unsigned short gf_t  = 44 // = 00101100

unsigned int v;     // input bits to be reversed
unsigned int r = v; // r will be reversed bits of v; first get LSB of v
int s = sizeof(v) * CHAR_BIT - 1; // extra shift needed at end

for (v >>= 1; v; v >>= 1)
{
  r <<= 1;
  r |= v & 1;
  s--;
}
r <<= s; // shift when v's highest bits are zero

unsigned int v; // 32-bit word to reverse bit order

// swap odd and even bits
v = ((v >> 1) & 0x55555555) | ((v & 0x55555555) << 1);
// swap consecutive pairs
v = ((v >> 2) & 0x33333333) | ((v & 0x33333333) << 2);
// swap nibbles ...
v = ((v >> 4) & 0x0F0F0F0F) | ((v & 0x0F0F0F0F) << 4);
// swap bytes
v = ((v >> 8) & 0x00FF00FF) | ((v & 0x00FF00FF) << 8);
// swap 2-byte long pairs
v = ( v >> 16             ) | ( v               << 16);

unsigned short v;

// swap odd and even bits
v = ((v >> 1) & 0x5555) | ((v & 0x5555) << 1);
// swap consecutive pairs
v = ((v >> 2) & 0x3333) | ((v & 0x3333) << 2);
// swap nibbles ...
v = ((v >> 4) & 0x0F0F) | ((v & 0x0F0F) << 4);
// swap bytes
v = ((v >> 8) & 0x00FF) | ((v & 0x00FF) << 8);

#include <stdio.h>
#include <assert.h>
#include <stdint.h>

inline uint16_t reverse(uint16_t v) {
  v = ((v >> 1) & 0x5555) | ((v & 0x5555) << 1); /* swap odd/even bits */
  v = ((v >> 2) & 0x3333) | ((v & 0x3333) << 2); /* swap bit pairs */
  v = ((v >> 4) & 0x0F0F) | ((v & 0x0F0F) << 4); /* swap nibbles */
  v = ((v >> 8) & 0x00FF) | ((v & 0x00FF) << 8); /* swap bytes */
  return v;
}

main() {
  uint16_t gf_t = 44;
  printf("%hun", reverse(gf_t));
}

v = ((v >> 1) & 0x5555) | ((v & 0x5555) << 1);
v = ((v >> 2) & 0x3333) | ((v & 0x3333) << 2);
v = ((v >> 4) & 0x0F0F) | ((v & 0x0F0F) << 4);
v = ((v >> 8) & 0x00FF) | ((v & 0x00FF) << 8);

int main() {

unsigned short gf_r = 0;
for ( int iter = 0; iter < sizeof(short) * 8; ++iter )
{
unsigned short tmp = gf_t;
tmp = tmp & 1;
gf_r = (gf_r << 1 ) | tmp;
gf_t = gf_t >> 1;
}

cout << hex << gf_r << endl;