129 lines
3.6 KiB
C
129 lines
3.6 KiB
C
/************************************************************************
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* $Id$
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************************************************************************
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*
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* plex86: run multiple x86 operating systems concurrently
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* Copyright (C) 1999-2003 Kevin P. Lawton
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*
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* descriptor.h: defines for descriptors and selectors
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*
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* This library is free software; you can redistribute it and/or
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* modify it under the terms of the GNU Lesser General Public
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* License as published by the Free Software Foundation; either
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* version 2 of the License, or (at your option) any later version.
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*
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* This library is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* Lesser General Public License for more details.
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*
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* You should have received a copy of the GNU Lesser General Public
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* License along with this library; if not, write to the Free Software
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* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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*/
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#ifndef __DESCRIPTOR_H__
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#define __DESCRIPTOR_H__
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#define SET_DESCRIPTOR(d, B, L, G, DB, AVL, P, DPL, T) {\
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d.base_high = (B) >> 24;\
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d.base_med = ((B) >> 16) & 0xff;\
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d.base_low = (B) & 0xffff;\
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d.limit_high = ((L) & 0xf0000) >> 16;\
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d.limit_low = ((L) & 0x0ffff);\
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d.g = (G);\
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d.d_b = (DB);\
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d.reserved = 0;\
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d.avl = (AVL);\
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d.p = (P);\
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d.dpl = (DPL);\
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d.type = (T);\
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}
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typedef struct {
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Bit16u limit_low; /* limit 0..15 */
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Bit16u base_low; /* base 0..15 */
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Bit8u base_med; /* base 16..23 */
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unsigned type:5; /* S/type field */
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unsigned dpl:2; /* DPL */
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unsigned p:1; /* present */
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unsigned limit_high:4; /* limit 16..19 */
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unsigned avl:1; /* Available for use by system software */
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unsigned reserved:1; /* 0 */
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unsigned d_b:1; /* D/B */
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unsigned g:1; /* granularity */
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Bit8u base_high; /* base 24..31 */
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} __attribute__ ((packed)) descriptor_t;
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typedef union {
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struct {
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Bit16u rpl:2;
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Bit16u ti:1;
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Bit16u index:13;
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} __attribute__ ((packed)) fields;
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Bit16u raw;
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} __attribute__ ((packed)) selector_t;
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#define D_DPL0 0
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#define D_DPL1 1
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#define D_DPL2 2
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#define D_DPL3 3
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#define D_BG 0
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#define D_PG 1
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#define D_D16 0
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#define D_D32 1
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#define D_NOTPRESENT 0
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#define D_PRESENT 1
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#define D_S 0x10
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#define D_DATA 0x10
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#define D_CODE 0x18
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#define D_EXECUTE 0x08
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#define D_EXDOWN 0x04
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#define D_CONFORM 0x04
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#define D_WRITE 0x02 /* writable (data segment) */
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#define D_READ 0x02 /* readable (code segment) */
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#define D_ACCESSED 0x01
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#define D_LDT 0x02 /* LDT segment */
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#define D_TASK 0x05 /* Task gate */
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#define D_TSS 0x09 /* TSS */
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#define D_CALL 0x0C /* 386 call gate */
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#define D_INT 0x0E /* 386 interrupt gate */
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#define D_TRAP 0x0F /* 386 trap gate */
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#define D_AVL0 0
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#define D_AVL1 1
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#define LimitOfDataDescriptor(d) \
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( d.g ? \
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( ((d.type & 0xc) == 0x4) ? \
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((d.limit_high << 16) | d.limit_low)<<12 : \
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((d.limit_high << 16) | d.limit_low)<<12 | 0xfff) : \
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((d.limit_high << 16) | d.limit_low) )
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#define BaseOfDescriptor(d) \
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( (d.base_low) | (d.base_med << 16) | (d.base_high << 24) )
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/*
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* selector stuff
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*/
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#define Selector(sel, ti, rpl) (((sel)<<3) | ((ti)<<2) | (rpl))
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#define RPL0 0
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#define RPL1 1
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#define RPL2 2
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#define RPL3 3
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typedef struct {
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Bit16u limit;
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Bit32u base;
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} __attribute__ ((packed)) gdt_info_t;
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#endif /* __DESCRIPTOR_H__ */
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