32-bit configuration bus
64-bit EDMA3 bus
Turbo-decoder coprocessor (TCP2)
REVT/XEVT
generation
CPU
interrupt
generation
TCP2 control
EDMA3 I/F unit Memory block Processing unit
TCP2_INT TCPXEVT TCPREVT
4Standalone(SA)Mode
Standalone(SA)Mode
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Figure3.TCP2BlockDiagram
Table1.FrameSizesforStandalone(SA)Modeand
Shared-Processing(SP)Mode
FrameSize(F)TCP2Mode
40⇐F⇐20730Standalonemode
F>20730Sharedprocessing
Instandalone(SA)mode,theDSPsendsthesystematicandparitydata,andtheinterleavertable.The
TCP2thenworksindependentlyoftheDSP(standalone),iteratesadefinedmaximumnumberoftimes,
andoutputsharddecisiondata.Inthismode,minimumDSPprocessingisrequired.Astoppingcriteria
canbeenabledtoreducetheprocessingdelay(seeSection4.3).Figure4showstheSAmode.
Thestandalonemodeisusedforframesinwhichtheturbointerleaverlengthislessthanorequalto
20730.Inthismode,thesystematic,parities,extrinsics,andturbointerleaverdatafitwithintheTCP2
memory,andseveraliterationsofdecodingarerunwithinthecoprocessorwithoutanyDSPintervention.
TheDSPsetsuptheEDMA3tosendthesystematicandparitydata,andtheinterleavertable(optional).
TheTCP2thenworksindependentlyoftheDSP.
12TMS320C6457Turbo-DecoderCoprocessor2SPRUGK1–March2009
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