3 files changed, 209 insertions, 32 deletions

diff --git a/TODO.txt b/TODO.txt
index 27ff198..f661363 100644
--- a/TODO.txt
+++ b/TODO.txt
@@ -2,7 +2,7 @@
 
 See the sections below for details
 
-* Implement some simple solver
+* Tests for simple solver
 * Extend cube and moves to include centers
 * More complex optimal solvers, pruning tables
 * Benchmarks
diff --git a/cube.c b/cube.c
index 4806b95..3cd4381 100644
--- a/cube.c
+++ b/cube.c
@@ -9,6 +9,7 @@
 #ifdef DEBUG
 #include <stdio.h>
 #define DBG_LOG(...) fprintf(stderr, __VA_ARGS__)
+#define DBG_WARN(condition, ...) if (!(condition)) DBG_LOG(__VA_ARGS__);
 #define DBG_ASSERT(condition, retval, ...) \
         if (!(condition)) {                \
                 DBG_LOG(__VA_ARGS__);      \
@@ -16,6 +17,7 @@
         }
 #else
 #define DBG_LOG(...)
+#define DBG_WARN(condition, ...)
 #define DBG_ASSERT(condition, retval, ...)
 #endif
 
@@ -255,6 +257,10 @@ typedef __m256i cube_fast_t;
 #define _cocw_avx2 _mm256_set_epi64x(0, 0, 0, 0x2020202020202020)
 #define _eo_avx2 _mm256_set_epi64x(0x10101010, 0x1010101010101010, 0, 0)
 #define zero_fast _mm256_set_epi64x(0, 0, 0, 0);
+#define solved_fast _mm256_set_epi8(                      \
+        0, 0, 0, 0, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, 0, \
+        0, 0, 0, 0, 0, 0, 0, 0, 7, 6, 5, 4, 3, 2, 1, 0    \
+)
 
 static cube_fast_t cubetofast(cube_t);
 static cube_t fasttocube(cube_fast_t);
@@ -1482,6 +1488,12 @@ equal_fast(cube_fast_t c1, cube_fast_t c2)
         return mask == 0xffffffffU;
 }
 
+static inline bool
+issolved_fast(cube_fast_t cube)
+{
+        return equal_fast(cube, solved_fast);
+}
+
 static inline cube_fast_t
 invertco_fast(cube_fast_t c)
 {
@@ -1614,7 +1626,11 @@ typedef cube_t cube_fast_t;
         r[k] ^= _eobit;    \
         r[l] ^= _eobit;
 
-static const cube_fast_t zero_fast = { .corner = {0}, .edge = {0} };
+static cube_fast_t zero_fast = { .corner = {0}, .edge = {0} };
+static cube_t solved_fast = {
+        .corner = {0, 1, 2, 3, 4, 5, 6, 7},
+        .edge = {0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11}
+};
 
 static cube_fast_t cubetofast(cube_t);
 static cube_t fasttocube(cube_fast_t);
@@ -2842,6 +2858,12 @@ equal_fast(cube_fast_t c1, cube_fast_t c2)
         return ret;
 }
 
+static inline bool
+issolved_fast(cube_fast_t cube)
+{
+        return equal_fast(cube, solved_fast);
+}
+
 static inline cube_fast_t
 inverse_fast(cube_fast_t cube)
 {
@@ -2930,7 +2952,7 @@ static void writecube_SRC(cube_t, char *);
 static uint8_t readmove(char);
 static uint8_t readmodifier(char);
 static uint8_t readtrans(char *);
-static void writemoves(uint8_t *, int, char *);
+static int writemoves(uint8_t *, int, char *);
 static void writetrans(uint8_t, char *);
 static cube_fast_t transform(cube_fast_t, uint8_t);
 static cube_fast_t move(cube_fast_t, uint8_t);
@@ -3256,7 +3278,7 @@ readtrans(char *buf)
         return _error;
 }
 
