C++ AcpiOsMapMemory函數代碼示例

static ACPI_STATUS
OslMapTable (
    ACPI_SIZE               Address,
    char                    *Signature,
    ACPI_TABLE_HEADER       **Table)
{
    ACPI_TABLE_HEADER       *MappedTable;
    UINT32                  Length;


    /* Map the header so we can get the table length */

    MappedTable = AcpiOsMapMemory (Address, sizeof (*MappedTable));
    if (!MappedTable)
    {
        return (AE_BAD_ADDRESS);
    }

    /* Check if table is valid */

    if (!ApIsValidHeader (MappedTable))
    {
        AcpiOsUnmapMemory (MappedTable, sizeof (*MappedTable));
        return (AE_BAD_HEADER);
    }

    /* If specified, signature must match */

    if (Signature &&
        !ACPI_COMPARE_NAME (Signature, MappedTable->Signature))
    {
        AcpiOsUnmapMemory (MappedTable, sizeof (*MappedTable));
        return (AE_NOT_EXIST);
    }

    /* Map the entire table */

    Length = MappedTable->Length;
    AcpiOsUnmapMemory (MappedTable, sizeof (*MappedTable));

    MappedTable = AcpiOsMapMemory (Address, Length);
    if (!MappedTable)
    {
        return (AE_BAD_ADDRESS);
    }

    (void) ApIsValidChecksum (MappedTable);

    *Table = MappedTable;

    return (AE_OK);
}

ACPI_STATUS
AcpiOsWriteMemory(ACPI_PHYSICAL_ADDRESS Address, UINT64 Value, UINT32 Width)
{
    void	*LogicalAddress;

    LogicalAddress = AcpiOsMapMemory(Address, Width / 8);
    if (LogicalAddress == NULL)
	return (AE_NOT_EXIST);

    switch (Width) {
    case 8:
	*(volatile uint8_t *)LogicalAddress = Value;
	break;
    case 16:
	*(volatile uint16_t *)LogicalAddress = Value;
	break;
    case 32:
	*(volatile uint32_t *)LogicalAddress = Value;
	break;
    case 64:
	*(volatile uint64_t *)LogicalAddress = Value;
	break;
    }

    AcpiOsUnmapMemory(LogicalAddress, Width / 8);

    return (AE_OK);
}

/*
 * AcpiOsWriteMemory:
 *
 *	Write a value to a memory location.
 */
ACPI_STATUS
AcpiOsWriteMemory(ACPI_PHYSICAL_ADDRESS Address, UINT32 Value, UINT32 Width)
{
	void *LogicalAddress;
	ACPI_STATUS rv = AE_OK;

	LogicalAddress = AcpiOsMapMemory(Address, Width / 8);
	if (LogicalAddress == NULL)
		return AE_NOT_FOUND;

	switch (Width) {
	case 8:
		*(volatile uint8_t *) LogicalAddress = Value;
		break;

	case 16:
		*(volatile uint16_t *) LogicalAddress = Value;
		break;

	case 32:
		*(volatile uint32_t *) LogicalAddress = Value;
		break;

	default:
		rv = AE_BAD_PARAMETER;
	}

	AcpiOsUnmapMemory(LogicalAddress, Width / 8);

	return rv;
}

void
AcpiTbInstallTable (
    ACPI_PHYSICAL_ADDRESS   Address,
    char                    *Signature,
    UINT32                  TableIndex)
{
    ACPI_TABLE_HEADER       *Table;
    ACPI_TABLE_HEADER       *FinalTable;
    ACPI_TABLE_DESC         *TableDesc;


    if (!Address)
    {
        ACPI_ERROR ((AE_INFO, "Null physical address for ACPI table [%s]",
            Signature));
        return;
    }

    /* Map just the table header */

    Table = AcpiOsMapMemory (Address, sizeof (ACPI_TABLE_HEADER));
    if (!Table)
    {
        ACPI_ERROR ((AE_INFO, "Could not map memory for table [%s] at %p",
            Signature, ACPI_CAST_PTR (void, Address)));
        return;
    }

ACPI_STATUS
AcpiOsReadMemory(ACPI_PHYSICAL_ADDRESS Address, UINT32 *Value, UINT32 Width)
{
    void	*LogicalAddress;

