basic apic + fix some stupid issues

created an initial stub implementation of the apic driver, added the madt to acpi, fixed an issue with the strncmp, made the pmm set only free pages rather than used ones

src/arch/x86_64/acpi.c

@@ -16,13 +16,12 @@ static volatile struct limine_rsdp_request rsdpreq = {
 	.revision = 0
 };
 
-static bool checksumok(sdt_t* table){
+bool acpi_checksumok(sdt_t* table){
 	uint8_t sum;
 	uint8_t* ptr = (uint8_t*)table;
 	
 	for(size_t i = 0; i < table->length; ++i)
 		sum += *ptr++;
-
 	return sum == 0;
 }
 
@@ -35,12 +34,11 @@ void* acpi_gettable(char* sig, size_t n){
 	for(size_t i = 0; i < sdtentrycount; ++i){
 		
 		sdt_t* table = usersdt ? (*(uint32_t*)ptr & 0xFFFFFFFF) : *(uint64_t*)ptr;
-		
 		table = (uint8_t*)table + (size_t)limine_hhdm_offset;
 
 		if(!strncmp(sig, table->signature, 4)){
 			if(n-- == 0)
-				return (uint8_t*)table + (size_t) limine_hhdm_offset;
+				return table;
 				
 		}
 		
@@ -76,7 +74,7 @@ void acpi_init(){
 
 	printf("Root System Description Table address: %p with %lu tables\n", sdt, sdtentrycount);
 
-	if(!checksumok(sdt))
+	if(!acpi_checksumok(sdt))
 		_panic("Invalid RSDT checksum!", 0);
 
 }