#
# 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.
#

.section K_TEXT_START
.global kernel_image_start

.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
	call memmap_arch_init
	xorw %ax,%ax
	movw %ax,%ds
	lgdt gdtr
	movl %cr0,%eax
	orl $0x1,%eax
	movl %eax,%cr0
	jmpl $8,$meeting_point
meeting_point:
.code32

	movw $16,%ax
	movw %ax,%es
	movw %ax,%gs
	movw %ax,%fs
	movw %ax,%ds			# kernel data + stack
        movw %ax,%ss
	movl $0x7c00,%esp

	lidt idtr

	call map_kernel

	movl $_hardcoded_ktext_size, hardcoded_ktext_size
	movl $_hardcoded_kdata_size, hardcoded_kdata_size
	movl $_hardcoded_load_address, hardcoded_load_address

	call main_bsp			# 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 on paging
	movl %cr0, %ebx
	orl $(1<<31), %ebx
	movl %ebx, %cr0
	ret


.section K_DATA_START

.align 4096
page_directory:
	.space 4096, 0