Visible to Intel only — GUID: oqw1486507465027
Ixiasoft
Visible to Intel only — GUID: oqw1486507465027
Ixiasoft
5.2.2.10.5. Idle OS Deletion
Deletion of Idles occurs in groups of four OS (when there are two consecutive OS) until the rx_enh_fifo_pfull flag deasserts. Every word—consisting of a lower word (LW) and an upper word (UW)—is checked for whether it can be deleted by looking at both the current and previous words.
For example, the current LW can be deleted if it is Idle and the previous UW is not a Terminate.
Deletable | Case | Word | Previous | Current | Output | |
---|---|---|---|---|---|---|
Lower Word | 1 | UW | !T | X | !T | X |
LW | X | I | X | X | ||
2 | UW | OS | X | OS | X | |
LW | X | OS | X | X | ||
Upper Word | 1 | UW | X | I | X | X |
LW | X | !T | X | !T | ||
2 | UW | X | OS | X | X | |
LW | X | OS | X | OS |
If only one word is deleted, data shifting is necessary because the datapath is two words wide. After two words have been deleted, the FIFO stops writing for one cycle and a synchronous flag (rx_control[8]) appears on the next block of 8-byte data. There is also an asynchronous status signal rx_enh_fifo_del, which does not go through the FIFO.