The Design and Implementation of the FreeBSD Operating System, Second Edition
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FreeBSD/Linux Kernel Cross Reference
sys/libkern/quad.h

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    1 /*-
    2  * Copyright (c) 1992, 1993
    3  *      The Regents of the University of California.  All rights reserved.
    4  *
    5  * This software was developed by the Computer Systems Engineering group
    6  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
    7  * contributed to Berkeley.
    8  *
    9  * Redistribution and use in source and binary forms, with or without
   10  * modification, are permitted provided that the following conditions
   11  * are met:
   12  * 1. Redistributions of source code must retain the above copyright
   13  *    notice, this list of conditions and the following disclaimer.
   14  * 2. Redistributions in binary form must reproduce the above copyright
   15  *    notice, this list of conditions and the following disclaimer in the
   16  *    documentation and/or other materials provided with the distribution.
   17  * 3. All advertising materials mentioning features or use of this software
   18  *    must display the following acknowledgement:
   19  *      This product includes software developed by the University of
   20  *      California, Berkeley and its contributors.
   21  * 4. Neither the name of the University nor the names of its contributors
   22  *    may be used to endorse or promote products derived from this software
   23  *    without specific prior written permission.
   24  *
   25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
   26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
   29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
   30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
   31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
   32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
   33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
   34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
   35  * SUCH DAMAGE.
   36  *
   37  *      @(#)quad.h      8.1 (Berkeley) 6/4/93
   38  * $FreeBSD$
   39  */
   40 
   41 /*
   42  * Quad arithmetic.
   43  *
   44  * This library makes the following assumptions:
   45  *
   46  *  - The type long long (aka quad_t) exists.
   47  *
   48  *  - A quad variable is exactly twice as long as `long'.
   49  *
   50  *  - The machine's arithmetic is two's complement.
   51  *
   52  * This library can provide 128-bit arithmetic on a machine with 128-bit
   53  * quads and 64-bit longs, for instance, or 96-bit arithmetic on machines
   54  * with 48-bit longs.
   55  */
   56 
   57 #include <sys/cdefs.h>
   58 #include <sys/types.h>
   59 #include <limits.h>
   60 
   61 /*
   62  * Depending on the desired operation, we view a `long long' (aka quad_t) in
   63  * one or more of the following formats.
   64  */
   65 union uu {
   66         quad_t  q;              /* as a (signed) quad */
   67         quad_t  uq;             /* as an unsigned quad */
   68         long    sl[2];          /* as two signed longs */
   69         u_long  ul[2];          /* as two unsigned longs */
   70 };
   71 
   72 /*
   73  * Define high and low longwords.
   74  */
   75 #define H               _QUAD_HIGHWORD
   76 #define L               _QUAD_LOWWORD
   77 
   78 /*
   79  * Total number of bits in a quad_t and in the pieces that make it up.
   80  * These are used for shifting, and also below for halfword extraction
   81  * and assembly.
   82  */
   83 #define QUAD_BITS       (sizeof(quad_t) * CHAR_BIT)
   84 #define LONG_BITS       (sizeof(long) * CHAR_BIT)
   85 #define HALF_BITS       (sizeof(long) * CHAR_BIT / 2)
   86 
   87 /*
   88  * Extract high and low shortwords from longword, and move low shortword of
   89  * longword to upper half of long, i.e., produce the upper longword of
   90  * ((quad_t)(x) << (number_of_bits_in_long/2)).  (`x' must actually be u_long.)
   91  *
   92  * These are used in the multiply code, to split a longword into upper
   93  * and lower halves, and to reassemble a product as a quad_t, shifted left
   94  * (sizeof(long)*CHAR_BIT/2).
   95  */
   96 #define HHALF(x)        ((x) >> HALF_BITS)
   97 #define LHALF(x)        ((x) & ((1 << HALF_BITS) - 1))
   98 #define LHUP(x)         ((x) << HALF_BITS)
   99 
  100 quad_t          __divdi3 __P((quad_t a, quad_t b));
  101 quad_t          __moddi3 __P((quad_t a, quad_t b));
  102 u_quad_t        __qdivrem __P((u_quad_t u, u_quad_t v, u_quad_t *rem));
  103 u_quad_t        __udivdi3 __P((u_quad_t a, u_quad_t b));
  104 u_quad_t        __umoddi3 __P((u_quad_t a, u_quad_t b));
  105 
  106 /*
  107  * XXX
  108  * Compensate for gcc 1 vs gcc 2.  Gcc 1 defines ?sh?di3's second argument
  109  * as u_quad_t, while gcc 2 correctly uses int.  Unfortunately, we still use
  110  * both compilers.
  111  */
  112 #if __GNUC__ >= 2
  113 typedef unsigned int    qshift_t;
  114 #else
  115 typedef u_quad_t        qshift_t;
  116 #endif

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