replace morton order by np unravel index

Author: brokkoli71

src/zarr/core/indexing.py

@@ -1325,20 +1325,7 @@ def make_slice_selection(selection: Any) -> list[slice]:
 
 
 def decode_morton(z: int, chunk_shape: ChunkCoords) -> ChunkCoords:
-    # Inspired by compressed morton code as implemented in Neuroglancer
-    # https://github.com/google/neuroglancer/blob/master/src/neuroglancer/datasource/precomputed/volume.md#compressed-morton-code
-    bits = tuple(math.ceil(math.log2(c)) for c in chunk_shape)
-    max_coords_bits = max(bits)
-    input_bit = 0
-    input_value = z
-    out = [0] * len(chunk_shape)
-
-    for coord_bit in range(max_coords_bits):
-        for dim in range(len(chunk_shape)):
-            if coord_bit < bits[dim]:
-                bit = (input_value >> input_bit) & 1
-                out[dim] |= bit << coord_bit
-                input_bit += 1
+    out = [int(i) for i in np.unravel_index(z, chunk_shape)]
     return tuple(out)