-static void
+static int
 writemoves(uint8_t *m, int n, char *buf)
 {
         int i;
@@ -3271,6 +3293,8 @@ writemoves(uint8_t *m, int n, char *buf)
                 *b = ' ';
         }
         *b = '\0';
+
+        return b - buf;
 }
 
 static void
@@ -3628,16 +3652,16 @@ Here you can find the implementation of all the solving algorithms.
 typedef struct {
         cube_fast_t cube;
         uint8_t depth;
-        int maxsols;
-        uint8_t *sols;
-        int nsols;
-        int nmoves;
+        int64_t maxsols;
+        char *sols;
+        int64_t nsols;
+        uint8_t nmoves;
         uint8_t moves[20];
-        int (*estimate)(cube_fast_t);
-} dfs_arg_t;
+        uint8_t (*estimate)(cube_fast_t);
+} dfsarg_generic_t;
 
 static bool
-allowednextmove(dfs_arg_t arg, uint8_t m)
+allowednextmove(dfsarg_generic_t arg, uint8_t m)
 {
         int n;
         uint8_t mbase, l1base, l2base, maxis, l1axis, l2axis;
@@ -3665,11 +3689,11 @@ allowednextmove(dfs_arg_t arg, uint8_t m)
 }
 
 static int
-solve_generic_dfs(dfs_arg_t arg)
+solve_generic_dfs(dfsarg_generic_t arg)
 {
-        dfs_arg_t nextarg;
-        int bound, ret;
-        uint8_t m;
+        dfsarg_generic_t nextarg;
+        uint8_t m, bound;
+        int64_t ret;
 
         bound = arg.estimate(arg.cube);
 
@@ -3679,11 +3703,13 @@ solve_generic_dfs(dfs_arg_t arg)
         if (bound == 0) {
                 if (arg.nmoves != arg.depth)
                         return 0;
-                memcpy(&arg.sols[arg.depth * arg.nsols], arg.moves, arg.depth);
+                arg.sols += writemoves(arg.moves, arg.depth, arg.sols);
+                *arg.sols = '\n';
+                arg.sols++;
                 return 1;
         }
 
-        memcpy(&nextarg, &arg, sizeof(dfs_arg_t));
+        memcpy(&nextarg, &arg, sizeof(dfsarg_generic_t));
         nextarg.nmoves = arg.nmoves + 1;
         for (m = 0, ret = 0; m < 18; m++) {
                 if (allowednextmove(arg, m)) {
@@ -3696,24 +3722,65 @@ solve_generic_dfs(dfs_arg_t arg)
         return ret;
 }
 
-/* TODO
-int
+static int64_t
 solve_generic(
-        cube_fast_t cube,
-        uint8_t depth,
-        int maxsols,
-        uint8_t *sols,
-        int (*estimate)(cube_fast_t)
+        cube_t cube,
+        char *nisstype,
+        /* TODO: handle NISS */
+        int8_t minmoves,
+        int8_t maxmoves,
+        int64_t maxsols,
+        int8_t optimal,
+        char *sols,
+        uint8_t (*estimate)(cube_fast_t)
+        /* TODO: add validator */
+        /* TODO: maybe add data for estimate */
+        /* TODO: add moveset (and allowednext?) */
 )
 {
-        dfs_arg_t arg;
+        dfsarg_generic_t arg;
+        int64_t ret, tmp, first;
 
-        if (!issolvable(cube) || depth > 20 || estimate == NULL)
+        if (!issolvable(cube)) {
+                DBG_LOG("solve: cube is not solvable\n");
                 return -1;
+        }
 
-        arg = (dfs_arg_t) {
-                .cube = cube,
-                .depth = depth,
+        DBG_WARN(!strcmp(nisstype, ""),
+            "solve: NISS not implemented yet, 'nisstype' ignored\n");
+
+        if (minmoves < 0) {
+                DBG_LOG("solve: 'minmoves' is negative, setting to 0\n");
+                minmoves = 0;
+        }
+
+        if (maxmoves < 0) {
+                DBG_LOG("solve: invalid 'maxmoves', setting to 20\n");
+                maxmoves = 20;
+        }
+
+        if (maxsols < 0) {
+                DBG_LOG("solve: 'maxsols' is negative\n");
+                return -1;
+        }
+
+        if (maxsols == 0) {
+                DBG_LOG("solve: 'maxsols' is 0\n");
+                return 0;
+        }
+
+        if (sols == NULL) {
+                DBG_LOG("solve: return parameter 'sols' is NULL\n");
+                return -1;
+        }
+
+        if (estimate == NULL) {
+                DBG_LOG("solve: 'estimate' is NULL\n");
+                return -1;
+        }
+
+        arg = (dfsarg_generic_t) {
+                .cube = cubetofast(cube),
                 .maxsols = maxsols,
                 .sols = sols,
                 .nsols = 0,
@@ -3722,6 +3789,116 @@ solve_generic(
                 .estimate = estimate,
         };
 
