1 files changed, 40 insertions, 11 deletions

diff --git a/src/solvers/h48/solve.h b/src/solvers/h48/solve.h
index 2a5e341..8f55501 100644
--- a/src/solvers/h48/solve.h
+++ b/src/solvers/h48/solve.h
@@ -11,6 +11,7 @@ typedef struct {
         uint8_t base;
         const uint32_t *cocsepdata;
         const uint8_t *h48data;
+        const uint8_t *h48data_fallback;
         uint64_t solutions_size;
         char **nextsol;
         uint8_t nissbranch;
@@ -112,16 +113,31 @@ solve_h48_stop(dfsarg_solveh48_t *arg)
 
         h48bound = get_h48_bound(arg->cube, data, arg->h, arg->k, arg->h48data);
 
-        /* If the h48 bound is > 0, we add the base value.        */
-        /* Otherwise, we use the cbound value instead (fallback). */
-        h48bound += h48bound == 0 ? cbound : arg->base;
+        /* If the h48 bound is > 0, we add the base value.    */
+        /* Otherwise, we use the fallback h0k4 value instead. */
+
+        if (arg->k == 2) {
+                if (h48bound == 0) {
+                        h48bound = get_h48_bound(
+                            arg->cube, data, 0, 4, arg->h48data_fallback);
+                } else {
+                        h48bound += arg->base;
+                }
+        }
         if (h48bound + arg->nmoves + arg->npremoves > arg->depth)
                 return true;
         if (h48bound + arg->nmoves + arg->npremoves == arg->depth)
                 arg->nissbranch = MM_INVERSEBRANCH;
 
         h48bound_inv = get_h48_bound(arg->inverse, data_inv, arg->h, arg->k, arg->h48data);
-        h48bound_inv += h48bound_inv == 0 ? cbound_inv : arg->base;
+        if (arg->k == 2) {
+                if (h48bound_inv == 0) {
+                        h48bound_inv = get_h48_bound(
+                            arg->inverse, data_inv, 0, 4, arg->h48data_fallback);
+                } else {
+                        h48bound_inv += arg->base;
+                }
+        }
         if (h48bound_inv + arg->nmoves + arg->npremoves > arg->depth)
                 return true;
         if (h48bound_inv + arg->nmoves + arg->npremoves == arg->depth)
@@ -194,12 +210,10 @@ solve_h48(
 {
         _Atomic int64_t nsols;
         dfsarg_solveh48_t arg;
-        tableinfo_t info;
+        tableinfo_t info, fbinfo;
 
-        if(readtableinfo_n(data_size, data, 2, &info) != NISSY_OK) {
-                LOG("solve_h48: error reading table\n");
-                return NISSY_ERROR_DATA;
-        }
+        if(readtableinfo_n(data_size, data, 2, &info) != NISSY_OK)
+                goto solve_h48_error_data;
 
         arg = (dfsarg_solveh48_t) {
                 .cube = cube,
@@ -209,12 +223,23 @@ solve_h48(
                 .h = info.h48h,
                 .k = info.bits,
                 .base = info.base,
-                .cocsepdata = get_cocsepdata_constptr(data),
-                .h48data = get_h48data_constptr(data),
+                .cocsepdata = (uint32_t *)((char *)data + INFOSIZE),
+                .h48data = (uint8_t *)data + COCSEP_FULLSIZE + INFOSIZE,
                 .solutions_size = solutions_size,
                 .nextsol = &solutions
         };
 
+        if (info.bits == 2) {
+                if (readtableinfo_n(data_size, data, 3, &fbinfo) != NISSY_OK)
+                        goto solve_h48_error_data;
+                /* We only support h0k4 as fallback table */
+                if (fbinfo.h48h != 0 || fbinfo.bits != 4)
+                        goto solve_h48_error_data;
+                arg.h48data_fallback = arg.h48data + info.next;
+        } else {
+                arg.h48data_fallback = NULL;
+        }
+
         nsols = 0;
         for (arg.depth = minmoves;
              arg.depth <= maxmoves && nsols < maxsolutions;
@@ -229,4 +254,8 @@ solve_h48(
         **arg.nextsol = '\0';
         (*arg.nextsol)++;
         return nsols;
+
+solve_h48_error_data:
+        LOG("solve_h48: error reading table\n");
+        return NISSY_ERROR_DATA;
 }