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IBM2520L8767
IBM Processor for ATM Resources
Packet Header
Page 50 of 553
atmrm.chapt03.01
08/27/99
Monitor_sequence_number
This eight-bit field contains the Monitor Sequence Number that is used to construct the hardware gen-
erated OAM cells. After initialization, this field should only be accessed by the hardware.
OAM_cell_transmitted
This one-bit field contains a flag indicating that an OAM cell has been sent. After initialization, this field
should only be accessed by the hardware.
Previous_PCR_bits_17_16
This two-bit field contains bits 17 and 16 of the PCR in the most recently segmented MPEG transport
stream packet. After initialization, this field should only be accessed by the hardware.
OAM_PTI_bit0 #
This one-bit field is copied directly to the low bit of the payload type field in the ATM header as the seg-
mentation logic is building an OAM cell.
Previous packet contained
PCR
This one-bit field is used during MPEG processing by the hardware to indicate that a previous transport
stream packet contained a PCR. After initialization, this field should only be accessed by the hardware.
OAM_CLP_value #
This one-bit field can be used to provide the value for the CLP bit in the hardware generated OAM cells.
If the OAM_CLP_source bit elsewhere in the LCD is in the correct state, this bit will be copied directly to
the CLP bit in the ATM header of the OAM cell.
OAM_block_size #
This two-bit field defines the number of user cells that are sent between OAM cells.
00 = 128 cells
01 = 256 cells
10 = 512 cells
11 = 1024 cells
Current_Blocking_Count
This eight-bit field contains the current count of four-byte values that have been assembled into cells
and sent out on this LCD for all fix block or MPEG AAL types. Other than initialization, this field should
only be accessed by the hardware.
Fixed_Blocking_size #
This eight-bit field should be initialized by the software to contain the number of four-byte values that
constitute a packet. For MPEG2 this register should be set to x’47’ (4
x’47’ = 188 byte transport stream
packet).
PID_field_is_valid
When set, this one-bit field indicates that the PID field in the LCD contains a valid PID. After initializa-
tion, this field should only be accessed by the hardware.
PID_bits_12_11
This two-bit field contains bits 12 and 11 of the previously saved PID. After initialization, this field
should only be accessed by the hardware.
Current_transport_stream_pac
ket
This five-bit field contains the number of the current transport stream packet that is being segmented.
After initialization, this field should only be accessed by the hardware.
Check_PCR
This one-bit field is set when the segmentation hardware has determined that it is time to check and
delay a cell if the PCR indicates. Other than initialization, this field should only be accessed by the
hardware.
PCR_present
This one-bit field is set by the hardware to indicate that the current transport stream packet contained a
PCR. Other than initialization, this field should only be accessed by the hardware.
PID_matches
This one-bit field is set by the hardware to indicate that the PID in the transport stream being seg-
mented matches the PID which was previously locked on.
Packets_per_AAL5_frame #
This five-bit field should be initialized by the software to indicate how many packets should be concate-
nated into an AAL5 frame.
previous_PCR_bits_15_0
This 16-bit field contains the least significant 16 bits of the last PCR that has been encountered. After
initialization, this field should only be accessed by the hardware.
PID_bits_10_0
This two-bit field contains bits 10 - 0 of the previously saved PID. After initialization, this field should
only be accessed by the hardware.
ABR Code Variables Definitions
(Page 5 of 7)
Field Name
Field Description