#if !defined(IMAGE_WALK_UNROLL)
# define IMAGE_WALK_UNROLL 1
#elif IMAGE_WALK_UNROLL != 1 && IMAGE_WALK_UNROLL != 2 && IMAGE_WALK_UNROLL != 4
# error IMAGE_WALK_UNROLL must be 1, 2 or 4
#endif
#if !defined(IMAGE_WALK_UNROLL)
# define IMAGE_WALK_UNROLL 1
#elif IMAGE_WALK_UNROLL != 1 && IMAGE_WALK_UNROLL != 2 && IMAGE_WALK_UNROLL != 4
# error IMAGE_WALK_UNROLL must be 1, 2 or 4
#endif