    LogicalAddress = AcpiOsMapMemory(Address, Width / 8);
    if (LogicalAddress == NULL)
	return (AE_NOT_EXIST);

    switch (Width) {
    case 8:
	*(u_int8_t *)Value = (*(volatile u_int8_t *)LogicalAddress);
	break;
    case 16:
	*(u_int16_t *)Value = (*(volatile u_int16_t *)LogicalAddress);
	break;
    case 32:
	*(u_int32_t *)Value = (*(volatile u_int32_t *)LogicalAddress);
	break;
    case 64:
	*(u_int64_t *)Value = (*(volatile u_int64_t *)LogicalAddress);
	break;
    default:
	/* debug trap goes here */
	break;
    }

    AcpiOsUnmapMemory(LogicalAddress, Width / 8);

    return (AE_OK);
}

void
AcpiTbParseFadt (
    void)
{
    UINT32                  Length;
    ACPI_TABLE_HEADER       *Table;


    /*
     * The FADT has multiple versions with different lengths,
     * and it contains pointers to both the DSDT and FACS tables.
     *
     * Get a local copy of the FADT and convert it to a common format
     * Map entire FADT, assumed to be smaller than one page.
     */
    Length = AcpiGbl_RootTableList.Tables[AcpiGbl_FadtIndex].Length;

    Table = AcpiOsMapMemory (
        AcpiGbl_RootTableList.Tables[AcpiGbl_FadtIndex].Address, Length);
    if (!Table)
    {
        return;
    }

    /*
     * Validate the FADT checksum before we copy the table. Ignore
     * checksum error as we want to try to get the DSDT and FACS.
     */
    (void) AcpiTbVerifyChecksum (Table, Length);

    /* Create a local copy of the FADT in common ACPI 2.0+ format */

    AcpiTbCreateLocalFadt (Table, Length);

    /* All done with the real FADT, unmap it */

    AcpiOsUnmapMemory (Table, Length);

    /* Obtain the DSDT and FACS tables via their addresses within the FADT */

    AcpiTbInstallFixedTable ((ACPI_PHYSICAL_ADDRESS) AcpiGbl_FADT.XDsdt,
        ACPI_SIG_DSDT, &AcpiGbl_DsdtIndex);

    /* If Hardware Reduced flag is set, there is no FACS */

    if (!AcpiGbl_ReducedHardware)
    {
        if (AcpiGbl_FADT.Facs)
        {
            AcpiTbInstallFixedTable ((ACPI_PHYSICAL_ADDRESS) AcpiGbl_FADT.Facs,
                ACPI_SIG_FACS, &AcpiGbl_FacsIndex);
        }
        if (AcpiGbl_FADT.XFacs)
        {
            AcpiTbInstallFixedTable ((ACPI_PHYSICAL_ADDRESS) AcpiGbl_FADT.XFacs,
                ACPI_SIG_FACS, &AcpiGbl_XFacsIndex);
        }
    }
}

ACPI_STATUS
AcpiTbAcquireTempTable (
    ACPI_TABLE_DESC         *TableDesc,
    ACPI_PHYSICAL_ADDRESS   Address,
    UINT8                   Flags)
{
    ACPI_TABLE_HEADER       *TableHeader;


    switch (Flags & ACPI_TABLE_ORIGIN_MASK)
    {
    case ACPI_TABLE_ORIGIN_INTERNAL_PHYSICAL:

        /* Get the length of the full table from the header */

        TableHeader = AcpiOsMapMemory (Address, sizeof (ACPI_TABLE_HEADER));
        if (!TableHeader)
        {
            return (AE_NO_MEMORY);
        }

        AcpiTbInitTableDescriptor (TableDesc, Address, Flags, TableHeader);
        AcpiOsUnmapMemory (TableHeader, sizeof (ACPI_TABLE_HEADER));
        return (AE_OK);

    case ACPI_TABLE_ORIGIN_INTERNAL_VIRTUAL:
    case ACPI_TABLE_ORIGIN_EXTERNAL_VIRTUAL:

        TableHeader = ACPI_CAST_PTR (ACPI_TABLE_HEADER,
            ACPI_PHYSADDR_TO_PTR (Address));
        if (!TableHeader)
        {
            return (AE_NO_MEMORY);
        }

        AcpiTbInitTableDescriptor (TableDesc, Address, Flags, TableHeader);
        return (AE_OK);

    default:

        break;
    }

    /* Table is not valid yet */

    return (AE_NO_MEMORY);
}

void
AcpiTbParseFadt (
    ACPI_NATIVE_UINT        TableIndex,
    UINT8                   Flags)
{
    UINT32                  Length;
    ACPI_TABLE_HEADER       *Table;


