From cca36469168bac04f2b31250c002fd815eac8c46 Mon Sep 17 00:00:00 2001
From: Petr Baudis <pasky@ucw.cz>
Date: Fri, 15 Jan 2010 02:22:20 +0100
Subject: [PATCH] foreach_{8,diag}neighbor(): Simplify+speed up, use persistent
 shift array

---
 board.c | 14 ++++++++++++++
 board.h | 27 +++++++++------------------
 2 files changed, 23 insertions(+), 18 deletions(-)

diff --git a/board.c b/board.c
index 55a49f4..8cb509c 100644
--- a/board.c
+++ b/board.c
@@ -179,6 +179,20 @@ board_clear(struct board *board)
 
 	board->komi = komi;
 
+	/* Setup neighborhood iterators */
+	board->nei8[0] = -size - 1; // (-1,-1)
+	board->nei8[1] = 1;
+	board->nei8[2] = 1;
+	board->nei8[3] = size - 2; // (-1,0)
+	board->nei8[4] = 2;
+	board->nei8[5] = size - 2; // (-1,1)
+	board->nei8[6] = 1;
+	board->nei8[7] = 1;
+	board->dnei[0] = -size - 1;
+	board->dnei[1] = 2;
+	board->dnei[2] = size*2 - 2;
+	board->dnei[3] = 2;
+
 	/* Setup initial symmetry */
 	board->symmetry.d = 1;
 	board->symmetry.x1 = board->symmetry.y1 = board_size(board) / 2;
diff --git a/board.h b/board.h
index 75bedb1..61cd85f 100644
--- a/board.h
+++ b/board.h
@@ -84,6 +84,9 @@ struct board {
 	float komi;
 	int handicap;
 
+	/* Iterator offsets for foreach_neighbor*() */
+	int nei8[8], dnei[4];
+
 	int moves;
 	struct move last_move;
 	struct move last_move2; /* second-to-last move */
@@ -294,32 +297,20 @@ float board_official_score(struct board *board, struct move_queue *mq);
 
 #define foreach_8neighbor(board_, coord_) \
 	do { \
-		coord_t q__[8]; int q__i = 0; \
-		coord_pos(q__[q__i++], coord_raw(coord_) - board_size(board_) - 1, (board_)); \
-		coord_pos(q__[q__i++], coord_raw(coord_) - board_size(board_), (board_)); \
-		coord_pos(q__[q__i++], coord_raw(coord_) - board_size(board_) + 1, (board_)); \
-		coord_pos(q__[q__i++], coord_raw(coord_) - 1, (board_)); \
-		coord_pos(q__[q__i++], coord_raw(coord_) + 1, (board_)); \
-		coord_pos(q__[q__i++], coord_raw(coord_) + board_size(board_) - 1, (board_)); \
-		coord_pos(q__[q__i++], coord_raw(coord_) + board_size(board_), (board_)); \
-		coord_pos(q__[q__i++], coord_raw(coord_) + board_size(board_) + 1, (board_)); \
 		int fn__i; \
-		for (fn__i = 0; fn__i < q__i; fn__i++) { \
-			coord_t c = q__[fn__i];
+		coord_t c = (coord_); \
+		for (fn__i = 0; fn__i < 8; fn__i++) { \
+			c += (board_)->nei8[fn__i];
 #define foreach_8neighbor_end \
 		} \
 	} while (0)
 
 #define foreach_diag_neighbor(board_, coord_) \
 	do { \
-		coord_t q__[4]; int q__i = 0; \
-		coord_pos(q__[q__i++], coord_raw(coord_) - board_size(board_) - 1, (board_)); \
-		coord_pos(q__[q__i++], coord_raw(coord_) - board_size(board_) + 1, (board_)); \
-		coord_pos(q__[q__i++], coord_raw(coord_) + board_size(board_) - 1, (board_)); \
-		coord_pos(q__[q__i++], coord_raw(coord_) + board_size(board_) + 1, (board_)); \
 		int fn__i; \
-		for (fn__i = 0; fn__i < q__i; fn__i++) { \
-			coord_t c = q__[fn__i];
+		coord_t c = (coord_); \
+		for (fn__i = 0; fn__i < 4; fn__i++) { \
+			c += (board_)->dnei[fn__i];
 #define foreach_diag_neighbor_end \
 		} \
 	} while (0)
-- 
2.11.4.GIT