fizzbuzz.c

#define MAX_DIGITS 5

#define NUMBER *p-- = itoa(i, buf); buf += MAX_DIGITS+1; --i;
#define FIZZ *p-- = "Fizz"; --i;
#define BUZZ *p-- = "Buzz"; --i;
#define FIZZBUZZ *p-- = "FizzBuzz"; --i;

char* itoa(int value, char* s) {
    size_t i = MAX_DIGITS;
    s[i--] = '\0';
    char* ret = s + i;

#define WRITE_DIGIT(n)                          \
    {                                           \
      int place_val = (value / n) % 10;         \
      s[i] = place_val + '0';                   \
      ret = place_val == 0 ? ret : s + i;       \
      i--;                                      \
    }

    WRITE_DIGIT(1);
    WRITE_DIGIT(10);
    WRITE_DIGIT(100);
    WRITE_DIGIT(1000);
    WRITE_DIGIT(10000);

    return ret;

#undef WRITE_DIGIT
}

char mem[1024*128];
char ** fizzBuzz(int n, int* returnSize){
    char* buf = mem;
    char** v = (void*) buf;
    buf += sizeof(char*)*n;
    *returnSize = n;

    int i = n;
    while (i > 0) {
        char** p = &v[i-1];
        switch (i%15) {
        case 14: NUMBER
        case 13: NUMBER
        case 12: FIZZ
        case 11: NUMBER
        case 10: BUZZ
        case 9: FIZZ
        case 8: NUMBER
        case 7: NUMBER
        case 6: FIZZ
        case 5: BUZZ
        case 4: NUMBER
        case 3: FIZZ
        case 2: NUMBER
        case 1: NUMBER
        case 0:
            if (i == 0) break;
            FIZZBUZZ
        }
    }

    return v;
}