bf.monga

/* BF INTERPRETER IN MONGA
Copyright 25/10/16 
Modified  17/12/16
Lucas Menezes */

int sleep(int t);
int exit(int number);
char getchar();
void putchar(int c);

char[] readFile(char[] filename);


char[] newCharArrayZeroed(int n) {
	int i;
	char[] array;
	array = new char[n];
	i=0;
	while(i<n) {
		array[i] = 0;
		i=i+1;
	}
	return array;
}
int[] newIntArrayZeroed(int n) {
	int i;
	int[] array;
	array = new int[n];
	i=0;
	while(i<n) {
		array[i] = 0;
		i=i+1;
	}
	return array;
}

void error(char[] errorString, int signal) {
	@ errorString ; @"\n";
	exit(signal);
}


void execute(char[] program)
{
	/*does array contains its size? */
	/* expects it to finish with null? */
	char[] memory; 
	int prgIdx;
	int memIdx;
	int[] loopStack;
	int stackIdx;
	int internalLoopCount;
	memory = newCharArrayZeroed(30000);
	prgIdx = 0;
	memIdx = 0;
	loopStack = newIntArrayZeroed(500); 
	stackIdx = 0;

	while(program[prgIdx]) /*assume it finishes in null like a C String*/
	{
		/*@program[prgIdx];*/
		
		if(program[prgIdx] == '>') {
			memIdx = memIdx + 1;
			if(memIdx >= 30000) 
				error("Access Violation, no cell 30000",-1);
		} 
		else if(program[prgIdx] == '<') {
			memIdx = memIdx - 1;
			if(memIdx < 0) 
				error("Access Violation, no cell zero",-1);
		}
		else if(program[prgIdx] == '+') {
			memory[memIdx] = (memory[memIdx] as int) + 1;
		} 
		else if(program[prgIdx] == '-') {
			memory[memIdx] = (memory[memIdx] as int) - 1;
		} 
		else if(program[prgIdx] == ',') {
			memory[memIdx] = getchar();
		} 
		else if(program[prgIdx] == '.') {
			@ memory[memIdx];
		} 
		else if(program[prgIdx] == '[') {
			
			/*@"Will begin loop? "; 
			@memory[memIdx] as int; @"\n";*/
			if(memory[memIdx]){
				/*@"Entered Loop\n";*/
				stackIdx = stackIdx + 1;
				loopStack[stackIdx] = prgIdx;
				/*@stackIdx; @"\n";*/
			}
			else {
				/*jump to next ]*/
				/*@"Won't enter loop\n";*/
				prgIdx = prgIdx + 1;
				internalLoopCount = 0;
				while(!(program[prgIdx] == ']' && 
					internalLoopCount == 0)) 
					/*@"Inside While: "; 
				@"memIdx "; @memIdx; 
				@"\n"; */
				/* while not match stop requirements*/
				{
					if(program[prgIdx] == '[')
					{
						internalLoopCount = internalLoopCount + 1;
					}
					else if(program[prgIdx] == ']')
					{
						internalLoopCount = internalLoopCount - 1;
	
					}
					prgIdx = prgIdx + 1;
				}

			}
		} 
		else if(program[prgIdx] == ']') {
			
			/*@"Will exit loop? "; 
			@memory[memIdx] as int; 
			@"\n";*/
			if(memory[memIdx]) {
				/*@"continue looping\n";*/
				prgIdx = loopStack[stackIdx];
			}
			else {
				/*@"exit loop\n";*/
				stackIdx = stackIdx - 1;
				/*@stackIdx; @"\n";*/
			}
		} else {

		}
		prgIdx = prgIdx + 1;
		/*@"prgIdx "; @prgIdx; @"\n";*/
	}
	
}
void main (int argc, char[][] argv) {
	char[] programStr;
	if(argc == 2) {
		programStr = readFile(argv[1]);
	}
	else {
		programStr =  ">+++++++++[<++++++++>-]<.>+++++++[<++++>-]<+.+++++++..+++.[-]>++++++++[<++++>-]<.#>+++++++++++[<+++++>-]<.>++++++++[<+++>-]<.+++.------.--------.[-]>++++++++[<++++>-]<+.[-]++++++++++.";
	}	
	execute(programStr);
}