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BitFields
next_descriptor_pointer
buffer_pointer
dest_id pri
tt
ssize mailbox
port_id
Word
Offset
SRIOFunctionalDescription
Table20.TXDMAStateCompletionPointer(CP)(AddressOffset58h–5BCh)
BitNameDescription
31–0TXQueueTXQueueCompletionPointer:ThisfieldistheDSPcorememoryaddressforthetransmitqueue
CompletionPointercompletionpointer.ThisregisteriswrittenbytheDSPcorewiththebufferdescriptoraddressfor
thelastbufferprocessedbytheDSPcoreduringinterruptprocessing.Theportusesthevalue
writtentodetermineiftheinterruptshouldbedeasserted.
Figure22.TXBufferDescriptorFields
Table21.TXBufferDescriptorFieldDefinitions
FieldDescription
next_descriptor_pointerNextDescriptorPointer:The32-bitwordalignedmemoryaddressofthenextbuffer
descriptorintheTXqueue.Thisisthemechanismusedtoreferencethenextbuffer
descriptorfromthecurrentbufferdescriptor.Ifthevalueofthispointeriszerothenthe
currentbufferisthelastbufferinthequeue.TheDSPcoresetsthe
next_descriptor_pointer.
buffer_pointerBufferPointer:Thebytealignedmemoryaddressofthebufferassociatedwiththe
bufferdescriptor.TheDSPcoresetsthebuffer_pointer.
sop=1StartofMessage:Indicatesthatthedescriptorbufferisthefirstbufferinthemessage.
•Thisbitwillalwaysbesetasthisdeviceonlysupportsonebufferpermessage.
eop=1EndofMessage:Indicatesthatthedescriptorbufferisthelastbufferinthemessage.
•Thisbitwillalwaysbesetasthisdeviceonlysupportsonebufferpermessage.
ownershipOwnership:Indicatesownershipofthemessageandisvalidonlyonsop.Thisbitisset
bytheDSPcoreandclearedbytheportwhenthemessagehasbeentransmitted.The
DSPcoreusesthisbittoreclaimbuffers.
0:ThemessageisownedbytheDSPcore
1:Themessageisownedbytheport
eoqEndOfQueue:Setbytheporttoindicatethatallmessagesinthequeuehavebeen
transmittedandtheTXqueueisempty.Endofqueueisdeterminedbytheportwhen
thenext_descriptor_pointeriszeroonaneopbuffer.Thisbitisvalidonlyoneop.
0:TheTXqueuehasmoremessagestotransfer.
1:TheDescriptorbufferisthelastbufferinthelastmessageinthequeue.
teardown_completeTeardownComplete:SetbytheporttoindicatethattheDSPcorecommanded
teardownprocessiscomplete,andthechannelbuffersmaybereclaimedbytheDSP
core.
0:Theporthasnotcompletedtheteardownprocess.
1:Theporthascompletedthecommandedteardownprocess.
52SerialRapidIO(SRIO)SPRUE13A–September2006
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