From 57a7520545134ab95f7bb0397dcbe991c906a3e9 Mon Sep 17 00:00:00 2001
From: Sebastiano Tronto <sebastiano@tronto.net>
Date: Wed, 6 Aug 2025 16:34:21 +0200
Subject: Added HTR solver

---
 src/solvers/coord/htr.h | 125 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 src/solvers/coord/htr.h

(limited to 'src/solvers/coord/htr.h')

diff --git a/src/solvers/coord/htr.h b/src/solvers/coord/htr.h
new file mode 100644
index 0000000..cfd451b
--- /dev/null
+++ b/src/solvers/coord/htr.h
@@ -0,0 +1,125 @@
+STATIC uint64_t coordinate_htr_coord(cube_t, const unsigned char *);
+STATIC cube_t coordinate_htr_cube(uint64_t, const unsigned char *);
+STATIC bool coordinate_htr_isnasty(uint64_t, const unsigned char *);
+STATIC size_t coordinate_htr_gendata(unsigned char *);
+
+STATIC bool htr_checkmoves(bool *, uint8_t, const uint8_t *);
+STATIC bool htr_solution_prune(const solution_moves_t [static 1]);
+STATIC bool is_cp_htr(uint64_t, const unsigned char *);
+
+STATIC coord_t coordinate_htr = {
+	.name = "HTR",
+	.coord = &coordinate_htr_coord,
+	.cube = &coordinate_htr_cube,
+	.isnasty = &coordinate_htr_isnasty,
+	.gendata = coordinate_htr_gendata,
+	.max = CLASSES_CP_16 * COMB_8_4,
+	.trans_mask = TM_UDFIX,
+	.moves_mask_gendata = MM18_DR,
+	.moves_mask_solve = MM18_DRHTR,
+	.is_admissible = &solution_lastqt_cw,
+	.solution_prune = &htr_solution_prune,
+	.is_solvable = &is_drfinnoe_solvable,
+	.is_solved = &is_cp_htr,
+	.allow_niss = true,
+	.pruning_distribution = {
+		[0] = 22,
+		[1] = 18,
+		[2] = 86,
+		[3] = 268,
+		[4] = 920,
+		[5] = 4042,
+		[6] = 12716,
+		[7] = 24852,
+		[8] = 33116,
+		[9] = 45032,
+		[10] = 47144,
+		[11] = 21676,
+		[12] = 3692,
+		[13] = 176
+	},
+	.pruning_max = 13,
+	.sym = {
+		.classes = CLASSES_CP_16,
+		.max = FACT_8,
+		.coord = &coord_cp,
+		.cube = &invcoord_cp,
+		.max2 = COMB_8_4,
+		.coord2 = &coord_epudsep,
+		.cube2 = &invcoord_epudsep,
+		.merge = &coordinate_merge_ce,
+	},
+};
+
+STATIC uint64_t
+coordinate_htr_coord(cube_t cube, const unsigned char *data)
+{
+	return coord_coord_generic(&coordinate_htr, cube, data);
+}
+
+STATIC cube_t
+coordinate_htr_cube(uint64_t i, const unsigned char *data)
+{
+	return coord_cube_generic(&coordinate_htr, i, data);
+}
+
+STATIC bool
+coordinate_htr_isnasty(uint64_t i, const unsigned char *data)
+{
+	return coord_isnasty_generic(&coordinate_htr, i, data);
+}
+
+STATIC size_t
+coordinate_htr_gendata(unsigned char *data)
+{
+	return coord_gendata_generic(&coordinate_htr, data);
+}
+
+STATIC bool
+htr_checkmoves(bool *f, uint8_t n, const uint8_t *moves)
+{
+	uint8_t i;
+	bool is_d, is_u;
+
+	for (i = 0; i < n; i++) {
+		is_d = moves[i] == MOVE_D || moves[i] == MOVE_D3;
+		is_u = moves[i] == MOVE_U || moves[i] == MOVE_U3;
+		if (is_d && *f)
+			return true;
+		*f = *f || is_d || is_u;
+
+		if (i < n-1 && moveaxis(moves[i]) == 0 &&
+		    parallel(moves[i], moves[i+1]))
+			return true;
+	}
+
+	return false;
+}
+
+STATIC bool
+htr_solution_prune(const solution_moves_t s[static 1])
+{
+	bool f;
+
+	f = false;
+
+	return htr_checkmoves(&f, s->nmoves, s->moves) ||
+	       htr_checkmoves(&f, s->npremoves, s->premoves);
+}
+
+STATIC bool
+is_cp_htr(uint64_t i, const unsigned char *data)
+{
+	static uint8_t is_cp16_htr_table[DIV_ROUND_UP(CLASSES_CP_16, 8)] = {
+		[0] = 81, [7] = 144, [8] = 16, [25] = 130, [26] = 34,
+		[37] = 64, [38] = 48, [39] = 8, [212] = 20, [226] = 32,
+		[227] = 2, [298] = 160, [300] = 128, [301] = 1
+	};
+
+	uint64_t e, c;
+
+	e = i % COMB_8_4;
+	c = i / COMB_8_4;
+
+	return e == 0 && is_cp16_htr_table[c / 8] & (UINT8_C(1) << (c % 8));
+}
-- 
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