196 lines
7.7 KiB
C
Executable File
196 lines
7.7 KiB
C
Executable File
/////////////////////////////////////////////////////////////////////////
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// $Id: descriptor.h,v 1.32 2009-10-14 20:45:29 sshwarts Exp $
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/////////////////////////////////////////////////////////////////////////
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//
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// Copyright (c) 2007-2009 Stanislav Shwartsman
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// Written by Stanislav Shwartsman [sshwarts at sourceforge net]
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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 B 02110-1301 USA
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/////////////////////////////////////////////////////////////////////////
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#ifndef BX_DESCRIPTOR_H
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#define BX_DESCRIPTOR_H
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//
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// |---------------------------------------------|
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// | Segment Descriptor |
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// |---------------------------------------------|
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// |33222222|2|2|2|2| 11 11 |1|11|1|11 | |
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// |10987654|3|2|1|0| 98 76 |5|43|2|1098|76543210|
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// |--------|-|-|-|-|-------|-|--|-|----|--------|
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// |Base |G|D|L|A|Limit |P|D |S|Type|Base |
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// |[31-24] | |/| |V|[19-16]| |P | | |[23-16] |
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// | | |B| |L| | |L | | | |
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// |------------------------|--------------------|
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// | Base [15-0] | Limit [15-0] |
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// |------------------------|--------------------|
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//
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typedef struct { /* bx_selector_t */
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Bit16u value; /* the 16bit value of the selector */
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#if BX_CPU_LEVEL >= 2
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/* the following fields are extracted from the value field in protected
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mode only. They're used for sake of efficiency */
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Bit16u index; /* 13bit index extracted from value in protected mode */
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Bit8u ti; /* table indicator bit extracted from value */
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Bit8u rpl; /* RPL extracted from value */
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#endif
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} bx_selector_t;
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#define BX_SELECTOR_RPL(selector) ((selector) & 0x03)
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#define BX_SELECTOR_RPL_MASK (0xfffc)
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typedef struct
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{
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// do not go above 4 bits !
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#define SegValidCache (0x01)
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#define SegAccessROK (0x02)
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#define SegAccessWOK (0x04)
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unsigned valid; // Holds above values, Or'd together. Used to
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// hold only 0 or 1.
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bx_bool p; /* present */
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Bit8u dpl; /* descriptor privilege level 0..3 */
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bx_bool segment; /* 0 = system/gate, 1 = data/code segment */
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Bit8u type; /* For system & gate descriptors:
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* 0 = invalid descriptor (reserved)
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* 1 = 286 available Task State Segment (TSS)
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* 2 = LDT descriptor
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* 3 = 286 busy Task State Segment (TSS)
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* 4 = 286 call gate
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* 5 = task gate
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* 6 = 286 interrupt gate
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* 7 = 286 trap gate
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* 8 = (reserved)
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* 9 = 386 available TSS
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* 10 = (reserved)
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* 11 = 386 busy TSS
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* 12 = 386 call gate
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* 13 = (reserved)
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* 14 = 386 interrupt gate
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* 15 = 386 trap gate */
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// For system & gate descriptors:
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#define BX_GATE_TYPE_NONE (0x0)
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#define BX_SYS_SEGMENT_AVAIL_286_TSS (0x1)
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#define BX_SYS_SEGMENT_LDT (0x2)
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#define BX_SYS_SEGMENT_BUSY_286_TSS (0x3)
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#define BX_286_CALL_GATE (0x4)
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#define BX_TASK_GATE (0x5)
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#define BX_286_INTERRUPT_GATE (0x6)
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#define BX_286_TRAP_GATE (0x7)
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/* 0x8 reserved */
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#define BX_SYS_SEGMENT_AVAIL_386_TSS (0x9)
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/* 0xa reserved */
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#define BX_SYS_SEGMENT_BUSY_386_TSS (0xb)
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#define BX_386_CALL_GATE (0xc)
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/* 0xd reserved */
