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PM7380-PI 参数 Datasheet PDF下载

PM7380-PI图片预览
型号: PM7380-PI
PDF下载: 下载PDF文件 查看货源
内容描述: 帧引擎和数据链路管理32P672 [FRAME ENGINE AND DATA LINK MANAGER 32P672]
分类和应用:
文件页数/大小: 332 页 / 2479 K
品牌: PMC [ PMC-SIERRA, INC ]
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RELEASED  
PM7380 FREEDM-32P672  
DATA SHEET  
PMC-1990262  
ISSUE 5  
FRAME ENGINE AND DATA LINK MANAGER 32P672  
Table 10 – Transmit Descriptor Reference  
Bit 17  
Bit 0  
STATUS[2:0]  
TDR[14:0]  
Field  
Description  
Status[2:0]  
The TMAC672 fills in the Status field to indicate to the  
host the results of processing the TD. The encoding is:  
Status[1:0] Description  
00  
01  
10  
11  
Last or only buffer of packet, buffer read.  
Buffer of partial packet, buffer read.  
Unprovisioned channel, buffer not read.  
Malformed packet (e.g. Bytes In Buffer field  
set to 0), buffer not read.  
Status[2]  
Description  
0
No underflow detected.  
1
Underflow detected.  
TDR[14:0]  
The TDR[14:0] field contains the offset of the TD  
returned.  
If a TDR is returned to the host with the status field set to “10” (unprovisioned  
channel), the TDR may point to a binary tree of TDs and buffers (as indicated by  
the CE and V bits in the TDs). It is the responsibility of the host to traverse the  
tree to reclaim all the buffers. If a TDR is returned to the host with the status  
field set to any other value, the TDR will only point to one TD and buffer  
regardless of the values of V and CE in that TD.  
The underflow status bit (Status[2]) is normally attached to the TDR belonging to  
a packet experiencing underflow. For long packets spanning multiple buffers,  
underflow is reported only once at the first available TDR of that channel. All  
subsequent TDRs of that packet will be returned normally without the underflow  
status. In rare cases, due to internal buffering by the FREEDM-32P672, a  
packet may experience underflow at the very end of a packet, just as the TDR is  
being returned to the TDR free queue. The underflow status will then be  
reported in the first TDR of the immediate next packet of that channel. Because  
of the uncertainty with the reporting of underflows between the current verse the  
subsequent packet, the underflow status should only be used to gather  
performance statistics on channels and not for initiating packet specific  
responses such as retransmission.  
PROPRIETARY AND CONFIDENTIAL TO PMC-SIERRA,INC., AND FOR ITS CUSTOMERS’ INTERNAL USE  
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