db_access.c revision 8876 
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 *	$Id: db_access.c,v 1.6 1994/08/18 22:34:18 wollman Exp $
27 */
28
29/*
30 *	Author: David B. Golub, Carnegie Mellon University
31 *	Date:	7/90
32 */
33#include <sys/param.h>
34#include <sys/systm.h>
35#include <sys/proc.h>
36#include <ddb/ddb.h>
37
38/*
39 * Access unaligned data items on aligned (longword)
40 * boundaries.
41 */
42
43unsigned db_extend[] = {	/* table for sign-extending */
44	0,
45	0xFFFFFF80U,
46	0xFFFF8000U,
47	0xFF800000U
48};
49
50db_expr_t
51db_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
79void
80db_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
101