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/*
* plex86: run multiple x86 operating systems concurrently
* Copyright (C) 1999-2000 Kevin P. Lawton
*
* descriptor.h: defines for descriptors and selectors
*
* 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 __DESCRIPTOR_H__
#define __DESCRIPTOR_H__
#define SET_DESCRIPTOR(d, B, L, G, DB, AVL, P, DPL, T) {\
d.base_high = (B) >> 24;\
d.base_med = ((B) >> 16) & 0xff;\
d.base_low = (B) & 0xffff;\
d.limit_high = ((L) & 0xf0000) >> 16;\
d.limit_low = ((L) & 0x0ffff);\
d.g = (G);\
d.d_b = (DB);\
d.reserved = 0;\
d.avl = (AVL);\
d.p = (P);\
d.dpl = (DPL);\
d.type = (T);\
}
typedef struct {
Bit16u limit_low; /* limit 0..15 */
Bit16u base_low; /* base 0..15 */
Bit8u base_med; /* base 16..23 */
unsigned type:5; /* S/type field */
unsigned dpl:2; /* DPL */
unsigned p:1; /* present */
unsigned limit_high:4; /* limit 16..19 */
unsigned avl:1; /* Available for use by system software */
unsigned reserved:1; /* 0 */
unsigned d_b:1; /* D/B */
unsigned g:1; /* granularity */
Bit8u base_high; /* base 24..31 */
} __attribute__ ((packed)) descriptor_t;
typedef union {
struct {
Bit16u rpl:2;
Bit16u ti:1;
Bit16u index:13;
} __attribute__ ((packed)) fields;
Bit16u raw;
} __attribute__ ((packed)) selector_t;
#define D_DPL0 0
#define D_DPL1 1
#define D_DPL2 2
#define D_DPL3 3
#define D_BG 0
#define D_PG 1
#define D_D16 0
#define D_D32 1
#define D_NOTPRESENT 0
#define D_PRESENT 1
#define D_S 0x10
#define D_DATA 0x10
#define D_CODE 0x18
#define D_EXECUTE 0x08
#define D_EXDOWN 0x04
#define D_CONFORM 0x04
#define D_WRITE 0x02 /* writable (data segment) */
#define D_READ 0x02 /* readable (code segment) */
#define D_ACCESSED 0x01
#define D_LDT 0x02 /* LDT segment */
#define D_TASK 0x05 /* Task gate */
#define D_TSS 0x09 /* TSS */
#define D_CALL 0x0C /* 386 call gate */
#define D_INT 0x0E /* 386 interrupt gate */
#define D_TRAP 0x0F /* 386 trap gate */
#define D_AVL0 0
#define D_AVL1 1
#define LimitOfDataDescriptor(d) \
( d.g ? \
( ((d.type & 0xc) == 0x4) ? \
((d.limit_high << 16) | d.limit_low)<<12 : \
((d.limit_high << 16) | d.limit_low)<<12 | 0xfff) : \
((d.limit_high << 16) | d.limit_low) )
#define BaseOfDescriptor(d) \
( (d.base_low) | (d.base_med << 16) | (d.base_high << 24) )
/*
* selector stuff
*/
#define Selector(sel, ti, rpl) (((sel)<<3) | ((ti)<<2) | (rpl))
#define RPL0 0
#define RPL1 1
#define RPL2 2
#define RPL3 3
#endif /* __DESCRIPTOR_H__ */
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