13 files changed, 144 insertions, 2 deletions

diff --git a/doc/solvers.md b/doc/solvers.md
index 837cec6..12df168 100644
--- a/doc/solvers.md
+++ b/doc/solvers.md
@@ -129,6 +129,17 @@ NISS will not be used.
 * Moveset: {U, U', U2, D, D', D2, R2, L2, F2, B2}.
 * Data size: 54MB.
 
+### Solve corners
+
+Solve the corners of the cube. Note: centers are considered fixed,
+this is not the same as solving a 2x2x2 cube.
+
+* Name: `coord_DRFIN_UF`. Other rotations in place of `UF` are allowed,
+  but they are irrelevant to the solver. Provided alias: `corners`.
+* Requisites: none.
+* Moveset: HTM (all 18 basic moves).
+* Data size: 1.2MB.
+
 ### Undocumented coordinate solvers
 
 There are some coordinate solvers that have not been listed above. These
diff --git a/src/arch/avx2.h b/src/arch/avx2.h
index 5a62213..b80b0fb 100644
--- a/src/arch/avx2.h
+++ b/src/arch/avx2.h
@@ -160,6 +160,16 @@ coord_co(cube_t c)
         return ret;
 }
 
+STATIC_INLINE void
+copy_co(cube_t cube[static 1], cube_t co)
+{
+        cube_t coclean;
+
+        coclean = _mm256_and_si256(co, CO2_AVX2);
+        *cube = _mm256_andnot_si256(CO2_AVX2, *cube);
+        *cube = _mm256_or_si256(*cube, coclean);
+}
+
 STATIC_INLINE cube_t
 invcoord_co(uint64_t coord)
 {
@@ -174,7 +184,7 @@ invcoord_co(uint64_t coord)
 
         cc = _mm256_loadu_si256((__m256i *)mem);
         cube = SOLVED_CUBE;
-        copy_corners(&cube, cc);
+        copy_co(&cube, cc);
 
         return cube;
 }
diff --git a/src/arch/common.h b/src/arch/common.h
index f06f8d7..4412562 100644
--- a/src/arch/common.h
+++ b/src/arch/common.h
@@ -35,6 +35,7 @@ STATIC_INLINE cube_t invcoord_epudsep(uint64_t);
 STATIC_INLINE bool is_eo_even(cube_t);
 
 STATIC_INLINE void copy_corners(cube_t [static 1], cube_t);
+STATIC_INLINE void copy_co(cube_t [static 1], cube_t);
 STATIC_INLINE void copy_edges(cube_t [static 1], cube_t);
 STATIC_INLINE void set_eo(cube_t [static 1], uint64_t);
 
diff --git a/src/arch/neon.h b/src/arch/neon.h
index 9871125..f997813 100644
--- a/src/arch/neon.h
+++ b/src/arch/neon.h
@@ -232,6 +232,16 @@ coord_co(cube_t c)
         return ret;
 }
 
+STATIC_INLINE void
+copy_co(cube_t cube[static 1], cube_t co)
+{
+        uint8x8_t coclean;
+
+        coclean = vand_u8(co.corner, CO2_NEON);
+        cube->corner = vbic_u8(cube->corner, CO2_NEON);
+        cube->corner = vorr_u8(cube->corner, coclean);
+}
+
 STATIC_INLINE cube_t
 invcoord_co(uint64_t coord)
 {
diff --git a/src/arch/portable.h b/src/arch/portable.h
index c7f2de0..4b66fb6 100644
--- a/src/arch/portable.h
+++ b/src/arch/portable.h
@@ -154,6 +154,19 @@ inverse(cube_t cube)
         return ret;
 }
 
+STATIC_INLINE void
+copy_co(cube_t cube[static 1], cube_t co)
+{
+        uint8_t c;
+        size_t i;
+
+        for (i = 0; i < 8; i++) {
+                c = cube->corner[i] & COBITS;
+                cube->corner[i] ^= c;
+                cube->corner[i] |= co.corner[i] & COBITS;
+        }
+}
+
 STATIC_INLINE uint64_t
 coord_co(cube_t c)
 {
diff --git a/src/core/cube.h b/src/core/cube.h
index 3ba282e..9e79dda 100644
--- a/src/core/cube.h
+++ b/src/core/cube.h
@@ -1,3 +1,5 @@
+STATIC bool cube_true(cube_t);
+
 STATIC cube_t cubefromarray(uint8_t [static 8], uint8_t [static 12]);
 STATIC bool isconsistent(oriented_cube_t);
 STATIC bool issolvable(oriented_cube_t);
@@ -19,6 +21,13 @@ STATIC uint8_t b32tocorner(char);
 STATIC char edgetob32(uint8_t);
 STATIC char cornertob32(uint8_t);
 
+/* Used e.g. by the CORNERS coordinate, when a function pointer is needed */
+STATIC bool
+cube_true(cube_t cube)
+{
+        return true;
+}
+
 STATIC cube_t
 cubefromarray(uint8_t c[static 8], uint8_t e[static 12])
 {
diff --git a/src/solvers/coord/common.h b/src/solvers/coord/common.h
index 5f2435d..d154636 100644
--- a/src/solvers/coord/common.h
+++ b/src/solvers/coord/common.h
@@ -14,6 +14,7 @@ STATIC bool coord_is_solved(
 
 STATIC cube_t coordinate_merge_ce(cube_t, cube_t);
 STATIC cube_t coordinate_merge_ec(cube_t, cube_t);
+STATIC cube_t coordinate_merge_cpco(cube_t, cube_t);
 
