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/* Project:     OSLib

 * Description: The OS Construction Kit

 * Date:                1.6.2000

 * Idea by:             Luca Abeni & Gerardo Lamastra

 *

 * OSLib is an SO project aimed at developing a common, easy-to-use

 * low-level infrastructure for developing OS kernels and Embedded

 * Applications; it partially derives from the HARTIK project but it

 * currently is independently developed.

 *

 * OSLib is distributed under GPL License, and some of its code has

 * been derived from the Linux kernel source; also some important

 * ideas come from studying the DJGPP go32 extender.

 *

 * We acknowledge the Linux Community, Free Software Foundation,

 * D.J. Delorie and all the other developers who believe in the

 * freedom of software and ideas.

 *

 * For legalese, check out the included GPL license.

 */

/* The first things to do when an OSLib application starts :	*/

/* Set up segment registers & stack; then execute startup code	*/

/* When the application returns the gate-jmp make us return to	*/

/* RM through X interface!					*/

/* Use X standard GDT selectors */

#include <ll/i386/sel.h>

#include <ll/i386/linkage.h>

#include <ll/i386/defs.h>

#include <ll/i386/mb-hdr.h>

/* #define __DEBUG__ */

#ifdef __LINUX__ /* ELF mode */

#define MULTIBOOT_FLAGS (MULTIBOOT_MEMORY_INFO)

#else /* else it is COFF! */

#define MULTIBOOT_FLAGS (MULTIBOOT_MEMORY_INFO | MULTIBOOT_AOUT_KLUDGE)

#endif

.extern SYMBOL_NAME(_startup)

.extern SYMBOL_NAME(_stkbase)

.extern SYMBOL_NAME(_stktop)

.extern SYMBOL_NAME(halt)

.data

ASMFILE(X0)

.globl SYMBOL_NAME(IDT)

.globl SYMBOL_NAME(GDT_base)

.globl SYMBOL_NAME(mb_signature)

.globl SYMBOL_NAME(mbi)

/* GDT Definition */

GDT:

.word	0,0,0,0		/* X_NULL_SEL */

.word	0,0,0,0		/* X_DATA16_SEL */

.word	0,0,0,0		/* X_CODE16_SEL */

.word	0,0,0,0		/* X_CODE32_SEL */

			/* X_RM_BACK_GATE */

rmBckGateFix1:		/* X_FLATCODE_SEL */

.word	0

.word	X_FLATCODE_SEL

.word	0x8C00

rmBckGateFix2:

.word	0

.word	0,0,0,0		/* X_PM_BACK_GATE */

.word	0xFFFF		/* X_FLATDATA_SEL */

.word	0

.word	0x9200

.word	0x00CF

.word	0xFFFF		/* X_FLATCODE_SEL */

.word	0

.word	0x9A00

.word	0x00CF

.word	0,0,0,0		/* X_CALLBIOS_SEL */

.word	0,0,0,0		/* X_CALLBIOS_GATE */

.word	0,0,0,0		/* X_VM86_TSS */

.word	0,0,0,0		/* X_MAIN_TSS */

	.fill 256 - 12,8,0

GDT_descr:

.word 256*8-1

SYMBOL_NAME_LABEL(GDT_base)

.long GDT

IDT_descr:

	.word 256*8-1		# idt contains 256 entries

	.long SYMBOL_NAME(IDT)

/* MultiBoot Data Stuff definition */

SYMBOL_NAME_LABEL(mb_signature) .long 0

SYMBOL_NAME_LABEL(mbi) .long 0

.bss		/* This MUST be in the BSS !!! */

/* IDT definition */

SYMBOL_NAME_LABEL(IDT)

	.fill 256,8,0		# idt is uninitialized

/* Protected mode stack */

base:

.space 	8192,0

tos:

.text

.globl	SYMBOL_NAME(_start)

.globl SYMBOL_NAME(__exit)

.globl	SYMBOL_NAME(start)

.globl start

SYMBOL_NAME_LABEL(_start)

SYMBOL_NAME_LABEL(start)

start:

.align		8

/*start:*/

		jmp	boot_entry

		/*

		Here we go with the multiboot header...

