db_access.c

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    1 /*
    2  * Mach Operating System
    3  * Copyright (c) 1991,1990 Carnegie Mellon University
    4  * All Rights Reserved.
    5  *
    6  * Permission to use, copy, modify and distribute this software and its
    7  * documentation is hereby granted, provided that both the copyright
    8  * notice and this permission notice appear in all copies of the
    9  * software, derivative works or modified versions, and any portions
   10  * thereof, and that both notices appear in supporting documentation.
   11  *
   12  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS
   13  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
   14  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
   15  *
   16  * Carnegie Mellon requests users of this software to return to
   17  *
   18  *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
   19  *  School of Computer Science
   20  *  Carnegie Mellon University
   21  *  Pittsburgh PA 15213-3890
   22  *
   23  * any improvements or extensions that they make and grant Carnegie the
   24  * rights to redistribute these changes.
   25  *
   26  * $FreeBSD$
   27  */
   28 
   29 /*
   30  *      Author: David B. Golub, Carnegie Mellon University
   31  *      Date:   7/90
   32  */
   33 #include <sys/param.h>
   34 
   35 #include <ddb/ddb.h>
   36 #include <ddb/db_access.h>
   37 
   38 /*
   39  * Access unaligned data items on aligned (longword)
   40  * boundaries.
   41  */
   42 
   43 static unsigned db_extend[] = { /* table for sign-extending */
   44         0,
   45         0xFFFFFF80U,
   46         0xFFFF8000U,
   47         0xFF800000U
   48 };
   49 
   50 db_expr_t
   51 db_get_value(addr, size, is_signed)
   52         db_addr_t       addr;
   53         register int    size;
   54         boolean_t       is_signed;
   55 {
   56         char            data[sizeof(int)];
   57         register db_expr_t value;
   58         register int    i;
   59 
   60         db_read_bytes(addr, size, data);
   61 
   62         value = 0;
   63 #if     BYTE_MSF
   64         for (i = 0; i < size; i++)
   65 #else   /* BYTE_LSF */
   66         for (i = size - 1; i >= 0; i--)
   67 #endif
   68         {
   69             value = (value << 8) + (data[i] & 0xFF);
   70         }
   71 
   72         if (size < 4) {
   73             if (is_signed && (value & db_extend[size]) != 0)
   74                 value |= db_extend[size];
   75         }
   76         return (value);
   77 }
   78 
   79 void
   80 db_put_value(addr, size, value)
   81         db_addr_t       addr;
   82         register int    size;
   83         register db_expr_t value;
   84 {
   85         char            data[sizeof(int)];
   86         register int    i;
   87 
   88 #if     BYTE_MSF
   89         for (i = size - 1; i >= 0; i--)
   90 #else   /* BYTE_LSF */
   91         for (i = 0; i < size; i++)
   92 #endif
   93         {
   94             data[i] = value & 0xFF;
   95             value >>= 8;
   96         }
   97 
   98         db_write_bytes(addr, size, data);
   99 }
  100

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

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