1/*
2 * Copyright (c) 2000 Apple Computer, Inc. All rights reserved.
3 *
4 * @APPLE_OSREFERENCE_LICENSE_HEADER_START@
5 *
6 * This file contains Original Code and/or Modifications of Original Code
7 * as defined in and that are subject to the Apple Public Source License
8 * Version 2.0 (the 'License'). You may not use this file except in
9 * compliance with the License. The rights granted to you under the License
10 * may not be used to create, or enable the creation or redistribution of,
11 * unlawful or unlicensed copies of an Apple operating system, or to
12 * circumvent, violate, or enable the circumvention or violation of, any
13 * terms of an Apple operating system software license agreement.
14 *
15 * Please obtain a copy of the License at
16 * http://www.opensource.apple.com/apsl/ and read it before using this file.
17 *
18 * The Original Code and all software distributed under the License are
19 * distributed on an 'AS IS' basis, WITHOUT WARRANTY OF ANY KIND, EITHER
20 * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
21 * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
22 * FITNESS FOR A PARTICULAR PURPOSE, QUIET ENJOYMENT OR NON-INFRINGEMENT.
23 * Please see the License for the specific language governing rights and
24 * limitations under the License.
25 *
26 * @APPLE_OSREFERENCE_LICENSE_HEADER_END@
27 */
28/*
29 * Copyright (c) 1992 NeXT Computer, Inc.
30 *
31 * Intel386 Family:	Segment descriptors.
32 *
33 * HISTORY
34 *
35 * 29 March 1992 ? at NeXT
36 *	Created.
37 */
38
39/*
40 * Code segment descriptor.
41 */
42
43typedef struct code_desc {
44    unsigned short	limit00;
45    unsigned short	base00;
46    unsigned char	base16;
47    unsigned char	type	:5,
48#define DESC_CODE_EXEC	0x18
49#define DESC_CODE_READ	0x1a
50			dpl	:2,
51			present	:1;
52    unsigned char	limit16	:4,
53				:2,
54			opsz	:1,
55#define DESC_CODE_16B	0
56#define DESC_CODE_32B	1
57			granular:1;
58#define DESC_GRAN_BYTE	0
59#define DESC_GRAN_PAGE	1
60    unsigned char	base24;
61} code_desc_t;
62
63/*
64 * Data segment descriptor.
65 */
66
67typedef struct data_desc {
68    unsigned short	limit00;
69    unsigned short	base00;
70    unsigned char	base16;
71    unsigned char	type	:5,
72#define DESC_DATA_RONLY	0x10
73#define DESC_DATA_WRITE	0x12
74			dpl	:2,
75			present	:1;
76    unsigned char	limit16	:4,
77				:2,
78			stksz	:1,
79#define DESC_DATA_16B	0
80#define DESC_DATA_32B	1
81			granular:1;
82    unsigned char	base24;
83} data_desc_t;
84
85/*
86 * LDT segment descriptor.
87 */
88
89typedef struct ldt_desc {
90    unsigned short	limit00;
91    unsigned short	base00;
92    unsigned char	base16;
93    unsigned char	type	:5,
94#define DESC_LDT	0x02
95				:2,
96			present	:1;
97    unsigned char	limit16	:4,
98				:3,
99			granular:1;
100    unsigned char	base24;
101} ldt_desc_t;
102
103#include <architecture/i386/sel.h>
104
105/*
106 * Call gate descriptor.
107 */
108
109typedef struct call_gate {
110    unsigned short	offset00;
111    sel_t		seg;
112    unsigned int	argcnt	:5,
113    				:3,
114			type	:5,
115#define DESC_CALL_GATE	0x0c
116			dpl	:2,
117			present	:1,
118			offset16:16;
119} call_gate_t;
120
121/*
122 * Trap gate descriptor.
123 */
124
125typedef struct trap_gate {
126    unsigned short	offset00;
127    sel_t		seg;
128    unsigned int		:8,
129    			type	:5,
130#define DESC_TRAP_GATE	0x0f
131			dpl	:2,
132			present	:1,
133			offset16:16;
134} trap_gate_t;
135
136
137/*
138 * Interrupt gate descriptor.
139 */
140
141typedef struct intr_gate {
142    unsigned short	offset00;
143    sel_t		seg;
144    unsigned int		:8,
145    			type	:5,
146#define DESC_INTR_GATE	0x0e
147			dpl	:2,
148			present	:1,
149			offset16:16;
150} intr_gate_t;
151