		---------------------------------------

		*/

.align		8

boot_hdr:

.align		8

		.long	MULTIBOOT_MAGIC

		.long   MULTIBOOT_FLAGS

		/* Checksum */

		.long	-(MULTIBOOT_MAGIC+MULTIBOOT_FLAGS)

#ifndef __LINUX__ /* COFF mode */

		.long	boot_hdr

/*		.long	SYMBOL_NAME(start)*/

		.long   start

		.long	_edata

		.long	_end

		.long	boot_entry

#endif

boot_entry:	/* Just a brief debug check */

		#ifdef __DEBUG__

		/* A Brown 1 should appear... */

		    movl	$0xB8000,%edi

		    addl	$158,%edi

		    movb	$'1',%gs:0(%edi)

		    incl	%edi

		    movb	$6,%gs:0(%edi)

		#endif

		/*

		 * Hopefully if it gets here, CS & DS are

		 * Correctly set for FLAT LINEAR mode

		 */

		/* Test if GDT is usable */

		movl	%gs:0(%ebx),%ecx

		andl	$0x0200,%ecx	/* MB_INFO_BOOT_LOADER_NAME */

movl	$0xB8000,%edi

addl	$150,%edi

movb	$'1',%gs:0(%edi)

incl	%edi

movb	$6,%gs:0(%edi)

		jz	GDT_is_not_OK

incl	%edi

movb	$'2',%gs:0(%edi)

incl	%edi

movb	$6,%gs:0(%edi)

		movl	%gs:64(%ebx), %ebp /* Name Address... */

		cmpb	$'X', %gs:0(%ebp)

		je	GDT_is_OK

GDT_is_not_OK:

		/*

		 * Fix the X_RM_BACK_GATE with the address of halt()

		*/

/* Now I test if the check mechanism is OK... */

		movl	$SYMBOL_NAME(halt),%eax

		movw	%ax,%gs:rmBckGateFix1

		shrl	$16,%eax

		movw	%ax,%gs:rmBckGateFix2

		/* Load GDT, using the predefined assignment! */

		lgdt	GDT_descr

movl	$0xB8000,%edi

addl	$146,%edi

movb	$'0',%gs:0(%edi)

incl	%edi

movb	$6,%gs:0(%edi)

GDT_is_OK:	movw	$(X_FLATDATA_SEL),%ax

		movw	%ax,%ds

		movw	%ax,%es

		movw	%ax,%ss

		movw	%ax,%fs

		movw	%ax,%gs

		movl	$tos,%esp

		movl	$base,SYMBOL_NAME(_stkbase)

		movl	$tos,SYMBOL_NAME(_stktop)

		/* Store the MULTIBOOT informations */

		movl	%eax,SYMBOL_NAME(mb_signature)

		movl	%ebx,SYMBOL_NAME(mbi)

		/* Store the X passed GDT address!

		 * If GDT is not available is a dummy instruction!

		 */

		sgdt 	GDT_descr

		/* Now probably is the case to load CS... */

		ljmp $X_FLATCODE_SEL, $load_cs

load_cs:

		/* Load IDT */

		lidt	IDT_descr

		cld

		call SYMBOL_NAME(_startup)

		/* Well I hope when I reach this

		   The X_RM_BACK_GATE has been setup correctly

		   even if the kernel has not been loaded through X!

		*/

		.byte	0x0EA		   /* Direct gate jmp */

		.long	0

		.word	X_RM_BACK_GATE

/* Simple function to terminate PM application	*/

/* void __exit(int code)				*/

SYMBOL_NAME_LABEL(__exit)

		pushl	%ebp

		movl	%esp,%ebp

		movl	8(%ebp),%eax

		.byte	0x0ea		   /* Direct gate jmp */

		.long	0

		.word	X_RM_BACK_GATE