    /*
     * The FADT has multiple versions with different lengths,
     * and it contains pointers to both the DSDT and FACS tables.
     *
     * Get a local copy of the FADT and convert it to a common format
     * Map entire FADT, assumed to be smaller than one page.
     */
    Length = AcpiGbl_RootTableList.Tables[TableIndex].Length;

    Table = AcpiOsMapMemory (
                AcpiGbl_RootTableList.Tables[TableIndex].Address, Length);
    if (!Table)
    {
        return;
    }

    /*
     * Validate the FADT checksum before we copy the table. Ignore
     * checksum error as we want to try to get the DSDT and FACS.
     */
    (void) AcpiTbVerifyChecksum (Table, Length);

    /* Obtain a local copy of the FADT in common ACPI 2.0+ format */

    AcpiTbCreateLocalFadt (Table, Length);

    /* All done with the real FADT, unmap it */

    AcpiOsUnmapMemory (Table, Length);

    /* Obtain the DSDT and FACS tables via their addresses within the FADT */

    AcpiTbInstallTable ((ACPI_PHYSICAL_ADDRESS) AcpiGbl_FADT.XDsdt,
        Flags, ACPI_SIG_DSDT, ACPI_TABLE_INDEX_DSDT);

    AcpiTbInstallTable ((ACPI_PHYSICAL_ADDRESS) AcpiGbl_FADT.XFacs,
        Flags, ACPI_SIG_FACS, ACPI_TABLE_INDEX_FACS);
}

ACPI_STATUS
AcpiTbAcquireTable (
    ACPI_TABLE_DESC         *TableDesc,
    ACPI_TABLE_HEADER       **TablePtr,
    UINT32                  *TableLength,
    UINT8                   *TableFlags)
{
    ACPI_TABLE_HEADER       *Table = NULL;


    switch (TableDesc->Flags & ACPI_TABLE_ORIGIN_MASK)
    {
    case ACPI_TABLE_ORIGIN_INTERNAL_PHYSICAL:

        Table = AcpiOsMapMemory (TableDesc->Address, TableDesc->Length);
        break;

    case ACPI_TABLE_ORIGIN_INTERNAL_VIRTUAL:
    case ACPI_TABLE_ORIGIN_EXTERNAL_VIRTUAL:

        Table = ACPI_CAST_PTR (ACPI_TABLE_HEADER,
            ACPI_PHYSADDR_TO_PTR (TableDesc->Address));
        break;

    default:

        break;
    }

    /* Table is not valid yet */

    if (!Table)
    {
        return (AE_NO_MEMORY);
    }

    /* Fill the return values */

    *TablePtr = Table;
    *TableLength = TableDesc->Length;
    *TableFlags = TableDesc->Flags;
    return (AE_OK);
}

ACPI_TABLE_HEADER *
AcpiTbTableOverride (
    ACPI_TABLE_HEADER       *TableHeader,
    ACPI_TABLE_DESC         *TableDesc)
{
    ACPI_STATUS             Status;
    ACPI_TABLE_HEADER       *NewTable = NULL;
    ACPI_PHYSICAL_ADDRESS   NewAddress = 0;
    UINT32                  NewTableLength = 0;
    UINT8                   NewFlags;
    char                    *OverrideType;


    /* (1) Attempt logical override (returns a logical address) */

    Status = AcpiOsTableOverride (TableHeader, &NewTable);
    if (ACPI_SUCCESS (Status) && NewTable)
    {
        NewAddress = ACPI_PTR_TO_PHYSADDR (NewTable);
        NewTableLength = NewTable->Length;
        NewFlags = ACPI_TABLE_ORIGIN_OVERRIDE;
        OverrideType = "Logical";
        goto FinishOverride;
    }

    /* (2) Attempt physical override (returns a physical address) */

    Status = AcpiOsPhysicalTableOverride (TableHeader,
        &NewAddress, &NewTableLength);
    if (ACPI_SUCCESS (Status) && NewAddress && NewTableLength)
    {
        /* Map the entire new table */

        NewTable = AcpiOsMapMemory (NewAddress, NewTableLength);
        if (!NewTable)
        {
            ACPI_EXCEPTION ((AE_INFO, AE_NO_MEMORY,
                "%4.4s %p Attempted physical table override failed",
                TableHeader->Signature,
                ACPI_CAST_PTR (void, TableDesc->Address)));
            return (NULL);
        }

