word.c

#include "word.h"

/* credit to Henry S. Warren, Hacker's Delight, Addison-Wesley, 2002 */
uint64_t TOBI32(uint64_t in) {
  uint32_t hi = in >> 32;
  uint32_t lo = in;
  uint32_t r0, r1;
  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);
  return (uint64_t)r1 << 32 | r0;
}

/* credit to Henry S. Warren, Hacker's Delight, Addison-Wesley, 2002 */
uint64_t FROMBI32(uint64_t in) {
  uint32_t r0 = in;
  uint32_t r1 = in >> 32;
  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);
  return (uint64_t)hi << 32 | lo;
}