Split isconsistent() and issolvable()

1 files changed, 64 insertions, 38 deletions

diff --git a/src/cube_array.c b/src/cube_array.c
index b0b5e1e..a9b9709 100644
--- a/src/cube_array.c
+++ b/src/cube_array.c
@@ -149,6 +149,7 @@ cube_t solvedcube = {
 
 static cube_t errorcube = { .e = {0}, .c = {0} };
 
+static bool isconsistent(cube_t);
 static uint8_t readco(char *);
 static uint8_t readcp(char *);
 static uint8_t readeo(char *);
@@ -402,58 +403,41 @@ permsign(uint8_t *a, int n)
         return ret % 2;
 }
 
-bool
-isconsistent(cube_t cube)
+static bool
+isconsistent(cube_t c)
 {
-        int8_t p, psum, eosum, co, cosum;
+        uint8_t i, p, e;
         bool found[12];
-        int i;
 
-        psum = 0;
         for (i = 0; i < 12; i++)
                 found[i] = false;
         for (i = 0; i < 12; i++) {
-                p = cube.e[i] & _pbits;
+                p = c.e[i] & _pbits;
+                e = c.e[i] & ~_pbits;
                 if (p >= 12)
                         goto inconsistent_ep;
+                if (e != 0 && e != _eobit)
+                        goto inconsistent_eo;
                 found[p] = true;
         }
         for (i = 0; i < 12; i++)
                 if (!found[i])
                         goto inconsistent_ep;
-        psum = permsign(cube.e, 12);
 
         for (i = 0; i < 8; i++)
                 found[i] = false;
         for (i = 0; i < 8; i++) {
-                p = cube.c[i] & _pbits;
+                p = c.c[i] & _pbits;
+                e = c.c[i] & ~_pbits;
                 if (p >= 8)
                         goto inconsistent_cp;
+                if (e != 0 && e != _ctwist_cw && e != _ctwist_ccw)
+                        goto inconsistent_co;
                 found[p] = true;
         }
         for (i = 0; i < 8; i++)
                 if (!found[i])
-                        goto inconsistent_cp;
-        psum += permsign(cube.c, 8);
-
-        if (psum % 2 != 0)
-                goto inconsistent_parity;
-
-        eosum = 0;
-        for (i = 0; i < 12; i++)
-                eosum += (cube.e[i] & _eobit) >> _eoshift;
-        if (eosum % 2 != 0)
-                goto inconsistent_eo;
-
-        cosum = 0;
-        for (i = 0; i < 8; i++) {
-                co = (cube.c[i] & _cobits) >> _coshift;
-                if (co > 2)
                         goto inconsistent_co;
-                cosum += co;
-        }
-        if (cosum % 3 != 0)
-                goto inconsistent_co;
 
         return true;
 
@@ -461,28 +445,70 @@ inconsistent_ep:
 #ifdef DEBUG
         fprintf(stderr, "Inconsistent EP\n");
 #endif
-        goto inconsistent_return;
+        return false;
 inconsistent_cp:
 #ifdef DEBUG
         fprintf(stderr, "Inconsistent CP\n");
 #endif
-        goto inconsistent_return;
-inconsistent_parity:
-#ifdef DEBUG
-        fprintf(stderr, "Inconsistent parity\n");
-#endif
-        goto inconsistent_return;
+        return false;
 inconsistent_eo:
 #ifdef DEBUG
         fprintf(stderr, "Inconsistent EO\n");
 #endif
-        goto inconsistent_return;
+        return false;
 inconsistent_co:
 #ifdef DEBUG
         fprintf(stderr, "Inconsistent CO\n");
 #endif
-        goto inconsistent_return;
-inconsistent_return:
+        return false;
+}
+
+bool
+issolvable(cube_t cube)
+{
+        int8_t i, eo, co;
+
+#ifdef DEBUG
+        if (!isconsistent(cube))
+                goto issolvable_inconsistent;
+#endif
+
+        if (permsign(cube.e, 12) != permsign(cube.c, 8))
+                goto issolvable_parity;
+
+        eo = 0;
+        for (i = 0; i < 12; i++)
+                eo += (cube.e[i] & _eobit) >> _eoshift;
+        if (eo % 2 != 0)
+                goto issolvable_eo;
+
+        co = 0;
+        for (i = 0; i < 8; i++)
+                co += (cube.c[i] & _cobits) >> _coshift;
+        if (co % 3 != 0)
+                goto issolvable_co;
+
+        return true;
+
+issolvable_inconsistent:
+#ifdef DEBUG
+        fprintf(stderr, "issolvable: cube is inconsistent\n");
+#endif
+        return false;
+issolvable_parity:
+#ifdef DEBUG
+        fprintf(stderr, "EP and CP parities are different\n");
+#endif
+        return false;
+issolvable_eo:
+#ifdef DEBUG
+        fprintf(stderr, "Odd number of flipped edges\n");
+#endif
+        return false;
+issolvable_co:
+#ifdef DEBUG
+        fprintf(stderr, "Sum of corner orientation is not multiple of 3\n");
+#endif
         return false;
 }