Subversion Repositories dmt_tx

from myhdl import *

def flipSign(in_data, out_data, overflow, width):

  '''Flip the sign of the input value.

  The min value will cause an overflow and will be saturated to the max

  value when flipping its sign

  I/O Signals

  ===========

  in_data   : signal with the input data

  out_data  : signal having input data with flipped sign

  overflow  : signal whether an overflow occured. That only happens for

              min value, as the max value = abs(min) - 1

  Parameter

  =========

  width     : input width

  '''

  min = -2**(width-1)

  max = 2**(width-1)-1

  @always_comb

  def rtl():

    if in_data == min:

      out_data.next = max

      overflow.next = True

    else:

      out_data.next = -in_data

      overflow.next = False

  return instances()