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/////////////////////////////////////////////////////////////////////////
// $Id: descriptor.h,v 1.16 2006/08/25 19:56:03 sshwarts Exp $
/////////////////////////////////////////////////////////////////////////
//
// Copyright (C) 2001 MandrakeSoft S.A.
//
// MandrakeSoft S.A.
// 43, rue d'Aboukir
// 75002 Paris - France
// http://www.linux-mandrake.com/
// http://www.mandrakesoft.com/
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
/////////////////////////////////////////////////////////////////////////
#ifndef BX_DESCRIPTOR_H
#define BX_DESCRIPTOR_H
typedef struct { /* bx_selector_t */
Bit16u value; /* the 16bit value of the selector */
#if BX_CPU_LEVEL >= 2
/* the following fields are extracted from the value field in protected
mode only. They're used for sake of efficiency */
Bit16u index; /* 13bit index extracted from value in protected mode */
Bit8u ti; /* table indicator bit extracted from value */
Bit8u rpl; /* RPL extracted from value */
#endif
} bx_selector_t;
#define BX_SELECTOR_RPL(selector) ((selector) & 0x03)
#define BX_SELECTOR_RPL_MASK (0xfffc)
typedef struct
{
#define SegValidCache (0x1)
#define SegAccessROK (0x2)
#define SegAccessWOK (0x4)
unsigned valid; // Holds above values, Or'd together. Used to
// hold only 0 or 1.
bx_bool p; /* present */
Bit8u dpl; /* descriptor privilege level 0..3 */
bx_bool segment; /* 0 = system/gate, 1 = data/code segment */
Bit8u type; /* For system & gate descriptors:
* 0 = invalid descriptor (reserved)
* 1 = 286 available Task State Segment (TSS)
* 2 = LDT descriptor
* 3 = 286 busy Task State Segment (TSS)
* 4 = 286 call gate
* 5 = task gate
* 6 = 286 interrupt gate
* 7 = 286 trap gate
* 8 = (reserved)
* 9 = 386 available TSS
* 10 = (reserved)
* 11 = 386 busy TSS
* 12 = 386 call gate
* 13 = (reserved)
* 14 = 386 interrupt gate
* 15 = 386 trap gate */
// For system & gate descriptors:
#define BX_GATE_TYPE_NONE (0x0)
#define BX_SYS_SEGMENT_AVAIL_286_TSS (0x1)
#define BX_SYS_SEGMENT_LDT (0x2)
#define BX_SYS_SEGMENT_BUSY_286_TSS (0x3)
#define BX_286_CALL_GATE (0x4)
#define BX_TASK_GATE (0x5)
#define BX_286_INTERRUPT_GATE (0x6)
#define BX_286_TRAP_GATE (0x7)
/* 0x8 reserved */
#define BX_SYS_SEGMENT_AVAIL_386_TSS (0x9)
/* 0xa reserved */
#define BX_SYS_SEGMENT_BUSY_386_TSS (0xb)
#define BX_386_CALL_GATE (0xc)
/* 0xd reserved */
#define BX_386_INTERRUPT_GATE (0xe)
#define BX_386_TRAP_GATE (0xf)
// For data/code descriptors:
#define BX_DATA_READ_ONLY (0x0)
#define BX_DATA_READ_ONLY_ACCESSED (0x1)
#define BX_DATA_READ_WRITE (0x2)
#define BX_DATA_READ_WRITE_ACCESSED (0x3)
#define BX_DATA_READ_ONLY_EXPAND_DOWN (0x4)
#define BX_DATA_READ_ONLY_EXPAND_DOWN_ACCESSED (0x5)
#define BX_DATA_READ_WRITE_EXPAND_DOWN (0x6)
#define BX_DATA_READ_WRITE_EXPAND_DOWN_ACCESSED (0x7)
#define BX_CODE_EXEC_ONLY (0x8)
#define BX_CODE_EXEC_ONLY_ACCESSED (0x9)
#define BX_CODE_EXEC_READ (0xa)
#define BX_CODE_EXEC_READ_ACCESSED (0xb)
#define BX_CODE_EXEC_ONLY_CONFORMING (0xc)
#define BX_CODE_EXEC_ONLY_CONFORMING_ACCESSED (0xd)
