The embedder could hand the module functions for manipulating external buffers via externrefs. (I'm not sure if that's a good idea, or not, just that it could.)

The embedder could hand the module functions for manipulating external buffers via externrefs. (I'm not sure if that's a good idea, or not, just that it could.) But if the module wants to compute on the values in the buffer, at some level it would have to copy the data in/out.