db_access.c revision 798 
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 1.2 1993/10/16 16:47:04 rgrimes Exp $
27 */
28
29/*
30 *	Author: David B. Golub, Carnegie Mellon University
31 *	Date:	7/90
32 */
33#include "param.h"
34#include "proc.h"
35#include <machine/db_machdep.h>		/* type definitions */
36
37/*
38 * Access unaligned data items on aligned (longword)
39 * boundaries.
40 */
41
42extern void	db_read_bytes();	/* machine-dependent */
43extern void	db_write_bytes();	/* machine-dependent */
44
45unsigned db_extend[] = {	/* table for sign-extending */
46	0,
47	0xFFFFFF80U,
48	0xFFFF8000U,
49	0xFF800000U
50};
51
52db_expr_t
53db_get_value(addr, size, is_signed)
54	db_addr_t	addr;
55	register int	size;
56	boolean_t	is_signed;
57{
58	char		data[sizeof(int)];
59	register db_expr_t value;
60	register int	i;
61
62	db_read_bytes(addr, size, data);
63
64	value = 0;
65#if	BYTE_MSF
66	for (i = 0; i < size; i++)
67#else	/* BYTE_LSF */
68	for (i = size - 1; i >= 0; i--)
69#endif
70	{
71	    value = (value << 8) + (data[i] & 0xFF);
72	}
73
74	if (size < 4) {
75	    if (is_signed && (value & db_extend[size]) != 0)
76		value |= db_extend[size];
77	}
78	return (value);
79}
80
81void
82db_put_value(addr, size, value)
83	db_addr_t	addr;
84	register int	size;
85	register db_expr_t value;
86{
87	char		data[sizeof(int)];
88	register int	i;
89
90#if	BYTE_MSF
91	for (i = size - 1; i >= 0; i--)
92#else	/* BYTE_LSF */
93	for (i = 0; i < size; i++)
94#endif
95	{
96	    data[i] = value & 0xFF;
97	    value >>= 8;
98	}
99
100	db_write_bytes(addr, size, data);
101}
102
103