[Discuss-gnuradio] Request for comment: Adding fixed point to VOLK

[Albin Stigö]

Hi,

Volk has functions for converting between int and float by casting and
multiplying with a scalar. I'd like to purpose functions for the
special case where scalar is 1/INT32_MAX (and 1/INT16_MAX etc) as this
is a very common use case and might be available to an optimization.
Certain CPUs (armv8 in particular [1], not sure about x86? [2]) has
hardware instructions for converting fixed point to float and back.

In particular I'm interested in adding the common Q1.31 and Q1.15
formats (full range signed int32_t and full range int16_t to
(-1.0)-1.0 float).

Would be grateful for input regarding this and in particular ideas for
naming the functions.


--Albin

[1] 
http://infocenter.arm.com/help/index.jsp?topic=/com.arm.doc.dui0801h/pge1427897637493.html
[2] 
https://software.intel.com/en-us/articles/fast-floating-point-to-integer-conversions