FreeBSD/Linux Kernel Cross Reference
sys/i386/include/param.h

     /*-
      * Copyright (c) 1990 The Regents of the University of California.
      * All rights reserved.
      *
      * This code is derived from software contributed to Berkeley by
      * William Jolitz.
      *
      * 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.
     *
     *      from: @(#)param.h       5.8 (Berkeley) 6/28/91
     * $FreeBSD: src/sys/i386/include/param.h,v 1.23.2.1 1999/09/05 08:11:56 peter Exp $
     */
    
    #ifndef _MACHINE_PARAM_H_
    #define _MACHINE_PARAM_H_
    
    /*
     * Machine dependent constants for Intel 386.
     */
    
    #define MACHINE         "i386"
    #define MID_MACHINE     MID_I386
    
    /*
     * Round p (pointer or byte index) up to a correctly-aligned value
     * for all data types (int, long, ...).   The result is unsigned int
     * and must be cast to any desired pointer type.
     */
    #define ALIGNBYTES      (sizeof(int) - 1)
    #define ALIGN(p)        (((unsigned)(p) + ALIGNBYTES) & ~ALIGNBYTES)
    
    #define PAGE_SHIFT      12              /* LOG2(PAGE_SIZE) */
    #define PAGE_SIZE       (1<<PAGE_SHIFT) /* bytes/page */
    #define PAGE_MASK       (PAGE_SIZE-1)
    #define NPTEPG          (PAGE_SIZE/(sizeof (pt_entry_t)))
    
    #define NPDEPG          (PAGE_SIZE/(sizeof (pd_entry_t)))
    #define PDRSHIFT        22              /* LOG2(NBPDR) */
    #define NBPDR           (1<<PDRSHIFT)   /* bytes/page dir */
    
    #define DEV_BSHIFT      9               /* log2(DEV_BSIZE) */
    #define DEV_BSIZE       (1<<DEV_BSHIFT)
    
    #define BLKDEV_IOSIZE   2048
    #define MAXPHYS         (64 * 1024)     /* max raw I/O transfer size */
    
    #define UPAGES  2               /* pages of u-area */
    
    /*
     * Constants related to network buffer management.
     * MCLBYTES must be no larger than CLBYTES (the software page size), and,
     * on machines that exchange pages of input or output buffers with mbuf
     * clusters (MAPPED_MBUFS), MCLBYTES must also be an integral multiple
     * of the hardware page size.
     */
    #ifndef MSIZE
    #define MSIZE           128             /* size of an mbuf */
    #endif  /* MSIZE */
    
    #ifndef MCLSHIFT
    #define MCLSHIFT        11              /* convert bytes to m_buf clusters */
    #endif  /* MCLSHIFT */
    #define MCLBYTES        (1 << MCLSHIFT) /* size of an m_buf cluster */
    #define MCLOFSET        (MCLBYTES - 1)  /* offset within an m_buf cluster */
    
    /*
     * Some macros for units conversion
     */
    
    /* clicks to bytes */
    #define ctob(x) ((x)<<PAGE_SHIFT)
    
    /* bytes to clicks */
   #define btoc(x) (((unsigned)(x)+PAGE_MASK)>>PAGE_SHIFT)
   
   /*
    * btodb() is messy and perhaps slow because `bytes' may be an off_t.  We
    * want to shift an unsigned type to avoid sign extension and we don't
    * want to widen `bytes' unnecessarily.  Assume that the result fits in
    * a daddr_t.
    */
   #define btodb(bytes)                    /* calculates (bytes / DEV_BSIZE) */ \
           (sizeof (bytes) > sizeof(long) \
            ? (daddr_t)((unsigned long long)(bytes) >> DEV_BSHIFT) \
            : (daddr_t)((unsigned long)(bytes) >> DEV_BSHIFT))
   
   #define dbtob(db)                       /* calculates (db * DEV_BSIZE) */ \
           ((off_t)(db) << DEV_BSHIFT)
   
   /*
    * Mach derived conversion macros
    */
   #define trunc_page(x)           ((unsigned)(x) & ~PAGE_MASK)
   #define round_page(x)           ((((unsigned)(x)) + PAGE_MASK) & ~PAGE_MASK)
   
   #define atop(x)                 ((unsigned)(x) >> PAGE_SHIFT)
   #define ptoa(x)                 ((unsigned)(x) << PAGE_SHIFT)
   
   #define i386_btop(x)            ((unsigned)(x) >> PAGE_SHIFT)
   #define i386_ptob(x)            ((unsigned)(x) << PAGE_SHIFT)
   
   #endif /* !_MACHINE_PARAM_H_ */

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