#define BX_CODE_EXEC_READ_CONFORMING (0xe)
#define BX_CODE_EXEC_READ_CONFORMING_ACCESSED (0xf)
union {
struct {
bx_address base; /* base address: 286=24bits, 386=32bits, long=64 */
Bit32u limit; /* limit: 286=16bits, 386=20bits */
Bit32u limit_scaled; /* for efficiency, this contrived field is set to
* limit for byte granular, and
* (limit << 12) | 0xfff for page granular seg's
*/
#if BX_CPU_LEVEL >= 3
bx_bool g; /* granularity: 0=byte, 1=4K (page) */
bx_bool d_b; /* default size: 0=16bit, 1=32bit */
#if BX_SUPPORT_X86_64
bx_bool l; /* long mode: 0=compat, 1=64 bit */
#endif
bx_bool avl; /* available for use by system */
#endif
} segment;
struct {
Bit8u word_count; /* 5bits (0..31) #words to copy from caller's stack
* to called procedure's stack. (call gates only)*/
Bit16u dest_selector;
Bit16u dest_offset;
} gate286;
#if BX_CPU_LEVEL >= 3
struct {
Bit8u dword_count; /* 5bits (0..31) #dwords to copy from caller's stack
* to called procedure's stack. (call gates only) */
Bit16u dest_selector;
Bit32u dest_offset;
} gate386;
#endif
struct { /* type 5: Task Gate Descriptor */
Bit16u tss_selector; /* TSS segment selector */
} taskgate;
struct {
bx_address base; /* 24 (tss286) or 32/64 (tss386) bit TSS base */
Bit32u limit; /* 16/32 bit TSS limit */
#if BX_CPU_LEVEL >= 3
Bit32u limit_scaled; // Same notes as for 'segment' field
bx_bool g; /* granularity: 0=byte, 1=4K (page) */
bx_bool avl; /* available for use by system */
#endif
} tss;
struct {
bx_address base; /* 286=24 386+ = 32/64 bit LDT base */
Bit32u limit; /* 286+ = 16/32 bit LDT limit */
#if BX_CPU_LEVEL >= 3
Bit32u limit_scaled; // Same notes as for 'segment' field
bx_bool g; /* granularity: 0=byte, 1=4K (page) */
bx_bool avl; /* available for use by system */
#endif
} ldt;
} u;
} bx_descriptor_t;
#define IS_PRESENT(descriptor) (descriptor.p)
#if BX_SUPPORT_X86_64
#define IS_LONG64_SEGMENT(descriptor) (descriptor.u.segment.l)
#else
#define IS_LONG64_SEGMENT(descriptor) (0)
#endif
#define IS_CODE_SEGMENT(type) (((type) >> 3) & 0x1)
#define IS_CODE_SEGMENT_CONFORMING(type) (((type) >> 2) & 0x1)
#define IS_DATA_SEGMENT_EXPAND_DOWN(type) (((type) >> 2) & 0x1)
#define IS_CODE_SEGMENT_READABLE(type) (((type) >> 1) & 0x1)
#define IS_DATA_SEGMENT_WRITEABLE(type) (((type) >> 1) & 0x1)
#define IS_SEGMENT_ACCESSED(type) ( (type) & 0x1)
#define BX_SEGMENT_CODE (0x8)
#define BX_SEGMENT_DATA_EXPAND_DOWN (0x4)
#define BX_SEGMENT_CODE_CONFORMING (0x4)
#define BX_SEGMENT_DATA_WRITE (0x2)
#define BX_SEGMENT_CODE_READ (0x2)
#define BX_SEGMENT_ACCESSED (0x1)
#define IS_DATA_SEGMENT(type) (! IS_CODE_SEGMENT(type))
#define IS_CODE_SEGMENT_NON_CONFORMING(type) \
(! IS_CODE_SEGMENT_CONFORMING(type))
typedef struct {
bx_selector_t selector;
bx_descriptor_t cache;
} bx_segment_reg_t;
#if BX_CPU_LEVEL < 2
/* no GDTR or IDTR register in an 8086 */
#else
typedef struct {
bx_address base; /* base address: 24bits=286,32bits=386,64bits=x86-64 */
Bit16u limit; /* limit, 16bits */
} bx_global_segment_reg_t;
#endif
#endif
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