Multiply two Q15 fixed-point numbers.
MCUs without an FPU use fixed-point math. In Q15 every `int16_t` represents `value / 32768.0`. Multiply two Q15 numbers:
```c
int16_t q15_mul(int16_t a, int16_t b) {
return (int16_t)(((int32_t)a * (int32_t)b) >> 15);
}
```
Implement `q15_mul` and call it from main.Sign in to save your code and track progress across devices.
