warp.bit\_count
===============

.. currentmodule:: warp._src.lang

.. function:: bit_count(x: Int) -> int32

   .. wp-function-tags::
      :kernel: true
      :python: true
      :differentiable: false

   Return the number of set bits in an integer.
   
   Signed inputs use their two's-complement representation, including the sign
   bit. In contrast, Python's ``int.bit_count()`` counts set bits in the
   absolute value, so the results can differ for negative inputs.
   
   :param x: A signed or unsigned scalar integer of 8, 16, 32, or 64 bits.
             Python ``int`` inputs are treated as ``int32``.
   
   :returns: The number of set bits in the fixed-width binary representation of ``x``.
   
   .. rubric:: Example
   
   >>> wp.bit_count(45)
   4
   >>> wp.bit_count(wp.int8(-1))
   8
   >>> wp.bit_count(wp.int64(-1))
   64
   >>> (-1).bit_count()  # Python counts bits in the absolute value.
   1