FreeBSD/Linux Kernel Cross Reference
sys/libkern/quad.h

     /*-
      * Copyright (c) 1992, 1993
      *      The Regents of the University of California.  All rights reserved.
      *
      * This software was developed by the Computer Systems Engineering group
      * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
      * contributed to Berkeley.
      *
      * 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.
     * 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.
     * 3. All advertising materials mentioning features or use of this software
     *    must display the following acknowledgement:
     *      This product includes software developed by the University of
     *      California, Berkeley and its contributors.
     * 4. Neither the name of the University nor the names of its contributors
     *    may be used to endorse or promote products derived from this software
     *    without specific prior written permission.
     *
     * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``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 REGENTS OR CONTRIBUTORS 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.
     *
     *      @(#)quad.h      8.1 (Berkeley) 6/4/93
     * $FreeBSD: releng/5.2/sys/libkern/quad.h 114216 2003-04-29 13:36:06Z kan $
     */
    
    #ifndef _LIBKERN_QUAD_H
    #define _LIBKERN_QUAD_H
    
    /*
     * Quad arithmetic.
     *
     * This library makes the following assumptions:
     *
     *  - The type long long (aka quad_t) exists.
     *
     *  - A quad variable is exactly twice as long as `long'.
     *
     *  - The machine's arithmetic is two's complement.
     *
     * This library can provide 128-bit arithmetic on a machine with 128-bit
     * quads and 64-bit longs, for instance, or 96-bit arithmetic on machines
     * with 48-bit longs.
     */
    
    #include <sys/cdefs.h>
    #include <sys/types.h>
    #include <sys/limits.h>
    #include <sys/syslimits.h>
    
    /*
     * Depending on the desired operation, we view a `long long' (aka quad_t) in
     * one or more of the following formats.
     */
    union uu {
            quad_t  q;              /* as a (signed) quad */
            quad_t  uq;             /* as an unsigned quad */
            long    sl[2];          /* as two signed longs */
            u_long  ul[2];          /* as two unsigned longs */
    };
    
    /*
     * Define high and low longwords.
     */
    #define H               _QUAD_HIGHWORD
    #define L               _QUAD_LOWWORD
    
    /*
     * Total number of bits in a quad_t and in the pieces that make it up.
     * These are used for shifting, and also below for halfword extraction
     * and assembly.
     */
    #define QUAD_BITS       (sizeof(quad_t) * CHAR_BIT)
    #define LONG_BITS       (sizeof(long) * CHAR_BIT)
    #define HALF_BITS       (sizeof(long) * CHAR_BIT / 2)
    
    /*
     * Extract high and low shortwords from longword, and move low shortword of
     * longword to upper half of long, i.e., produce the upper longword of
     * ((quad_t)(x) << (number_of_bits_in_long/2)).  (`x' must actually be u_long.)
     *
     * These are used in the multiply code, to split a longword into upper
     * and lower halves, and to reassemble a product as a quad_t, shifted left
     * (sizeof(long)*CHAR_BIT/2).
     */
   #define HHALF(x)        ((x) >> HALF_BITS)
   #define LHALF(x)        ((x) & ((1 << HALF_BITS) - 1))
   #define LHUP(x)         ((x) << HALF_BITS)
   
   quad_t          __divdi3(quad_t a, quad_t b);
   quad_t          __moddi3(quad_t a, quad_t b);
   u_quad_t        __qdivrem(u_quad_t u, u_quad_t v, u_quad_t *rem);
   u_quad_t        __udivdi3(u_quad_t a, u_quad_t b);
   u_quad_t        __umoddi3(u_quad_t a, u_quad_t b);
   int             __ucmpdi2(u_quad_t a, u_quad_t b);
   
   /*
    * XXX
    * Compensate for gcc 1 vs gcc 2.  Gcc 1 defines ?sh?di3's second argument
    * as u_quad_t, while gcc 2 correctly uses int.  Unfortunately, we still use
    * both compilers.
    */
   #if __GNUC__ >= 2
   typedef unsigned int    qshift_t;
   #else
   typedef u_quad_t        qshift_t;
   #endif
   #endif /* _LIBKERN_QUAD_H */

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