/*
 Program Name:  BF
 Version:       1.0
 Date:          2007-01-21
 Description:   Interpreter for the Brainfuck Programming Language
 License:       GPL
 Author:        pi8027
 Source Lang:   C
*/

#include<stdio.h>
#include<stdlib.h>
#define DATA_SIZE 512

char * memory_pointer;
char * memory_beginning_pointer;

void Execute_Brainfuck(char * instruction_pointer){
	int loop_nest = 0;
	char * instruction_beginning_loop_pointer;
	while(*instruction_pointer != 0){
		if(*instruction_pointer == 1){
			memory_pointer++;
		}
		else if(*instruction_pointer == 2){
			memory_pointer--;
		}
		else if(*instruction_pointer == 3){
			(*memory_pointer)++;
		}
		else if(*instruction_pointer == 4){
			(*memory_pointer)--;
		}
		else if(*instruction_pointer == 5){
			putchar(*memory_pointer);
		}
		else if(*instruction_pointer == 6){
			*memory_pointer = getchar();
		}
		else if(*instruction_pointer == 7){
			instruction_beginning_loop_pointer = instruction_pointer + 1;
			while(*instruction_pointer != 0){
				instruction_pointer++;
				if(*instruction_pointer == 7){
					loop_nest++;
				}
				else if(*instruction_pointer == 8){
					if(loop_nest == 0){
						break;
					}
					else{
						loop_nest--;
					}
				}
			}
			*instruction_pointer = 0;
			while(*memory_pointer != 0){
				Execute_Brainfuck(instruction_beginning_loop_pointer);
			}
			*instruction_pointer = 8;
		}
		if(0 > memory_pointer - memory_beginning_pointer || DATA_SIZE <= memory_pointer - memory_beginning_pointer){
			fputs("Error.\n" , stderr);
			exit(1);
		}
		instruction_pointer++;
	}
	return;
}

int main( int argc , char *argv[] ){
	int getf;
	FILE *fp;
	char * instruction_pointer;
	char * instruction_beginning_pointer;
	int instruction_size = 1024;
	memory_beginning_pointer = (char *) calloc(DATA_SIZE,sizeof(char));
	instruction_beginning_pointer = (char *) calloc(1024,sizeof(char));
	instruction_pointer = instruction_beginning_pointer;
	memory_pointer = (char *) memory_beginning_pointer + DATA_SIZE/2;
	fp = fopen(argv[1] , "r");
	if (fp == NULL || memory_beginning_pointer == NULL || instruction_beginning_pointer == NULL){
		fputs("Error.\n" , stderr);
		exit(1);
	}
	while(1) {
		if (ferror(fp)){
			fputs("Error.\n" , stderr);
			exit(1);
		}
		getf = fgetc(fp);
		if(!feof(fp)){
			if(getf == 0x3e){
				*instruction_pointer = 1;
			}
			else if(getf == 0x3c){
				*instruction_pointer = 2;
			}
			else if(getf == 0x2b){
				*instruction_pointer = 3;
			}
			else if(getf == 0x2d){
				*instruction_pointer = 4;
			}
			else if(getf == 0x2e){
				*instruction_pointer = 5;
			}
			else if(getf == 0x2c){
				*instruction_pointer = 6;
			}
			else if(getf == 0x5b){
				*instruction_pointer = 7;
			}
			else if(getf == 0x5d){
				*instruction_pointer = 8;
			}
			else if(getf == 0x23){
				while(getf != 0x0a && getf != 0x0d && getf != 0x00){
					getf = fgetc(fp);
				}
				continue;
			}
			else{
				continue;
			}
			instruction_pointer++;
			if(instruction_size - 1 == instruction_pointer - instruction_beginning_pointer){
				instruction_beginning_pointer = (char *)realloc(instruction_beginning_pointer,instruction_size + 1024);
				instruction_size = instruction_size + 1024;
				if(instruction_beginning_pointer == NULL){
					fputs("Error.\n" , stderr);
					exit(1);
				}
			}
		}
		else{
			break;
		}
	}
	Execute_Brainfuck(instruction_beginning_pointer);
	fclose(fp);
	free(instruction_beginning_pointer);
	free(memory_beginning_pointer);
	return 0;
}