namespace acpi {

static void* find_sdt(rsdt* rsdt, const char* signature)
{
    u32 entries = (rsdt->header.length - sizeof rsdt->header) / sizeof rsdt->list;
    for (u32 i = 0; i < entries; i++) {
        table_header* entry = &rsdt->list[i];
        if (!memcmp(entry->signature, signature, 4)) {
            check_sdt(entry);
            return (void*)entry;
        }
    }
    return nullptr;
}

void init()
{
    constexpr auto rsdp_start = "RSD PTR ";
    acpi::rsdp* rsdp{};

    for (u32 addr = 0xf0000; addr < 0xfffff; addr++) {
        if (!memcmp((u32*)addr, rsdp_start, 8)) {
            rsdp = (acpi::rsdp*)addr;
            break;
        }
    }

    if (!rsdp) {
        u8* ebda = (u8*)(*((u16*)0x40e) << 4);
        for (u32 i = 0; i <= KiB(1); i += 16) {
            if (!memcmp(ebda + i, rsdp_start, 8)) {
                rsdp = (acpi::rsdp*)(ebda + i);
                break;
            }
        }
    }

	// this works
    constexpr auto test = "APIC";
    for (u32 i = 0x7fe0000; i < 0x7ffffff; i++) {
        if (!memcmp((u32*)i, test, 4)) {
            vga::print("%s: 0x%x\n", test, i);
            break;
        }
    }

    auto rsdt = rsdp->rsdt;

	// this also works
    auto fadt = (acpi::fadt*)find_sdt(rsdt, "FACP");
    vga::print("FADT: 0x%x\n", fadt);

    // this doesn't work
    // auto madt = ( acpi::madt* )find_sdt(rsdt, "APIC");
    // vga::print("MADT: 0x%x\n", madt);
}

}