[InMemoryDataset redesign] read_many_slices_param

versioned_hdf5/subchunk_map.pxd

@@ -11,6 +11,7 @@ cdef class IndexChunkMapper:
     cdef readonly hsize_t last_chunk_size
 
     cpdef tuple[object, object, object] chunk_submap(self, hsize_t chunk_idx)
+    cpdef tuple[object, object | None] read_many_slices_params(self)
 
     cpdef object chunks_indexer(self)
     cpdef object whole_chunks_idxidx(self)
@@ -19,3 +20,34 @@ cdef class IndexChunkMapper:
     cdef tuple[hsize_t, hsize_t] _chunk_start_stop(
         self, hsize_t chunk_idx
     ) noexcept nogil
+
+
+cpdef hsize_t[:, :, :] read_many_slices_params_nd(
+    transfer_type,  # TransferType Python enum
+    list[IndexChunkMapper] mappers,
+    hsize_t[:, :] chunk_idxidx,
+    hsize_t[:] src_slab_offsets,
+    hsize_t[:] dst_slab_offsets,
+)
+
+
+# At the moment of writing, Cython enums are unusable in pure python mode:
+# https://github.com/cython/cython/issues/4252
+# The below is for user reference only and not actually used in the code.
+
+cdef enum ReadManySlicesColumn:
+    """Axis 1 of the return value of IndexChunkMapper.read_many_slices_params"""
+    chunk_sub_start = 0
+    value_sub_start = 1
+    count = 2
+    chunk_sub_stride = 3
+    value_sub_stride = 4
+
+
+cdef enum ReadManySlicesNDColumn:
+    """Axis 1 of the return value of read_many_slices_params_nd"""
+    src_start = 0
+    dst_start = 1
+    count_ = 2  # Two enums can't define the same label
+    src_stride = 3
+    dst_stride = 4