xref: /freebsd/sys/ddb/db_access.c (revision f0adf7f5cdd241db2f2c817683191a6ef64a4e95)
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("$FreeBSD$");
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 
45 static unsigned db_extend[] = {	/* table for sign-extending */
46 	0,
47 	0xFFFFFF80U,
48 	0xFFFF8000U,
49 	0xFF800000U
50 };
51 
52 db_expr_t
53 db_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(u_int64_t)];
59 	register db_expr_t value;
60 	register int	i;
61 
62 	if (db_read_bytes(addr, size, data) != 0) {
63 		db_printf("*** error reading from address %llx ***\n",
64 		    (long long)addr);
65 		kdb_reenter();
66 	}
67 
68 	value = 0;
69 #if	BYTE_MSF
70 	for (i = 0; i < size; i++)
71 #else	/* BYTE_LSF */
72 	for (i = size - 1; i >= 0; i--)
73 #endif
74 	{
75 	    value = (value << 8) + (data[i] & 0xFF);
76 	}
77 
78 	if (size < 4) {
79 	    if (is_signed && (value & db_extend[size]) != 0)
80 		value |= db_extend[size];
81 	}
82 	return (value);
83 }
84 
85 void
86 db_put_value(addr, size, value)
87 	db_addr_t	addr;
88 	register int	size;
89 	register db_expr_t value;
90 {
91 	char		data[sizeof(int)];
92 	register int	i;
93 
94 #if	BYTE_MSF
95 	for (i = size - 1; i >= 0; i--)
96 #else	/* BYTE_LSF */
97 	for (i = 0; i < size; i++)
98 #endif
99 	{
100 	    data[i] = value & 0xFF;
101 	    value >>= 8;
102 	}
103 
104 	if (db_write_bytes(addr, size, data) != 0) {
105 		db_printf("*** error writing to address %llx ***\n",
106 		    (long long)addr);
107 		kdb_reenter();
108 	}
109 }
110