ACPI_STATUS
AcpiTbVerifyTable (
    ACPI_TABLE_DESC         *TableDesc)
{
    ACPI_STATUS             Status = AE_OK;


    ACPI_FUNCTION_TRACE (TbVerifyTable);


    /* Map the table if necessary */

    if (!TableDesc->Pointer)
    {
        if ((TableDesc->Flags & ACPI_TABLE_ORIGIN_MASK) ==
            ACPI_TABLE_ORIGIN_MAPPED)
        {
            TableDesc->Pointer = AcpiOsMapMemory (
                TableDesc->Address, TableDesc->Length);
        }

        if (!TableDesc->Pointer)
        {
            return_ACPI_STATUS (AE_NO_MEMORY);
        }
    }

    /* FACS is the odd table, has no standard ACPI header and no checksum */

    if (!ACPI_COMPARE_NAME (&TableDesc->Signature, ACPI_SIG_FACS))
    {
        /* Always calculate checksum, ignore bad checksum if requested */

        Status = AcpiTbVerifyChecksum (TableDesc->Pointer, TableDesc->Length);
    }

    return_ACPI_STATUS (Status);
}

//.........這裏部分代碼省略.........
        /*
         * October 2009: Attempt to map from the requested address to the
         * end of the region. However, we will never map more than one
         * page, nor will we cross a page boundary.
         */
        MapLength = (ACPI_SIZE)
            ((MemInfo->Address + MemInfo->Length) - Address);

        /*
         * If mapping the entire remaining portion of the region will cross
         * a page boundary, just map up to the page boundary, do not cross.
         * On some systems, crossing a page boundary while mapping regions
         * can cause warnings if the pages have different attributes
         * due to resource management.
         *
         * This has the added benefit of constraining a single mapping to
         * one page, which is similar to the original code that used a 4k
         * maximum window.
         */
        PageBoundaryMapLength = (ACPI_SIZE)
            (ACPI_ROUND_UP (Address, ACPI_DEFAULT_PAGE_SIZE) - Address);
        if (PageBoundaryMapLength == 0)
        {
            PageBoundaryMapLength = ACPI_DEFAULT_PAGE_SIZE;
        }

        if (MapLength > PageBoundaryMapLength)
        {
            MapLength = PageBoundaryMapLength;
        }

        /* Create a new mapping starting at the address given */

        MemInfo->MappedLogicalAddress = AcpiOsMapMemory (Address, MapLength);
        if (!MemInfo->MappedLogicalAddress)
        {
            ACPI_ERROR ((AE_INFO,
                "Could not map memory at 0x%8.8X%8.8X, size %u",
                ACPI_FORMAT_UINT64 (Address), (UINT32) MapLength));
            MemInfo->MappedLength = 0;
            return_ACPI_STATUS (AE_NO_MEMORY);
        }

        /* Save the physical address and mapping size */

        MemInfo->MappedPhysicalAddress = Address;
        MemInfo->MappedLength = MapLength;
    }

    /*
     * Generate a logical pointer corresponding to the address we want to
     * access
     */
    LogicalAddrPtr = MemInfo->MappedLogicalAddress +
        ((UINT64) Address - (UINT64) MemInfo->MappedPhysicalAddress);

    ACPI_DEBUG_PRINT ((ACPI_DB_INFO,
        "System-Memory (width %u) R/W %u Address=%8.8X%8.8X\n",
        BitWidth, Function, ACPI_FORMAT_UINT64 (Address)));

    /*
     * Perform the memory read or write
     *
     * Note: For machines that do not support non-aligned transfers, the target
     * address was checked for alignment above. We do not attempt to break the
     * transfer up into smaller (byte-size) chunks because the AML specifically

ACPI_STATUS
AcpiExSystemMemorySpaceHandler (
    UINT32                  Function,
    ACPI_PHYSICAL_ADDRESS   Address,
    UINT32                  BitWidth,
    ACPI_INTEGER            *Value,
    void                    *HandlerContext,
    void                    *RegionContext)
{
    ACPI_STATUS             Status = AE_OK;
    void                    *LogicalAddrPtr = NULL;
    ACPI_MEM_SPACE_CONTEXT  *MemInfo = RegionContext;
    UINT32                  Length;
    ACPI_SIZE               WindowSize;
#ifdef ACPI_MISALIGNMENT_NOT_SUPPORTED
    UINT32                  Remainder;
#endif


    ACPI_FUNCTION_TRACE (ExSystemMemorySpaceHandler);


