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Shared-Processing (SP) Mode

Each sub-frame is independent of each other. There are three types of sub-frames. The first sub-frame starts the trellis from the zero state. The last sub-frame ends the trellis from a known state. The remaining middle subframes do not start or end from a known state.

The EDMA3 transfers ACNT*BCNT number of bytes in A-Sync Mode and ACNT*BCNT*CCNT number of bytes in AB-Sync Mode. The total number of bytes for both modes should be a multiple of 8. Also, the starting address of the first sub-frame that the EDMA3 will transfer needs to be memory-mapped.

In the shared processing mode:

∙Prolog length must be multiples of 8

∙Starting address for reading extrinsic RAM must be:

RAM base address + middle and last subframes prolog length

∙CRC is turned off

∙SNR is turned off

∙Prolog reduction is turned off

∙Extrinsic scaling is turned off

The turbo decoding of the full frame is performed in several steps as described below:

∙The EDMA3 sends the input buffers for one sub-frame (the MAP0 inputs are described in Figure 19).

∙The TCP2 performs the MAP0 for the current sub-frame.

∙The EDMA3 reads the MAP output (extrinsic) of the current sub-frame and writes it into the DSP memory.

The steps for the MAP0 process are repeated for all the other sub-frames.

Once all the sub-frames MAP0 have been computed, the full MAP0 extrinsic (= apriori 1) is then available. This allows the DSP to interleave the extrinsic output 1 to prepare the next MAP (= MAP1). Once this interleaving is done, the same process is applied, in MAP1 configuration:

∙The EDMA3 sends the input buffers for one sub-frame (the MAP0 inputs are described in Figure 19).

∙The TCP2 performs the MAP1 for the current sub-frame

∙The EDMA3 reads the MAP output (extrinsic) of the current sub-frame and writes it into the DSP memory.

The steps for the MAP1 process are repeated for all the other sub-frames.

Once all the sub-frames MAP1 have been computed, the full extrinsic (=apriori 2) is then available. This allows the DSP to de-interleave the extrinsic output 2 to prepare the next MAP (=MAP0). Once this de-interleaving is done, the same process is applied, in MAP0 configuration. Steps 1-4 are then repeated for all iterations. The DSP is in charge of any stopping criteria algorithm implementation and computing the final hard decisions. Figure 19 shows a description of the TCP2 processing unit functional block diagram in shared processing mode.

