word.c

#include "word.h"

/* credit to Henry S. Warren, Hacker's Delight, Addison-Wesley, 2002 */
share_t TOBI32(share_t in) {
  uint32_t r0, r1;
  uint32_t lo = in.e;
  uint32_t hi = in.o;
  r0 = (lo ^ (lo >> 1)) & 0x22222222, lo ^= r0 ^ (r0 << 1);
  r0 = (lo ^ (lo >> 2)) & 0x0C0C0C0C, lo ^= r0 ^ (r0 << 2);
  r0 = (lo ^ (lo >> 4)) & 0x00F000F0, lo ^= r0 ^ (r0 << 4);
  r0 = (lo ^ (lo >> 8)) & 0x0000FF00, lo ^= r0 ^ (r0 << 8);
  r1 = (hi ^ (hi >> 1)) & 0x22222222, hi ^= r1 ^ (r1 << 1);
  r1 = (hi ^ (hi >> 2)) & 0x0C0C0C0C, hi ^= r1 ^ (r1 << 2);
  r1 = (hi ^ (hi >> 4)) & 0x00F000F0, hi ^= r1 ^ (r1 << 4);
  r1 = (hi ^ (hi >> 8)) & 0x0000FF00, hi ^= r1 ^ (r1 << 8);
  r0 = (lo & 0x0000FFFF) | (hi << 16);
  r1 = (lo >> 16) | (hi & 0xFFFF0000);
  in.e = r0;
  in.o = r1;
  return in;
}

/* credit to Henry S. Warren, Hacker's Delight, Addison-Wesley, 2002 */
share_t FROMBI32(share_t in) {
  uint32_t r0 = in.e;
  uint32_t r1 = in.o;
  uint32_t lo = (r0 & 0x0000FFFF) | (r1 << 16);
  uint32_t hi = (r0 >> 16) | (r1 & 0xFFFF0000);
  r0 = (lo ^ (lo >> 8)) & 0x0000FF00, lo ^= r0 ^ (r0 << 8);
  r0 = (lo ^ (lo >> 4)) & 0x00F000F0, lo ^= r0 ^ (r0 << 4);
  r0 = (lo ^ (lo >> 2)) & 0x0C0C0C0C, lo ^= r0 ^ (r0 << 2);
  r0 = (lo ^ (lo >> 1)) & 0x22222222, lo ^= r0 ^ (r0 << 1);
  r1 = (hi ^ (hi >> 8)) & 0x0000FF00, hi ^= r1 ^ (r1 << 8);
  r1 = (hi ^ (hi >> 4)) & 0x00F000F0, hi ^= r1 ^ (r1 << 4);
  r1 = (hi ^ (hi >> 2)) & 0x0C0C0C0C, hi ^= r1 ^ (r1 << 2);
  r1 = (hi ^ (hi >> 1)) & 0x22222222, hi ^= r1 ^ (r1 << 1);
  in.e = lo;
  in.o = hi;
  return in;
}