Fri, 25 Mar 2011 10:00:24 -0700, Eli Stevens (Gmail) wrote:
I'm working on getting support for 16-bit floats into cython and have run into what seems like a numpy bug (I'm a new contributor to both projects, so bear with me ;).
https://github.com/wickedgrey/numpy/ commit/29f9f1b709cc2c346b8514859c58a761df80f031
Adding NPY_HALF to the switch statement on line 350 of numpy/core/src/multiarray/buffer.c doesn't seem controversial (unless it needs to be spelled NPY_FLOAT16 or something similar), but I have no idea how to test the change.
The buffer interface cannot be used to export the half-float types, since the type is not specified in PEP 3118. Numpy cannot unilaterally add nonstandard format codes to the spec. What can be done instead is exporting the half-float items (and any other non-3118 types) as plain bytes. I think this is the way to go. On the Cython side, you'd need to detect when you are working with Numpy arrays, and get the half-float type information from the Numpy dtype rather than from the exported buffer. -- Pauli Virtanen