#include "include/rsdp.h"
#include "include/utils.h"
#include "include/screen.h"

OS_RSDPDescriptor* os_find_RSDP() {
	os_u16* ebda_addr_raw = (os_u16*)0x40E;
	os_u32 ebda_addr_0 = ((os_u32)(*ebda_addr_raw));
	os_u32 ebda_addr = ebda_addr_0 << 4;
	os_u8* ebda = (os_u8*)ebda_addr;
	os_u8* current_ptr = ebda;

	while((os_u32)(current_ptr - ebda) < 1024) {
		if (os_data_compare(current_ptr, (os_u8*)OS_RSDP_SIG, 8) == OS_TRUE) {
			OS_RSDPDescriptor* ptr = (OS_RSDPDescriptor*)current_ptr;

			os_u32 sum = 0;
			for(os_u32 i = 0; i < sizeof(OS_RSDPDescriptor); i++) {
				sum += current_ptr[i];
			}

			if (((os_u8) sum) != 0) {
				current_ptr += 16;
				continue;
			}

			return ptr;
		}
		current_ptr += 16;
	}

	os_u8* bios_area_ptr = (os_u8*)0x000E0000;
	os_u8* bios_end_ptr = (os_u8*)0x000E0000 + 0x20000;
	current_ptr = bios_area_ptr;

	while(current_ptr < bios_end_ptr) {
		if (os_data_compare(current_ptr, (os_u8*)OS_RSDP_SIG, 8) == OS_TRUE) {
			OS_RSDPDescriptor* ptr = (OS_RSDPDescriptor*)current_ptr;

			os_u32 sum = 0;
			for(os_u32 i = 0; i < sizeof(OS_RSDPDescriptor); i++) {
				sum += current_ptr[i];
			}

			if (((os_u8) sum) != 0) {
				current_ptr += 16;
				continue;
			}

			return ptr;
		}
		current_ptr += 16;
	}


	return (OS_RSDPDescriptor*)0;
}

OS_RSDPDescriptor_20* os_find_RSDP_20() {
	return (OS_RSDPDescriptor_20*)0;
}