/*
 * This file contains the entrance point for the Kernel proper.  The code here
 * is called by the bootloader when it finishes.  The kmain routine is
 * responsible for setting up memory and starting the processes running.
 */

#include <stdint.h>
#include <string.h>
#include <unistd.h>
#include <sys/mount.h>
#include <sys/stat.h>
#include <nucleus/panic.h>
#include <nucleus/memory.h>
#include <nucleus/task.h>
#include <nucleus/vfs.h>
#include "multiboot.h"
#include "desc.h"
#include "acpi/acpi.h"

extern char _bss[], _end[];
void page_fault_handler(struct InterruptFrame *frame, uint32_t err);

/* Per-CPU Setup */
void
cpu_load(void)
{
	/* Initialise SSE */
	asm volatile(
		"mov %cr0, %eax;"
		"andl $0xfffffffb, %eax;"
		"orl $0x2, %eax;"
		"mov %eax, %cr0;"
		"mov %cr4, %eax;"
		"orl $0x600, %eax;"
		"mov %eax, %cr4;"
	);

	/* Initialise CR4.PGE */
	asm volatile(
		"mov %cr4, %eax;"
		"orl $0x10, %eax;"
		"mov %eax, %cr4;"
	);

	/* Tables */
	cpu_load_idt();
	cpu_load_gdt();

	asm volatile("sti");
}

/* Kernel main function */
_Noreturn void
kmain(struct MultibootInfo *mbinfo)
{
	void *ebda = (void *) (*((uint16_t *) 0x040E) << 4);
	memset(_bss, 0, _end - _bss);

	/* Setup frame allocator */
	init_frames(mbinfo->mmapLen, (void *) mbinfo->mmapAddr);

	/* Processor startup */
	init_idt();
	init_pic();
	cpu_load();

	/* Initialise paging */
	init_paging();
	/* Initialise multitasking */
	init_tasking();
	/* Initialise the VFS */
	init_vfs();
	/* Search ACPI tables */
	init_acpi(ebda);
	init_pci();

	/* Enable userspace page-fault handler */
	register_exception(14, page_fault_handler);

	/* Mount drive */
	mkdir("root", 0);
	mount("/dev/hd0", "/root", "ext2fs", MS_RDONLY, NULL);
	chroot("/root");
	chdir("/");
	mount("devfs", "/dev", "devfs", 0, NULL);

	/* Start init */
	char *argv[] = { "init", NULL };
	execve("/bin/init", argv, NULL);
	panic("Could not run init");
}