From 6b48baaf6b67cc7364d5945eb6d9b25ea9683bd9 Mon Sep 17 00:00:00 2001
From: tslil clingman <tslil@posteo.de>
Date: Tue, 26 Jan 2021 22:39:28 -0500
Subject: Somehting along these lines, i'm tired

---
 include/zobrist.c | 104 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 104 insertions(+)
 create mode 100644 include/zobrist.c

(limited to 'include/zobrist.c')

diff --git a/include/zobrist.c b/include/zobrist.c
new file mode 100644
index 0000000..8eeb758
--- /dev/null
+++ b/include/zobrist.c
@@ -0,0 +1,104 @@
+#include "zobrist.h"
+
+// ===================================================================
+// Globals
+// ===================================================================
+
+static uint64_t *zobrist[15];
+
+// ===================================================================
+// Helpers
+// ===================================================================
+
+
+// ===================================================================
+// Exported method implementations
+// ===================================================================
+
+int
+zobrist_init(void) {
+	for (int k=0; k<15; k++) {
+		if (zobrist[k] != NULL) return EXIT_FAILURE;
+	}
+
+	for (int j=0; j<15; j++) {
+		zobrist[j] = malloc(sizeof(uint64_t)*board_size*board_size*(2*3+1));
+		for (int k=0; k<board_size*board_size*(2*3+1); k++) {
+			XORSHIFT64;
+			zobrist[j][k] = RANDOM64;
+		}
+	}
+
+	return EXIT_SUCCESS;
+}
+
+void
+zobrist_free(void) {
+	for (int k=0; k<15; k++) {
+		if (zobrist[k] != NULL) {
+			free(zobrist[k]);
+			zobrist[k] = NULL;
+		}
+	}
+}
+
+uint64_t
+zobrist_compute(void) {
+	uint64_t hash = 0;
+	for (uint8_t l=0; l<board_size*board_size; l++) {
+		colour_stack_t c = colours[l];
+		const uint8_t count = COUNT_AT(l);
+		enum STONE_VARIANT s = STONE_AT(l);
+		for (uint8_t h=0; h<count; h++, c >>= 1)
+			hash ^= zobrist[h][l*(2*3+1)+(c&1)*3+s];
+	}
+	return hash;
+}
+
+uint64_t
+zobrist_apply(const action_t action, uint64_t hash) {
+	const enum A_TYPE type = GET_TYPE(action);
+	const int8_t loc = GET_LOC(action);
+	if (type == A_PLACE) {
+		hash ^= zobrist[0][loc*(2*3+1)
+											 +current_colour*3
+											 +GET_DATA0(action)];
+	} else {
+		const uint8_t gaps = GET_DATA0(action) & 0x7F,
+			crush = GET_DATA0(action) & 0x80,
+			num = GET_DATA1(action) & 0x0F,
+			dir = GET_DATA1(action) >> 4;
+		const int8_t delta = move_deltas[dir];
+
+		// TODO: adapt this
+		int8_t steps = 1;
+		uint8_t gap_bit = 1, total = 1;
+		for (int8_t d = 1; d < num; d++, total++, gap_bit <<= 1) {
+			if (gaps & gap_bit) {
+				colours[loc] <<= total;
+				colours[loc] |= colours[loc+steps*delta] & ((1 << total) - 1);
+				colours[loc+steps*delta] >>= total;
+				celldat[loc] += total*NUM_INC;
+				celldat[loc+steps*delta] -= total*NUM_INC;
+				total = 0;
+				steps++;
+			}
+		}
+		colours[loc] <<= total;
+		colours[loc] |= colours[loc+steps*delta] & ((1 << total) - 1);
+		colours[loc+steps*delta] >>= total;
+
+		celldat[loc] += total*NUM_INC;
+		// celldat[loc] &= CLR_STONE; is not necessary, as STONE_FLAT == 0
+		celldat[loc] |= STONE_AT(loc+steps*delta);
+		celldat[loc+steps*delta] -= total*NUM_INC;
+		celldat[loc+steps*delta] &= CLR_STONE;
+		if (crush) {
+			celldat[loc+steps*delta] |= STONE_STANDING;
+		} else {
+			celldat[loc+steps*delta] |= STONE_FLAT; // should be optimised out
+		}
+
+	}
+	return hash;
+}
-- 
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