db_access.c revision 273265 
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: stable/10/sys/ddb/db_access.c 273265 2014-10-18 19:22:59Z pfg $");
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
45static 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
56db_expr_t
57db_get_value(db_addr_t addr, int size, boolean_t is_signed)
58{
59	char		data[sizeof(u_int64_t)];
60	register db_expr_t value;
61	register 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
86void
87db_put_value(db_addr_t addr, int size, db_expr_t value)
88{
89	char		data[sizeof(int)];
90	register 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}
108