exfldio.c

acpi tools for linux include acpiexec and acpixtract

                    return_ACPI_STATUS (Status);
                }

                MergedValue |= (CurrentValue & ~Mask);
            }
            break;

        case AML_FIELD_UPDATE_WRITE_AS_ONES:

            /* Set positions outside the field to all ones */

            MergedValue |= ~Mask;
            break;

        case AML_FIELD_UPDATE_WRITE_AS_ZEROS:

            /* Set positions outside the field to all zeros */

            MergedValue &= Mask;
            break;

        default:

            ACPI_ERROR ((AE_INFO,
                "Unknown UpdateRule value: %X",
                (ObjDesc->CommonField.FieldFlags & AML_FIELD_UPDATE_RULE_MASK)));
            return_ACPI_STATUS (AE_AML_OPERAND_VALUE);
        }
    }

    ACPI_DEBUG_PRINT ((ACPI_DB_BFIELD,
        "Mask %8.8X%8.8X, DatumOffset %X, Width %X, Value %8.8X%8.8X, MergedValue %8.8X%8.8X\n",
        ACPI_FORMAT_UINT64 (Mask),
        FieldDatumByteOffset,
        ObjDesc->CommonField.AccessByteWidth,
        ACPI_FORMAT_UINT64 (FieldValue),
        ACPI_FORMAT_UINT64 (MergedValue)));

    /* Write the merged value */

    Status = AcpiExFieldDatumIo (ObjDesc, FieldDatumByteOffset,
                &MergedValue, ACPI_WRITE);

    return_ACPI_STATUS (Status);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiExExtractFromField
 *
 * PARAMETERS:  ObjDesc             - Field to be read
 *              Buffer              - Where to store the field data
 *              BufferLength        - Length of Buffer
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Retrieve the current value of the given field
 *
 ******************************************************************************/

ACPI_STATUS
AcpiExExtractFromField (
    ACPI_OPERAND_OBJECT     *ObjDesc,
    void                    *Buffer,
    UINT32                  BufferLength)
{
    ACPI_STATUS             Status;
    ACPI_INTEGER            RawDatum;
    ACPI_INTEGER            MergedDatum;
    UINT32                  FieldOffset = 0;
    UINT32                  BufferOffset = 0;
    UINT32                  BufferTailBits;
    UINT32                  DatumCount;
    UINT32                  FieldDatumCount;
    UINT32                  i;


    ACPI_FUNCTION_TRACE (ExExtractFromField);


    /* Validate target buffer and clear it */

    if (BufferLength <
            ACPI_ROUND_BITS_UP_TO_BYTES (ObjDesc->CommonField.BitLength))
    {
        ACPI_ERROR ((AE_INFO,
            "Field size %X (bits) is too large for buffer (%X)",
            ObjDesc->CommonField.BitLength, BufferLength));

        return_ACPI_STATUS (AE_BUFFER_OVERFLOW);
    }
    ACPI_MEMSET (Buffer, 0, BufferLength);

    /* Compute the number of datums (access width data items) */

    DatumCount = ACPI_ROUND_UP_TO (
                        ObjDesc->CommonField.BitLength,
                        ObjDesc->CommonField.AccessBitWidth);
    FieldDatumCount = ACPI_ROUND_UP_TO (
                        ObjDesc->CommonField.BitLength +
                        ObjDesc->CommonField.StartFieldBitOffset,
                        ObjDesc->CommonField.AccessBitWidth);

    /* Priming read from the field */

    Status = AcpiExFieldDatumIo (ObjDesc, FieldOffset, &RawDatum, ACPI_READ);
    if (ACPI_FAILURE (Status))
    {
        return_ACPI_STATUS (Status);
    }
    MergedDatum = RawDatum >> ObjDesc->CommonField.StartFieldBitOffset;

    /* Read the rest of the field */

    for (i = 1; i < FieldDatumCount; i++)
    {
        /* Get next input datum from the field */

