Forth 2012: M*

( n₁ n₂ -- d )

d is the signed product of n₁ times n₂.

See:

Rationale:

This word is a useful early step in calculation, going to extra precision conveniently. It has been in use since the Forth systems of the early 1970's.

Testing:

T{       0       0 M* ->       0 S>D }T
T{       0       1 M* ->       0 S>D }T
T{       1       0 M* ->       0 S>D }T
T{       1       2 M* ->       2 S>D }T
T{       2       1 M* ->       2 S>D }T
T{       3       3 M* ->       9 S>D }T
T{      -3       3 M* ->      -9 S>D }T
T{       3      -3 M* ->      -9 S>D }T
T{      -3      -3 M* ->       9 S>D }T
T{       0 MIN-INT M* ->       0 S>D }T
T{       1 MIN-INT M* -> MIN-INT S>D }T
T{       2 MIN-INT M* ->       0 1S }T
T{       0 MAX-INT M* ->       0 S>D }T
T{       1 MAX-INT M* -> MAX-INT S>D }T
T{       2 MAX-INT M* -> MAX-INT     1 LSHIFT 0 }T
T{ MIN-INT MIN-INT M* ->       0 MSB 1 RSHIFT   }T
T{ MAX-INT MIN-INT M* ->     MSB MSB 2/         }T
T{ MAX-INT MAX-INT M* ->       1 MSB 2/ INVERT }T