B2C

It's Brainfuck, with 2 cells, invented by User:None1.

Introduction

B2C is a Brainfuck derivative (or a Brainfuck equivalent, depends on how you think) with only 2 cells.

Since there are only 2 cells, B2C doesn't need 2 commands to move the pointer, it just need one command, which is the | command. The | command moves the pointer from one cell to the other.

Example Programs

Cat Program

+[,.]    [The same as the one in Brainfuck]

Non-terminating version

+[|,.|]

Nope. Interpreter

++++++[|+++++++++++++|-]|.[-]|++++++++++[|+++++++++++|-]|+.+.
-----------.[-]|+++++[|+++++++++|-]|+.

Hello World (last because it's the hardest one)

+++++++++[|++++++++|-]|.[-]|++++++++++[|++++++++++|-]|+.
+++++++..+++.[-]|++++++++[|++++|-]|.[-]|
++++++++++[|++++++++|-]|+++++++.[-]|+++++++++++[|++++++++++|-]|
+.+++.------.--------.[-]+++++++++++[|+++|-]|.

Interpreter

The following is an interpreter in JavaScript:

function b2c(program,input){
    var stack=[];
    var matches={};
    var ip=0;
    var tape=[0,0];
    var p=0;
    var output='';
    for(var i=0;i<program.length;i++){
        if(program[i]=='['){
            stack.push(i);
        }
        if(program[i]==']'){
            if(stack.length==0){
                throw new Error('Right bracket does not match left bracket');
            }
            var mt=stack.pop();
            matches[mt]=i;
            matches[i]=mt;
        }
    }
    if(stack.length!=0){
        throw new Error('Left bracket does not match right bracket');
    }
    while(ip<program.length){
        if(program[ip]=='+'){
            tape[p]=tape[p]+1;
            if(tape[p]==256) tape[p]=0;
            ip=ip+1;
        }
        if(program[ip]=='-'){
            tape[p]=tape[p]-1;
            if(tape[p]==-1) tape[p]=255;
            ip=ip+1;
        }
        if(program[ip]=='|'){
            p=1-p;
            ip=ip+1;
        }
        if(program[ip]==','){
            if(input==''){
                tape[p]=0;
            }else{
                tape[p]=input.charCodeAt(0)%256;
                input=input.slice(1);
            }
            ip=ip+1;
        }
        if(program[ip]=='.'){
            output+=String.fromCharCode(tape[p]);
            ip=ip+1;
        }
        if(program[ip]=='['){
            if(tape[p]==0){
                ip=matches[ip];
            }else{
                ip=ip+1;
            }
        }
        if(program[ip]==']'){
            if(tape[p]!=0){
                ip=matches[ip];
            }else{
                ip=ip+1;
            }
        }
        if(!('+-,.[]|'.includes(program[ip]))){
            ip=ip+1;
        }
    }
    return output;
}

The minimized version is like this:

function b2c(r,t){for(var e=[],o={},h=0,n=[0,0],c=0,a="",f=0;f<r.length;f++)if("["==r[f]&&e.push(f),"]"==r[f]){if(0==e.length)throw new Error("Right bracket does not match left bracket");var i=e.pop();o[i]=f,o[f]=i}if(0!=e.length)throw new Error("Left bracket does not match right bracket");for(;h<r.length;)"+"==r[h]&&(n[c]=n[c]+1,256==n[c]&&(n[c]=0),h+=1),"-"==r[h]&&(n[c]=n[c]-1,-1==n[c]&&(n[c]=255),h+=1),"|"==r[h]&&(c=1-c,h+=1),","==r[h]&&(""==t?n[c]=0:(n[c]=t.charCodeAt(0)%256,t=t.slice(1)),h+=1),"."==r[h]&&(a+=String.fromCharCode(n[c]),h+=1),"["==r[h]&&(0==n[c]?h=o[h]:h+=1),"]"==r[h]&&(0!=n[c]?h=o[h]:h+=1),"+-,.[]|".includes(r[h])||(h+=1);return a}

External resources

• Online interpreter