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

1 files changed, 46 insertions, 16 deletions

diff --git a/src/solvers/h48/gendata_h48.h b/src/solvers/h48/gendata_h48.h
index 55c4f34..ae0b732 100644
--- a/src/solvers/h48/gendata_h48.h
+++ b/src/solvers/h48/gendata_h48.h
@@ -61,13 +61,13 @@ gendata_h48short(gendata_h48short_arg_t *arg)
         return arg->map->n;
 }
 
-/* Generic function that dispatches to the data generators */
 STATIC int64_t
 gendata_h48(gendata_h48_arg_t *arg)
 {
-        uint64_t size, cocsepsize, h48size, fallbacksize;
+        uint64_t size, cocsepsize, h48size, fallbacksize, fallback2size, of;
+        long long r;
         void *cocsepdata_offset;
-        tableinfo_t cocsepinfo, h48info;
+        tableinfo_t cocsepinfo, h48info, fallbackinfo;
         gendata_h48_arg_t arg_h0k4;
 
         if (arg == NULL) {
@@ -78,7 +78,8 @@ gendata_h48(gendata_h48_arg_t *arg)
         cocsepsize = COCSEP_FULLSIZE;
         h48size = INFOSIZE + H48_TABLESIZE(arg->h, arg->k);
         fallbacksize = arg->k == 2 ? INFOSIZE + H48_TABLESIZE(0, 4) : 0;
-        size = cocsepsize + h48size + fallbacksize;
+        fallback2size = EOESEP_FULLSIZE;
+        size = cocsepsize + h48size + fallbacksize + fallback2size;
 
         if (arg->buf == NULL)
                 return size; /* Dry-run */
@@ -110,18 +111,22 @@ gendata_h48(gendata_h48_arg_t *arg)
                 return NISSY_ERROR_INVALID_SOLVER;
         }
 
-        if (readtableinfo(arg->buf_size, arg->buf, &cocsepinfo) != NISSY_OK) {
+        r = readtableinfo(arg->buf_size, arg->buf, &cocsepinfo);
+        if (r != NISSY_OK) {
                 LOG("gendata_h48: could not read info for cocsep table\n");
                 return NISSY_ERROR_UNKNOWN;
         }
 
         cocsepinfo.next = cocsepsize;
-        if (writetableinfo(&cocsepinfo, arg->buf_size, arg->buf) != NISSY_OK) {
+        r = writetableinfo(&cocsepinfo, arg->buf_size, arg->buf);
+        if (r != NISSY_OK) {
                 LOG("gendata_h48: could not write info for cocsep table"
                     " with updated 'next' value\n");
                 return NISSY_ERROR_UNKNOWN;
         }
 
+        /* Add h0k4 fallback table */
+
         if (arg->k == 2) {
                 arg_h0k4 = *arg;
                 arg_h0k4.h = 0;
@@ -134,16 +139,42 @@ gendata_h48(gendata_h48_arg_t *arg)
 
                 gendata_h48h0k4(&arg_h0k4);
 
-                if (readtableinfo_n(arg->buf_size, arg->buf, 2, &h48info)
-                    != NISSY_OK) {
-                        LOG("gendata_h48: could not read info for h48 table\n");
+        }
+
+        /* Add eoesep fallback table */
+
+        gendata_eoesep((char *)arg->buf + (size - fallback2size), 20);
+
+        /* Update tableinfo with correct next values */
+
+        r = readtableinfo_n(arg->buf_size, arg->buf, 2, &h48info);
+        if (r != NISSY_OK) {
+                LOG("gendata_h48: could not read info for h48 table\n");
+                return NISSY_ERROR_UNKNOWN;
+        }
+        h48info.next = h48size;
+        r = writetableinfo(&h48info,
+             arg->buf_size - cocsepsize, (char *)arg->buf + cocsepsize);
+        if (r != NISSY_OK) {
+                LOG("gendata_h48: could not write info for h48 table\n");
+                return NISSY_ERROR_UNKNOWN;
+        }
+
+        if (arg->k == 2) {
+                r = readtableinfo_n(arg->buf_size, arg->buf, 3, &fallbackinfo);
+                if (r != NISSY_OK) {
+                        LOG("gendata_h48: could not read info for h48 "
+                            "fallback table\n");
                         return NISSY_ERROR_UNKNOWN;
                 }
 
-                h48info.next = h48size;
-                if (writetableinfo(&h48info, arg->buf_size - cocsepsize,
-                    (char *)arg->buf + cocsepsize) != NISSY_OK) {
-                        LOG("gendata_h48: could not write info for h48 table\n");
+                of = cocsepsize + h48size;
+                fallbackinfo.next = fallbacksize;
+                r = writetableinfo(&fallbackinfo,
+                    arg->buf_size - of, (char *)arg->buf + of);
+                if (r != NISSY_OK) {
+                        LOG("gendata_h48: could not write info for h48 "
+                            "fallback table\n");
                         return NISSY_ERROR_UNKNOWN;
                 }
         }
@@ -302,9 +333,8 @@ gendata_h48k2(gendata_h48_arg_t *arg)
          *
          * The following values for the base have been hand-picked. I first
          * performed some statistics on the frequency of these values, but
-         * they turned out to be unreliable. I have not figured out why yet.
-         * In the end I resorted to generating the same table with multiple
-         * base value and see what was best.
+         * they turned out to be unreliable. In the end I generated the same
+         * table with multiple base value and see what was best.
          *
          * A curious case is h3, which has this distribution for base 8:
          *   [0] = 6686828