commands/swifi/db_access.c

   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 /*
  28  *      Author: David B. Golub, Carnegie Mellon University
  29  *      Date:   7/90
  30  */
  31 #include "ddb.h"
  32 #include "db_access.h"
  33
  34 #include "extra.h"
  35
  36 /*
  37  * Access unaligned data items on aligned (longword)
  38  * boundaries.
  39  */
  40
  41 static unsigned db_extend[] = { /* table for sign-extending */
  42         0,
  43         0xFFFFFF80U,
  44         0xFFFF8000U,
  45         0xFF800000U
  46 };
  47
  48 void
  49 db_read_bytes(addr, size, data)
  50         vm_offset_t     addr;
  51         register int    size;
  52         register char   *data;
  53 {
  54         register char   *src;
  55
  56         src = (char *)addr;
  57         while (--size >= 0)
  58             *data++ = text_read_ub(src++);
  59
  60 }
  61
  62 db_expr_t
  63 db_get_value(addr, size, is_signed)
  64         db_addr_t       addr;
  65         register int    size;
  66         boolean_t       is_signed;
  67 {
  68         char            data[sizeof(int)];
  69         register db_expr_t value;
  70         register int    i;
  71
  72         db_read_bytes(addr, size, data);
  73
  74         value = 0;
  75 #if     BYTE_MSF
  76         for (i = 0; i < size; i++)
  77 #else   /* BYTE_LSF */
  78         for (i = size - 1; i >= 0; i--)
  79 #endif
  80         {
  81             value = (value << 8) + (data[i] & 0xFF);
  82         }
  83
  84         if (size < 4) {
  85             if (is_signed && (value & db_extend[size]) != 0)
  86                 value |= db_extend[size];
  87         }
  88         return (value);
  89 }
  90