dbg0.c

一个操作系统,用C语言实现开发的,我在一个浙江大学的操作系统实验网站找到.大家学习以下

// Kernel Debug0

asm(".code16");

#include <knldefs.h>

#define C_TOPIC		0x0a00
#define C_LIGHT		0x0f00
#define C_DARK		0x0700

void display(const char*);

void longtohex(long val, int mi, int ma, char *buf, int r)
{
	int i, j;
	for(i=mi; i<=ma; i++)
	{
		j = (char)(val>>(4*(r?i:(ma-i)))) & 0x0f;
		buf[i] = j>=10?j-10+'A':(j+'0');
	}
	buf[ma-mi+1]=0;
}

void u8tohex(_u8 val, char *buf)
{
	longtohex((long)(u_long)val, 0, 1, buf, 0);
}

void u16tohex(_u16 val, char *buf)
{
	longtohex((long)(u_long)val, 0, 3, buf, 0);
}

void u32tohex(_u32 val, char *buf)
{
	longtohex((long)val, 0, 7, buf, 0);
}

void ClearScr(void)
{
	asm("pushw %%es; movw %%ax, %%es; xorl %%eax, %%eax; cld; rep; stosl; popw %%es"::"a"(0xb800), "c"(1000), "D"(0));
}

void kdisplayc(int x, int y, int c, const char *str)
{
	_u16 offset = y*160+x*2;
	asm("pushw %es; movw $0xb800, %ax; movw %ax, %es");
	while(*str)
	{ asm("movw %%ax, %%es:(%%ebx)"::"a"((_u16)c+(_u8)*str), "b"(offset)); offset+=2; str++; }	
	asm("popw %es");
}

void kdisplay(int x, int y, const char* str)
{
	kdisplayc(x, y, 0x0700, str);
}

void kputchc(int x, int y, char ch, int c)
{
	asm("pushw %%es; movw $0xb800, %%ax; movw %%ax, %%es\n"
		"movw %%cx, %%es:(%%ebx); popw %%es"::"c"((_u16)c+(_u8)ch), "b"(y*160+x*2));
}

void kputch(int x, int y, char ch)
{
	kputchc(x, y, ch, 0x0700);
}

_u8 WaitKey(void)
{
	_u32 r;
	asm("movw $0, %%ax; int $0x16":"=a"(r));
	return (_u8)(r>>8);
}

void ShowMem(_u32 addr, int y, int cnt)
{
	char buf[80];
	int i, j;
	_u32 byte;

	for(i=0; i<cnt; i++)
	{
		u32tohex(addr, buf); buf[8]=':'; buf[9]=0;
		kdisplayc(0, i+y, C_LIGHT, buf);
		for(j=0; j<16; j++)
		{
			asm("pushw %%ds; movw %%ax, %%ds; movl $1, %%ecx; cld; rep; movsb; popw %%ds"::"D"(&byte),"a"(addr>>16),"S"((_u16)addr));
			u8tohex((_u8)byte, buf+j*3);
			buf[j*3+2]=' ';
			kputch(10+48+3+j, i+y, (char)byte);
			if((_u16)addr==0xffff) addr=(addr&0xffff0000)+0x10000000;
			else addr++;
		}
		buf[j*3]=0;
		kdisplay(10, i+y, buf);
	}
}

_u32 ChangeAddr(_u32 addr, long add)
{
	_u16 seg, off;
	seg = addr>>16; off = (_u16)addr;
	if(add<0 && (long)(_u32)off<-add) seg-=0x1000;
	if(add>0 && 0x10000-off<add) seg+=0x1000;
	off += (_s16)add;
	if(add!=0)
	{
		addr=((_u32)seg<<16)|off;
		ShowMem(addr, 3, 20);		
	}
	return addr;
}

void dbg0(void)
{
	char ch, buf[32];
	_u32 uTopAddr = 0x10000000;
	int loop=1;
	
	ClearScr();	
	kdisplayc(0, 0, C_TOPIC, "Kernel Debug Mode");	
	
	kdisplay(20, 0, "Press ESC to start normal kernel");
	kdisplayc(26, 0, C_LIGHT, "ESC");
	
	ShowMem(uTopAddr, 3, 20);
	kdisplay(0, 24, "Key pressed: ");	
	while(loop)
	{
		ch=WaitKey();
		u8tohex(ch, buf);
		kdisplay(13, 24, buf);
		switch(ch)
		{
		case 0x11: // Move up
			uTopAddr=ChangeAddr(uTopAddr, -0x10);
		    break;
		case 0x12:
			uTopAddr=ChangeAddr(uTopAddr, -0x100);
			break;
		case 0x13:
			uTopAddr=ChangeAddr(uTopAddr, -0x1000);
			break;
		case 0x14:
			uTopAddr=ChangeAddr(uTopAddr, -0x10000);			
			break;
		case 0x15:
			uTopAddr=ChangeAddr(uTopAddr, -0x100000);
			break;
		case 0x16:
			uTopAddr=ChangeAddr(uTopAddr, -0x1000000);
			break;
		case 0x17:
			uTopAddr=ChangeAddr(uTopAddr, -0x10000000);
			break;
		case 0x1f: // Move down
			uTopAddr=ChangeAddr(uTopAddr, 0x10);
		    break;
		case 0x20:
			uTopAddr=ChangeAddr(uTopAddr, 0x100);
			break;
		case 0x21:
			uTopAddr=ChangeAddr(uTopAddr, 0x1000);
			break;
		case 0x22:
			uTopAddr=ChangeAddr(uTopAddr, 0x10000);
			break;
		case 0x23:
			uTopAddr=ChangeAddr(uTopAddr, 0x100000);
			break;
		case 0x24:
			uTopAddr=ChangeAddr(uTopAddr, 0x1000000);
			break;
		case 0x25:
			uTopAddr=ChangeAddr(uTopAddr, 0x10000000);
			break;			
		case 1:
			loop=0;
			break;	
		}
	}
	ClearScr();
}