        FieldOffset += ObjDesc->CommonField.AccessByteWidth;
        Status = AcpiExFieldDatumIo (ObjDesc, FieldOffset,
                    &RawDatum, ACPI_READ);
        if (ACPI_FAILURE (Status))
        {
            return_ACPI_STATUS (Status);
        }

        /*
         * Merge with previous datum if necessary.
         *
         * Note: Before the shift, check if the shift value will be larger than
         * the integer size. If so, there is no need to perform the operation.
         * This avoids the differences in behavior between different compilers
         * concerning shift values larger than the target data width.
         */
        if ((ObjDesc->CommonField.AccessBitWidth -
            ObjDesc->CommonField.StartFieldBitOffset) < ACPI_INTEGER_BIT_SIZE)
        {
            MergedDatum |= RawDatum <<
                (ObjDesc->CommonField.AccessBitWidth -
                    ObjDesc->CommonField.StartFieldBitOffset);
        }

        if (i == DatumCount)
        {
            break;
        }

        /* Write merged datum to target buffer */

        ACPI_MEMCPY (((char *) Buffer) + BufferOffset, &MergedDatum,
            ACPI_MIN(ObjDesc->CommonField.AccessByteWidth,
                BufferLength - BufferOffset));

        BufferOffset += ObjDesc->CommonField.AccessByteWidth;
        MergedDatum = RawDatum >> ObjDesc->CommonField.StartFieldBitOffset;
    }

    /* Mask off any extra bits in the last datum */

    BufferTailBits = ObjDesc->CommonField.BitLength %
                        ObjDesc->CommonField.AccessBitWidth;
    if (BufferTailBits)
    {
        MergedDatum &= ACPI_MASK_BITS_ABOVE (BufferTailBits);
    }

    /* Write the last datum to the buffer */

    ACPI_MEMCPY (((char *) Buffer) + BufferOffset, &MergedDatum,
        ACPI_MIN(ObjDesc->CommonField.AccessByteWidth,
            BufferLength - BufferOffset));

    return_ACPI_STATUS (AE_OK);
}


/*******************************************************************************
 *
 * FUNCTION:    AcpiExInsertIntoField
 *
 * PARAMETERS:  ObjDesc             - Field to be written
 *              Buffer              - Data to be written
 *              BufferLength        - Length of Buffer
 *
 * RETURN:      Status
 *
 * DESCRIPTION: Store the Buffer contents into the given field
 *
 ******************************************************************************/

ACPI_STATUS
AcpiExInsertIntoField (
    ACPI_OPERAND_OBJECT     *ObjDesc,
    void                    *Buffer,
    UINT32                  BufferLength)
{
    ACPI_STATUS             Status;
    ACPI_INTEGER            Mask;
    ACPI_INTEGER            WidthMask;
    ACPI_INTEGER            MergedDatum;
    ACPI_INTEGER            RawDatum = 0;
    UINT32                  FieldOffset = 0;
    UINT32                  BufferOffset = 0;
    UINT32                  BufferTailBits;
    UINT32                  DatumCount;
    UINT32                  FieldDatumCount;
    UINT32                  i;
    UINT32                  RequiredLength;
    void                    *NewBuffer;


    ACPI_FUNCTION_TRACE (ExInsertIntoField);


    /* Validate input buffer */

    NewBuffer = NULL;
    RequiredLength = ACPI_ROUND_BITS_UP_TO_BYTES (
                        ObjDesc->CommonField.BitLength);
    /*
     * We must have a buffer that is at least as long as the field
     * we are writing to.  This is because individual fields are
     * indivisible and partial writes are not supported -- as per
     * the ACPI specification.
     */
    if (BufferLength < RequiredLength)
    {
        /* We need to create a new buffer */

        NewBuffer = ACPI_ALLOCATE_ZEROED (RequiredLength);
        if (!NewBuffer)
        {
            return_ACPI_STATUS (AE_NO_MEMORY);
        }

