Advanced Configuration and Power Interface Specification

ACPI Source Language (ASL)Reference
Store (“5678”, Local1)
Add (0x1234, Local1, BUF1)
In the Add statement above, Local1 contains a String object and must undergo conversion to an
Integer object before the Add operation can proceed.
In some cases, the operator may take more than one type of operand (such as Integer and String). In
this case, depending on the type of the operand, the highest priority conversion is applied. The table
below describes the source operand conversions available. For example:
Store (Buffer (1) {}, Local0)
Name (ABCD, Buffer (10) {1, 2, 3, 4, 5, 6, 7, 8, 9, 0})
CreateDWordField (ABCD, 2, XYZ)
Name (MNOP, ”1234”)
Concatenate (XYZ, MNOP, Local0)
The Concatenate operator can take an Integer, Buffer or String for its first two parameters and the
type of the first parameter determines how the second parameter will be converted. In this example,
the first parameter is of type Buffer Field (from the CreateDWordField operator). What should it be
converted to: Integer, Buffer or String? According to Table 19-357, the highest priority conversion
is to Integer. Therefore, both of the following objects will be converted to Integers:
XYZ (0x05040302)
MNOP (0x31, 0x32, 0x33, 0x34)
And will then be joined together and the resulting type and value will be:
Buffer (0x02, 0x03, 0x04, 0x05, 0x31, 0x32, 0x33, 0x34)
19.3.5.5 Implicit Result Object Conversion
For all ASL operators that generate and store a result value (including the Store operator), the result
object is processed and stored by the AML interpreter as follows:
• If the ASL operator is one of the explicit conversion operators (ToString, ToInteger, etc., and the
CopyObject operator), no conversion is performed. (In other words, the result object is stored
directly to the target and completely overwrites any existing object already stored at the target.)
• If the target is a method local or argument (LocalX or ArgX), no conversion is performed and
the result is stored directly to the target.
• If the target is a fixed type such as a named object or field object, an attempt is made to convert
the source to the existing target type before storing.
• If conversion is impossible, abort the running control method and issue a fatal error.
An implicit result conversion can occur anytime the result of an operator is stored into an object that
is of a fixed type. For example:
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