db_access.c

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    1 /*      $NetBSD: db_access.c,v 1.17 2002/02/15 07:33:49 simonb Exp $    */
    2 
    3 /*
    4  * Mach Operating System
    5  * Copyright (c) 1991,1990 Carnegie Mellon University
    6  * All Rights Reserved.
    7  *
    8  * Permission to use, copy, modify and distribute this software and its
    9  * documentation is hereby granted, provided that both the copyright
   10  * notice and this permission notice appear in all copies of the
   11  * software, derivative works or modified versions, and any portions
   12  * thereof, and that both notices appear in supporting documentation.
   13  *
   14  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
   15  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
   16  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   17  *
   18  * Carnegie Mellon requests users of this software to return to
   19  *
   20  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   21  *  School of Computer Science
   22  *  Carnegie Mellon University
   23  *  Pittsburgh PA 15213-3890
   24  *
   25  * any improvements or extensions that they make and grant Carnegie the
   26  * rights to redistribute these changes.
   27  *
   28  *      Author: David B. Golub, Carnegie Mellon University
   29  *      Date:   7/90
   30  */
   31 
   32 #include <sys/cdefs.h>
   33 __KERNEL_RCSID(0, "$NetBSD: db_access.c,v 1.17 2002/02/15 07:33:49 simonb Exp $");
   34 
   35 #include <sys/param.h>
   36 #include <sys/proc.h>
   37 
   38 #include <machine/db_machdep.h>         /* type definitions */
   39 #include <machine/endian.h>
   40 
   41 #include <ddb/db_access.h>
   42 
   43 /*
   44  * Access unaligned data items on aligned (longword)
   45  * boundaries.
   46  */
   47 
   48 const int db_extend[] = {       /* table for sign-extending */
   49         0,
   50         0xFFFFFF80,
   51         0xFFFF8000,
   52         0xFF800000
   53 };
   54 
   55 db_expr_t
   56 db_get_value(db_addr_t addr, size_t size, boolean_t is_signed)
   57 {
   58         char data[sizeof(db_expr_t)];
   59         db_expr_t value;
   60         size_t i;
   61 
   62         db_read_bytes(addr, size, data);
   63 
   64         value = 0;
   65 #if BYTE_ORDER == LITTLE_ENDIAN
   66         for (i = size; i-- > 0;)
   67 #else /* BYTE_ORDER == BIG_ENDIAN */
   68         for (i = 0; i < size; i++)
   69 #endif /* BYTE_ORDER */
   70                 value = (value << 8) + (data[i] & 0xFF);
   71 
   72         if (size < 4 && is_signed && (value & db_extend[size]) != 0)
   73                 value |= db_extend[size];
   74         return (value);
   75 }
   76 
   77 void
   78 db_put_value(db_addr_t addr, size_t size, db_expr_t value)
   79 {
   80         char data[sizeof(db_expr_t)];
   81         size_t i;
   82 
   83 #if BYTE_ORDER == LITTLE_ENDIAN
   84         for (i = 0; i < size; i++)
   85 #else /* BYTE_ORDER == BIG_ENDIAN */
   86         for (i = size; i-- > 0;)
   87 #endif /* BYTE_ORDER */
   88         {
   89                 data[i] = value & 0xFF;
   90                 value >>= 8;
   91         }
   92 
   93         db_write_bytes(addr, size, data);
   94 }

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FreeBSD/Linux Kernel Cross Reference sys/ddb/db_access.c

FreeBSD/Linux Kernel Cross Reference
sys/ddb/db_access.c