2.63

/*
 * srl-sra.c
 */

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

unsigned srl(unsigned x, int k) {
  unsigned xsra = (int) x >> k;

  int w = sizeof(int) << 3;
  int mask = (int) -1 << (w - k);
  return xsra & ~mask;
}

int sra(int x, int k) {
  int xsrl = (unsigned) x >> k;

  int w = sizeof(int) << 3;
  int mask = (int) -1 << (w - k);
  //let mask remain unchanged when the first bit of x is 1, otherwise 0.
  int m = 1 << (w - 1);
  mask &= ! (x & m) - 1;
  return xsrl | mask;
}

int main(int argc, char* argv[]) {
  unsigned test_unsigned = 0x12345678;
  int test_int = 0x12345678;

  assert(srl(test_unsigned, 4) == test_unsigned >> 4);
  assert(sra(test_int, 4) == test_int >> 4);

  test_unsigned = 0x87654321;
	test_int = 0x87654321;

	assert (srl (test_unsigned, 4) == test_unsigned >> 4);
	assert (sra (test_int, 4) == test_int >> 4);
  
  return 0;
}