#include "lnxboot.h"

extern void _start();

[[gnu::section(".lnxhead")]]
[[gnu::used]]
[[gnu::aligned(1)]]
[[gnu::unavailable("not present at runtime. use setup_info instead")]]
struct setup_info bzhead = {
	.setup_sects = 1, // 1 512-byte sector
	.boot_flag = 0xAA55,
	.syssize = 16,
	.jump_instruction = 0xEB,
	.jump_offset = sizeof(struct setup_info) - __builtin_offsetof(struct setup_info, signature),
	.signature = 0x53726448,
	.version = 0x020F,
	.loadflags = 0x01, // LOADED_HIGH,
	.kernel_alignment = 1,
	.relocatable_kernel = 1,
	.xloadflags = 0x13, // XLF_KERNEL_64 | XLF_CAN_BE_LOADED_ABOVE_4G | XLF_5LEVEL
	.cmdline_size = 255, // max command line size
	.init_size = 0x10000 // we dont need THAT much memory
};

struct setup_info*  setup_info;
struct boot_params* boot_params;

unsigned short serial_port;

void outb(unsigned short port, unsigned char value) {
	asm volatile (
		  "outb %b0, %1"
		::"a" (value)
		 ,"d" (port)
	);
}

void serial_putc(char c) {
	outb(serial_port, c);
}

void serial_puts(const char* s) {
	while (*s) serial_putc(*(s++));
}

void serial_put_formatted_u64(u64 v) {
	if (v == 0) {
		serial_putc('0');
	} else {
		u64 max = 1;

		while (v > max) max *= 10;

		while (v) {
			serial_putc('0' + (u8)(v / max));

			v   %= max;
			max /= 10;
		}
	}
}

[[gnu::section(".text._start"), gnu::naked]]
extern void _start() {
	asm ( // grab the setup_info and boot_params locations
	      	  "mov  %%rsi,  %1\n"
		  "mov  %%rsi,  %0\n"
		  "addq $0x1f1, %0"
		: "=m" (setup_info),
		  "=m" (boot_params)
	);
	asm ("jmp entry");
}

[[gnu::section(".text._start")]]
void entry() {
	// get the zero page
	//boot_params = (struct boot_params*)(
	//		  0x202 - 0x1f1
	//		+ setup_info->jump_offset
	//		+ (u64)setup_info);

	// orignally we would try to import the serial port from the kernel (see kexec tools)
	// as you can see, we gave up!
	// serial_port = (unsigned short)*(long*)&serial_base;
	serial_port = 0x3f8;

	// construct pointers
	u8* cmdline_ptr = (u8*)((u64)setup_info->cmd_line_ptr | ((u64)boot_params->ext_cmd_line_ptr << 32));

	// check out command line
	serial_puts(cmdline_ptr);
	serial_putc('\r');
	serial_putc('\n');

	// we dont have the privilege of getting a rodata segment. any reads off our stack cause a triple fault
	// for some fucking reason. allocate our strings and shit on the stack.
	//char s_you_fucked_up[] = "!!! YOU FUCKED UP !!!\n";
	//char s_vga_you_fucked_up[] = "YOU FUCKED UP.\n";
	//char s_description[] = "A SERIOUS ERROR HAS OCCURED AND LINDOWS HAS STOPPED TO PREVENT FURTHER DAMAGE.";
	//char s_registers[] = "REGISTERS:";
	//char s_call_trace[] = "CALL TRACE:";
	//char s_dumpcore[] = "[(D)UMP CORE]";
	//char s_poweroff[] = "[(P)OWER OFF]";
	//char s_reboot[]   = "[(R)EBOOT   ]";

	// You fucked up.
	//serial_puts(s_you_fucked_up);
	//serial_puts(s_description);
	//serial_putc('\n');

	// register dump
	//serial_puts(s_registers);
	//serial_putc('\n');
	//serial_putc('\n');

	// call trace
	//serial_puts(s_call_trace);
	//serial_putc('\n');
	//serial_putc('\n');

	// thing
	// serial_puts("test\n");
	// serial_puts(bzhead.cmd_line_ptr);
	
	// Die.
	asm ("cli");
	asm ("hlt");
}