efi_guid struct gets equals, simplify EFI acpi_init

Change-Id: Id4bc985dc1e6f44b594f6ca5dabd3fdac8e1cac2
Reviewed-on: https://review.haiku-os.org/c/haiku/+/3545
Reviewed-by: Alex von Gluck IV <[email protected]>

headers/private/kernel/platform/efi/types.h

@@ -82,6 +82,14 @@ typedef struct efi_guid {
     uint16_t data2;
     uint16_t data3;
     uint8_t data4[8];
+
+	bool equals(const efi_guid& other) const {
+		bool matches = data1 == other.data1 && data2 == other.data2
+			&& data3 == other.data3;
+		for (auto i = 0; matches && i < 8; i++)
+			matches = data4[i] == other.data4[i];
+		return matches;
+	}
 } efi_guid;
 
 typedef void* efi_handle;

src/system/boot/platform/efi/acpi.cpp

@@ -205,15 +205,10 @@ acpi_init()
 
 	// Try to find the ACPI RSDP.
 	for (uint32 i = 0; i < entries; i++) {
-		acpi_rsdp *rsdp = NULL;
+		if (!table[i].VendorGuid.equals(acpi))
+			continue;
 
-		efi_guid vendor = table[i].VendorGuid;
+		acpi_rsdp *rsdp = (acpi_rsdp *)(table[i].VendorTable);
-
-		if (vendor.data1 == acpi.data1
-			&& vendor.data2 == acpi.data2
-			&& vendor.data3 == acpi.data3
-			&& strncmp((char *)vendor.data4, (char *)acpi.data4, 8) == 0) {
-			rsdp = (acpi_rsdp *)(table[i].VendorTable);
 		if (strncmp((char *)rsdp, ACPI_RSDP_SIGNATURE, 8) == 0)
 			TRACE(("acpi_init: found ACPI RSDP signature at %p\n", rsdp));
 
@@ -222,5 +217,4 @@ acpi_init()
 			break;
 		}
 	}
-	}
 }