/*8==================================D~~~~*
 * BrainFuck Interpreter                  *
 * v0.5                                   *       /\
 *8==================================D~~~~*      /4/
 * Written by poutine/DALnet              *     /1/
 * 2008-02-05                             *    /./
 *8==================================D~~~~*   /5/
                                         .*. /$/
                                         |*| \/
                                         |*|/
                                         |*|
                                        / * \
 >+++++++++++[<+++++>-]<+++.[-]>       /_/.\_\
 >++++++++++[<++++>-]<+.[-]           /  .  . \
 +++++[<++>-]<.[-]                    |.   .  |
                                      |_______|
                                      |Sea    |
NOTES:                                |Monkeys|
 * Can do 30K slots or more           | ____  |
                                      |/o~~ \ |
                                      || o~~| |
                                      ||o~~ | |
                                      |\____/ |
                                      |_______|
                                      (_______)

*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

void parse_brainfuck_file(FILE *bf)
{
        unsigned char *bfprogram = NULL;
        unsigned char *eip       = NULL;

        unsigned char *slots     = NULL;
        unsigned char *ptr       = NULL;

        size_t slotsize          = 0;
        size_t slotindex         = 0;

        size_t ret               = 0;
        size_t i                 = 0;

        if ((bfprogram = malloc(1024)) == NULL)
        {
                printf("Could not allocate memory for brainfuck code, barfing.\n");
                exit(EXIT_FAILURE);
        }

        for(i=0;(ret = fread(&bfprogram[(i) ? (i*1024)-1 : 0],1,1024,bf)) == 1024;i++)
        {
                if ((bfprogram = realloc(bfprogram,(i*1024)+1024+1024)) == NULL)
                {
                        printf("Could not allocate memory for brainfuck code, barfing.\n");
                        exit(EXIT_FAILURE);
                }
        }

        if (!feof(bf))
        {
                printf("Error during file read\n");
                exit(EXIT_FAILURE);
        }

        bfprogram[(i*1024)+ret+1] = '\0';

        /* Put the first char as eip of parent's code structure */
        eip = bfprogram;

        /* Allocate slots */
        if ((slots = malloc(sizeof(char) * (1024))) == NULL)
        {
                printf("Could not allocate memory for internal slots, barfing\n");
                exit(EXIT_FAILURE);
        }

        memset(slots,0,1024);

        slotindex = 0;
        slotsize  = 1024;

        ptr       = slots;

        while (*eip)
        {
                switch (*eip)
                {
                        case '>':
                                if (slotindex == slotsize)
                                {
                                        if ((slots = realloc(slots,(sizeof(char) * 1024) * slotsize+1024)) == NULL)
                                        {
                                                printf("Could not resize slots array\n");
                                                exit(EXIT_FAILURE);
                                        }

                                        memset(&slots[slotindex+1],0,1024);

                                        slotsize += 1024;
                                }

                                ptr++;
                                slotindex++;
                                break;
                        case '<':
                                if (slotindex == 0)
                                {
                                        printf("Tried going below slot 0, quitting\n");
                                        exit(EXIT_FAILURE);
                                }

                                ptr--;
                                slotindex--;
                                break;
                        case '+':
                                (*ptr)++;
                                break;
                        case '-':
                                (*ptr)--;
                                break;
                        case ',':
                                (*ptr) = getchar();
                                break;
                        case '.':
                                putchar(*ptr);
                                break;
                        case ']':
                                if (*ptr)
                                        while (*eip--)
                                                if (*eip == '[')
                                                        break;
                                break;

                }

                eip++;
        }

        free(bfprogram);
        free(slots);

        return;
}


int main(int argc, char *argv[])
{
        FILE *bf;

        if (argc != 2)
        {
                printf("Syntax Error: ./bf4 <brainfuck file>\n");
                return EXIT_FAILURE;
        }

        if ((bf = fopen(argv[1],"r")) == NULL)
        {
                printf("Error, could not open '%s'\n"
                                         "Syntax: ./bf5 <brainfuck file>\n",argv[1]);
                return EXIT_FAILURE;
        }

        parse_brainfuck_file(bf);

        fclose(bf);

        return EXIT_SUCCESS;
}