2.79

/*
 * mul3div4.c
 */
#include <stdio.h>
#include <assert.h>
#include <limits.h>

/*
 * code from 2.78
 *
 * Divide by power of 2, -> x/2^k
 * Assume 0 <= k < w-1
 */
int divide_power2(int x, int k) {
  int is_neg = x & INT_MIN;
  (is_neg && (x = x + (1 << k) - 1));
  return x >> k;
}

int mul3div4(int x) {
  int mul3 = (x << 1) + x;
  return divide_power2(mul3, 2);
}

int main(int argc, char* argv[]) {
  int x = 0x87654321;
  assert(mul3div4(x) == x * 3 / 4);
  return 0;
}