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#define BX_386_INTERRUPT_GATE (0xe)
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#define BX_386_TRAP_GATE (0xf)
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// For data/code descriptors:
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#define BX_DATA_READ_ONLY (0x0)
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#define BX_DATA_READ_ONLY_ACCESSED (0x1)
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#define BX_DATA_READ_WRITE (0x2)
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#define BX_DATA_READ_WRITE_ACCESSED (0x3)
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#define BX_DATA_READ_ONLY_EXPAND_DOWN (0x4)
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#define BX_DATA_READ_ONLY_EXPAND_DOWN_ACCESSED (0x5)
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#define BX_DATA_READ_WRITE_EXPAND_DOWN (0x6)
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#define BX_DATA_READ_WRITE_EXPAND_DOWN_ACCESSED (0x7)
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#define BX_CODE_EXEC_ONLY (0x8)
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#define BX_CODE_EXEC_ONLY_ACCESSED (0x9)
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#define BX_CODE_EXEC_READ (0xa)
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#define BX_CODE_EXEC_READ_ACCESSED (0xb)
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#define BX_CODE_EXEC_ONLY_CONFORMING (0xc)
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#define BX_CODE_EXEC_ONLY_CONFORMING_ACCESSED (0xd)
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#define BX_CODE_EXEC_READ_CONFORMING (0xe)
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#define BX_CODE_EXEC_READ_CONFORMING_ACCESSED (0xf)
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union {
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struct {
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bx_address base; /* base address: 286=24bits, 386=32bits, long=64 */
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Bit32u limit_scaled; /* for efficiency, this contrived field is set to
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* limit for byte granular, and
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* (limit << 12) | 0xfff for page granular seg's
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*/
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#if BX_CPU_LEVEL >= 3
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bx_bool g; /* granularity: 0=byte, 1=4K (page) */
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bx_bool d_b; /* default size: 0=16bit, 1=32bit */
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#if BX_SUPPORT_X86_64
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bx_bool l; /* long mode: 0=compat, 1=64 bit */
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#endif
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bx_bool avl; /* available for use by system */
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#endif
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} segment;
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struct {
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Bit8u param_count; /* 5bits (0..31) #words/dword to copy from caller's
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* stack to called procedure's stack. */
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Bit16u dest_selector;
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Bit32u dest_offset;
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} gate;
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struct { /* type 5: Task Gate Descriptor */
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Bit16u tss_selector; /* TSS segment selector */
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} taskgate;
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} u;
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} bx_descriptor_t;
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#define IS_PRESENT(descriptor) (descriptor.p)
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#if BX_SUPPORT_X86_64
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#define IS_LONG64_SEGMENT(descriptor) (descriptor.u.segment.l)
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#else
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#define IS_LONG64_SEGMENT(descriptor) (0)
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#endif
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#define IS_CODE_SEGMENT(type) (((type) >> 3) & 0x1)
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#define IS_CODE_SEGMENT_CONFORMING(type) (((type) >> 2) & 0x1)
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#define IS_DATA_SEGMENT_EXPAND_DOWN(type) (((type) >> 2) & 0x1)
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#define IS_CODE_SEGMENT_READABLE(type) (((type) >> 1) & 0x1)
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#define IS_DATA_SEGMENT_WRITEABLE(type) (((type) >> 1) & 0x1)
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#define IS_SEGMENT_ACCESSED(type) ((type) & 0x1)
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#define BX_SEGMENT_CODE (0x8)
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#define BX_SEGMENT_DATA_EXPAND_DOWN (0x4)
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#define BX_SEGMENT_CODE_CONFORMING (0x4)
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#define BX_SEGMENT_DATA_WRITE (0x2)
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#define BX_SEGMENT_CODE_READ (0x2)
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#define BX_SEGMENT_ACCESSED (0x1)
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#define IS_DATA_SEGMENT(type) (! IS_CODE_SEGMENT(type))
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#define IS_CODE_SEGMENT_NON_CONFORMING(type) \
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(! IS_CODE_SEGMENT_CONFORMING(type))
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typedef struct {
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bx_selector_t selector;
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bx_descriptor_t cache;
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} bx_segment_reg_t;
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#if BX_CPU_LEVEL < 2
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/* no GDTR or IDTR register in an 8086 */
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#else
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typedef struct {
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bx_address base; /* base address: 24bits=286,32bits=386,64bits=x86-64 */
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Bit16u limit; /* limit, 16bits */
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} bx_global_segment_reg_t;
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#endif
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#endif
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