Stack Manipulation

2DROP

two-drop ( x1 x2 -- ), Drop cell pair x1 x2 from the stack.

2DUP

two-dupe ( x1 x2 -- x1 x2 x1 x2 ), Duplicate cell pair x1 x2.

2OVER

two-over ( x1 x2 x3 x4 -- x1 x2 x3 x4 x1 x2 ), Copy cell pair x1 x2 to the top of the stack.

2SWAP

two-swap ( x1 x2 x3 x4 -- x3 x4 x1 x2 ), Exchange the top two cell pairs.

>R

to-r

Interpretation: Interpretation semantics for this word are undefined.

Execution: ( x -- ) ( R: -- x )

Move x to the return stack.

DEPTH

( -- +n )

+n is the number of single-cell values contained in the data stack before +n was placed on the stack.

?DUP

question-dupe ( x -- 0 | x x ), Duplicate x if it is non-zero.

DROP

( x -- ), Remove x from the stack.

DUP

dupe ( x -- x x ), Duplicate x.

OVER

( x1 x2 -- x1 x2 x1 ), Place a copy of x1 on top of the stack.

R>

r-from

Interpretation: Interpretation semantics for this word are undefined.

Execution: ( -- x ) ( R: x -- )

Move x from the return stack to the data stack.

R@

r-fetch

Interpretation: Interpretation semantics for this word are undefined.

Execution: ( -- x ) ( R: x -- x )

Copy x from the return stack to the data stack.

ROT

rote ( x1 x2 x3 -- x2 x3 x1 ), Rotate the top three stack entries.

SWAP

( x1 x2 -- x2 x1 ), Exchange the top two stack items.