The Design and Implementation of the FreeBSD Operating System, Second Edition
Now available: The Design and Implementation of the FreeBSD Operating System (Second Edition)


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FreeBSD/Linux Kernel Cross Reference
sys/ddb/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 /*
   27  *      Author: David B. Golub, Carnegie Mellon University
   28  *      Date:   7/90
   29  */
   30 
   31 #include <sys/cdefs.h>
   32 __FBSDID("$FreeBSD$");
   33 
   34 #include <sys/param.h>
   35 #include <sys/kdb.h>
   36 
   37 #include <ddb/ddb.h>
   38 #include <ddb/db_access.h>
   39 
   40 /*
   41  * Access unaligned data items on aligned (longword)
   42  * boundaries.
   43  */
   44 
   45 static unsigned db_extend[] = { /* table for sign-extending */
   46         0,
   47         0xFFFFFF80U,
   48         0xFFFF8000U,
   49         0xFF800000U
   50 };
   51 
   52 #ifndef BYTE_MSF
   53 #define BYTE_MSF        0
   54 #endif
   55 
   56 db_expr_t
   57 db_get_value(db_addr_t addr, int size, bool is_signed)
   58 {
   59         char            data[sizeof(u_int64_t)];
   60         db_expr_t       value;
   61         int             i;
   62 
   63         if (db_read_bytes(addr, size, data) != 0) {
   64                 db_printf("*** error reading from address %llx ***\n",
   65                     (long long)addr);
   66                 kdb_reenter();
   67         }
   68 
   69         value = 0;
   70 #if     BYTE_MSF
   71         for (i = 0; i < size; i++)
   72 #else   /* BYTE_LSF */
   73         for (i = size - 1; i >= 0; i--)
   74 #endif
   75         {
   76             value = (value << 8) + (data[i] & 0xFF);
   77         }
   78 
   79         if (size < 4) {
   80             if (is_signed && (value & db_extend[size]) != 0)
   81                 value |= db_extend[size];
   82         }
   83         return (value);
   84 }
   85 
   86 void
   87 db_put_value(db_addr_t addr, int size, db_expr_t value)
   88 {
   89         char            data[sizeof(int)];
   90         int             i;
   91 
   92 #if     BYTE_MSF
   93         for (i = size - 1; i >= 0; i--)
   94 #else   /* BYTE_LSF */
   95         for (i = 0; i < size; i++)
   96 #endif
   97         {
   98             data[i] = value & 0xFF;
   99             value >>= 8;
  100         }
  101 
  102         if (db_write_bytes(addr, size, data) != 0) {
  103                 db_printf("*** error writing to address %llx ***\n",
  104                     (long long)addr);
  105                 kdb_reenter();
  106         }
  107 }

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