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Texas Instruments TMS320C645X User Manual

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SRIO Functional Description

Table 17. RX Buffer Descriptor Field Descriptions

Field

Description

next_descriptor_pointer

Next Descriptor Pointer: The 32-bit word aligned memory address of the next buffer
descriptor in the RX queue. This references the next buffer descriptor from the current
buffer descriptor. If the value of this pointer is zero, then the current buffer is the last
buffer in the queue. The host sets the next_descriptor_pointer.

buffer_pointer

Buffer Pointer: The byte aligned memory address of the buffer associated with the
buffer descriptor. The host sets the buffer_pointer.

Sop = 1

Start of Message: Indicates that the descriptor buffer is the first buffer in the message.

This bit will always be set, as this device only supports one buffer per message.

Eop = 1

End of Message: Indicates that the descriptor buffer is the last buffer in the message.

This bit will always be set, as this device only supports one buffer per message.

ownership

Ownership: Indicates ownership of the message and is valid only on sop. This bit is set
by the host and cleared by the port when the message has been transmitted. The host
uses this bit to reclaim buffers.

0: The message is owned by the host

1: The message is owned by the port

eoq

End Of Queue: Set by the port to indicate that the RX queue empty condition exists.
This bit is valid only on eop. The port determines the end of queue condition by a zero
next_descriptor_pointer.

0: The RX queue has more buffers available for reception.

1: The Descriptor buffer is the last buffer in the last message in the queue.

Teardown_Complete

Teardown Complete: Set by the port to indicate that the host commanded teardown
process is complete, and the channel buffers may be reclaimed by the host.

0: The port has not completed the teardown process.

1: The port has completed the commanded teardown process.

message_length

Message Length: Initially written by the CPU to specify the maximum number of
double-words the buffer can receive. Updated by the peripheral (after receiving a
message) to indicate the actual number of double-words in the entire message.
Message payloads are limited to a maximum size of 512 double-words (4096bytes).

000000000b: 512 double words

000000001b: 1 double word

000000010b: 2 double words

. . .

111111111b: 511 double words

Src_id

Source Node ID: Unique node identifier of the source of the message.

tt

RapidIO tt field specifying 8- or 16-bit DeviceIDs

00: 8b deviceIDs

01: 16b deviceIDs

10: reserved

11: reserved

pri

Message Priority: Specifies the SRIO priority at which the message was sent.

cc

Completion Code:

000: Good completion. Message received.

001: Error, RX message length greater than supported buffer descriptor
message_length

010: Error, TimeOut on receiving one of the segments

011: DMA transfer error on one or more segments

100: Queue teardown completed, data invalid

101: 111 Reserved

SPRU976 – March 2006

Serial RapidIO (SRIO)

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