pub struct DmaStartOperation<'c> { /* private fields */ }Expand description
A dma_start operation. Non-blocking DMA operation that starts a transfer.
DmaStartOp starts a non-blocking DMA operation that transfers data from a source memref to a destination memref. The source and destination memref need not be of the same dimensionality, but need to have the same elemental type. The operands include the source and destination memref’s each followed by its indices, size of the data transfer in terms of the number of elements (of the elemental type of the memref), a tag memref with its indices, and optionally at the end, a stride and a number_of_elements_per_stride arguments. The tag location is used by a DmaWaitOp to check for completion. The indices of the source memref, destination memref, and the tag memref have the same restrictions as any load/store. The optional stride arguments should be of ‘index’ type, and specify a stride for the slower memory space (memory space with a lower memory space id), transferring chunks of number_of_elements_per_stride every stride until %num_elements are transferred. Either both or no stride arguments should be specified. If the source and destination locations overlap the behavior of this operation is not defined.
For example, a DmaStartOp operation that transfers 256 elements of a memref ‘%src’ in memory space 0 at indices [%i, %j] to memref ‘%dst’ in memory space 1 at indices [%k, %l], would be specified as follows:
%num_elements = arith.constant 256
%idx = arith.constant 0 : index
%tag = memref.alloc() : memref<1 x i32, affine_map<(d0) -> (d0)>, 4>
dma_start %src[%i, %j], %dst[%k, %l], %num_elements, %tag[%idx] :
memref<40 x 128 x f32>, affine_map<(d0) -> (d0)>, 0>,
memref<2 x 1024 x f32>, affine_map<(d0) -> (d0)>, 1>,
memref<1 x i32>, affine_map<(d0) -> (d0)>, 2>
If %stride and %num_elt_per_stride are specified, the DMA is expected to transfer %num_elt_per_stride elements every %stride elements apart from memory space 0 until %num_elements are transferred.
dma_start %src[%i, %j], %dst[%k, %l], %num_elements, %tag[%idx], %stride,
%num_elt_per_stride :
TODO: add additional operands to allow source and destination striding, and multiple stride levels. TODO: Consider replacing src/dst memref indices with view memrefs.