src/ieee754/fpfma/util.py

   1 from ieee754.fpcommon.fpbase import FPFormat
   2 from nmigen.hdl.ast import signed, unsigned
   3
   4
   5 def expanded_exponent_shape(fpformat):
   6     assert isinstance(fpformat, FPFormat)
   7     return signed(fpformat.e_width + 3)
   8
   9
  10 EXPANDED_MANTISSA_EXTRA_LSBS = 3
  11
  12
  13 def expanded_mantissa_shape(fpformat):
  14     assert isinstance(fpformat, FPFormat)
  15     return signed(fpformat.fraction_width * 3 +
  16                   2 + EXPANDED_MANTISSA_EXTRA_LSBS)
  17
  18
  19 def multiplicand_mantissa_shape(fpformat):
  20     assert isinstance(fpformat, FPFormat)
  21     return unsigned(fpformat.fraction_width + 1)
  22
  23
  24 def product_mantissa_shape(fpformat):
  25     assert isinstance(fpformat, FPFormat)
  26     return unsigned(multiplicand_mantissa_shape(fpformat).width * 2)
  27
  28
  29 def get_fpformat(pspec):
  30     width = pspec.width
  31     assert isinstance(width, int)
  32     fpformat = getattr(pspec, "fpformat", None)
  33     if fpformat is None:
  34         fpformat = FPFormat.standard(width)
  35     else:
  36         assert isinstance(fpformat, FPFormat)
  37     assert width == fpformat.width
  38     return fpformat