 STATIC uint64_t
 coord_coord_generic(
@@ -215,3 +216,14 @@ coordinate_merge_ec(cube_t edges, cube_t corners)
 {
         return coordinate_merge_ce(corners, edges);
 }
+
+STATIC cube_t
+coordinate_merge_cpco(cube_t cp, cube_t co)
+{
+        cube_t merged;
+
+        merged = cp;
+        copy_co(&merged, co);
+
+        return merged;
+}
diff --git a/src/solvers/coord/coord.h b/src/solvers/coord/coord.h
index db40239..2ef8482 100644
--- a/src/solvers/coord/coord.h
+++ b/src/solvers/coord/coord.h
@@ -8,6 +8,7 @@
 #include "cpepe.h"
 #include "drfin.h"
 #include "htr.h"
+#include "corners.h"
 #include "list.h"
 #include "utils.h"
 #include "gendata.h"
diff --git a/src/solvers/coord/corners.h b/src/solvers/coord/corners.h
new file mode 100644
index 0000000..cc0d9a5
--- /dev/null
+++ b/src/solvers/coord/corners.h
@@ -0,0 +1,72 @@
+#define CLASSES_CP_48 984
+
+STATIC uint64_t coordinate_corners_coord(const cube_t, const unsigned char *);
+STATIC cube_t coordinate_corners_cube(uint64_t, const unsigned char *);
+STATIC bool coordinate_corners_isnasty(uint64_t, const unsigned char *);
+STATIC size_t coordinate_corners_gendata(unsigned char *);
+
+STATIC coord_t coordinate_corners = {
+        .name = "CORNERS",
+        .coord = &coordinate_corners_coord,
+        .cube = &coordinate_corners_cube,
+        .isnasty = &coordinate_corners_isnasty,
+        .gendata = coordinate_corners_gendata,
+        .max = CLASSES_CP_48 * POW_3_7,
+        .trans_mask = TM_ALLTRANS,
+        .moves_mask_gendata = MM18_ALLMOVES,
+        .moves_mask_solve = MM18_ALLMOVES,
+        .is_admissible = &solution_always_valid,
+        .solution_prune = NULL,
+        .is_solvable = &cube_true,
+        .is_solved = NULL,
+        .allow_niss = false,
+        .pruning_distribution = {
+                [0] = 1,
+                [1] = 2,
+                [2] = 9,
+                [3] = 76,
+                [4] = 708,
+                [5] = 5022,
+                [6] = 28248,
+                [7] = 132076,
+                [8] = 505705,
+                [9] = 1102421,
+                [10] = 375380,
+                [11] = 2360,
+        },
+        .pruning_max = 11,
+        .sym = {
+                .classes = CLASSES_CP_48,
+                .max = FACT_8,
+                .coord = &coord_cp,
+                .cube = &invcoord_cp,
+                .max2 = POW_3_7,
+                .coord2 = &coord_co,
+                .cube2 = &invcoord_co,
+                .merge = &coordinate_merge_cpco,
+        },
+};
+
+STATIC uint64_t
+coordinate_corners_coord(const cube_t cube, const unsigned char *data)
+{
+        return coord_coord_generic(&coordinate_corners, cube, data);
+}
+
+STATIC cube_t
+coordinate_corners_cube(uint64_t i, const unsigned char *data)
+{
+        return coord_cube_generic(&coordinate_corners, i, data);
+}
+
+STATIC bool
+coordinate_corners_isnasty(uint64_t i, const unsigned char *data)
+{
+        return coord_isnasty_generic(&coordinate_corners, i, data);
+}
+
+STATIC size_t
+coordinate_corners_gendata(unsigned char *data)
+{
+        return coord_gendata_generic(&coordinate_corners, data);
+}
diff --git a/src/solvers/coord/list.h b/src/solvers/coord/list.h
index 9b59969..f2b7368 100644
--- a/src/solvers/coord/list.h
+++ b/src/solvers/coord/list.h
@@ -6,6 +6,7 @@ coord_t *all_coordinates[] = {
         &coordinate_drslice,
         &coordinate_cpepe,
         &coordinate_htr,
+        &coordinate_corners,
         NULL
 };
 
diff --git a/src/solvers/coord/types_macros.h b/src/solvers/coord/types_macros.h
index 98f9822..a9e604c 100644
--- a/src/solvers/coord/types_macros.h
+++ b/src/solvers/coord/types_macros.h
@@ -30,6 +30,7 @@ typedef struct {
         bool (*is_admissible)(const solution_moves_t[static 1]);
         bool (*solution_prune)(const solution_moves_t[static 1]);
         bool (*is_solvable)(cube_t);
+        /* if is_solved is nulle, coord == 0 is used */
         bool (*is_solved)(uint64_t, const unsigned char *);
         uint64_t pruning_distribution[INFO_DISTRIBUTION_LEN];
         uint8_t pruning_max;
diff --git a/src/solvers/dispatch.h b/src/solvers/dispatch.h
index 71b3947..8147929 100644
--- a/src/solvers/dispatch.h
+++ b/src/solvers/dispatch.h
@@ -65,6 +65,7 @@ const char *solver_aliases[][2] = {
         { "htr-drud", "coord_HTR_UF" },
         { "htr-drrl", "coord_HTR_LF" },
         { "htr-drfb", "coord_HTR_BU" },
+        { "corners", "coord_CORNERS_UF" },
         { NULL, NULL }
 };
 
diff --git a/src/solvers/solvers.h b/src/solvers/solvers.h
index 27ae627..e19b08a 100644
--- a/src/solvers/solvers.h
+++ b/src/solvers/solvers.h
@@ -3,6 +3,6 @@
 #include "tables_types_macros.h"
 #include "tables.h"
 #include "distribution.h"
-#include "h48/h48.h"
 #include "coord/coord.h"
+#include "h48/h48.h"
 #include "dispatch.h"