    /* Validate and translate the bit width */

    switch (BitWidth)
    {
    case 8:
        Length = 1;
        break;

    case 16:
        Length = 2;
        break;

    case 32:
        Length = 4;
        break;

    case 64:
        Length = 8;
        break;

    default:
        ACPI_ERROR ((AE_INFO, "Invalid SystemMemory width %d",
            BitWidth));
        return_ACPI_STATUS (AE_AML_OPERAND_VALUE);
    }

#ifdef ACPI_MISALIGNMENT_NOT_SUPPORTED
    /*
     * Hardware does not support non-aligned data transfers, we must verify
     * the request.
     */
    (void) AcpiUtShortDivide ((ACPI_INTEGER) Address, Length, NULL, &Remainder);
    if (Remainder != 0)
    {
        return_ACPI_STATUS (AE_AML_ALIGNMENT);
    }
#endif

    /*
     * Does the request fit into the cached memory mapping?
     * Is 1) Address below the current mapping? OR
     *    2) Address beyond the current mapping?
     */
    if ((Address < MemInfo->MappedPhysicalAddress) ||
        (((ACPI_INTEGER) Address + Length) >
            ((ACPI_INTEGER)
            MemInfo->MappedPhysicalAddress + MemInfo->MappedLength)))
    {
        /*
         * The request cannot be resolved by the current memory mapping;
         * Delete the existing mapping and create a new one.
         */
        if (MemInfo->MappedLength)
        {
            /* Valid mapping, delete it */

            AcpiOsUnmapMemory (MemInfo->MappedLogicalAddress,
                MemInfo->MappedLength);
        }

        /*
         * Don't attempt to map memory beyond the end of the region, and
         * constrain the maximum mapping size to something reasonable.
         */
        WindowSize = (ACPI_SIZE)
            ((MemInfo->Address + MemInfo->Length) - Address);

        if (WindowSize > ACPI_SYSMEM_REGION_WINDOW_SIZE)
        {
            WindowSize = ACPI_SYSMEM_REGION_WINDOW_SIZE;
        }

        /* Create a new mapping starting at the address given */

        MemInfo->MappedLogicalAddress = AcpiOsMapMemory (
            (ACPI_PHYSICAL_ADDRESS) Address, WindowSize);
        if (!MemInfo->MappedLogicalAddress)
        {
//.........這裏部分代碼省略.........

static ACPI_STATUS
OslAddTablesToList(
    void)
{
    ACPI_PHYSICAL_ADDRESS   TableAddress;
    OSL_TABLE_INFO          *Info = NULL;
    OSL_TABLE_INFO          *NewInfo;
    ACPI_TABLE_HEADER       *Table;
    UINT8                   Instance;
    UINT8                   NumberOfTables;
    int                     i;


    /* Initialize the table list on first invocation */

    if (Gbl_TableListInitialized)
    {
        return (AE_OK);
    }

    /* Add mandatory tables to global table list first */

    for (i = 0; i < 4; i++)
    {
        NewInfo = calloc (1, sizeof (*NewInfo));
        if (!NewInfo)
        {
            return (AE_NO_MEMORY);
        }

        switch (i) {
        case 0:

            Gbl_TableListHead = Info = NewInfo;
            continue;

        case 1:

            ACPI_MOVE_NAME (NewInfo->Signature,
                Gbl_Revision ? ACPI_SIG_XSDT : ACPI_SIG_RSDT);
            break;

        case 2:

            ACPI_MOVE_NAME (NewInfo->Signature, ACPI_SIG_FACS);
            break;

        default:

            ACPI_MOVE_NAME (NewInfo->Signature, ACPI_SIG_DSDT);

        }

        Info->Next = NewInfo;
        Info = NewInfo;
        Gbl_TableListHead->Instance++;
    }

    /* Add normal tables from RSDT/XSDT to global list */

    if (Gbl_Revision)
    {
        NumberOfTables =
            (Gbl_Xsdt->Header.Length - sizeof (Gbl_Xsdt->Header))
            / sizeof (Gbl_Xsdt->TableOffsetEntry[0]);
    }
    else
    {
        NumberOfTables =
            (Gbl_Rsdt->Header.Length - sizeof (Gbl_Rsdt->Header))
            / sizeof (Gbl_Rsdt->TableOffsetEntry[0]);
    }

    for (i = 0; i < NumberOfTables; i++)
    {
        if (Gbl_Revision)
        {
            TableAddress = Gbl_Xsdt->TableOffsetEntry[i];
        }
        else
        {
            TableAddress = Gbl_Rsdt->TableOffsetEntry[i];
        }

