www.pudn.com > tcpipsim.rar > segments.h
/*-
* Copyright (c) 1989, 1990 William F. Jolitz
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* William Jolitz.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)segments.h 8.1 (Berkeley) 6/11/93
*/
/*
* 386 Segmentation Data Structures and definitions
* William F. Jolitz (william@ernie.berkeley.edu) 6/20/1989
*/
/*
* Selectors
*/
#define ISPL(s) ((s)&3) /* what is the priority level of a selector */
#define SEL_KPL 0 /* kernel priority level */
#define SEL_UPL 3 /* user priority level */
#define ISLDT(s) ((s)&SEL_LDT) /* is it local or global */
#define SEL_LDT 4 /* local descriptor table */
#define IDXSEL(s) (((s)>>3) & 0x1fff) /* index of selector */
#define LSEL(s,r) (((s)<<3) | SEL_LDT | r) /* a local selector */
#define GSEL(s,r) (((s)<<3) | r) /* a global selector */
/*
* Memory and System segment descriptors
*/
struct segment_descriptor {
unsigned sd_lolimit:16 ; /* segment extent (lsb) */
unsigned sd_lobase:24 ; /* segment base address (lsb) */
unsigned sd_type:5 ; /* segment type */
unsigned sd_dpl:2 ; /* segment descriptor priority level */
unsigned sd_p:1 ; /* segment descriptor present */
unsigned sd_hilimit:4 ; /* segment extent (msb) */
unsigned sd_xx:2 ; /* unused */
unsigned sd_def32:1 ; /* default 32 vs 16 bit size */
unsigned sd_gran:1 ; /* limit granularity (byte/page units)*/
unsigned sd_hibase:8 ; /* segment base address (msb) */
} ;
/*
* Gate descriptors (e.g. indirect descriptors)
*/
struct gate_descriptor {
unsigned gd_looffset:16 ; /* gate offset (lsb) */
unsigned gd_selector:16 ; /* gate segment selector */
unsigned gd_stkcpy:5 ; /* number of stack wds to cpy */
unsigned gd_xx:3 ; /* unused */
unsigned gd_type:5 ; /* segment type */
unsigned gd_dpl:2 ; /* segment descriptor priority level */
unsigned gd_p:1 ; /* segment descriptor present */
unsigned gd_hioffset:16 ; /* gate offset (msb) */
} ;
/*
* Generic descriptor
*/
union descriptor {
struct segment_descriptor sd;
struct gate_descriptor gd;
};
#define d_type gd.gd_type
/* system segments and gate types */
#define SDT_SYSNULL 0 /* system null */
#define SDT_SYS286TSS 1 /* system 286 TSS available */
#define SDT_SYSLDT 2 /* system local descriptor table */
#define SDT_SYS286BSY 3 /* system 286 TSS busy */
#define SDT_SYS286CGT 4 /* system 286 call gate */
#define SDT_SYSTASKGT 5 /* system task gate */
#define SDT_SYS286IGT 6 /* system 286 interrupt gate */
#define SDT_SYS286TGT 7 /* system 286 trap gate */
#define SDT_SYSNULL2 8 /* system null again */
#define SDT_SYS386TSS 9 /* system 386 TSS available */
#define SDT_SYSNULL3 10 /* system null again */
#define SDT_SYS386BSY 11 /* system 386 TSS busy */
#define SDT_SYS386CGT 12 /* system 386 call gate */
#define SDT_SYSNULL4 13 /* system null again */
#define SDT_SYS386IGT 14 /* system 386 interrupt gate */
#define SDT_SYS386TGT 15 /* system 386 trap gate */
/* memory segment types */
#define SDT_MEMRO 16 /* memory read only */
#define SDT_MEMROA 17 /* memory read only accessed */
#define SDT_MEMRW 18 /* memory read write */
#define SDT_MEMRWA 19 /* memory read write accessed */
#define SDT_MEMROD 20 /* memory read only expand dwn limit */
#define SDT_MEMRODA 21 /* memory read only expand dwn limit accessed */
#define SDT_MEMRWD 22 /* memory read write expand dwn limit */
#define SDT_MEMRWDA 23 /* memory read write expand dwn limit acessed */
#define SDT_MEME 24 /* memory execute only */
#define SDT_MEMEA 25 /* memory execute only accessed */
#define SDT_MEMER 26 /* memory execute read */
#define SDT_MEMERA 27 /* memory execute read accessed */
#define SDT_MEMEC 28 /* memory execute only conforming */
#define SDT_MEMEAC 29 /* memory execute only accessed conforming */
#define SDT_MEMERC 30 /* memory execute read conforming */
#define SDT_MEMERAC 31 /* memory execute read accessed conforming */
/* is memory segment descriptor pointer ? */
#define ISMEMSDP(s) ((s->d_type) >= SDT_MEMRO && (s->d_type) <= SDT_MEMERAC)
/* is 286 gate descriptor pointer ? */
#define IS286GDP(s) (((s->d_type) >= SDT_SYS286CGT \
&& (s->d_type) < SDT_SYS286TGT))
/* is 386 gate descriptor pointer ? */
#define IS386GDP(s) (((s->d_type) >= SDT_SYS386CGT \
&& (s->d_type) < SDT_SYS386TGT))
/* is gate descriptor pointer ? */
#define ISGDP(s) (IS286GDP(s) || IS386GDP(s))
/* is segment descriptor pointer ? */
#define ISSDP(s) (ISMEMSDP(s) || !ISGDP(s))
/* is system segment descriptor pointer ? */
#define ISSYSSDP(s) (!ISMEMSDP(s) && !ISGDP(s))
/*
* Software definitions are in this convenient format,
* which are translated into inconvenient segment descriptors
* when needed to be used by the 386 hardware
*/
struct soft_segment_descriptor {
unsigned ssd_base ; /* segment base address */
unsigned ssd_limit ; /* segment extent */
unsigned ssd_type:5 ; /* segment type */
unsigned ssd_dpl:2 ; /* segment descriptor priority level */
unsigned ssd_p:1 ; /* segment descriptor present */
unsigned ssd_xx:4 ; /* unused */
unsigned ssd_xx1:2 ; /* unused */
unsigned ssd_def32:1 ; /* default 32 vs 16 bit size */
unsigned ssd_gran:1 ; /* limit granularity (byte/page units)*/
};
extern ssdtosd() ; /* to decode a ssd */
extern sdtossd() ; /* to encode a sd */
/*
* region descriptors, used to load gdt/idt tables before segments yet exist
*/
struct region_descriptor {
unsigned rd_limit:16 ; /* segment extent */
char *rd_base; /* base address */
};
/*
* Segment Protection Exception code bits
*/
#define SEGEX_EXT 0x01 /* recursive or externally induced */
#define SEGEX_IDT 0x02 /* interrupt descriptor table */
#define SEGEX_TI 0x04 /* local descriptor table */
/* other bits are affected descriptor index */
#define SEGEX_IDX(s) ((s)>>3)&0x1fff)