// fma16.sv
// David_Harris@hmc.edu 26 February 2022
// 16-bit floating-point multiply-accumulate

// Operation: general purpose multiply, add, fma, with optional negation
//   If mul=1, p = x * y.  Else p = x.
//   If add=1, result = p + z.  Else result = p.
//   If negr or negz = 1, negate result or z to handle negations and subtractions
//   fadd: mul = 0, add = 1, negr = negz = 0
//   fsub: mul = 0, add = 1, negr = 0, negz = 1
//   fmul: mul = 1, add = 0, negr = 0, negz = 0
//   fmadd:  mul = 1, add = 1, negr = 0, negz = 0
//   fmsub:  mul = 1, add = 1, negr = 0, negz = 1
//   fnmadd: mul = 1, add = 1, negr = 1, negz = 0
//   fnmsub: mul = 1, add = 1, negr = 1, negz = 1

module fma16(
  input  logic [15:0] x, y, z,
  input  logic        mul, add, negr, negz,
  input  logic [1:0]  roundmode,  // 00: rz, 01: rne, 10: rp, 11: rn
  output logic [15:0] result);
 
endmodule