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Addbig is a OISC created by User:Joaozin003 which the only instruction is "Add the values of A and B, store the result in A and branch to C if the result is bigger than zero."

This instruction can be written in C-like syntax with the code:

*a += *b; if (*a > 0) goto c;

It is also the literal opposite of Subleq.

Programming in Addbig

The full Addbig instruction

In C-like syntax:

if (c == -1) return; if (b == -1) *a += (int)scanf(); else *a += *b; if (a == -1) { printf("%d", *a); *a = 0; if (*b > 0) goto c;} else if (*a > 0) goto c;

Memory Mapping

Since Addbig has no I/O, it is memory-mapped to address -1. Adding from -1 means input, and adding to -1 means output (the result does not go to address -1, it goes to the console, effectively discarding the result (for discarding the result by not using output, discard it into a unused address)).

And jumping to -1 effectively means ending the program, as that address is useless as a instruction (the first actual instruction is at address 0, the start of the program).

Storage of data

Data can be stored in lots of ways, but I'm just showing one:

The Stack

A stack is a way of storing data which follows the "first in, last out" pattern.

Stack Push

Stack push puts a value on top of the stack, and increases the stack pointer. I'm going to label the stack pointer with "sp" to help traverse code.

sp v 3 # v is the value to push
0 1 ... # increment stack pointer
Stack Pop

Stack pop takes a value out of the stack, stores it somewhere and decreases the stack pointer.

3 sp 6
0 0 -1
# zeroing out old stack top code goes here
1 5 ...


Here are some examples to show off the OISC:

Hello Program

-1 15 3
-1 16 6
-1 17 9
-1 18 12
-1 19 -1
72 101 108
108 111

The junk below the first 5 instructions is actually data to output (more precisely, the string "Hello" in ASCII), which never gets jumped to.


4 -1 6
0 0 -1
4 5 12
3 5 6
-1 3 15
0 0 -1

The program above takes a number, negates it, and outputs the negated number. The program uses looping to emulate subtraction from 0, which effectively means negation.

Cat Program Until <=0

-1 -1 0
2 3 -1

Indeed, this is one of the simplest programs ever.

See also