Stacked Brainfuck
This is brainfuck with the addition of a stack.
Commands
Stacked Brainfuck has the basic 8 commands.
The eight Basic language commands, each consisting of a single character:
| Character | Meaning |
|---|---|
>
|
Increment the pointer (to point to the next cell to the right). |
<
|
Decrement the pointer (to point to the next cell to the left). |
+
|
Increment (increase by one) the byte at the pointer. |
-
|
Decrement (decrease by one) the byte at the pointer. |
.
|
Output the value of the byte at the pointer. |
,
|
Accept one byte of input, storing its value in the byte at the pointer. |
[
|
Jump forward to the command after the corresponding ] if the byte at the pointer is zero.
|
]
|
Jump back to the command after the corresponding [ if the byte at the pointer is nonzero.
|
There is also a ! command, which serves the usual function of separating code and data.
11 Additional stack manipulation commands.
| Character | Meaning |
|---|---|
)
|
Pushes the value at the current cell onto the stack |
(
|
Pops the value on the stack into the current cell (an empty stack pops zero into the cell) |
@
|
Peeks the value on the stack, copying it into the current cell (without popping) |
$
|
Drops the value on the stack (as if it was popped), but does not write it to the cell |
=
|
Current cell is set to the SUM between its value and the value on the top of the stack (peek) |
_
|
current cell is set to the DIFFERENCE between its value and the value on the top of the stack (peek) |
}
|
Bitshifts the current cell value right by the value on the top of the stack (peek) |
{
|
Bitshifts the current cell value left by the value on the top of the stack (peek) |
|
|
Current cell is set to the bitwise OR between its value and the value on the top of the stack (peek) |
^
|
Current cell is set to the bitwise XOR between its value and the value on the top of the stack (peek) |
&
|
current cell is set to the bitwise AND between its value and the value on the top of the stack (peek) |
Hello World
+>+++++)<{)>==+++.=---.$=++..+++.<.)>)>(<_$=+++.>.)+++.(---._---.<<+.!
Using preloaded data. (in reverse)
[)>]([.(]!!dlroW olleH
Implementation
In the given implementation there are 65536 cells, each consisting of a single unsigned byte. The initial cell is at zero. The start of the stack is at the last cell. They grow towards each other (per usual). Cell's wrap (255 + 1 = 0; 0 - 1 = 255). Attempting to decrement from the initial cell causes no decremention.
Computational class
Stacked Brainfuck is obviously not Turing-complete, as it has bounded storage.
An alternative implementation to allow turing-completeness is to place the stack in negative cells below zero, or to separate it completely.