source: vis_dev/vis-2.1/examples/fpmpy/fpmpy.inv @ 15

# Define common subformulae.
\define START   (start=1 * FPM.state[1:0]=0)
\define BUSY    !(FPM.state[1:0]=0)
\define Validx  (x[6:3]=0 -> x[2:0]=0)
\define Validy  (y[6:3]=0 -> y[2:0]=0)
\define Validz  (z[6:3]=0 -> z[2:0]=0)
\define NaNx    (x[6:3]=b1111 * !(x[2:0]=0))
\define NaNy    (y[6:3]=b1111 * !(y[2:0]=0))
\define NaNz    (z[6:3]=b1111 * !(z[2:0]=0))
\define Infx    x[6:0]=b1111000
\define Infy    y[6:0]=b1111000
\define Infz    z[6:0]=b1111000

#PASS: Legal operands cannot produce illegal results. The only illegal
# operands in our case are the denormals.

(\BUSY * \Validx * \Validy) -> \Validz;

#FAIL: If the sign bits are different the result is negative.
# This formula fails because one operand may be NaN.

(\BUSY * !(y[7]==x[7])) -> z[7]=1;