#include "acpi.h"

#include "../types.h"
#include "../lnxboot.h"
#include "../util.h"

#include "../efi/memmap.h"
#include "../efi/guid.h"
#include "../efi/efi.h"

bool AcpiIsPresent = false;

struct AcpiRSDP* AcpiTheRSDP = 0;

void AcpiInitialize() {
	// Check boot params
	if (BootBootParams->acpi_rsdp_addr) {
		AcpiTheRSDP = BootBootParams->acpi_rsdp_addr;
		goto found;
	}

	// Check firmware
	if (EfiPresent()) {
		const struct EfiSystemTable* SystemTable = EfiGetSystemTable();
		const struct EfiConfigurationTable* ConfigurationTable = EfiTranslatePointer(SystemTable->ConfigurationTable);
		for (int i = 0; i < SystemTable->NumberOfTableEntries; i++) { // this used to break because the cckernel decided to give me one last fuck you
									      // and corrupt random portions of code, i really really hate DEFLATE.
			if (CompareMemory(&ConfigurationTable[i].VendorGuid, &EFI_ACPI_20_TABLE_GUID, sizeof(EfiGuid))) {
				AcpiTheRSDP = ConfigurationTable[i].VendorTable;
				goto found;
			}
		}
	}

	goto fail;

found:	// Is this a valid ACPI table?
	if (!CompareMemory(AcpiTheRSDP->Signature, "RSD PTR ", 8)) goto fail;
	
	// Check the sum
	u8 Sum = 0;
	for (int i = 0; i < sizeof(struct AcpiRSDP); i++) Sum += ((u8*)AcpiTheRSDP)[i];
	if (Sum != 0) goto fail;
	
	AcpiIsPresent = true;	
	return;

fail:   AcpiIsPresent = false;
	return;
}

bool AcpiPresent() { return AcpiIsPresent; }
struct AcpiRSDP* AcpiGetRSDP() { return AcpiTheRSDP; }