Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
ASL Data Type
Event
Field Unit (within an
Operation Region)
Description
Event synchronization object
Portion of an address space, bit-aligned and of one-bit granularity. Created using
Field, BankField, or IndexField.
Integer An n-bit little-endian unsigned integer. In ACPI 1.0 this was 32 bits. In ACPI 2.0
and later, this is 64 bits. The Integer (DWORD) designation indicates that only the
lower 32 bits have meaning and the upper 32 bits of 64-bit integers must be zero
(masking of upper bits is not required).
Integer Constant Created by the ASL terms “Zero”, “One”, “Ones”, and “Revision”.
Method
Control Method (Executable AML function)
Mutex
Mutex synchronization object
Object Reference Reference to an object created using the RefOf, Index, or CondRefOf operators
Operation Region Operation Region (A region within an Address Space)
Package Collection of ASL objects with a fixed number of elements (up to 255).
Power Resource Power Resource description object
Processor
Processor description object
RawDataBuffer An array of bytes. Uninitialized elements are zero by default. RawDataBuffer does
not contain any AML encoding bytes, only the raw bytes.
String
Null-terminated ASCII string.
Thermal Zone
Thermal Zone description object
Note: (Compatibility Note) The ability to store and manipulate object references was first introduced in
ACPI 2.0. In ACPI 1.0 references could not be stored in variables, passed as parameters or
returned from functions.
19.3.5.1 Data Type Conversion Overview
ASL provides two mechanisms to convert objects from one data type to another data type at run-time
(during execution of the AML interpreter). The first mechanism, Explicit Data Type Conversion,
allows the use of explicit ASL operators to convert an object to a different data type. The second
mechanism, Implicit Data Type Conversion, is invoked by the AML interpreter when it is necessary
to convert a data object to an expected data type before it is used or stored.
The following general rules apply to data type conversions:
• Input parameters are always subject to implicit data type conversion (also known as implicit
source operand conversion) whenever the operand type does not match the expected input type.
• Output (target) parameters for all operators except the explicit data conversion operators are
subject to implicit data type conversion (also known as implicit result object conversion)
whenever the target is an existing named object or named field that is of a different type than the
object to be stored.
• Output parameters for the explicit data conversion operators, as well as output parameters that
refer to a method local or argument (LocalX or ArgX) are not subject to implicit type
conversion.
790 April, 2015 Version 6.0