        Table = AcpiOsMapMemory (TableAddress, sizeof (*Table));
        if (!Table)
        {
            return (AE_BAD_ADDRESS);
        }

        Instance = 0;
        NewInfo = Gbl_TableListHead;
        while (NewInfo->Next != NULL)
        {
            NewInfo = NewInfo->Next;
            if (ACPI_COMPARE_NAME (Table->Signature, NewInfo->Signature))
            {
                Instance++;
            }
        }
//.........這裏部分代碼省略.........

static ACPI_STATUS
OslGetTableViaRoot (
    char                    *Signature,
    UINT32                  Instance,
    ACPI_TABLE_HEADER       **Table,
    ACPI_PHYSICAL_ADDRESS   *Address)
{
    ACPI_TABLE_HEADER       *LocalTable = NULL;
    ACPI_TABLE_HEADER       *MappedTable = NULL;
    UINT8                   NumberOfTables;
    UINT32                  CurrentInstance = 0;
    ACPI_PHYSICAL_ADDRESS   TableAddress = 0;
    ACPI_STATUS             Status;
    UINT32                  i;


    /* DSDT and FACS address must be extracted from the FADT */

    if (ACPI_COMPARE_NAME (Signature, ACPI_SIG_DSDT) ||
        ACPI_COMPARE_NAME (Signature, ACPI_SIG_FACS))
    {
        /*
         * Get the appropriate address, either 32-bit or 64-bit. Be very
         * careful about the FADT length and validate table addresses.
         * Note: The 64-bit addresses have priority.
         */
        if (ACPI_COMPARE_NAME (Signature, ACPI_SIG_DSDT))
        {
            if ((Gbl_Fadt->Header.Length >= MIN_FADT_FOR_XDSDT) &&
                Gbl_Fadt->XDsdt)
            {
                TableAddress = (ACPI_PHYSICAL_ADDRESS) Gbl_Fadt->XDsdt;
            }
            else if ((Gbl_Fadt->Header.Length >= MIN_FADT_FOR_DSDT) &&
                Gbl_Fadt->Dsdt)
            {
                TableAddress = (ACPI_PHYSICAL_ADDRESS) Gbl_Fadt->Dsdt;
            }
        }
        else /* FACS */
        {
            if ((Gbl_Fadt->Header.Length >= MIN_FADT_FOR_XFACS) &&
                Gbl_Fadt->XFacs)
            {
                TableAddress = (ACPI_PHYSICAL_ADDRESS) Gbl_Fadt->XFacs;
            }
            else if ((Gbl_Fadt->Header.Length >= MIN_FADT_FOR_FACS) &&
                Gbl_Fadt->Facs)
            {
                TableAddress = (ACPI_PHYSICAL_ADDRESS) Gbl_Fadt->Facs;
            }
        }
    }
    else /* Case for a normal ACPI table */
    {
        if (Gbl_Revision)
        {
            NumberOfTables =
                (Gbl_Xsdt->Header.Length - sizeof (Gbl_Xsdt->Header))
                / sizeof (Gbl_Xsdt->TableOffsetEntry[0]);
        }
        else /* Use RSDT if XSDT is not available */
        {
            NumberOfTables =
                (Gbl_Rsdt->Header.Length - sizeof (Gbl_Rsdt->Header))
                / sizeof (Gbl_Rsdt->TableOffsetEntry[0]);
        }

        /* Search RSDT/XSDT for the requested table */

        for (i = 0; i < NumberOfTables; i++)
        {
            if (Gbl_Revision)
            {
                TableAddress = Gbl_Xsdt->TableOffsetEntry[i];
            }
            else
            {
                TableAddress = Gbl_Rsdt->TableOffsetEntry[i];
            }

            MappedTable = AcpiOsMapMemory (TableAddress, sizeof (*MappedTable));
            if (!MappedTable)
            {
                return (AE_BAD_ADDRESS);
            }

            /* Does this table match the requested signature? */

            if (ACPI_COMPARE_NAME (MappedTable->Signature, Signature))
            {

                /* Match table instance (for SSDT/UEFI tables) */

                if (CurrentInstance == Instance)
                {
                    AcpiOsUnmapMemory (MappedTable, sizeof (*MappedTable));
                    break;
                }

//.........這裏部分代碼省略.........