How to read in C++ a short int (2 byte) LSB first value?

Question

How can I read two separate bytes each with LSB first?

2 speparate LSB first bytes -> one short int MSB first

e.g. 01001100 11001100 -> 00110010 00110011

short int lsbToMsb(char byte1, char byte2) {

  ...
  return msb;
}

Answer 1

Try this:

char reverseBits(char byte)
{
    char reverse_byte = 0;
    for (int i = 0; i < 8; i++) {
        if ((byte & (1 << i)))
            reverse_byte |= 1 << (7 - i);
    }
    return reverse_byte;
}
short int lsbToMsb(char byte1, char byte2) {
    byte1 = reverseBits(byte1);
    byte2 = reverseBits(byte2);
    short int msb = (byte1 << 8) | byte2;
    return msb;
}

int main(){
    char byte1 = 76;    // 01001100
    char byte2 = -52;   // 11001100
    short int msb = lsbToMsb(byte1, byte2);
    printf("%d", msb);
    
}

Output:

12851   // 00110010 00110011