62 lines
2.1 KiB
C
62 lines
2.1 KiB
C
/* Copyright (C) 2021 Mathieu Maret
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Copyright (C) 2004 The SOS Team
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Copyright (C) 1999 Free Software Foundation, Inc.
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This program is free software; you can redistribute it and/or
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modify it under the terms of the GNU General Public License
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as published by the Free Software Foundation; either version 2
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of the License, or (at your option) any later version.
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This program 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
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307,
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USA.
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*/
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#pragma once
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/**
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* @file segments.h
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*
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* Global and local (GDT/LDT) segment descriptor definition and
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* structure. These segments map virtual addresses (ie
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* data/instruction addresses, relative to these segment descriptors)
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* to linear addresses (ie addresses in the paged-memory space).
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*
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* @see Intel x86 doc, vol 3 chapter 3.
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*/
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/*
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* Global segment selectors (GDT) for SOS/x86.
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*
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* @see gdt.h
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*/
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#define SEG_NULL 0 /* NULL segment, unused by the procesor */
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#define SEG_KCODE 1 /* Kernel code segment */
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#define SEG_KDATA 2 /* Kernel data segment */
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#define SEG_UCODE 3 /* User code segment */
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#define SEG_UDATA 4 /* User data segment */
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#define SEG_K_TSS 5 /* Kernel TSS for priviledge change (user to kernel) */
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/**
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* Helper macro that builds a segment register's value
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*/
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#ifdef ASM_SOURCE
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#define BUILD_SEGMENT_REG_VALUE(desc_privilege,in_ldt,seg_index) \
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( (((desc_privilege) & 0x3) << 0) \
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| ((in_ldt & 1) << 2) \
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| ((seg_index) << 3) )
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#else
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#define BUILD_SEGMENT_REG_VALUE(desc_privilege, in_ldt, seg_index) \
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((((desc_privilege)&0x3) << 0) | (((in_ldt) ? 1 : 0) << 2) | ((seg_index) << 3))
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#endif
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/*
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* Local segment selectors (LDT) for SOS/x86
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*/
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/* None */
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