main.c

从网上下载的一个自己编写的简单的操作系统源代码,对底层了解很有好处的

/*
 *   ExpOS
 *   
 *
 *
 *
 *
 *   Copyright 2002.9.15
 *
 *
 */
  
#include <arch.h>
#include <drv/vga.h>
#include "../boot/boot.h"

#ifdef __cplusplus
extern "C" {
#endif

//arch.s
extern void nop_handler();



static void  print_memory_map()
{
	int i;
    kprintf("Dump mem map \r\n");
    struct boot *p = (struct boot *)(0xc0000000 + 0x90000);

    kprintf("Start             End               Size  Type\r\n");
	for (i = 0; i < p->e820nr; i++) {

		long long size= p->e820.map[i].size;

		kprintf("%016Lx--", p->e820.map[i].addr);     /* Start*/
		
		kprintf("%016Lx  ",   p->e820.map[i].addr+size);/* End  */
        /*kprintf("%08Lx ",  size);*/                   /* Size */

		if(size>0x100000)                              /* size */
  		    kprintf("%04dM ",size>>20);
		  else
		  	kprintf("%04dk ",size>>10);
		

		
		switch (p->e820.map[i].type) {                 /*type*/
		case E820_RAM:	kprintf("RAM     ");
				break;
		case E820_RESERVED:
				kprintf("Res     ");
				break;
		case E820_ACPI:
				kprintf("ACPI Data");
				break;
		case E820_NVS:
				kprintf("ACPI NVS ");
				break;
		default:	
			    kprintf("type %lu", p->e820.map[i].type);
				break;

		}
		
		
		kprintf("\r\n");
	}
}

void dump_kernel_img()
{
    extern char _text, _etext,_edata,_bss_start,_end;
    kprintf("\r\nDump kernel img");

	kprintf("\r\n      begin     end        size");
	kprintf("\r\n.text %08x--%08x      %08xk",
		&_text, &_etext,(&_etext-&_text)>>10) ;
	kprintf("\r\n.data %08x--%08x      %08xk",
		&_etext, &_edata,(&_edata-&_etext)>>10) ;
	kprintf("\r\n.bss  %08x--%08x      %08xk",
		&_bss_start, &_end,(&_end-&_bss_start)>>10) ;
	
}


/* PAGE_SHIFT determines the page size */
#define PAGE_SHIFT	12
#define PAGE_SIZE	(1UL << PAGE_SHIFT)
#define PAGE_MASK	(~(PAGE_SIZE-1))

int  main()
{
   int i=0;
      
   _lidt(); 
   console_init();
   rawvga_init();
   
   for(i=0; i<256; i++){
      //都填充为默认中断/异常处理函数
      _gate_fill(i, (unsigned int)nop_handler, IGA_K);
   }

   //设置中断门 0x20---0x2F , 
   // int -->gate(0x20--0x2f) ---> arch.s(int handler) -->irq_table-->irq handler
   _fill_int_gate();
   
   _init_8259(); //irq 0-7 --> Gate 20h-27h , irq 8-15 --->Gate 28h-2fh

   /* Intel 保留0-31 的中断门, 硬件irq从0x20开始*/
   //_gate_fill(0x20, (unsigned int)_timer, IGA_K); //install timer
   //_gate_fill(0x20, (unsigned int)_hw_gate00, IGA_K); //install timer
   for(i =0; i<16; i++){
   	 _irq_reg(i,(irq_act)nop_irq);
   }
   	
   _irq_reg(0, (irq_act)timer);
   

   _enirq_8259(0); //enable timer irq 0

   __asm__("sti");       


   
   /* dump mem map*/
   print_memory_map();
   dump_kernel_img();
   kprintf("\r\nCopyright "__DATE__".");

   kprintf("\r\nImage Build Time:"__TIME__".");

   /*  轮询模式的键盘驱动演示 */
   kprintf("\r\nDemo poll mode keyboard driver.");
   kbd_main();

   /* VGA graph */
   extern void vga_init(void);
   vga_init();
   video_logo();


   /* Setup kbd irq Handler */
   __asm__("cli");      
   //_gate_fill(0x21, (unsigned int)_kbd, IGA_K); //install kbd
   _irq_reg(1, (irq_act)kbd);
   _enirq_8259(1); //enable kbd irq 1
   __asm__("sti");       

   
   kprintf("\r\n系统空闲 \r\n");
   while(1){
      
       //live(); //re enter, bug?
   	  	
   }

  
   
}

/*
 * Test Gcc feature
 */
 __asm__( 
    "_interrupt:\n\t" 
	"pushl -256\n\t" 
	"jmp 1f \n\t 1:");



#ifdef __cplusplus
   } /*end extern "c"*/
#endif