diff options
Diffstat (limited to 'src/direction_func.h')
| -rw-r--r-- | src/direction_func.h | 13 |
1 files changed, 9 insertions, 4 deletions
diff --git a/src/direction_func.h b/src/direction_func.h index 8c8170a15..f3b714a8e 100644 --- a/src/direction_func.h +++ b/src/direction_func.h @@ -35,7 +35,9 @@ static inline Direction ReverseDir(Direction d) */ static inline DirDiff DirDifference(Direction d0, Direction d1) { - return (DirDiff)((d0 + 8 - d1) % 8); + /* Cast to uint so compiler can use bitmask. If the difference is negative + * and we used int instead of uint, further "+ 8" would have to be added. */ + return (DirDiff)((uint)(d0 - d1) % 8); } /** @@ -51,7 +53,8 @@ static inline DirDiff DirDifference(Direction d0, Direction d1) */ static inline DirDiff ChangeDirDiff(DirDiff d, DirDiff delta) { - return (DirDiff)((d + delta) % 8); + /* Cast to uint so compiler can use bitmask. Result can never be negative. */ + return (DirDiff)((uint)(d + delta) % 8); } /** @@ -66,7 +69,8 @@ static inline DirDiff ChangeDirDiff(DirDiff d, DirDiff delta) */ static inline Direction ChangeDir(Direction d, DirDiff delta) { - return (Direction)((d + delta) % 8); + /* Cast to uint so compiler can use bitmask. Result can never be negative. */ + return (Direction)((uint)(d + delta) % 8); } @@ -94,7 +98,8 @@ static inline DiagDirection ReverseDiagDir(DiagDirection d) */ static inline DiagDirection ChangeDiagDir(DiagDirection d, DiagDirDiff delta) { - return (DiagDirection)((d + delta) % 4); + /* Cast to uint so compiler can use bitmask. Result can never be negative. */ + return (DiagDirection)((uint)(d + delta) % 4); } /** |