Module Name: src
Committed By: rillig
Date: Sat May 28 19:47:24 UTC 2022
Modified Files:
src/games/gomoku: bdinit.c
Log Message:
gomoku: clean up initialization of overlap information
Fix variable names 'ia' and 'ib', which I forgot in the previous commit.
Move the documentation in the right places.
Split off another part of init_overlap, to make each function fit on a
single screen. Reducing the number of nested 'for' loops allows the
indentation to follow the NetBSD style.
No functional change.
To generate a diff of this commit:
cvs rdiff -u -r1.26 -r1.27 src/games/gomoku/bdinit.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/games/gomoku/bdinit.c
diff -u src/games/gomoku/bdinit.c:1.26 src/games/gomoku/bdinit.c:1.27
--- src/games/gomoku/bdinit.c:1.26 Sat May 28 18:55:16 2022
+++ src/games/gomoku/bdinit.c Sat May 28 19:47:24 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: bdinit.c,v 1.26 2022/05/28 18:55:16 rillig Exp $ */
+/* $NetBSD: bdinit.c,v 1.27 2022/05/28 19:47:24 rillig Exp $ */
/*
* Copyright (c) 1994
@@ -34,7 +34,7 @@
#include <sys/cdefs.h>
/* from: @(#)bdinit.c 8.2 (Berkeley) 5/3/95 */
-__RCSID("$NetBSD: bdinit.c,v 1.26 2022/05/28 18:55:16 rillig Exp $");
+__RCSID("$NetBSD: bdinit.c,v 1.27 2022/05/28 19:47:24 rillig Exp $");
#include <string.h>
#include "gomoku.h"
@@ -160,43 +160,65 @@ init_board(void)
init_overlap();
}
-/*-
- * ra direction of frame A
- * ia index of the spot in frame A (0 to 5)
- * rb direction of frame B
- * ib index of the spot in frame B (0 to 5)
+/*
+ * Variable names for frames A and B:
+ *
+ * fi index of the frame in the global 'frames'
+ * r direction: 0 = right, 1 = down right, 2 = down, 3 = down left
+ * d direction delta, difference between adjacent spot indexes
+ * si index of the spot in the frame, 0 to 5
+ */
+
+/*
+ * Each entry in the overlap array is a bit mask with eight bits corresponding
+ * to whether frame B overlaps frame A (as indexed by overlap[A * FAREA + B]).
+ *
+ * The eight bits correspond to whether A and B are open-ended (length 6) or
+ * closed (length 5).
+ *
+ * 0 A closed and B closed
+ * 1 A closed and B open
+ * 2 A open and B closed
+ * 3 A open and B open
+ * 4 A closed and B closed and overlaps in more than one spot
+ * 5 A closed and B open and overlaps in more than one spot
+ * 6 A open and B closed and overlaps in more than one spot
+ * 7 A open and B open and overlaps in more than one spot
+ *
+ * As pieces are played during the game, frames that no longer share an empty
+ * spot will be removed from the overlap array by setting the entry to 0.
*/
static u_char
-adjust_overlap(u_char ov, int ra, int ia, int rb, int ib, int mask)
+adjust_overlap(u_char ov, int ra, int sia, int rb, int sib, int mask)
{
- ov |= (ib == 5) ? mask & 0xA : mask;
+ ov |= (sib == 5) ? mask & 0xA : mask;
if (rb != ra)
return ov;
/* compute the multiple spot overlap values */
- switch (ia) {
+ switch (sia) {
case 0:
- if (ib == 4)
+ if (sib == 4)
ov |= 0xA0;
- else if (ib != 5)
+ else if (sib != 5)
ov |= 0xF0;
break;
case 1:
- if (ib == 5)
+ if (sib == 5)
ov |= 0xA0;
else
ov |= 0xF0;
break;
case 4:
- if (ib == 0)
+ if (sib == 0)
ov |= 0xC0;
else
ov |= 0xF0;
break;
case 5:
- if (ib == 1)
+ if (sib == 1)
ov |= 0xC0;
- else if (ib != 0)
+ else if (sib != 0)
ov |= 0xF0;
break;
default:
@@ -207,73 +229,56 @@ adjust_overlap(u_char ov, int ra, int ia
}
/*
- * Initialize the overlap array.
