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Post4 (Post-Forth)

Copyright 2007, 2024 Anthony Howe. All rights reserved.

Double-Cell Words

2CONSTANT

( x y <spaces>name -- )
Define the word name to represent the constant values x and y. When name is executed, the values x and y are pushed on to the stack.

    $dead $beef 2CONSTANT steak

2LITERAL

( x y -- ) immediate
Compile x and y into the definition so that they are later pushed onto the stack during execution of the definition.

     : SOMEWORD ... [ x y ] 2LITERAL ... ;

2ROT

( x1 x2 x3 x4 x5 x6 -- x3 x4 x4 x5 x1 x2 )
Rotate the top three cell pairs on the stack bringing cell pair x1 x2 to the top of the stack.

2VALUE

( lo hi <spaces>name -- )
Create name with two cells of data assigned hi and lo. When name is executed, the values lo hi are pushed to the stack. See TO.

2VARIABLE

( <spaces>name -- )
Create name with two cells of data. When name is executed push the aaddr of the data cells.

    2VARIABLE name          \ define name
    123 987 name 2!         \ store values to variable
    name 2@                 \ fetch value from variable

D+

( d1|ud1 d2|ud2 -- d3|ud3 )
Add the double-cells d2|ud2 to d1|ud1, giving the sum d3|ud3.

D-

( d1|ud1 d2|ud2 -- d3|ud3 )
Subtract the double-cells d2|ud2 from d1|ud1, giving the difference d3|ud3.

D.

( d -- )
Display double-cell d in free field format.

D.R

( d n -- )
Display double-cell d right aligned in a field n characters wide. If the number of characters required to display d is greater than n, all digits are displayed with no leading spaces in a field as wide as necessary.

D0<

( d -- bool )
bool is true if and only if the double-cell d (lo hi) is less than to zero (0).

D0=

( d -- bool )
bool is true if and only if the double-cell d (lo hi) is equal to zero (0).

D<

( d1 d2 -- bool )
bool is true if and only if the double-cell d1 is less then d2.

D=

( d1 d2 -- bool )
bool is true if and only if the double-cell d1 is equal to d2.

D>S

( d -- n )
Convert the double-cell number d (lo hi) to the single-cell number n with the same numerical value.

D2*

( xd -- yd )
The double-cell yd is the result of shifting xd one bit toward the most-significant bit, filling the vacated least-significant bit with zero.

D2/

( xd -- yd )
The double-cell yd is the result of shifting xd one bit toward the least-significant bit leaving the most-significant bit unchanged, .ie arithmetic right shift.

DABS

( d -- ud )
Double-cell ud is the absolute value of d.

DMAX

(S: d1 d2 -- d3 )
Double-cell d3 is the greater of d1 and d2.

DMIN

(S: d1 d2 -- d3 )
Double-cell d3 is the lesser of d1 and d2.

DNEGATE

( d1 -- d2 )
Negate the double-cell d1, giving its arithmetic inverse d2.

DU<

( ud1 ud2 -- bool )
bool is true if and only if the unsigned double-cell ud1 is less then ud2.

M*/

( d1 n1 +n2 -- d2 )
Multiply d1 by n1 producing the triple-cell intermediate result t. Divide t by n2 giving the double-cell quotient d2.

M+

( d1|ud1 n -- d2|ud2 )
Add single-cell n to the double-cell d1|ud1 (lo hi) giving the sum d2|ud2.

Post4 Specific Words

max-d

( -- d ) constant
Largest usable double-cell signed integer. This is a deviation from ENVIRONMENT? queries.

max-ud

( -- ud ) constant
Largest usable double-cell unsigned integer. This is a deviation from ENVIRONMENT? queries.

min-d

( -- d ) constant
Smallest usable double-cell signed integer.