sys/ddb/db_access.c

   1 /*      $NetBSD: db_access.c,v 1.18 2007/02/21 22:59:56 thorpej 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 1.18 2007/02/21 22:59:56 thorpej Exp $");
  34
  35 #include <sys/param.h>
  36 #include <sys/proc.h>
  37 #include <sys/endian.h>
  38
  39 #include <ddb/ddb.h>
  40
  41 /*
  42  * Access unaligned data items on aligned (longword)
  43  * boundaries.
  44  */
  45
  46 const int db_extend[] = {       /* table for sign-extending */
  47         0,
  48         0xFFFFFF80,
  49         0xFFFF8000,
  50         0xFF800000
  51 };
  52
  53 db_expr_t
  54 db_get_value(db_addr_t addr, size_t size, bool is_signed)
  55 {
  56         char data[sizeof(db_expr_t)];
  57         db_expr_t value;
  58         size_t i;
  59
  60         db_read_bytes(addr, size, data);
  61
  62         value = 0;
  63 #if BYTE_ORDER == LITTLE_ENDIAN
  64         for (i = size; i-- > 0;)
  65 #else /* BYTE_ORDER == BIG_ENDIAN */
  66         for (i = 0; i < size; i++)
  67 #endif /* BYTE_ORDER */
  68                 value = (value << 8) + (data[i] & 0xFF);
  69
  70         if (size < 4 && is_signed && (value & db_extend[size]) != 0)
  71                 value |= db_extend[size];
  72         return (value);
  73 }
  74
  75 void
  76 db_put_value(db_addr_t addr, size_t size, db_expr_t value)
  77 {
  78         char data[sizeof(db_expr_t)];
  79         size_t i;
  80
  81 #if BYTE_ORDER == LITTLE_ENDIAN
  82         for (i = 0; i < size; i++)
  83 #else /* BYTE_ORDER == BIG_ENDIAN */
  84         for (i = size; i-- > 0;)
  85 #endif /* BYTE_ORDER */
  86         {
  87                 data[i] = value & 0xFF;
  88                 value >>= 8;
  89         }
  90
  91         db_write_bytes(addr, size, data);
  92 }
  93
  94 void *
  95 db_read_ptr(const char *name)
  96 {
  97         db_expr_t val;
  98         void *p;
  99
 100         if (!db_value_of_name(name, &val)) {
 101                 db_printf("db_read_ptr: cannot find `%s'\n", name);
 102                 db_error(NULL);
 103                 /* NOTREACHED */
 104         }
 105         db_read_bytes((db_addr_t)val, sizeof(p), (char *)&p);
 106         return p;
 107 }
 108
 109 int
 110 db_read_int(const char *name)
 111 {
 112         db_expr_t val;
 113         int p;
 114
 115         if (!db_value_of_name(name, &val)) {
 116                 db_printf("db_read_int: cannot find `%s'\n", name);
 117                 db_error(NULL);
 118                 /* NOTREACHED */
 119         }
 120         db_read_bytes((db_addr_t)val, sizeof(p), (char *)&p);
 121         return p;
 122 }