Toffoli is a turing tarpit based on toffoli gates. It was created as a pltgames submission.
To use the interpreter, call toffoli.py on the command line with your code as input, eg:
python toffoli.py hello_world.toff
As a proof of turing-completness, a brainfuck to Toffoli compiler is included in the utils directory as "bf_compiler.py".
Memory in Toffoli is an infinite array, starting at adress 0, of bits that are initalised to 0.
Toffoli syntax is very simple, just the name of the instruction, followed by the inputs, separated by spaces:
[instruction] [input1] [input2] [input3] ...
Each input can be either a number or a reference to a memory address. Numbers are written literally while memory addresses are prefaced by a #. By putting a number before the #, you reference the pointer starting at that location e.g.:
- 1 is the number 1
- #7 is a reference to memory address 7
- 4#7 means to use the 4 bit pointer that starts at location 7 as input
Toffoli contains four instructions:
- TOFF
- JMP
- IN
- OUT
Usage:
TOFF [num/addr] [num/addr] [num/addr] [addr]
A toffoli gate, or a controlled-controlled-NOT gate works as follows:
If the first two inputs are both 1, output the result of appling a NOT gate to the third input
Otherwise, output the third input unchanged
The TOFF instruction applies a toffoli gate to the first three inputs and stores the result in the address given as the fourth input.
Usage:
JMP [num/addr] [num]
If the first input is not 0, or if the value stored at the bit refered to by the first input is 1, then continue execution at the instruction numbered by the second input. Instructions are numbered starting at 0.
Usage:
IN [addr]
Take one character as input and store the corresponding byte in the 8
bits starting at [addr].
Usage:
OUT [addr]
Interpret the 8 bits starting at [addr] as a character and output it.