DS537 Datasheet, PDF (75/148 Pages) Xilinx, Inc – LogiCORE IP XPS LL TEMAC

LogiCORE IP XPS LL TEMAC (v2.03a)
These DMA cores are designed to operate with many LocalLink cores in addition to the XPS_LL_TEMAC so their
documents are necessarily general and do not make reference specifically to the data used for TCP/ IP Checksum
Off load. This document will briefly show the mapping between how these two core’s data maps to the fields in the
LocalLink for the purposes of TCP / IP Checksum Off load.
Please note that the information that follows is specific to these two core’s implementation at the time that this
document is written and that the implementation may change in the future. If the implementation of these two
cores does change, this data sheet will not necessarily be updated to show the new implementation.
These DMA cores use registers to point to data areas in external memory called Buffer Descriptors. The Buffer
Descriptors are eight 32-bit words in external memory and contain DMA operation control information, pointers to
other areas of external memory which contain data to move (DMA) which are called Data Buffers, and generic
Application Defined words which map to header and footer fields of the LocalLink bus.
Figure 48 shows the mapping between the DMA Buffer Descriptor words in external memory and the fields in the
LocalLink bus for the transmit case and Figure 49 shows the mapping for the receive case.
X-Ref Target - Figure 48
DMA Core Register
CURDESC_PTR
register value
Buffer Descriptors
in external memory
NXTDESC_PTR
CURBUF_ADDR
CURBUF_LENGTH
STS_CTRL_APP0
APP1
APP2
APP3
APP4
Data Buffer
in external memory
Data
NXTDESC_PTR
CURBUF_ADDR
CURBUF_LENGTH
STS_CTRL_APP0
APP1
APP2
APP3
APP4
Data Buffer
in external memory
Data
Unused
0x0
LlinkTemac_CLK
LlinkTemac_Data(0:31)
Header
Payload (variable) FTR
He_{adeHr WeaodredHr0WeaodredHr1WeaodredHr2WeaodredHr3We-aoTdrXedHr_4WCe-aSoTdCrXedNHr_5TWCe-RaSoTdLBrXedEr_6GWCISoNIrNd&I7TTX_PCaySloINaSdEWRoTrds} Footer _{Word 0}
DS537_48_091909
Figure 48: Transmit DMA Buffer Descriptor LocalLink Field Mapping
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