#include <stdio.h>
#include <stdint.h>
 
int main(void)
{
    uint16_t w = 0xb2e3;         // our 16 bit word
    uint16_t mask0 = 0x0001;     // mask for LS bit
    uint16_t mask1 = 0x8000;     // mask for MS bit
    uint16_t shift = 15;         // distance between high and low bit positions
    int b;
 
    for (b = 0; b < 8; ++b)      // for each pair of low/high bits
    {
        uint16_t b0 = w & mask0; // get low bit
        uint16_t b1 = w & mask1; // get high bit
        w &= ~(mask0 | mask1);   // clear low/high bit in word
        b0 <<= shift;            // swap bit positions
        b1 >>= shift;
        w |= (b0 | b1);          // insert swapped bits back into word
        mask0 <<= 1;             // update masks for next pair of bits
        mask1 >>= 1;
        shift -= 2;              // update distance for next pair of bits 
    }
 
    printf("%#x\n", w);          // w should now contain 0xc74d
 
    return 0;
}
 

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