FreeBSD/Linux Kernel Cross Reference
sys/dev/random/uint128.h

     /*-
      * Copyright (c) 2015 Mark R V Murray
      * All rights reserved.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
      * 1. Redistributions of source code must retain the above copyright
      *    notice, this list of conditions and the following disclaimer
     *    in this position and unchanged.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
     * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
     * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
     * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
     * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
     * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
     * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    
    #ifndef SYS_DEV_RANDOM_UINT128_H_INCLUDED
    #define SYS_DEV_RANDOM_UINT128_H_INCLUDED
    
    #include <sys/endian.h>
    
    /* This whole thing is a crock :-(
     *
     * Everyone knows you always need the __uint128_t types!
     */
    
    #ifdef __SIZEOF_INT128__
    #define USE_REAL_UINT128_T
    #endif
    
    #ifdef USE_REAL_UINT128_T
    typedef __uint128_t uint128_t;
    #define UINT128_ZERO 0ULL
    #else
    typedef struct {
            /* Ignore endianness */
            uint64_t u128t_word0;
            uint64_t u128t_word1;
    } uint128_t;
    static const uint128_t very_long_zero = {0UL,0UL};
    #define UINT128_ZERO very_long_zero
    #endif
    
    static __inline void
    uint128_increment(uint128_t *big_uintp)
    {
    #ifdef USE_REAL_UINT128_T
            (*big_uintp)++;
    #else
            big_uintp->u128t_word0++;
            if (big_uintp->u128t_word0 == 0UL)
                    big_uintp->u128t_word1++;
    #endif
    }
    
    static __inline void
    uint128_add64(uint128_t *big_uintp, uint64_t add)
    {
    #ifdef USE_REAL_UINT128_T
            (*big_uintp) += add;
    #else
            uint64_t word0p;
    
            word0p = big_uintp->u128t_word0 + add;
            if (word0p < big_uintp->u128t_word0)
                    big_uintp->u128t_word1++;
            big_uintp->u128t_word0 = word0p;
    #endif
    }
    
    static __inline bool
    uint128_equals(uint128_t a, uint128_t b)
    {
    #ifdef USE_REAL_UINT128_T
            return (a == b);
    #else
            return (a.u128t_word0 == b.u128t_word0 &&
                a.u128t_word1 == b.u128t_word1);
    #endif
    }
    
    static __inline int
    uint128_is_zero(uint128_t big_uint)
    {
            return (uint128_equals(big_uint, UINT128_ZERO));
    }
    
   static __inline uint128_t
   le128dec(const void *pp)
   {
           const uint8_t *p = pp;
   
   #ifdef USE_REAL_UINT128_T
           return (((uint128_t)le64dec(p + 8) << 64) | le64dec(p));
   #else
           return ((uint128_t){
               .u128t_word0 = le64dec(p),
               .u128t_word1 = le64dec(p + 8),
               });
   #endif
   }
   
   static __inline void
   le128enc(void *pp, uint128_t u)
   {
           uint8_t *p = pp;
   
   #ifdef USE_REAL_UINT128_T
           le64enc(p, (uint64_t)(u & UINT64_MAX));
           le64enc(p + 8, (uint64_t)(u >> 64));
   #else
           le64enc(p, u.u128t_word0);
           le64enc(p + 8, u.u128t_word1);
   #endif
   }
   
   #endif /* SYS_DEV_RANDOM_UINT128_H_INCLUDED */

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