Advanced Configuration and Power Interface Specification

ACPI Source Language (ASL)Reference
Name (BUFF, Buffer () {0x01, 0x02, 0x03, 0x04, 0x05})
// Store 0x55 into the third byte of the buffer
Store (0x55, Index (BUFF, 2))
The Index operator returns a reference to an 8-bit Buffer Field (similar to that created using
CreateByteField).
If Source is evaluated to a buffer data type, the ObjectReference refers to the byte at Index within
Source. If Source is evaluated to a buffer data type, a Store operation will only change the byte at
Index within Source.
The following example ASL code shows the results of a series of Store operations:
Name (SRCB, Buffer () {0x10, 0x20, 0x30, 0x40})
Name (BUFF, Buffer () {0x1, 0x2, 0x3, 0x4})
The following will store 0x78 into the 3 rd byte of the destination buffer:
Store (0x12345678, Index (BUFF, 2))
The following will store 0x10 into the 2 nd byte of the destination buffer:
Store (SRCB, Index (BUFF, 1))
The following will store 0x41 (an ‘A’) into the 4 th byte of the destination buffer:
Store (“ABCDEFGH”, Index (BUFF, 3))
Note: (Compatibility Note) First introduced in ACPI 2.0. In ACPI 1.0, the behavior of storing data larger
than 8-bits into a buffer using Index was undefined.
19.6.60.3 Index with Strings
The following example ASL code shows a way to store into the 3 rd character in a string:
Name (STR, “ABCDEFGHIJKL”)
// Store ‘H’ (0x48) into the third character to the string
Store (“H”, Index (STR, 2))
The Index operator returns a reference to an 8-bit Buffer Field (similar to that created using
CreateByteField).
Note: (Compatibility Note) First introduced in ACPI 2.0.
19.6.61 IndexField (Declare Index/Data Fields)
Syntax
IndexField (IndexName, DataName, AccessType, LockRule, UpdateRule) {FieldUnitList}
Version 6.0 849