1 files changed, 50 insertions, 0 deletions
diff --git a/include/zobrist.c b/include/zobrist.c
new file mode 100644
index 0000000..feff5fa
--- /dev/null
+++ b/include/zobrist.c
@@ -0,0 +1,50 @@
+#include "zobrist.h"
+
+// ===================================================================
+// Globals
+// ===================================================================
+
+static uint64_t *zobrist;
+
+// ===================================================================
+// Helpers
+// ===================================================================
+
+
+// ===================================================================
+// Exported method implementations
+// ===================================================================
+
+int
+zobrist_init(void) {
+	if (zobrist != NULL) return EXIT_FAILURE;
+
+	zobrist = malloc(sizeof(uint64_t)*board_size*board_size*(15*2*3));
+	for (int k=0; k<board_size*board_size*(15*2*3); k++) {
+		XORSHIFT64;
+		zobrist[k] = RANDOM64;
+	}
+
+	return EXIT_SUCCESS;
+}
+
+void
+zobrist_free(void) {
+	if (zobrist != NULL) {
+		free(zobrist);
+		zobrist = 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[l*(15*2*3)+h*2*3+(c&1)*3+s];
+	}
+	return hash;
+}