Simple Brainfuck interpreter as fuck.

bfck.c

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

void interpret(const char *code);

int main(int argc, char **argv) {
    char *file_contents;
    long input_file_size;
    FILE *input_file;

    if (argc < 2) {
        printf("Using: bfck <source code path>\n");
        return 1;
    }
    input_file = fopen(argv[1], "rb");
    if (ferror(input_file)) {
        printf("can't open source file : %s", argv[1]);
        return 1;
    }
    fseek(input_file, 0, SEEK_END);
    input_file_size = ftell(input_file);
    rewind(input_file);
    file_contents = (char *) malloc((input_file_size + 1) * sizeof(char));
    fread(file_contents, sizeof(char), input_file_size, input_file);
    fclose(input_file);
    file_contents[input_file_size] = 0;
    interpret(file_contents);
    free(file_contents);
}

void interpret(const char *code) {
    char buf[64 * 1024];
    char *p = buf;
    int l = 0;

    for (; *code; code++) {
        switch (*code) {
            case '>': p++;                      break;
            case '<': p--;                      break;
            case '+': (*p)++;                   break;
            case '-': (*p)--;                   break;
            case '.': putchar(*p);              break;
            case ',': *p = (char) getchar();    break;
            case '[':
                if (!*p) {
                    code++;
                    while (l > 0 || *code != ']') {
                        switch (*code) {
                            case '[':
                                l++; break;
                            case ']':
                                l--; break;
                            default: break;
                        }
                        code++;
                    }
                }
                break;
            case ']':
                if (*p) {
                    code--;
                    while (l > 0 || *code != '[') {
                        switch (*code) {
                            case '[':
                                l++; break;
                            case ']':
                                l--; break;
                            default: break;
                        }
                        code--;
                    }
                    code--;
                }
                break;
            default: break;
        }
    }
}