Question

C code required

* byteSwap - swaps the nth byte and the mth byte
* Examples: byteSwap(0x12345678, 1, 3) = 0x56341278
* byteSwap(0xDEADBEEF, 0, 2) = 0xDEEFBEAD
* You may assume that 0 <= n <= 3, 0 <= m <= 3
* Legal ops: ! ~ & ^ | + << >>
* Max ops: 25
* Rating: 2
*/

Answer 1

#include <stdio.h>

int byteSwap(int x, int n, int m) {
        // offset is simply bitPosition for bytes..
        // So byte 1 means bit position 8.
        int nOffset = n << 3;
        int mOffset = m << 3;

        int nthByte = ((x & (0xFF << nOffset) ) >> nOffset) & 0xFF;
        int mthByte = ((x & (0xFF << mOffset) ) >> mOffset) & 0xFF;

        int i = nthByte << mOffset;
        int j = mthByte << nOffset;

        // reset nTh & mthByte.
        x &= ~((0xFF << nOffset) | (0xFF << mOffset));

        // at last join the reseted value with mth and nTh bytes
        int ans = x | i | j;

        return ans;
}


int main(void) {
  printf("%0X\n", byteSwap(0x12345678, 1, 3));
  printf("%0X\n", byteSwap(0xDEADBEEF, 0, 2));
  return 0;
}

**************************************************

Thanks for your question. We try our best to help you with detailed answers, But in any case, if you need any modification or have a query/issue with respect to above answer, Please ask that in the comment section. We will surely try to address your query ASAP and resolve the issue.

Please consider providing a thumbs up to this question if it helps you. by Doing that, You will help other students, who are facing similar issue.