Use LUT for group indexes instead of calculating on-the-fly

genlut.c

@@ -0,0 +1,84 @@
+/*
+ * Copyright (C) 2022 Camden Dixie O'Brien
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as
+ * published by the Free Software Foundation, either version 3 of the
+ * License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public
+ * License along with this program.  If not, see
+ * <https://www.gnu.org/licenses/>.
+ */
+
+#include "sud.h"
+
+#include <stdio.h>
+
+#define Q(x) #x
+#define PRLUT(x) prlut(Q(x), x)
+
+static void prlut(const char *name, unsigned lut[NCELLS][NDIGITS - 1])
+{
+	printf("const unsigned %s[NCELLS][NDIGITS - 1] = {\n", name);
+	for (unsigned i = 0; i < NCELLS; ++i) {
+		printf("\t[%2u] = { ", i);
+		for (unsigned j = 0; j < NDIGITS - 1; ++j) {
+			printf("%2u", lut[i][j]);
+			if (j != NDIGITS - 2)
+				putchar(',');
+			putchar(' ');
+		}
+		fputs("},\n", stdout);
+	}
+	fputs("};\n", stdout);
+}
+
+int main(void)
+{
+	unsigned rowidx_lut[NCELLS][NDIGITS - 1];
+	unsigned colidx_lut[NCELLS][NDIGITS - 1];
+	unsigned segidx_lut[NCELLS][NDIGITS - 1];
+
+	/* Populate tables. */
+	unsigned rowi, coli, segi;
+	for (unsigned r = 0; r < NDIGITS; ++r) {
+		for (unsigned c = 0; c < NDIGITS; ++c) {
+			/* Calculate row and column indices. */
+			rowi = coli = 0;
+			for (unsigned i = 0; i < NDIGITS; ++i) {
+				if (i != c)
+					rowidx_lut[r * NDIGITS + c][rowi++] = r * NDIGITS + i;
+				if (i != r)
+					colidx_lut[r * NDIGITS + c][coli++] = i * NDIGITS + c;
+			}
+
+			/* Calculate segment indices. */
+			segi = 0;
+			const unsigned sr = SEGLEN * (r / SEGLEN);
+			const unsigned sc = SEGLEN * (c / SEGLEN);
+			for (unsigned i = sr; i < sr + SEGLEN; ++i) {
+				for (unsigned j = sc; j < sc + SEGLEN; ++j) {
+					if (i == r && j == c)
+						continue;
+					segidx_lut[r * NDIGITS + c][segi++] = i * NDIGITS + j;
+				}
+			}
+		}
+	}
+
+	printf("/*\n * This file is auto-generated; do not edit.\n */\n\n");
+	printf("#include \"lut.h\"\n\n");
+	PRLUT(rowidx_lut);
+	putchar('\n');
+	PRLUT(colidx_lut);
+	putchar('\n');
+	PRLUT(segidx_lut);
+
+	return 0;
+}