sysy/performance_c/sy/brainfuck-bootstrap.sy

#include "sylib.h"
// Brainfuck Interpreter
// Reads program from stdin, interprets and outputs to stdout.
//
// Main optimization targets:
// jump table, inline variables, etc.

int program_length = 0;
int program[65536] = {};
int tape[65536] = {};
int input[65536] = {};
int input_length = 0;
int output[65536] = {};
int output_length = 0;

int get_bf_char()
{
    int get = getch();
    while (get != 62 && get != 60 && get != 43 && get != 45 && get != 91 && get != 93 && get != 46 && get != 44 && get != 35) {
        get = getch();
    }
    return get;
}

void read_program()
{
    int get = get_bf_char();
    while (get != 35) {
        program[program_length] = get;
        get = get_bf_char();
        program_length = program_length + 1;
    }

    // read input
    // input starts with an `i`
    int verify = getch();
    if (verify != 105) {
        return;
    }
    // and a length
    input_length = getint();
    // and a random char
    getch();
    int i = 0;
    while (i < input_length) {
        input[i] = getch();
        i = i + 1;
    }
}

void run_program()
{
    int ip = 0;
    int read_head = 0;
    int input_head = 0;
    int return_address[512] = {};
    int return_address_top = 0;
    output_length = 0;
    while (ip < program_length) {
        int code = program[ip];
        if (code == 62) {
            read_head = read_head + 1;
        } else if (code == 60) {
            read_head = read_head - 1;
        } else if (code == 43) {
            tape[read_head] = tape[read_head] + 1;
        } else if (code == 45) {
            tape[read_head] = tape[read_head] - 1;
        } else if (code == 91) {
            int val = tape[read_head];
            if (val != 0) {
                return_address[return_address_top] = ip;
                return_address_top = return_address_top + 1;
            } else {
                // find the matching ]
                int loop = 1;
                while (loop > 0) {
                    ip = ip + 1;
                    if (program[ip] == 93) {
                        loop = loop - 1;
                    }
                    if (program[ip] == 91) {
                        loop = loop + 1;
                    }
                }
            }
        } else if (code == 93) {
            int val = tape[read_head];
            if (val == 0) {
                return_address_top = return_address_top - 1;
            } else {
                ip = return_address[return_address_top - 1];
            }
        } else if (code == 46) {
            output[output_length] = tape[read_head];
            output_length = output_length + 1;
        } else if (code == 44) {
            if (input_head >= input_length) {
                tape[read_head] = 0;
            } else {
                tape[read_head] = input[input_head];
                input_head = input_head + 1;
            }
        }
        ip = ip + 1;
    }
}

void output_()
{
    int i = 0;
    while (i < output_length) {
        putch(output[i]);
        i = i + 1;
    }
}

int main()
{
    read_program();
    starttime();
    run_program();
    stoptime();
    output_();
    return 0;
}