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Replace broken GCFx(), GCFy() by sctoff()

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GCFx() and GCFy() pointlessly duplicate sctoff(), and don't work when
the argument is less than -WORLD_X or -WORLD_Y, respectively.  With
current code, this happens only for impractically tiny worlds:
emp_setbitmap() writes to bitmap[] out of bounds, and smashes the
heap.
This commit is contained in:
Markus Armbruster 2008-08-23 14:04:10 -04:00
parent 6316c4185a
commit c89f8172ec
1 changed files with 10 additions and 13 deletions
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23
src/lib/subs/getbit.c
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@ -114,25 +114,22 @@ static int *bitmaps[5] = {
bitmap4, bitmap4,
}; };
#define GCFx(x) ((x + WORLD_X) % WORLD_X)
#define GCFy(y) ((y + WORLD_Y) % WORLD_Y)
int int
emp_getbit(int x, int y, unsigned char *bitmap) emp_getbit(int x, int y, unsigned char *bitmap)
{ {
int id; int id = sctoff(x, y);
if (id < 0)
id = (GCFy(y)) * WORLD_X / 2 + GCFx(x) / 2; return 0;
return bitmap[id / 8] & bit(id & 07); return bitmap[id >> 3] & bit(id & 07);
} }
void void
emp_setbit(int x, int y, unsigned char *bitmap) emp_setbit(int x, int y, unsigned char *bitmap)
{ {
int id; int id = sctoff(x, y);
if (id < 0)
id = (GCFy(y)) * WORLD_X / 2 + GCFx(x) / 2; return;
bitmap[id / 8] |= bit(id & 07); bitmap[id >> 3] |= bit(id & 07);
} }
static void static void
@ -145,8 +142,8 @@ emp_setbitmap(int x, int y, unsigned char *bitmap, int *bitmaps)
for (mp = bitmaps; *mp != 9999;) { for (mp = bitmaps; *mp != 9999;) {
dx = x + *mp++; dx = x + *mp++;
dy = y + *mp++; dy = y + *mp++;
id = (GCFy(dy)) * WORLD_X / 2 + GCFx(dx) / 2; id = sctoff(dx, dy);
bitmap[id / 8] |= bit(id & 07); bitmap[id >> 3] |= bit(id & 07);
} }
} }