Advanced Configuration and Power Interface Specification

Advanced Configuration and Power Interface Specification
Description
A thermal zone may be declared in the namespace anywhere within the \_SB scope. For
compatibility with operating systems implementing ACPI 1.0, a thermal zone may also be declared
under the \_TZ scope. An ACPI-compatible namespace may define Thermal Zone objects in either
the \_SB or \_TZ scope but not both.
For example ASL code that uses a ThermalZone statement, see Section 11, “Thermal Management.”
19.6.128 Timer (Get 64-Bit Timer Value)
Syntax
Timer => Integer
Description
The timer opcode returns a monotonically increasing value that can be used by ACPI methods to
measure time passing, this enables speed optimization by allowing AML code to mark the passage
of time independent of OS ACPI interpreter implementation.
The Sleep opcode can only indicate waiting for longer than the time specified.
The value resulting from this opcode is 64 bits. It is monotonically increasing, but it is not
guaranteed that every result will be unique, i.e. two subsequent instructions may return the same
value. The only guarantee is that each subsequent evaluation will be greater-than or equal to the
previous ones.
The period of this timer is 100 nanoseconds. While the underlying hardware may not support this
granularity, the interpreter will do the conversion from the actual timer hardware frequency into 100
nanosecond units.
Users of this opcode should realize that a value returned only represents the time at which the
opcode itself executed. There is no guarantee that the next opcode in the instruction stream will
execute in any particular time bound.
The OSPM can implement this using the ACPI Timer and keep track of overrun. Other
implementations are possible. This provides abstraction away from chipset differences
Note: (Compatibility Note) New for ACPI 3.0
19.6.129 ToBCD (Convert Integer to BCD)
Syntax
ToBCD (Value, Result) => Integer
Arguments
Value is evaluated as an integer
Description
The ToBCD operator is used to convert Value from a numeric (Integer) format to a BCD format and
optionally store the numeric value into Result.
892 April, 2015 Version 6.0