1 files changed, 29 insertions, 27 deletions

diff --git a/src/steps.c b/src/steps.c
index ccf33df..7d1823e 100644
--- a/src/steps.c
+++ b/src/steps.c
@@ -1162,74 +1162,76 @@ static int
 estimate_optimal_HTM(DfsArg *arg)
 {
         int target, ret;
-        Move lbase;
+        Move bl1;
         Cube aux;
 
-        target = arg->d - arg->current_alg->len;
-        ret = -1;
-        arg->inverse = (Cube){0};
+        ret              = -1;
+        target           = arg->d - arg->current_alg->len;
+        bl1              = base_move(arg->last1);
+        arg->inverse     = (Cube){0};
         arg->badmovesinv = 0;
-        arg->badmoves = 0;
+        arg->badmoves    = 0;
 
+        /* Corners */
         arg->ed->corners = ptableval(&pd_corners_HTM, arg->cube);
         UPDATECHECKSTOP(ret, arg->ed->corners, target);
 
+        /* Normal probing */
         arg->ed->normal_ud = ptableval(&pd_khuge_HTM, arg->cube);
         UPDATECHECKSTOP(ret, arg->ed->normal_ud, target);
-        if (arg->ed->normal_ud == target) {
-                arg->badmovesinv |= (1<<U) | (1<<U2) | (1<<U3) |
-                                    (1<<D) | (1<<D2) | (1<<D3);
-        }
-
         aux = apply_trans(fd, arg->cube);
         arg->ed->normal_fb = ptableval(&pd_khuge_HTM, aux);
         UPDATECHECKSTOP(ret, arg->ed->normal_fb, target);
-        if (arg->ed->normal_fb == target) {
-                arg->badmovesinv |= (1<<F) | (1<<F2) | (1<<F3) |
-                                    (1<<B) | (1<<B2) | (1<<B3);
-        }
-
         aux = apply_trans(rf, arg->cube);
         arg->ed->normal_rl = ptableval(&pd_khuge_HTM, aux);
         UPDATECHECKSTOP(ret, arg->ed->normal_rl, target);
-        if (arg->ed->normal_rl == target) {
-                arg->badmovesinv |= (1<<R) | (1<<R2) | (1<<R3) |
-                                    (1<<L) | (1<<L2) | (1<<L3);
-        }
 
+        /* If ret == 0, it's solved (corners + triple slice solved) */
         if (ret == 0)
                 return ret;
 
+        /* Michel de Bondt's trick*/
         if (arg->ed->normal_ud == arg->ed->normal_fb &&
             arg->ed->normal_fb == arg->ed->normal_rl)
                 UPDATECHECKSTOP(ret, arg->ed->normal_ud + 1, target);
 
-        /* TODO: avoid computation of inverse if unnecessary */
-        lbase = base_move(arg->last1);
+        /* Inverse probing */
         arg->inverse = inverse_cube(arg->cube);
-
-        if ((lbase != U && lbase != D) || (arg->ed->inverse_ud == -1)) {
+        if ((bl1 != U && bl1 != D) || (arg->ed->inverse_ud == -1)) {
                 arg->ed->inverse_ud = ptableval(&pd_khuge_HTM, arg->inverse);
         }
         UPDATECHECKSTOP(ret, arg->ed->inverse_ud, target);
-
-        if ((lbase != F && lbase != B) || (arg->ed->inverse_fb == -1)) {
+        if ((bl1 != F && bl1 != B) || (arg->ed->inverse_fb == -1)) {
                 aux = apply_trans(fd, arg->inverse);
                 arg->ed->inverse_fb = ptableval(&pd_khuge_HTM, aux);
         }
         UPDATECHECKSTOP(ret, arg->ed->inverse_fb, target);
-
-        if ((lbase != R && lbase != L) || (arg->ed->inverse_rl == -1)) {
+        if ((bl1 != R && bl1 != L) || (arg->ed->inverse_rl == -1)) {
                 aux = apply_trans(rf, arg->inverse);
                 arg->ed->inverse_rl = ptableval(&pd_khuge_HTM, aux);
         }
         UPDATECHECKSTOP(ret, arg->ed->inverse_rl, target);
 
+        /* Michel de Bondt's trick*/
         if (arg->ed->inverse_ud == arg->ed->inverse_fb &&
             arg->ed->inverse_fb == arg->ed->inverse_rl) {
                 UPDATECHECKSTOP(ret, arg->ed->inverse_ud + 1, target);
         }
 
+        /* nxopt trick */
+        if (arg->ed->normal_ud == target) {
+                arg->badmovesinv |= (1<<U) | (1<<U2) | (1<<U3) |
+                                    (1<<D) | (1<<D2) | (1<<D3);
+        }
+        if (arg->ed->normal_fb == target) {
+                arg->badmovesinv |= (1<<F) | (1<<F2) | (1<<F3) |
+                                    (1<<B) | (1<<B2) | (1<<B3);
+        }
+        if (arg->ed->normal_rl == target) {
+                arg->badmovesinv |= (1<<R) | (1<<R2) | (1<<R3) |
+                                    (1<<L) | (1<<L2) | (1<<L3);
+        }
+
         if (arg->ed->inverse_ud == target) {
                 arg->badmoves |= (1<<U) | (1<<U2) | (1<<U3) |
                                  (1<<D) | (1<<D2) | (1<<D3);