char  out_buf[4096];
int   out_pos = 0;

int buf_putc(char c) {
    out_buf[out_pos] = c;
    out_pos++;
    if (out_pos >= 4096) {
        syscall(1, 1, out_buf, out_pos);
        out_pos = 0;
    }
    return 1;
}

int buf_flush() {
    if (out_pos > 0) {
        syscall(1, 1, out_buf, out_pos);
        out_pos = 0;
    }
    return 0;
}


int my_strlen(char *s) {
    int n = 0;
    while (s[n] != 0) { n++; }
    return n;
}

int print_str(char *s) {
    int i = 0;
    while (s[i] != 0) { buf_putc(s[i]); i++; }
    return i;
}


int print_int(int n) {
    char tmp[24];
    int  len = 0;
    int  neg = n < 0;
    if (neg) { buf_putc('-'); n = -n; }
    if (n == 0) { buf_putc('0'); return neg + 1; }
    while (n > 0) {
        tmp[len] = (char)('0' + n % 10);
        n = n / 10;
        len++;
    }

    int i = len - 1;
    while (i >= 0) { buf_putc(tmp[i]); i--; }
    return neg + len;
}


int print_hex(int n) {
    char hex[16] = {'0','1','2','3','4','5','6','7',
                    '8','9','a','b','c','d','e','f'};
    if (n == 0) { buf_putc('0'); return 1; }
    char tmp[18];
    int  len = 0;
    int  u = n;
    while (u != 0) {
        tmp[len] = hex[u & 15];
        u = u / 16;
        len++;
    }
    int i = len - 1;
    while (i >= 0) { buf_putc(tmp[i]); i--; }
    return len;
}


int my_printf(char *fmt, int a, int b, int c) {
    int arg_idx = 0;
    int i = 0;
    int total = 0;
    while (fmt[i] != 0) {
        if (fmt[i] != '%') {
            buf_putc(fmt[i]);
            total++;
            i++;
            continue;
        }
        i++;  /* skip '%' */
        int arg = arg_idx == 0 ? a : (arg_idx == 1 ? b : c);
        arg_idx++;
        if (fmt[i] == 'd') {
            total += print_int(arg);
        } else if (fmt[i] == 's') {
            total += print_str((char*)arg);
        } else if (fmt[i] == 'c') {
            buf_putc((char)arg);
            total++;
        } else if (fmt[i] == 'x') {
            total += print_hex(arg);
        } else if (fmt[i] == '%') {
            buf_putc('%');
            total++;
            arg_idx--;  /* %% doesn't consume an arg */
        } else {
            buf_putc('%'); buf_putc(fmt[i]);
            total += 2;
        }
        i++;
    }
    return total;
}


int fact(int n) {
    return n <= 1 ? 1 : n * fact(n - 1);
}

int fib(int n) {
    if (n <= 1) return n;
    return fib(n - 1) + fib(n - 2);
}

int main() {
    my_printf("=== JIT printf demo ===\n", 0, 0, 0);

    my_printf("Hello, %s!\n", "world", 0, 0);
    my_printf("int: %d  neg: %d\n", 42, -7, 0);
    my_printf("hex: 0x%x\n", 255, 0, 0);
    my_printf("char: %c\n", 'A', 0, 0);
    my_printf("percent: 100%%\n", 0, 0, 0);

    my_printf("\nFactorials:\n", 0, 0, 0);
    int i = 1;
    while (i <= 8) {
        my_printf("  %d! = %d\n", i, fact(i), 0);
        i++;
    }

    my_printf("\nFibonacci:\n  ", 0, 0, 0);
    i = 0;
    while (i < 10) {
        my_printf("%d ", fib(i), 0, 0);
        i++;
    }
    my_printf("\n", 0, 0, 0);


    my_printf("\nCountdown: ", 0, 0, 0);
    int n = 5;
    do {
        my_printf("%d ", n, 0, 0);
        n--;
    } while (n > 0);
    my_printf("\n", 0, 0, 0);


    my_printf("Odd 1-9:   ", 0, 0, 0);
    i = 0;
    while (i < 10) {
        i++;
        if (i % 2 == 0) continue;
        my_printf("%d ", i, 0, 0);
        if (i == 9) break;
    }
    my_printf("\n", 0, 0, 0);

    buf_flush();
    return 0;
}