lib/u64.h

/* Unsigned integers with arithmetic modulo 2**64

   Copyright (C) 2006, 2009-2026 Free Software Foundation, Inc.

   This file is free software: you can redistribute it and/or modify
   it under the terms of the GNU Lesser General Public License as
   published by the Free Software Foundation; either version 2.1 of the
   License, or (at your option) any later version.

   This file is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <https://www.gnu.org/licenses/>.  */

/* Written by Paul Eggert.  */

#ifndef U64_H
#define U64_H 1

/* This file uses _GL_INLINE_HEADER_BEGIN, _GL_INLINE.  */
#if !_GL_CONFIG_H_INCLUDED
 #error "Please include config.h first."
#endif

#include <limits.h>
#include <stddef.h>
#include <stdint.h>

#include <byteswap.h>

_GL_INLINE_HEADER_BEGIN
#ifndef _GL_U64_INLINE
# define _GL_U64_INLINE _GL_INLINE
#endif

#ifdef __cplusplus
extern "C" {
#endif


#if defined UINT64_MAX && INT_MAX < UINT64_MAX

/* Native implementations are trivial.  See below for comments on what
   these operations do.  */
typedef uint64_t u64;
# define u64hilo(hi, lo) ((u64) (((u64) (hi) << 32) + (lo)))
# define u64init(hi, lo) u64hilo (hi, lo)
# define u64lo(x) ((u64) (x))
# define u64getlo(x) ((uint32_t) ((x) & UINT32_MAX))
# define u64size(x) u64lo (x)
# define u64not(x) (~(x))
# define u64lt(x, y) ((x) < (y))
# define u64and(x, y) ((x) & (y))
# define u64or(x, y) ((x) | (y))
# define u64xor(x, y) ((x) ^ (y))
# define u64plus(x, y) ((x) + (y))
# define u64shl(x, n) ((x) << (n))
# define u64shr(x, n) ((x) >> (n))
# define u64bswap(x) bswap_64 (x)

#else

# define _GL_U64_MASK32 0xfffffffful /* 2**32 - 1.  */

/* u64 represents a 64-bit unsigned integer value equal to (HI << 32) + LO.
   Implement it with unsigned int, which the GNU coding standards say
   is wide enough to hold 32 bits, and which does not signal an error
   when adding (theoretically possible with types like uint_fast32_t).
   u64init (HI, LO), is like u64hilo (HI, LO), but for use in
   initializer contexts.  */
# ifdef WORDS_BIGENDIAN
typedef struct { unsigned int hi, lo; } u64;
#  define u64init(hi, lo) { hi, lo }
# else
typedef struct { unsigned int lo, hi; } u64;
#  define u64init(hi, lo) { lo, hi }
# endif

/* Given the high and low-order 32-bit quantities HI and LO, return a u64
   value representing (HI << 32) + LO.  */
_GL_U64_INLINE u64
u64hilo (unsigned int hi, unsigned int lo)
{
  u64 r;
  r.hi = hi;
  r.lo = lo;
  return r;
}

/* Return a u64 value representing the 32-bit quantity LO.  */
_GL_U64_INLINE u64
u64lo (unsigned int lo)
{
  u64 r;
  r.hi = 0;
  r.lo = lo;
  return r;
}

/* Return the low 32 bits of the u64 value X.  */
_GL_U64_INLINE unsigned int
u64getlo (u64 x)
{
  return x.lo & _GL_U64_MASK32;
}

/* Return a u64 value representing SIZE, where 0 <= SIZE < 2**64.  */
_GL_U64_INLINE u64
u64size (size_t size)
{
  u64 r;
  r.hi = size >> 31 >> 1;
  r.lo = size & _GL_U64_MASK32;
  return r;
}

/* Return the bitwise NOT of X.  */
_GL_U64_INLINE u64
u64not (u64 x)
{
  u64 r;
  r.hi = ~x.hi;
  r.lo = ~x.lo;
  return r;
}

/* Return X < Y.  */
_GL_U64_INLINE bool
u64lt (u64 x, u64 y)
{
  return x.hi < y.hi || (x.hi == y.hi && x.lo < y.lo);
}

/* Return X & Y.  */
_GL_U64_INLINE u64
u64and (u64 x, u64 y)
{
  u64 r;
  r.hi = x.hi & y.hi;
  r.lo = x.lo & y.lo;
  return r;
}

/* Return X | Y.  */
_GL_U64_INLINE u64
u64or (u64 x, u64 y)
{
  u64 r;
  r.hi = x.hi | y.hi;
  r.lo = x.lo | y.lo;
  return r;
}

/* Return X ^ Y.  */
_GL_U64_INLINE u64
u64xor (u64 x, u64 y)
{
  u64 r;
  r.hi = x.hi ^ y.hi;
  r.lo = x.lo ^ y.lo;
  return r;
}

/* Return X + Y, wrapping around on overflow.  */
_GL_U64_INLINE u64
u64plus (u64 x, u64 y)
{
  u64 r;
  r.lo = (x.lo + y.lo) & _GL_U64_MASK32;
  r.hi = (x.hi + y.hi + (r.lo < x.lo)) & _GL_U64_MASK32;
  return r;
}

/* Return X << N, where 0 <= N < 64.  */
_GL_U64_INLINE u64
u64shl (u64 x, int n)
{
  u64 r;
  if (n < 32)
    {
      r.hi = (x.hi << n & _GL_U64_MASK32) | x.lo >> (32 - n);
      r.lo = x.lo << n & _GL_U64_MASK32;
    }
  else
    {
      r.hi = x.lo << (n - 32) & _GL_U64_MASK32;
      r.lo = 0;
    }
  return r;
}

/* Return X >> N.  */
_GL_U64_INLINE u64
u64shr (u64 x, int n)
{
  u64 r;
  if (n < 32)
    {
      r.hi = x.hi >> n;
      r.lo = (x.hi << (32 - n) & _GL_U64_MASK32) | x.lo >> n;
    }
  else
    {
      r.hi = 0;
      r.lo = x.hi >> (n - 32);
    }
  return r;
}

/* Return X with bytes in reverse order.  */
_GL_U64_INLINE u64
u64bswap (u64 x)
{
  return u64hilo (bswap_32 (x.lo), bswap_32 (x.hi));
}

#endif

/* Return X rotated left by N bits, where 0 < N < 64.  */
_GL_U64_INLINE u64
u64rol (u64 x, int n)
{
  return u64or (u64shl (x, n), u64shr (x, 64 - n));
}


#ifdef __cplusplus
}
#endif

_GL_INLINE_HEADER_END

#endif