Avoid undefined behaviour for geometries as a1b1 [defect]

kervinck · kervinck · commit faf542a1dece · 2016-06-21T23:51:29.000+02:00
Reported by Rasmus A. using CodeSonar, appreciated!

This not only fixes potential undefined behaviour, but the old code
worked by accident anyway for the other geometries (wrapping from
rank8 to rank1 didn't cause any harm but was unintended...)
diff --git a/kpk.c b/kpk.c
@@ -118,8 +118,8 @@ int kpkGenerate(void)
 
                 // Valid positions after black move, pawn capture allowed
                 valid[ix] = ~allKing(bit(wKing));
-                if (file(wPawn) != fileA) valid[ix] &= ~bit(wPawn+N+W);
-                if (file(wPawn) != fileH) valid[ix] &= ~bit(wPawn+N+E);
+                if (rank(wPawn) != rank8 && file(wPawn) != fileA) valid[ix] &= ~bit(wPawn+N+W);
+                if (rank(wPawn) != rank8 && file(wPawn) != fileH) valid[ix] &= ~bit(wPawn+N+E);
         }
 
         int changed;

Original file line number	Diff line number	Diff line change
`@@ -118,8 +118,8 @@ int kpkGenerate(void)`
`118`	`118`
`119`	`119`	`// Valid positions after black move, pawn capture allowed`
`120`	`120`	`valid[ix] = ~allKing(bit(wKing));`
`121`		`- if (file(wPawn) != fileA) valid[ix] &= ~bit(wPawn+N+W);`
`122`		`- if (file(wPawn) != fileH) valid[ix] &= ~bit(wPawn+N+E);`
	`121`	`+ if (rank(wPawn) != rank8 && file(wPawn) != fileA) valid[ix] &= ~bit(wPawn+N+W);`
	`122`	`+ if (rank(wPawn) != rank8 && file(wPawn) != fileH) valid[ix] &= ~bit(wPawn+N+E);`
`123`	`123`	`}`
`124`	`124`
`125`	`125`	`int changed;`