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SRIOFunctionalDescription
Table17.RXBufferDescriptorFieldDescriptions
FieldDescription
next_descriptor_pointerNextDescriptorPointer:The32-bitwordalignedmemoryaddressofthenextbuffer
descriptorintheRXqueue.Thisreferencesthenextbufferdescriptorfromthecurrent
bufferdescriptor.Ifthevalueofthispointeriszero,thenthecurrentbufferisthelast
bufferinthequeue.Thehostsetsthenext_descriptor_pointer.
buffer_pointerBufferPointer:Thebytealignedmemoryaddressofthebufferassociatedwiththe
bufferdescriptor.Thehostsetsthebuffer_pointer.
Sop=1StartofMessage:Indicatesthatthedescriptorbufferisthefirstbufferinthemessage.
•Thisbitwillalwaysbeset,asthisdeviceonlysupportsonebufferpermessage.
Eop=1EndofMessage:Indicatesthatthedescriptorbufferisthelastbufferinthemessage.
•Thisbitwillalwaysbeset,asthisdeviceonlysupportsonebufferpermessage.
ownershipOwnership:Indicatesownershipofthemessageandisvalidonlyonsop.Thisbitisset
bythehostandclearedbytheportwhenthemessagehasbeentransmitted.Thehost
usesthisbittoreclaimbuffers.
0:Themessageisownedbythehost
1:Themessageisownedbytheport
eoqEndOfQueue:SetbytheporttoindicatethattheRXqueueemptyconditionexists.
Thisbitisvalidonlyoneop.Theportdeterminestheendofqueueconditionbyazero
next_descriptor_pointer.
0:TheRXqueuehasmorebuffersavailableforreception.
1:TheDescriptorbufferisthelastbufferinthelastmessageinthequeue.
Teardown_CompleteTeardownComplete:Setbytheporttoindicatethatthehostcommandedteardown
processiscomplete,andthechannelbuffersmaybereclaimedbythehost.
0:Theporthasnotcompletedtheteardownprocess.
1:Theporthascompletedthecommandedteardownprocess.
message_lengthMessageLength:InitiallywrittenbytheCPUtospecifythemaximumnumberof
double-wordsthebuffercanreceive.Updatedbytheperipheral(afterreceivinga
message)toindicatetheactualnumberofdouble-wordsintheentiremessage.
Messagepayloadsarelimitedtoamaximumsizeof512double-words(4096bytes).
000000000b:512doublewords
000000001b:1doubleword
000000010b:2doublewords
...
111111111b:511doublewords
Src_idSourceNodeID:Uniquenodeidentifierofthesourceofthemessage.
ttRapidIOttfieldspecifying8-or16-bitDeviceIDs
00:8bdeviceIDs
01:16bdeviceIDs
10:reserved
11:reserved
priMessagePriority:SpecifiestheSRIOpriorityatwhichthemessagewassent.
ccCompletionCode:
000:Goodcompletion.Messagereceived.
001:Error,RXmessagelengthgreaterthansupportedbufferdescriptor
message_length
010:Error,TimeOutonreceivingoneofthesegments
011:DMAtransfererrorononeormoresegments
100:Queueteardowncompleted,datainvalid
101:111Reserved
SPRU976–March2006SerialRapidIO(SRIO)45
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