FreeBSD/Linux Kernel Cross Reference
sys/ddb/db_access.c
1 /*-
2 * SPDX-License-Identifier: MIT-CMU
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
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 /*
29 * Author: David B. Golub, Carnegie Mellon University
30 * Date: 7/90
31 */
32
33 #include <sys/cdefs.h>
34 __FBSDID("$FreeBSD$");
35
36 #include <sys/param.h>
37 #include <sys/kdb.h>
38 #include <sys/endian.h>
39
40 #include <ddb/ddb.h>
41 #include <ddb/db_access.h>
42
43 /*
44 * Access unaligned data items on aligned (longword)
45 * boundaries.
46 */
47
48 static unsigned db_extend[] = { /* table for sign-extending */
49 0,
50 0xFFFFFF80U,
51 0xFFFF8000U,
52 0xFF800000U
53 };
54
55 db_expr_t
56 db_get_value(db_addr_t addr, int size, bool is_signed)
57 {
58 char data[sizeof(uint64_t)];
59 db_expr_t value;
60 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_ORDER == _BIG_ENDIAN
70 for (i = 0; i < size; i++)
71 #else /* _LITTLE_ENDIAN */
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(db_addr_t addr, int size, db_expr_t value)
87 {
88 char data[sizeof(int)];
89 int i;
90
91 #if _BYTE_ORDER == _BIG_ENDIAN
92 for (i = size - 1; i >= 0; i--)
93 #else /* _LITTLE_ENDIAN */
94 for (i = 0; i < size; i++)
95 #endif
96 {
97 data[i] = value & 0xFF;
98 value >>= 8;
99 }
100
101 if (db_write_bytes(addr, size, data) != 0) {
102 db_printf("*** error writing to address %llx ***\n",
103 (long long)addr);
104 kdb_reenter();
105 }
106 }
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