Memory manipulation

Here are words that move and sort data in local RAM.

move

Moves data from source to destination.

move dsn for a! @+ a push a! !+ a pop next drop drop ;

This is the best code if data won't overlap or if destination is not greater than source. The strategy is to increment both source and destination in register a

Fetch word from source
Save incremented a on return stack
Store to destination
Restore addresses and repeat
Discard addresses

+move

Moves data from source to destination when data overlap and destination is greater than source. As in pushing an entry into a table. The count is n-1, which is convenient.

+move dsn dup push . + a! pop dup push . + a
begin a! @ a -1 . + push a! ! a -1 . + pop next drop drop ;

Clearly the code for move is shorter and faster.

The first line moves source and destination to the end of their regions. It is unnecessary if they already point there.

Push count onto return stack for begin
Add count to source and save in a (convenient that it's n-1)
Retrieve count (pop dup push) and add to destination
Restore source
Start loop
Fetch from source
Decrement address and save on return stack
Store to destination
Decrement address and restore source
Repeat
Discard addresses

bubble

This bubble sort takes an entry at the beginning of a sorted table and finds its place. The table must have a stopper greater than any possible entry. This is the smallest (only) sort I know.

bubble nt a! for @+ @ - + - -if
@ a -1 + a! @ push !+ pop ! then drop next ;

The two adds do not need a dot before them because they're in slot 3.

Set a and start loop
Subtract entry from its successor
If not possible (negative) entries must be exchanged
- Fetch the second
- Decrement a
- Fetch the first and save on return stack
- Store the second
- Restore and store the first
Drop the result of subtract
Repeat

Looks like building this table should start from high address and grow toward lower.