveaxis(m);
+        base = trans_move_table[t][a];
+        if (movebase(m) != 2 * a)
+                base = moveopposite(base);
+
+        modifier = m % 3;
+        if (t >= TRANS_UFm)
+                modifier = 2 - modifier;
+
+        return base + modifier;
+}
+
+STATIC uint64_t
+symmetry_mask(cube_t cube)
+{
+        uint64_t t, ret;
+        cube_t transformed;
+
+        for (t = 0, ret = 0; t < 48; t++) {
+                transformed = transform(cube, t);
+                ret |= ((uint64_t)equal(cube, transformed)) << t;
+        }
+
+        return ret;
+}