Altera Arria V Hard IP for PCI Express - Manual (Page 235)

Chapter 17: Testbench and Design Example 17–13
Chaining DMA Design Examples
December 2013 Altera Corporation Arria V Hard IP for PCI Express
User Guide
1 Note that the chaining DMA descriptor table should not cross a 4 KByte boundary.
Table 17–8 shows the layout of the descriptor fields following the descriptor header.
Table 17–9 shows the layout of the control fields of the chaining DMA descriptor.
Table 17–7. Chaining DMA Descriptor Table
Byte Address Offset to
Base Source
Descriptor Type Description
0x0
Descriptor Header
Reserved
0x4 Reserved
0x8 Reserved
0xC
EPLAST - when enabled by the EPLAST_ENA bit
in the control register or descriptor, this location
records the number of the last descriptor
completed by the chaining DMA module.
0x10
Descriptor 0
Control fields, DMA length
0x14 Endpoint address
0x18 RC address upper dword
0x1C RC address lower dword
0x20
Descriptor 1
Control fields, DMA length
0x24 Endpoint address
0x28 RC address upper dword
0x2C RC address lower dword
. . .
0x ..0
Descriptor
Control fields, DMA length
0x ..4 Endpoint address
0x ..8 RC address upper dword
0x ..C RC address lower dword
Table 17–8. Chaining DMA Descriptor Format Map
3122 21 16 150
Reserved Control Fields (refer to Table 17–9 ) DMA Length
Endpoint Address
RC Address Upper DWORD
RC Address Lower DWORD
Table 17–9. Chaining DMA Descriptor Format Map (Control Fields)
2118 17 16
Reserved EPLAST_ENA MSI