Intel
®
81341 and 81342—Application DMA Unit
Intel
®
81341 and 81342 I/O Processors
Developer’s Manual
December 2007
468
Order Number: 315037-002US
Each word in the chain descriptor is analogous to control register values. Bit definitions
for the words in the chain descriptor are the same as for the control registers.
• The first word is the local memory address of the next chain descriptor. A value of
zero specifies the end of the chain. This value is loaded into the ADMA Next
Descriptor Address Register. Because basic chain descriptors must be aligned on an
8-word boundary, the unit may ignore bits 04:00 of this address.
• The second word is the Descriptor Control Word. This word configures the
Application DMA for one operation. This value is loaded into the ADMA Descriptor
Control Register.
• The third word is the CRC Address / Memory Block Fill Data word. When the CRC
operation is enabled, the CRC address is used to load a 32-bit value to seed the
CRC calculation. Also, the CRC address is used as the destination for the write back
of the CRC result. When the Memory Block fill operation is enabled, this Register is
used as the immediate data to fill memory with. This value is loaded into the CRC
Address / Memory Block Fill Data Register.
• The fourth word contains the 24-bit, Byte Count value. This value specifies the
number of bytes of data in the current chain descriptor. Also, the upper byte of this
word is the Transfer Status field that may be written back to the Byte Count Word
at the end of the ADMA transfer when the Status Write Back Enable in the ADCR is
set. This value is loaded into the ADMA Byte Count Register.
• The fifth word is the lower 32-bit destination address The ADMA uses this value for
the lower 32-bits of the destination address for the data transfer operation, the
Memory Block Fill operation, and the XOR-transfer operation. This value is loaded
into the Destination Lower Address Register.
• The sixth word is the upper 32-bit destination address. The ADMA uses this value
for the upper 32-bits of the destination address for the data transfer operation, the
Memory Block Fill operation, and the XOR-transfer operation. This value is loaded
into the Destination Upper Address Register.
• The seventh word is the lower 32-bit source address for the data transfer operation
or the lower 32-bit source address for source 0 of the XOR-transfer operation. This
value is loaded into the Source Lower Address Register 0.
• The eighth word is the upper 32-bit source address for the data transfer operation
or the upper 32-bit source address for source 0 of the XOR-transfer operation. This
value is loaded into the Source Upper Address Register 0.