Convert 24 bit signed int signal to 16 bit signed int signal

To put it as simply as I can.

1. I receive data from device and the signal is 24 bit signed int.


2. I want to create 16 bit WAV file.


3. For this purpose I want to keep writing upcoming audio buffer with 256 samples to *.wav file stream.


4. How can I convert buffer values (well values written in simple pointer to 256 element array) from [24 bit signed int] to [16 bit signed int].

Is there any scaling value? For example when I wanted to cast [24 bit signed int] to [24 bit signed double] I did it like this:

for (int i=0; i<256; i++) {
   bufferInDouble = *((int*)bufferRawData[currentPan]+i) / (double)0x7fffffff;
}

Any similar method could be there?