sched.h

别人的根据linux0.11改的一个小的操作系统

#ifndef	_SCHED_H
#define _SCHED_H

#define NR_TASK	3                               /* Max tasks */

#define FIRST_TSS_ENTRY 4                       /* The first tss descriptor is 4th in GDT. */
#define FIRST_LDT_ENDTY 5                       /* The first ldt descriptor is 5th in GDT. */

#define _TSS(n) ((((unsigned long)n)<<4)+0x20)  /* Get the tss selector as the task number. */
#define _LDT(n) ((((unsigned long)n)<<4)+0x28)  /* Get the ldt selcctor as the task number. */

#define cli() asm("cli;"::)                     /* clear interrupt mark. */
#define sti() asm("sti;"::)                     /* set interrupt mark. */

/* Load tr register. */
#define ltr(n) asm(\
		"ltr %%ax;"\
		::"a"(_TSS(n)))
/* Load ldt register. */
#define lldt(n) asm(\
		"lldt %%ax;"\
		::"a"(_LDT(n)))

#define cl_nt()	asm("pushfl;"\
		"andl $0xffffbfff,(%esp);"\
		"popfl;")

/*system pointer*/
extern char *_gdt;              /*base address of GDT*/
extern char *_idt;              /*base address of IDT*/
extern char *_stack_ptr;        /*system stack top pointer*/
extern char *_tss0;             /*tss0 base address*/
extern char *_ldt0;             /*ldt0 base address*/

struct gate_struct{             /*trap descriptor struct*/
	unsigned short	addrL;                  /*base address low 16bits*/
	unsigned short	segsel;                 /*default is 0x08*/
	unsigned char	sitems;                 /*call gate stack items*/
	unsigned char	type;                   /*gate descriptor type*/
	unsigned short	addrH;                  /*base address high 16bits*/
};


struct desc_struct{                     /*descriptor struct,gdt or ldt*/
	unsigned short	limit;                  /*segment limit*/
	unsigned short	baseL;                  /*base address low 16bits*/
	unsigned char 	baseM;                  /*base address middle 8bits*/
	unsigned char	access;                 /*access type*/
	unsigned char	gran;                   /*gran*/
	unsigned char	baseH;                  /*address high 8bits*/
};

#define	GDT_ADDR	((struct desc_struct*)_gdt)    /* GDT base address. */
#define IDT_ADDR	((struct gate_struct*)_idt)    /* IDT base address. */
struct i387_struct{
	long	cwd;
	long	swd;
	long	twd;
	long	fip;
	long	fcs;
	long	foo;
	long    fos;
	long	st_space[20];	//8*10 bytes for each FP-reg=80 bytes
};
//task state segment struct
struct tss_struct{
	long	back_link;
	long	esp0;
	long	ss0;
	long	esp1;
	long	ss1;
	long	esp2;
	long	ss2;
	long	cr3;
	long	eip;
	long	eflags;
	long	eax;
	long	ecx;
	long	edx;
	long	ebx;
	long	esp;
	long	ebp;
	long	esi;
	long	edi;
	long	es;
	long	cs;
	long	ss;
	long	ds;
	long	fs;
	long	gs;
	long	ldt;
	long	trace_bitmap;
	//struct i387_struct i387;
};
/*
struct task_struct{
	//these are hardcoded -don't touch
	long	state;
	long	couter;
	long	priority;
	long	signal;
	//struct	sigaction sigaction[32];
	long	blocked;
	//various fields
	int	exit_code;
	unsigned long start_code,end_code,end_data,brk,start_stack;
	long 	pid,father,pgrp,session,leader;
	unsigned short uid,euid,suid;
	unsigned short gid,egid,sgid;
	long 	alarm;
	long	utime,stime,cutime,cstime,start_time;
	unsigned short used_math;
	//file system information
	int	tty;
	unsigned short umask;
	//ldt for this task 0-zero1 -cs 2- ds&ss
	struct desc_struct ldt[3];
	//tss for this task;
	struct tss_struct tss;
};*/
struct task_struct{
    long pid;                   //4B
    char pname[16];             //16B
    long priority;              //4B
    long counter;               //4B
    long ldt_sel;               //4B
    long tss_sel;               //4B
    struct desc_struct ldt[4];  //32B
    struct tss_struct tss;      //68B
    struct task_struct *next;   //4B
    char stack_krn[116];        // kernel mode stack area.
    char stack_user[256];       // user mode stck area.
};

struct desc_struct *desc[252];
struct task_struct task[NR_TASK];
unsigned long process_id;

struct task_struct *p_current;      /* Point to current task that is running. */
struct task_struct *p_previous;     /* Point to previous task. */
struct task_struct *p_ready;        /* Point to ready task. */
struct task_struct *p_head;         /* Point to task linked list head. */

void sched_init();                  /* Initialize task 0 */
void set_trap(int,char *);          /* Set trap gate. */
void do_timer();                    /* Timer interrupt function. */
void task_init(void *);             /* Initialize a new task, make it ready. */
void schedule();                    /* System schedule function. */

char *get_com();                    /* no use */
void exec_com(char *);              /* no use */

#endif