-        return solve_generic_dfs(arg);
+        ret = 0;
+        first = -1;
+        for (arg.depth = minmoves; arg.depth <= maxmoves; arg.depth++) {
+                tmp = solve_generic_dfs(arg);
+                ret += tmp;
+                if (tmp != 0)
+                        first = arg.depth;
+
+                DBG_LOG("Found %" PRId64 " solutions at depth %" PRIu8 "\n",
+                        tmp, arg.depth);
+
+                if (ret >= maxsols)
+                        break;
+
+                if (optimal >= 0 && first >= 0 && arg.depth - first == optimal)
+                        break;
+        }
+
+        DBG_ASSERT(ret <= maxsols, ret,
+            "solve: found more than 'maxsols' solutions\n");
+
+        return ret;
+}
+
+static uint8_t
+estimate_simple(cube_fast_t cube)
+{
+        return issolved_fast(cube) ? 0 : 1;
+}
+
+static int64_t
+solve_simple(
+        cube_t cube,
+        int8_t minmoves,
+        int8_t maxmoves,
+        int64_t maxsols,
+        int8_t optimal,
+        char *solutions
+)
+{
+        return solve_generic(
+                cube,
+                "",
+                minmoves,
+                maxmoves,
+                maxsols,
+                optimal,
+                solutions,
+                &estimate_simple
+        );
+}
+
+int64_t
+solve(
+        cube_t cube,
+        char *solver,
+        char *options,
+        char *nisstype,
+        int8_t minmoves,
+        int8_t maxmoves,
+        int64_t maxsols,
+        int8_t optimal,
+        void *data,
+        char *solutions
+)
+{
+        DBG_WARN(!strcmp(options, ""),
+             "solve: 'options' not implemented yet, ignoring\n");
+
+        DBG_WARN(!strcmp(nisstype, ""),
+             "solve: NISS not implemented yet, ignoring 'nisstype'\n");
+
+        DBG_WARN(data == NULL,
+            "solve: 'data' not implemented yet, ignoring\n");
+
+        if (!strcmp(solver, "simple")) {
+                return solve_simple(
+                        cube,
+                        minmoves,
+                        maxmoves,
+                        maxsols,
+                        optimal,
+                        solutions
+                );
+        } else {
+                DBG_LOG("solve: unknown solver\n");
+                return -1;
+        }
+
+        DBG_LOG("solve: error\n");
+        return -1;
+}
+
+void
+multisolve(int n, cube_t *cube, char *solver, void *data, char *sols)
+{
+        char *s;
+        int i;
+
+        s = sols;
+        for (i = 0; i < n; i++) {
+                solve(cube[i], solver, "", "normal", 0, -1, 1, 0, NULL, s);
+                while (s++);
+        }
+}
+
+int64_t
+gendata(char *solver, void *data)
+{
+        DBG_LOG("gendata: not implemented yet\n");
+
+        return -1;
 }
-*/
diff --git a/cube.h b/cube.h
index 791d167..0a39d12 100644
--- a/cube.h
+++ b/cube.h
@@ -130,7 +130,7 @@ int64_t solve(
                           * maximum length is unlimited.
                           */
         int64_t maxsols, /* The maximum number of solutions. */
-        int64_t optimal, /* All solutions at most "optimal" moves from the
+        int8_t optimal,  /* All solutions at most "optimal" moves from the
                           * shortest solution (respecting minmoves) are found.
                           * If negative, this parameter is ignored.
                           */