FloatToFixed constructor

Implementation

FloatToFixed(FloatingPoint float, {super.name = 'FloatToFixed'}) {
  float = float.clone()..gets(addInput('float', float, width: float.width));

  final bias = FloatingPointValue.computeBias(float.exponent.width);
  // E4M3 expands the max exponent by 1.
  m = ((float.exponent.width == 4) & (float.mantissa.width == 3))
      ? bias + 1
      : bias;
  n = bias + float.mantissa.width - 1;
  final outputWidth = m + n + 1;

  final jBit = Logic(name: 'jBit')..gets(float.isNormal());
  final shift = Logic(name: 'shift', width: float.exponent.width)
    ..gets(
        mux(jBit, float.exponent - 1, Const(0, width: float.exponent.width)));

  final number = Logic(name: 'number', width: outputWidth)
    ..gets([
          Const(0, width: outputWidth - float.mantissa.width - 1),
          jBit,
          float.mantissa
        ].swizzle() <<
        shift);

  _fixed <= mux(float.sign, ~number + 1, number);
  addOutput('fixed', width: outputWidth) <= _fixed;
}