db_access.c revision 4 
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 * HISTORY
28 * $Log: db_access.c,v $
29 * Revision 1.1  1992/03/25  21:44:50  pace
30 * Initial revision
31 *
32 * Revision 2.3  91/02/05  17:05:44  mrt
33 * 	Changed to new Mach copyright
34 * 	[91/01/31  16:16:22  mrt]
35 *
36 * Revision 2.2  90/08/27  21:48:20  dbg
37 * 	Fix type declarations.
38 * 	[90/08/07            dbg]
39 * 	Created.
40 * 	[90/07/25            dbg]
41 *
42 */
43/*
44 *	Author: David B. Golub, Carnegie Mellon University
45 *	Date:	7/90
46 */
47#include "param.h"
48#include "proc.h"
49#include <machine/db_machdep.h>		/* type definitions */
50
51/*
52 * Access unaligned data items on aligned (longword)
53 * boundaries.
54 */
55
56extern void	db_read_bytes();	/* machine-dependent */
57extern void	db_write_bytes();	/* machine-dependent */
58
59int db_extend[] = {	/* table for sign-extending */
60	0,
61	0xFFFFFF80,
62	0xFFFF8000,
63	0xFF800000
64};
65
66db_expr_t
67db_get_value(addr, size, is_signed)
68	db_addr_t	addr;
69	register int	size;
70	boolean_t	is_signed;
71{
72	char		data[sizeof(int)];
73	register db_expr_t value;
74	register int	i;
75
76	db_read_bytes(addr, size, data);
77
78	value = 0;
79#if	BYTE_MSF
80	for (i = 0; i < size; i++)
81#else	/* BYTE_LSF */
82	for (i = size - 1; i >= 0; i--)
83#endif
84	{
85	    value = (value << 8) + (data[i] & 0xFF);
86	}
87
88	if (size < 4) {
89	    if (is_signed && (value & db_extend[size]) != 0)
90		value |= db_extend[size];
91	}
92	return (value);
93}
94
95void
96db_put_value(addr, size, value)
97	db_addr_t	addr;
98	register int	size;
99	register db_expr_t value;
100{
101	char		data[sizeof(int)];
102	register int	i;
103
104#if	BYTE_MSF
105	for (i = size - 1; i >= 0; i--)
106#else	/* BYTE_LSF */
107	for (i = 0; i < size; i++)
108#endif
109	{
110	    data[i] = value & 0xFF;
111	    value >>= 8;
112	}
113
114	db_write_bytes(addr, size, data);
115}
116
117