Texas Instruments TMS320C6457 DSP manual Sub-block and Sliding Window Segmentation

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Architecture

Data from memory

Figure 95. MAP Unit Block Diagram

	Beta		Beta
	Beta		memory
			memory

Extrinsic


	Scratch		Alpha
	memory

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Extrinsic signals

The TCP2 can enable or disable the max star function by modifying the E_MAX_STAR bit in the TCPIC3 register.

∙E_MAX_STAR = 0 = Enable max star

∙E_MAX_STAR = 1 = Disable max star

Log-map algorithm is implemented in a highly paralleled manner using the sliding window principle. The max-log-map algorithm is implemented with apriori scaled prior to the map decoder.

8.1Sub-block and Sliding Window Segmentation

The MAP unit splits the frame (in standalone mode) or the sub-frame (in shared processing mode) into sub-blocks.

If the size of the frame is n and the number of states in the encoder trellis is S, then beta states must be stored in the beta memory. To reduce the amount of memory required to store the beta states, the sliding window technique is used. This technique divides the frame size n into several smaller pieces of size r (reliability section). Because the starting state is unknown, a prolog section is added. The initial state of the starting location of the prolog section is unknown. After processing the prolog states and the constraint length, the values of the last prolog states have a high probability of being in the same states as if the states were known from the start. Each sub-block consists of 1or 2 sliding windows. Each sliding window consists of three portions:

∙Alpha prolog portion

∙Reliability portion

∙Beta Prolog portion

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TMS320C6457 Turbo-Decoder Coprocessor 2

SPRUGK1–March 2009

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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 About This Manual Notational ConventionsRelated Documentation From Texas Instruments TrademarksFeatures TMS320C6457 Turbo-Decoder CoprocessorGPP and IS2000 Turbo-Encoder Block Diagram IntroductionGPP and IS2000 Turbo-Decoder Block Diagram OverviewStandalone SA Mode TCP2 ModeInput Data Format Systematic and Parity DataRsvd SP9 SP8 SP7 SP6 SP5 SP4 SP3 SP2 SP1 SP0 SP9 SP8 SP7 SP6 SP5 SP4 SP3 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 Output Decision Data Format Stopping CriteriaInterleaver Indexes Interleaver DataStopping Test Unit SNR Threshold TerminationCRC Termination Shared-Processing SP Mode Parameter TerminationMaximum 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 Registers TCP2 RegistersTCP2 RAMs NameRegisters Peripheral Identification Register PID Peripheral Identification Register PID Field DescriptionsBit Field DescriptionTCP2 Input Configuration Register 0 TCPIC0 Bit Field Value DescriptionTCP2 Input Configuration Register 1 TCPIC1 TCP2 Input Configuration Register 2 TCPIC2SNR MaxitTCP2 Input Configuration Register 3 TCPIC3 TCP2 Input Configuration Register 4 TCPIC4 CrciterpassCrclen TCP2 Input Configuration Register 5 TCPIC5 Tail SymbolsCRC Examples CrcpolyTCP2 Input Configuration Register 6 TCPIC6 TAIL110 TCP2 Input Configuration Register 7 TCPIC7 TAIL211 TCP2 Input Configuration Register 8 TCPIC8 TAIL312 TCP2 Input Configuration Register 9 TCPIC9 TAIL413 TCP2 Input Configuration Register 10 TCPIC10 14 TCP2 Input Configuration Register 11 TCPIC11TAIL5 TCP2 Input Configuration Register 11 TCPIC11 15 TCP2 Input Configuration Register 12 TCPIC12 16 TCP2 Input Configuration Register 13 TCPIC13EXTSCALE03 EXTSCALE4717 TCP2 Input Configuration Register 14 TCPIC14 EXTSCALE81118 TCP2 Input Configuration Register 15 TCPIC15 Extrinsic Scale RegistersEXTSCALE1215 Iteration Number19 TCP2 Output Parameter Register 0 TCPOUT0 20 TCP2 Output Parameter Register 1 TCPOUT1TCP2 Output Parameter Register 0 TCPOUT0 Field Descriptions TCP2 Output Parameter Register 1 TCPOUT1 Field Descriptions21 TCP2 Output Parameter Register 2 TCPOUT2 22 TCP2 Execution Register TcpexeTCP2 Output Parameter Register 2 TCPOUT2 Field Descriptions TCP2 Execution Register Tcpexe Field Descriptions23 TCP2 Endian Register Tcpend TCP2 Endian Register Tcpend Field DescriptionsEndian Extr Intr Endianextr24 TCP2 Error Register Tcperr TCP2 Error Register Tcperr Field DescriptionsSubframe length 25 TCP2 Status Register Tcpstat TCP2 Status Register Tcpstat Field DescriptionsTcpstate Waiting for RAM extrinsic memory 0 to be read 26 TCP2 Emulation Register Tcpemu TCP2 Emulation Register Tcpemu Field DescriptionsSoft = Soft FreeEndianness Data Memory for SystematicData Memory 6362 6156 5550 4944 4338 3732 3130 2924 2318 1712 116EN = 0 Big-Endian Mode Rate = 1/4 EN = 0 Big-Endian Mode Rate = 3/4 Hard Decision DataHard Decisions in DSP Memory Tcpendian Register for Endianness ManagerData HD1 HD0Tcpendian Programming Register Endianintr =Interleaver Indexes in DSP Memory Data Native Format DSP Memory FormatINTER0 INTER1 INTER2 INTER3 INTER3 INTER2 INTER1 INTER0Extrinsic 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 MAP Unit Block Diagram Sub-block and Sliding Window SegmentationSubframe Segmentation SP mode only Examples for NUMBLOCK, NUMSUBBLOCK, NUMSW, and WinrelReliability and Prolog Length Calculation Added Features Code RatesValid Re-Encode Symbols Used for Comparison ProgrammingInput Sign Log EquationEDMA3 Parameters in Standalone SA Mode EDMA3 Parameters in Shared Processing SP ModeEDMA3 Resources 1 TCP2 Dedicated EDMA3 ResourcesProgramming Standalone SA Mode Input Configuration Parameters TransferEDMA3 Programming Systematics and Parities TransferInterleaver Indexes Transfer Hard-Decisions Transfer Input Configurations Parameters Programming Output Parameters TransferProgramming Shared-Processing SP Mode Opmod TCPIC0Inter TCPIC0 Outf TCPIC0Input Configuration Parameters Transfer Priori Transfer Extrinsics Transfer Output Parameters Events GenerationInter TCPIC0 Inter = Outf Debug Mode Pause After Each Map Errors and StatusErrors Error Status ERRUnexpected Signal to Noise Ratio SNR Unexpected Memory Access ACCUnexpected Frame Length F Unexpected Prolog Length PStatus 13.2.12 TCP2 Active State Status Activestate 13.2.13 TCP2 Active Iteration Status Activeiter13.2.14 TCP2 SNR Status snrexceed 13.2.15 TCP2 CRC Status CrcpassProducts Applications DSPRfid