/*GazOS Operating SystemCopyright (C) 1999  Gareth Owen <gaz@athene.co.uk>This program is free software; you can redistribute it and/ormodify it under the terms of the GNU General Public Licenseas published by the Free Software Foundation; either version 2of the License, or (at your option) any later version.This program is distributed in the hope that it will be useful,but WITHOUT ANY WARRANTY; without even the implied warranty ofMERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See theGNU General Public License for more details.You should have received a copy of the GNU General Public Licensealong with this program; if not, write to the Free SoftwareFoundation, Inc., 59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.*/#include "string.h"#include "gazfs.h"#include "fdc.h"#include "video.h"#include "gdt.h"#include "idt.h"#include "io.h"#include "8259.h"#include "keyboard.h"#include "delay.h"#include "pit.h"#include "math.h"#include "mem.h"#define uchar  unsigned char		/* Defentitions to make life	*/#define uint   unsigned int		/* Easy for us:  uchar, uint	*/#define ulong  unsigned long int	/* and ulong			*/#define iuchar inline unsigned char	/* Inline functions		*/#define ivoid  inline voiduchar KERNEL_STACK[8192];		/* The stack to use: 8k stack	*/unsigned int cpuspeed=0;		/* CPU Speed in Megahertz */unsigned long memtotal = 0;		/* Memory Total in bytes */void _start(void);			/* The entry point		*/void main();				/* The main kernel program 	*/void _exit(void);			/* What to do when finished	*/void ulong_strcnv(uchar *str, ulong i); /* Convert a dword to a string  */extern void pit_ISR(void);extern unsigned long uptime_count;desc_table(GDT, 3){	{dummy:0},	stnd_desc(0, 0xFFFFF, (D_CODE + D_READ + D_BIG + D_BIG_LIM)),	stnd_desc(0, 0xFFFFF, (D_DATA + D_WRITE + D_BIG + D_BIG_LIM)),};struct{	unsigned short limit __attribute__ ((packed));	union DT_entry *idt __attribute__ ((packed));} loadgdt = { (3 * sizeof(union DT_entry) - 1), GDT };void _start(void)			/* The kernel entry point	*/{   asm ("pushl $2; popf");		/* Zero the flags		*/	 asm volatile                /* Load the GDT and the kernel stack     */	 (                           /* We assume the loader has cleared ints */      		"lgdtl (loadgdt)     \n" /* Load our own GDT                      */	        "movw $0x10,%%ax     \n" /* Init data registers with flat_data    */      		"movw %%ax,%%ds      \n"      		"movw %%ax,%%es      \n"      		"movw %%ax,%%fs      \n"      		"movw %%ax,%%gs      \n"      		"movw %%ax,%%ss      \n" /* ... and the stack, too                */      		"movl $0xFFFF,%%esp       \n" /* Set the SP to the end of the stack    */      		"ljmp $0x08,$next    \n" /* Flush prefetch queue and skip MBHeadr */		"nop\n"		"nop\n"	        "next:               \n" /* Continue here                         */      		:      		: "r" (GDT), "p" (KERNEL_STACK+4096)      		: "%eax"   	);   main();				/* Call main()			*/   _exit();				/* Finish off			*/}/* Now we get the main kernel program 					*/void main(){	unsigned char tempstring[255];	unsigned long delaycount=0, loop=0, result, catcount = 0;	unsigned char buf[8192];	kprint("\n\nGazOS Version 1.0 Loading......\n");	kprint("Initializing the 8259 PIC...\n");	Init8259();	kprint("Loading IDT...\n");	InitIDT();        /* We want to calibrate the delay loop while all interrupts are */        /* masked, and before the scheduler is loaded.                  */	kprint("Calibrating delay loop... [");        delaycount = calibrateDelayLoop();        printlong(delaycount);        kprint("]\n");	cpuspeed = floor(delaycount/500);	count_memory();	kprint("Initializing Keyboard...\n");	InitKeyboard();	init_pit(18.2, 0);	// Every 54.945ms (18.2 times per second)	set_vector(pit_ISR, M_VEC, (D_INT + D_PRESENT + D_DPL3));	enable_irq(0);	init_floppy();	gazfs_init();	kprint("CPU = ");	printlong(cpuspeed);	kprint("Mhz  -  Mem.Total = ");	printlong(mem_end/1024);	kprint("K  -  Total Pages = ");	printlong(mem_end/4096);	kprint("\n");	while(1)	{		kprint("\nGazOS] /: ");		gets(tempstring);		kprint("\n");				if(!kstrcmp(tempstring, "ls")) displayrootdir();		if(tempstring[0] == 'c' && tempstring[1] == 'a' &&		   tempstring[2] == 't')		{		   	result = getdata(tempstring+4, 0, (unsigned long)(-1), buf);		   	if(result > 0)		   	{		   		catcount = 0;				for(loop=0; loop<result; loop++)				{					tempstring[0] = buf[loop];					tempstring[1] = 0;					kprint(tempstring);					if(tempstring[0] == 10) catcount++;					if(catcount >= 23)					{						kprint("Press any key...");						getch();						kprint("\n");						catcount = 0;					}				}		   	}		   	else		   		kprint("File not found or error\n");		}	}}void _exit(void)			/* Exit point of the kernel	*/{   while(inportb(0x64) & 0x02);		/* Reboot the computer		*/   outportb(0x64, 0xfe);   asm("cli;hlt");			/* Should it not work we halt 	*/					/* the computer now so the we	*/					/* do no harm			*/}