Treasure hunt

If only in 90 deg. intervals then it would be something like:

dim map(4, 4)
dim temp(4, 4)

;rotate right
for xiter = 0 to 4
  for yiter = 0 to 4
    temp(x, y) = map(4-y, x)
  next
next

;transfer back
for xiter = 0 to 4
  for yiter = 0 to 4
    map(x, y) = temp(x, y)
  next
next