sysy-data/functional_c/sy/68_brainfk.sy

#include "sylib.h"
/*
a brainfuck interpreter
reference: https://gist.github.com/maxcountryman/1699708
*/

// tape, input buffer, and read/write pointer
#define TAPE_LEN 65535
#define BUFFER_LEN 32768
// const int TAPE_LEN = 65536, BUFFER_LEN = 32768;
int tape[TAPE_LEN], program[BUFFER_LEN], ptr = 0;

// read the input program
void read_program()
{
    int i = 0, len = getint();
    while (i < len) {
        program[i] = getch();
        i = i + 1;
    }
    program[i] = 0;
}

// interpret the input program
void interpret(int input[])
{
    int cur_char, loop, i = 0;
    while (input[i]) {
        cur_char = input[i];
        if (cur_char == 62) {
            // '>'
            ptr = ptr + 1;
        } else if (cur_char == 60) {
            // '<'
            ptr = ptr - 1;
        } else if (cur_char == 43) {
            // '+'
            tape[ptr] = tape[ptr] + 1;
        } else if (cur_char == 45) {
            // '-'
            tape[ptr] = tape[ptr] - 1;
        } else if (cur_char == 46) {
            // '.'
            putch(tape[ptr]);
        } else if (cur_char == 44) {
            // ','
            tape[ptr] = getch();
        } else if (cur_char == 93 && tape[ptr]) {
            // ']'
            loop = 1;
            while (loop > 0) {
                i = i - 1;
                cur_char = input[i];
                if (cur_char == 91) {
                    // '['
                    loop = loop - 1;
                } else if (cur_char == 93) {
                    // ']'
                    loop = loop + 1;
                }
            }
        }
        i = i + 1;
    }
}

int main()
{
    read_program();
    interpret(program);
    return 0;
}