SPRUGK1–March 2009

TMS320C6457 Turbo-Decoder Coprocessor 2

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Contents Users Guide Submit Documentation Feedback Contents Added Features Programming EDMA3 Resources List of Figures Destination of Endianness Manager Outorder = List of Tables Notational Conventions About This ManualRelated Documentation From Texas Instruments TrademarksTMS320C6457 Turbo-Decoder Coprocessor FeaturesIntroduction GPP and IS2000 Turbo-Encoder Block DiagramOverview GPP and IS2000 Turbo-Decoder Block DiagramTCP2 Mode Standalone SA ModeSystematic and Parity Data Input Data FormatSP9 SP8 SP7 SP6 SP5 SP4 SP3 SP0 Rsvd SP9 SP8 SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0SP4 SP3 SP2 SP1 SP0 SP9 SP8 SP7 SP6 SP5 SP9 SP8 SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0EN = 0 Big-Endian Mode Rate = 1/4 Stopping Criteria Output Decision Data FormatInterleaver Indexes Interleaver DataStopping Test Unit SNR Threshold TerminationCRC Termination Parameter Termination Shared-Processing SP ModeMaximum Iterations Minimum IterationsShared-Processing SP Mode Block Diagram Subframe Equations Submit Documentation Feedback TCP2 Shared Processing Block Diagram EN = 1 Little-Endian Mode Rate = 1/3 Output Data Format Priori DataRsvd AP4 AP3 AP2 AP1 AP0 AP9 AP8 AP7 AP6 AP5 TCP2 Registers RegistersTCP2 RAMs NameRegisters Peripheral Identification Register PID Field Descriptions Peripheral Identification Register PIDBit Field DescriptionBit Field Value Description TCP2 Input Configuration Register 0 TCPIC0TCP2 Input Configuration Register 2 TCPIC2 TCP2 Input Configuration Register 1 TCPIC1SNR MaxitTCP2 Input Configuration Register 3 TCPIC3 TCP2 Input Configuration Register 4 TCPIC4 CrciterpassCrclen Tail Symbols TCP2 Input Configuration Register 5 TCPIC5CRC Examples CrcpolyTAIL1 TCP2 Input Configuration Register 6 TCPIC6TAIL2 10 TCP2 Input Configuration Register 7 TCPIC7TAIL3 11 TCP2 Input Configuration Register 8 TCPIC8TAIL4 12 TCP2 Input Configuration Register 9 TCPIC913 TCP2 Input Configuration Register 10 TCPIC10 14 TCP2 Input Configuration Register 11 TCPIC11TAIL5 TCP2 Input Configuration Register 11 TCPIC11 16 TCP2 Input Configuration Register 13 TCPIC13 15 TCP2 Input Configuration Register 12 TCPIC12EXTSCALE03 EXTSCALE47EXTSCALE811 17 TCP2 Input Configuration Register 14 TCPIC14Extrinsic Scale Registers 18 TCP2 Input Configuration Register 15 TCPIC15EXTSCALE1215 Iteration Number20 TCP2 Output Parameter Register 1 TCPOUT1 19 TCP2 Output Parameter Register 0 TCPOUT0TCP2 Output Parameter Register 0 TCPOUT0 Field Descriptions TCP2 Output Parameter Register 1 TCPOUT1 Field Descriptions22 TCP2 Execution Register Tcpexe 21 TCP2 Output Parameter Register 2 TCPOUT2TCP2 Output Parameter Register 2 TCPOUT2 Field Descriptions TCP2 Execution Register Tcpexe Field DescriptionsTCP2 Endian Register Tcpend Field Descriptions 23 TCP2 Endian Register TcpendEndian Extr Intr EndianextrTCP2 Error Register Tcperr Field Descriptions 24 TCP2 Error Register TcperrSubframe length 25 TCP2 Status Register Tcpstat TCP2 Status Register Tcpstat Field DescriptionsTcpstate Waiting for RAM extrinsic memory 0 to be read TCP2 Emulation Register Tcpemu Field Descriptions 26 TCP2 Emulation Register TcpemuSoft = Soft FreeData Memory for Systematic Endianness6362 6156 5550 4944 4338 3732 3130 2924 2318 1712 116 Data MemoryEN = 0 Big-Endian Mode Rate = 1/4 Hard Decision Data EN = 0 Big-Endian Mode Rate = 3/4Tcpendian Register for Endianness Manager Hard Decisions in DSP MemoryData HD1 HD0Endianintr = Tcpendian Programming RegisterInterleaver Indexes in DSP Memory Data Native Format DSP Memory FormatINTER3 INTER2 INTER1 INTER0 INTER0 INTER1 INTER2 INTER3Extrinsic Data Endianextr =Extrinsic in DSP Memory Endianextr = Data Source Kernel Endianextr = Architecture EXT7 EXT6 EXT5 EXT4 EXT3 EXT2 EXT1 EXT0EXT3 EXT2 EXT1 EXT0 EXT7 EXT6 EXT5 EXT4 Sub-block and Sliding Window Segmentation MAP Unit Block DiagramExamples for NUMBLOCK, NUMSUBBLOCK, NUMSW, and Winrel Subframe Segmentation SP mode onlyReliability and Prolog Length Calculation Code Rates Added FeaturesProgramming Valid Re-Encode Symbols Used for ComparisonInput Sign Log EquationEDMA3 Parameters in Shared Processing SP Mode EDMA3 Parameters in Standalone SA ModeEDMA3 Resources 1 TCP2 Dedicated EDMA3 ResourcesInput Configuration Parameters Transfer Programming Standalone SA ModeEDMA3 Programming Systematics and Parities TransferInterleaver Indexes Transfer Hard-Decisions Transfer Output Parameters Transfer Input Configurations Parameters ProgrammingOpmod TCPIC0 Programming Shared-Processing SP ModeInter TCPIC0 Outf TCPIC0Input Configuration Parameters Transfer Priori Transfer Extrinsics Transfer Output Parameters Events GenerationInter TCPIC0 Inter = Outf Errors and Status Debug Mode Pause After Each MapErrors Error Status ERRUnexpected Memory Access ACC Unexpected Signal to Noise Ratio SNRUnexpected Frame Length F Unexpected Prolog Length PStatus 13.2.13 TCP2 Active Iteration Status Activeiter 13.2.12 TCP2 Active State Status Activestate13.2.14 TCP2 SNR Status snrexceed 13.2.15 TCP2 CRC Status CrcpassProducts Applications DSPRfid
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