[src/trunk]: src/games/gomoku gomoku: clean up overlap info in 'checkframes'

[rillig <rillig%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/1cd8b2a66bf8
branches:  trunk
changeset: 366527:1cd8b2a66bf8
user:      rillig <rillig%NetBSD.org@localhost>
date:      Sun May 29 18:25:39 2022 +0000

description:
gomoku: clean up overlap info in 'checkframes'

In 2009, GCC had complained that the overlap_info might only be
partially filled. All possible code paths are sane though, so that was
probably a bug in GCC.

Remove the comment and the unnecessary initialization, rename the
variable since it doesn't match its behavior anymore. Sync nearby
comments with reality; there is no array anywhere near.

No functional change.

diffstat:

 games/gomoku/pickmove.c |  46 ++++++++++++++++++----------------------------
 1 files changed, 18 insertions(+), 28 deletions(-)

diffs (128 lines):

diff -r 45a40f8a44f3 -r 1cd8b2a66bf8 games/gomoku/pickmove.c
--- a/games/gomoku/pickmove.c   Sun May 29 18:05:25 2022 +0000
+++ b/games/gomoku/pickmove.c   Sun May 29 18:25:39 2022 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: pickmove.c,v 1.63 2022/05/29 18:05:25 rillig Exp $     */
+/*     $NetBSD: pickmove.c,v 1.64 2022/05/29 18:25:39 rillig Exp $     */
 
 /*
  * Copyright (c) 1994
@@ -34,7 +34,7 @@
 
 #include <sys/cdefs.h>
 /*     @(#)pickmove.c  8.2 (Berkeley) 5/3/95   */
-__RCSID("$NetBSD: pickmove.c,v 1.63 2022/05/29 18:05:25 rillig Exp $");
+__RCSID("$NetBSD: pickmove.c,v 1.64 2022/05/29 18:25:39 rillig Exp $");
 
 #include <stdlib.h>
 #include <string.h>
@@ -53,7 +53,7 @@
  * This structure is used to store overlap information between frames.
  */
 struct overlap_info {
-       int             o_intersect;    /* intersection spot */
+       spot_index      o_intersect;    /* intersection spot */
        u_char          o_off;          /* offset in frame of intersection */
        u_char          o_frameindex;   /* intersection frame index */
 };
@@ -661,18 +661,9 @@
        struct combostr **scbpp;
        int baseB, fcnt, emask, verts;
        union comboval ocb;
-       struct overlap_info vertices[1];
+       struct overlap_info ovi;
        char tmp[128];
 
-       /*
-        * XXX: when I made functions static gcc started warning about
-        * some members of vertices[0] maybe being used uninitialized.
-        * For now, I'm just going to clear it rather than wade through
-        * the logic to find out whether gcc or the code is wrong. I
-        * wouldn't be surprised if it were the code though. - dholland
-        */
-       memset(vertices, 0, sizeof(vertices));
-
        ocb.s = cv;
        baseB = ocb.cv_force + ocb.cv_win - 1;
        fcnt = ocb.cv_force - 2;
@@ -680,13 +671,13 @@
        for (struct elist *ep = osp->s_empty; ep != NULL; ep = ep->e_next) {
            /* check for various kinds of overlap */
            cbp = ep->e_combo;
-           verts = checkframes(cbp, ocbp, osp, cv, vertices);
+           verts = checkframes(cbp, ocbp, osp, cv, &ovi);
            if (verts < 0)
                continue;
 
            /* check to see if this frame forms a valid loop */
            if (verts > 0) {
-               sp = &board[vertices[0].o_intersect];
+               sp = &board[ovi.o_intersect];
 #ifdef DEBUG
                if (sp->s_occ != EMPTY) {
                    debuglog("loop: %c %s", "BW"[curcolor],
@@ -754,15 +745,14 @@
            ncbp->c_emask[0] = ep->e_emask;
            if (verts != 0) {
                ncbp->c_flags |= C_LOOP;
-               ncbp->c_dir = vertices[0].o_frameindex;
+               ncbp->c_dir = ovi.o_frameindex;
                ncbp->c_framecnt[1] = fcnt - 1;
                if (ncbp->c_framecnt[1] != 0) {
-                   n = (vertices[0].o_intersect - ocbp->c_vertex) /
-                       dd[ocbp->c_dir];
+                   n = (ovi.o_intersect - ocbp->c_vertex) / dd[ocbp->c_dir];
                    ncbp->c_emask[1] = emask & ~(1 << n);
                } else
                    ncbp->c_emask[1] = 0;
-               ncbp->c_voff[0] = vertices[0].o_off;
+               ncbp->c_voff[0] = ovi.o_off;
            } else {
                ncbp->c_dir = 0;
                ncbp->c_framecnt[1] = fcnt;
@@ -1074,14 +1064,14 @@
  * Return zero if it is valid to combine frame 'fcbp' with the frames
  * in 'cbp' and forms a linked chain of frames (i.e., a tree; no loops).
  * Return positive if combining frame 'fcbp' to the frames in 'cbp'
- * would form some kind of valid loop. Also return the intersection spots
- * in 'vertices[]' beside the known intersection at spot 'osp'.
+ * would form some kind of valid loop. Also return the intersection spot
+ * in 'ovi' beside the known intersection at spot 'osp'.
  * Return -1 if 'fcbp' should not be combined with 'cbp'.
  * 'cv' is the combo value for frame 'fcbp'.
  */
 static int
 checkframes(struct combostr *cbp, struct combostr *fcbp, struct spotstr *osp,
-           u_short cv, struct overlap_info *vertices)
+           u_short cv, struct overlap_info *ovi)
 {
        struct combostr *tcbp, *lcbp;
        int ovbit, n, mask, flags, fcnt;
@@ -1148,10 +1138,10 @@
                                     s == fcbp->c_vertex + 5 * dd[fcbp->c_dir]))
                                        return -1;      /* invalid overlap */
 
-                               vertices->o_intersect = s;
-                               vertices->o_off = (s - tcbp->c_vertex) /
+                               ovi->o_intersect = s;
+                               ovi->o_off = (s - tcbp->c_vertex) /
                                        dd[tcbp->c_dir];
-                               vertices->o_frameindex = myindex;
+                               ovi->o_frameindex = myindex;
                                verts++;
                        }
                }
@@ -1196,10 +1186,10 @@
                             s == fcbp->c_vertex + 5 * dd[fcbp->c_dir]))
                                return -1;      /* invalid overlap */
 
-                       vertices->o_intersect = s;
-                       vertices->o_off = (s - cbp->c_vertex) /
+                       ovi->o_intersect = s;
+                       ovi->o_off = (s - cbp->c_vertex) /
                                dd[cbp->c_dir];
-                       vertices->o_frameindex = 0;
+                       ovi->o_frameindex = 0;
                        verts++;
                }
        }