- * Each entry in the array is a bit mask with eight bits corresponding
- * to whether frame B overlaps frame A (as indexed by overlap[A * FAREA + B]).
- * The eight bits correspond to whether A and B are open-ended (length 6) or
- * closed (length 5).
- * 0 A closed and B closed
- * 1 A closed and B open
- * 2 A open and B closed
- * 3 A open and B open
- * 4 A closed and B closed and overlaps in more than one spot
- * 5 A closed and B open and overlaps in more than one spot
- * 6 A open and B closed and overlaps in more than one spot
- * 7 A open and B open and overlaps in more than one spot
- * As pieces are played, it can make frames not overlap if there are no
- * common open spaces shared between the two frames.
+ * Given a single spot 's' of frame A, update the overlap information for
+ * each frame B that overlaps frame A in that spot.
*/
static void
+init_overlap_frame(int fia, int ra, int sia, int s, int mask)
+{
+
+ for (int rb = 4; --rb >= 0;) {
+ int db = dd[rb];
+
+ for (int sib = 0; sib < 6; sib++) {
+ /* spb0 is the spot where frame B starts. */
+ const struct spotstr *spb0 = &board[s - sib * db];
+ if (spb0->s_occ == BORDER)
+ break;
+ if ((spb0->s_flags & BFLAG << rb) != 0)
+ continue;
+
+ int fib = (int)(spb0->s_frame[rb] - frames);
+ intersect[fia * FAREA + fib] = (short)s;
+ u_char *op = &overlap[fia * FAREA + fib];
+ *op = adjust_overlap(*op, ra, sia, rb, sib, mask);
+ }
+ }
+}
+
+static void
init_overlap(void)
{
memset(overlap, 0, sizeof(overlap));
memset(intersect, 0, sizeof(intersect));
- /*-
- * Variables for frames A and B:
- *
- * fi index of the frame in the global 'frames'
- * r direction: 0 = right, 1 = down right, 2 = down, 3 = down left
- * d direction delta, difference between adjacent spot indexes
- * si index of the spot in the frame, 0 to 5
- * sp data of the spot at index i
- */
-
- for (unsigned fia = FAREA; fia-- > 0; ) {
- struct combostr *fa = &frames[fia];
- int vertex = fa->c_vertex;
- struct spotstr *spa = &board[vertex];
- u_char ra = fa->c_dir;
- int da = dd[ra];
-
- /*
- * len = 5 if closed, 6 if open.
- * At this point, Black and White have the same values.
- */
- int len = 5 + spa->s_fval[BLACK][ra].cv_win;
-
- for (int sia = 0; sia < len; sia++, spa += da, vertex += da) {
- /* the sixth spot in frame A only overlaps if it is open */
- int mask = (sia == 5) ? 0xC : 0xF;
-
- for (int rb = 4; --rb >= 0; ) {
- struct spotstr *spb = spa;
- int db = dd[rb];
-
- /* for each frame that intersects at spot spa */
- for (int sib = 0; sib < 6; sib++, spb -= db) {
- if (spb->s_occ == BORDER)
- break;
- if ((spb->s_flags & BFLAG << rb) != 0)
- continue;
+ for (int fia = FAREA; fia-- > 0;) {
+ const struct combostr *fa = &frames[fia];
+ int s = fa->c_vertex;
+ u_char ra = fa->c_dir;
+ int da = dd[ra];
+
+ /*
+ * len = 5 if closed, 6 if open. At this early stage, Black
+ * and White have the same value for cv_win.
+ */
+ int len = 5 + board[s].s_fval[BLACK][ra].cv_win;
+
+ for (int sia = 0; sia < len; sia++) {
+ /* spot[5] in frame A only overlaps if it is open */
+ int mask = (sia == 5) ? 0xC : 0xF;
- int fib = (int)(spb->s_frame[rb] - frames);
- intersect[fia * FAREA + fib] = (short)vertex;
- u_char *op = &overlap[fia * FAREA + fib];
- *op = adjust_overlap(*op, ra, sia, rb, sib, mask);
- }
+ init_overlap_frame(fia, ra, sia, s + sia * da, mask);
}
- }
}
}
