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#

# Copyright (C) 2001-2004 Jakub Jermar

# All rights reserved.

#

# Redistribution and use in source and binary forms, with or without

# modification, are permitted provided that the following conditions

# are met:

#

# - Redistributions of source code must retain the above copyright

#   notice, this list of conditions and the following disclaimer.

# - Redistributions in binary form must reproduce the above copyright

#   notice, this list of conditions and the following disclaimer in the

#   documentation and/or other materials provided with the distribution.

# - The name of the author may not be used to endorse or promote products

#   derived from this software without specific prior written permission.

#

# THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR

# IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES

# OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.

# IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,

# INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT

# NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,

# DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY

# THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT

# (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF

# THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#

#include <arch/boot/boot.h>

#include <arch/boot/memmapasm.h>

.section K_TEXT_START

.global kernel_image_start

KTEXT=8

KDATA=16

.code16

#

# This is where we require any SPARTAN-kernel-compatible boot loader

# to pass control in real mode.

#

# Protected mode tables are statically initialised during compile

# time. So we can just load the respective table registers and

# switch to protected mode.

#

kernel_image_start:

	cli

	xorw %ax, %ax

	movw %ax, %ds

	movw %ax, %ss							# initialize stack segment register

	movl $BOOTSTRAP_OFFSET - 0x400, %esp	# initialize stack pointer

	call memmap_arch_init

	lgdt real_bootstrap_gdtr				# initialize Global Descriptor Table register

	movl %cr0, %eax

	orl $0x1, %eax

	movl %eax, %cr0							# switch to protected mode

	jmpl $KTEXT, $boot_image_start

.code32

.align 4

multiboot_header:

	.long MULTIBOOT_HEADER_MAGIC

	.long MULTIBOOT_HEADER_FLAGS

	.long -(MULTIBOOT_HEADER_MAGIC + MULTIBOOT_HEADER_FLAGS)	# checksum

	.long multiboot_header + BOOT_OFFSET

	.long unmapped_ktext_start + BOOT_OFFSET

	.long 0

	.long 0

	.long multiboot_image_start + BOOT_OFFSET

boot_image_start:

	movw $KDATA, %ax

	movw %ax, %es

	movw %ax, %gs

	movw %ax, %fs

	movw %ax, %ds			# kernel data + stack

	movw %ax, %ss

	movb $0xd1, %al			# enable A20 using the keyboard controller

	outb %al, $0x64

	movb $0xdf, %al

	outb %al, $0x60

	movl $BOOTSTRAP_OFFSET, %esi

	movl $BOOTSTRAP_OFFSET + BOOT_OFFSET, %edi

	movl $_hardcoded_kernel_size, %ecx

	cld

	rep movsb

	call map_kernel			# map kernel and turn paging on

	call main_bsp			# never returns

	cli

	hlt

multiboot_image_start:

	movl $BOOTSTRAP_OFFSET - 0x400, %esp			# initialize stack pointer

	lgdt protected_bootstrap_gdtr - 0x80000000		# initialize Global Descriptor Table register

	movw $KDATA, %cx

	movw %cx, %es

	movw %cx, %gs

	movw %cx, %fs

	movw %cx, %ds									# kernel data + stack

	movw %cx, %ss

	jmpl $KTEXT, $multiboot_meeting_point + BOOT_OFFSET

	multiboot_meeting_point:

	pushl %ebx										# save parameters from GRUB

	pushl %eax

	movl $BOOTSTRAP_OFFSET + BOOT_OFFSET, %esi

	movl $BOOTSTRAP_OFFSET, %edi

	movl $_hardcoded_unmapped_size, %ecx

	cld

	rep movsb

	call map_kernel									# map kernel and turn paging on

	popl %eax

	popl %ebx

	cmpl $MULTIBOOT_LOADER_MAGIC, %eax			# compare GRUB signature

	je valid_boot

		xorl %ecx, %ecx							# no memory size or map available

		movl %ecx, e801memorysize

		movl %ecx, e820counter

		jmp invalid_boot

	valid_boot:

		movl (%ebx), %eax						# ebx = physical address of struct multiboot_info

		bt $0, %eax								# mbi->flags[0] (mem_lower, mem_upper valid)

		jc mem_valid

			xorl %ecx, %ecx

			jmp mem_invalid

		mem_valid:

		movl 4(%ebx), %ecx						# mbi->mem_lower

		addl 8(%ebx), %ecx						# mbi->mem_upper

		mem_invalid:

		movl %ecx, e801memorysize

		bt $6, %eax								# mbi->flags[6] (mmap_length, mmap_addr valid)	

		jc mmap_valid

			xorl %edx, %edx

			jmp mmap_invalid

		mmap_valid:

		movl 44(%ebx), %ecx						# mbi->mmap_length

		movl 48(%ebx), %esi						# mbi->mmap_addr

		movl $e820table, %edi

		xorl %edx, %edx

		mmap_loop:

			cmpl $0, %ecx

			jle mmap_end

			movl 4(%esi), %eax					# mmap->base_addr_low

			movl %eax, (%edi)

			movl 8(%esi), %eax					# mmap->base_addr_high

			movl %eax, 4(%edi)

			movl 12(%esi), %eax					# mmap->length_low

			movl %eax, 8(%edi)

			movl 16(%esi), %eax					# mmap->length_high

			movl %eax, 12(%edi)

			movl 20(%esi), %eax					# mmap->type

			movl %eax, 16(%edi)

			movl (%esi), %eax					# mmap->size

			addl $0x4, %eax

			addl %eax, %esi

			subl %eax, %ecx

			addl $MEMMAP_E820_RECORD_SIZE, %edi

			incl %edx

			jmp mmap_loop

		mmap_end:

		mmap_invalid:

		movl %edx, e820counter

	invalid_boot:

	call main_bsp - BOOT_OFFSET						# never returns

	cli

	hlt

.global map_kernel

map_kernel:

	#

	# Here we setup mapping for both the unmapped and mapped sections of the kernel.

	# For simplicity, we set only one 4M page for 0x00000000 and one for 0x80000000.

	#

	movl %cr4, %ecx

	orl $(1<<4), %ecx

	movl %ecx, %cr4				# turn PSE on

	movl $((1<<7)|(1<<0)), %eax

	movl %eax, page_directory		# mapping 0x00000000 => 0x00000000

	movl $(page_directory+(4096/2)), %edx

	movl %eax, (%edx)			# mapping 0x80000000 => 0x00000000

	leal page_directory, %eax

	movl %eax, %cr3

	# turn paging on

	movl %cr0, %ebx

	orl $(1<<31), %ebx

	movl %ebx, %cr0

	ret

.section K_DATA_START

.align 4096

page_directory:

	.space 4096, 0