        /*
         * Copy the original data to the new buffer, starting
         * at Byte zero.  All unused (upper) bytes of the
         * buffer will be 0.
         */
        ACPI_MEMCPY ((char *) NewBuffer, (char *) Buffer, BufferLength);
        Buffer = NewBuffer;
        BufferLength = RequiredLength;
    }

    /*
     * Create the bitmasks used for bit insertion.
     * Note: This if/else is used to bypass compiler differences with the
     * shift operator
     */
    if (ObjDesc->CommonField.AccessBitWidth == ACPI_INTEGER_BIT_SIZE)
    {
        WidthMask = ACPI_INTEGER_MAX;
    }
    else
    {
        WidthMask = ACPI_MASK_BITS_ABOVE (ObjDesc->CommonField.AccessBitWidth);
    }

    Mask = WidthMask &
            ACPI_MASK_BITS_BELOW (ObjDesc->CommonField.StartFieldBitOffset);

    /* Compute the number of datums (access width data items) */

    DatumCount = ACPI_ROUND_UP_TO (ObjDesc->CommonField.BitLength,
                    ObjDesc->CommonField.AccessBitWidth);

    FieldDatumCount = ACPI_ROUND_UP_TO (ObjDesc->CommonField.BitLength +
                        ObjDesc->CommonField.StartFieldBitOffset,
                        ObjDesc->CommonField.AccessBitWidth);

    /* Get initial Datum from the input buffer */

    ACPI_MEMCPY (&RawDatum, Buffer,
        ACPI_MIN(ObjDesc->CommonField.AccessByteWidth,
            BufferLength - BufferOffset));

    MergedDatum = RawDatum << ObjDesc->CommonField.StartFieldBitOffset;

    /* Write the entire field */

    for (i = 1; i < FieldDatumCount; i++)
    {
        /* Write merged datum to the target field */

        MergedDatum &= Mask;
        Status = AcpiExWriteWithUpdateRule (ObjDesc, Mask,
                    MergedDatum, FieldOffset);
        if (ACPI_FAILURE (Status))
        {
            goto Exit;
        }

        FieldOffset += ObjDesc->CommonField.AccessByteWidth;

        /*
         * Start new output datum by merging with previous input datum
         * if necessary.
         *
         * Note: Before the shift, check if the shift value will be larger than
         * the integer size. If so, there is no need to perform the operation.
         * This avoids the differences in behavior between different compilers
         * concerning shift values larger than the target data width.
         */
        if ((ObjDesc->CommonField.AccessBitWidth -
            ObjDesc->CommonField.StartFieldBitOffset) < ACPI_INTEGER_BIT_SIZE)
        {
            MergedDatum = RawDatum >>
                (ObjDesc->CommonField.AccessBitWidth -
                    ObjDesc->CommonField.StartFieldBitOffset);
        }
        else
        {
            MergedDatum = 0;
        }

        Mask = WidthMask;

        if (i == DatumCount)
        {
            break;
        }

        /* Get the next input datum from the buffer */

        BufferOffset += ObjDesc->CommonField.AccessByteWidth;
        ACPI_MEMCPY (&RawDatum, ((char *) Buffer) + BufferOffset,
            ACPI_MIN(ObjDesc->CommonField.AccessByteWidth,
                     BufferLength - BufferOffset));
        MergedDatum |= RawDatum << ObjDesc->CommonField.StartFieldBitOffset;
    }

    /* Mask off any extra bits in the last datum */

    BufferTailBits = (ObjDesc->CommonField.BitLength +
            ObjDesc->CommonField.StartFieldBitOffset) %
                ObjDesc->CommonField.AccessBitWidth;
    if (BufferTailBits)
    {
        Mask &= ACPI_MASK_BITS_ABOVE (BufferTailBits);
    }

    /* Write the last datum to the field */

    MergedDatum &= Mask;
    Status = AcpiExWriteWithUpdateRule (ObjDesc,
                Mask, MergedDatum, FieldOffset);

Exit:
    /* Free temporary buffer if we used one */

    if (NewBuffer)
    {
        ACPI_FREE (NewBuffer);
    }
    return_ACPI_STATUS (Status);
}