Sundance Technology
BIT | BIT NAME |
22..21 | Reserved |
23DribbleBits
24RxDMAOverflow
27..25 | Reserved |
28ImpliedBufferEn- able
31..29 | Reserved |
ST201 |
| PRELIMINARY draft 2 |
|
BIT DESCRIPTION
Reserved for future use. Should be set to 0.
Indicates that the frame had accompanying dribble bits. This bit is informational only, and does not indicate a frame error.
Indicates that the RFD had insufficient buffer space for the frame data and there were still data left to be transferred by RxDMA when the ST201 ran out of fragment space. The ST201 will transfer what it can into the buffers provided, discard the remainder of the frame and set this bit.
Reserved for future use. Should be set to 0.
This bit enables a special RxDMA mode. Setting this bit instructs the ST201 not to fetch any RxDMAFragAddr/RxDMAFragLen entries from this RFD. Instead, the ST201 assumes there is one receive buffer of length 1528 bytes, starting immediately after ReceiveFrameStatus at (RFD address + 8).
The host system sets this bit when it prepares the RFD. The ST201 tests this bit before RxDMA a frame, at the same time it tests the RxD- MAComplete bit. When the ST201 updates ReceiveFrameStatus at the end of the RxDMA operation (in order to set RxDMAComplete), the value written to ImpliedBufferEnable is undefined. A driver cannot assume a certain value is left in this bit after the RFD is used. There- fore, the driver must write the desired value to this bit every time it releases a RFD to the ST201. This mode of operation reduces the number of information fetches by the ST201, and is intended for server applications in which frames are received into a ring of maximum frame sized buffers.
Reserved for future use. Should be set to 0.
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