__EXPREP_C__ _COMPONENT AcpiExDecodeFieldAccess AcpiExPrepCommonFieldObject AcpiExPrepFieldValue

ACPI_STATUS AcpiExPrepCommonFieldObject ( ACPI_OPERAND_OBJECT *  ObjDesc, UINT8  FieldFlags, UINT8  FieldAttribute, UINT32  FieldBitPosition, UINT32  FieldBitLength  ) Definition at line 407 of file exprep.c. Referenced by AcpiDsInitBufferField(), and AcpiExPrepFieldValue(). { UINT32 AccessBitWidth; UINT32 ByteAlignment; UINT32 NearestByteAddress; ACPI_FUNCTION_TRACE (ExPrepCommonFieldObject); /* * Note: the structure being initialized is the * ACPI_COMMON_FIELD_INFO; No structure fields outside of the common * area are initialized by this procedure. */ ObjDesc->CommonField.FieldFlags = FieldFlags; ObjDesc->CommonField.Attribute = FieldAttribute; ObjDesc->CommonField.BitLength = FieldBitLength; /* * Decode the access type so we can compute offsets. The access type gives * two pieces of information - the width of each field access and the * necessary ByteAlignment (address granularity) of the access. * * For AnyAcc, the AccessBitWidth is the largest width that is both * necessary and possible in an attempt to access the whole field in one * I/O operation. However, for AnyAcc, the ByteAlignment is always one * byte. * * For all Buffer Fields, the ByteAlignment is always one byte. * * For all other access types (Byte, Word, Dword, Qword), the Bitwidth is * the same (equivalent) as the ByteAlignment. */ AccessBitWidth = AcpiExDecodeFieldAccess (ObjDesc, FieldFlags, &ByteAlignment); if (!AccessBitWidth) { return_ACPI_STATUS (AE_AML_OPERAND_VALUE); } /* Setup width (access granularity) fields (values are: 1, 2, 4, 8) */ ObjDesc->CommonField.AccessByteWidth = (UINT8) ACPI_DIV_8 (AccessBitWidth); /* * BaseByteOffset is the address of the start of the field within the * region. It is the byte address of the first *datum* (field-width data * unit) of the field. (i.e., the first datum that contains at least the * first *bit* of the field.) * * Note: ByteAlignment is always either equal to the AccessBitWidth or 8 * (Byte access), and it defines the addressing granularity of the parent * region or buffer. */ NearestByteAddress = ACPI_ROUND_BITS_DOWN_TO_BYTES (FieldBitPosition); ObjDesc->CommonField.BaseByteOffset = (UINT32) ACPI_ROUND_DOWN (NearestByteAddress, ByteAlignment); /* * StartFieldBitOffset is the offset of the first bit of the field within * a field datum. */ ObjDesc->CommonField.StartFieldBitOffset = (UINT8) (FieldBitPosition - ACPI_MUL_8 (ObjDesc->CommonField.BaseByteOffset)); return_ACPI_STATUS (AE_OK); }