DSP-2835-教程-附录3-DSP汇编语言

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TechnicalTrainingOrganizationT

TOAppendixCTMS320C28x™MCUWorkshopLearningObjectivesPerformsimpleprogramcontrolusingbranchandconditionalcodesWriteC28xcodetoperformbasicarithmeticUsethemultipliertoimplementsum-of-productsequationsUsetheRPTinstruction(repeat)tooptimizeloopsUseMACforlongsum-of-productsEfficientlytransferthecontentsofoneareaofmemorytoanotherExamineread-modify-writeoperationsProgramControlALU/MultiplyOperationsDataMoveLogicalOperationsSpecialInstructionsBranchTypesandRangeBranchoffset+/-32K2-word

instructionLongBranchabsolute4M2-word

instructionPCShortBranch

offset+127/-128

1-wordinstructionProgramMemory0x0000000x3FFFFF3BranchTypesProgramControl-BranchesFunctionShortBranch

SB 8bit,cond 7/4 1FastShortBranch

SBF 8bit,EQ|NEQ|TC|NTC 4/4 1FastRelativeBranch

B 16bit,cond 7/4 2FastBranch

BF 16bit,cond 4/4 2AbsoluteBranch

LB 22bit 4 2DynamicBranch

LB *XAR7 4 1BranchonAR

BANZ 16bit,ARn-- 4/2 2Branchoncompare BAR 16bit,ARn,ARn,EQ|NEQ 4/2 2TheassemblerwilloptimizeBtoSBifpossibleNEQEQGTGEQLTLEQHIHIS(C)LO(NC)LOSNOVOVNTCTCUNCNBIOConditionCodeInstructionCyclesT/FSizeConditionflagsaresetontheprioruseoftheALUProgramControl-Call/ReturnFunctionCallCodeCall LCR 22bit 4 LRETR 4DynamicCall LCR *XARn 4 LRETR 4InterruptReturn

IRET 8CyclesReturncodeCyclesMoreCallvariationsintheuserguideareforcodebackwardcompatibilityStackLocal

VarRPCOldRPCPCFuncLCRFuncLRETRRPC22-bitoldRetAddrRetAddrNewRPCBANZLoopControlExamplelen.set5x .usect“samp”,6y .set(x+len) .sect“code” MOVLXAR2,#x MOVAR3,#len-2 MOVAL,*XAR2++sum: ADDAL,*XAR2++ BANZ sum,AR3-- MOV*(0:y),ALAR3COUNTDatax0x1x2x3x4xyXAR2AuxiliaryregisterusedasloopcounterBranchifAuxiliaryRegisternotzeroTestperformedonlower16-bitsofXARxonlyProgramControlALU/MultiplyOperationsDataMoveLogicalOperationsSpecialInstructionsALUandAccumulatorALUandBarrelShifterACCAH(31-16)AL(15-0)AH.MSBAH.LSBAL.MSBAL.LSB16/32datamem,16/32bitregistersProduct(32)MUXST0,ST18/16ImmAccumulator-BasicMathInstructionsMOV Ax,loc16ADD Ax,loc16SUB Ax,loc16AND Ax,loc16OR Ax,loc16XOR Ax,loc16AND Ax,loc16,#16bNOT AxNEG AxMOV loc16,AxAx=AHorALOperationsxxxAx,#16b;wordxxxBAx,#8b;bytexxxL ACC,#32b;longxxx=instruction:MOV,ADD,SUB,...

Ax=AH,orAL

Assemblerwillautomaticallyconvertto1wordinstruction.TwowordinstructionswithshiftoptionOnewordinstruction,noshiftADDACC,#01234h<<4ADDBAL,#34hACCOperationsMOV ACC,loc16<<shiftADD SUB }frommemory(leftshiftoptional)MOV ACC,#16b<<shiftADDSUB }16-bitconstant(leftshiftoptional)MOV loc16,ACC<<shift;ALMOVH loc16,ACC<<shift;AHFormatExVariationShifttheAccumulatorShiftfullACCLSL ACC<<shiftSFR ACC>>shiftLSL ACC<<TSFR ACC>>TACC31………0SFRACC31………0LSL0CCSXMShiftALorAHLSL AX<<TLSR AX<<TASR AX>>TLSL AX<<shift

LSR AX<<shiftASR AX>>shiftAx15………0ASRAx15………0LSL0CCSXMAx15………0LSRC0(1-16)(0-15)32BitShiftOperations[ACC]ACC31………00CExamples:LSLL ACC,TLSRL ACC,T

ASRL ACC,TACC31………0C0or1ACC31………0C0Note:T(4:0)areused;otherbitsareignoredbasedonSXMLogicalShiftLeft–Long:LSLLLogicalShiftRight–Long:LSRLArithmeticShiftRight–Long:ASRLMultiplyUnitPRegister(32)ACC(32)Shift(PM)32x32MultiplyUnit16x16DataMem

orRegister

ProgMem(16)orImmed(8,16)XTRegister

MUXTRegisterMultiplierInstructions

Instruction Execution Purpose MOV T,loc16 T=loc16 GetfirstoperandMPY ACC,T,loc16 ACC=T*loc16 ForsingleorfirstproductMPY P,T,loc16 P=T*loc16 FornthproductMPYB ACC,T,#8bu ACC=T*8bu Using8-bitunsignedconstMPYB P,T,#8bu P=T*8bu Using8-bitunsignedconstMOV ACC,P ACC=P Move1stproduct<<PMtoACCADD ACC,P ACC+=P Addnthproduct<<PMtoACCSUB ACC,P ACC-=P Subnthproduct<<PMfr.ACCInstructionMPYA P,T,#16b ACC+=P<<PM then P=T*#16bMPYA P,T,loc16 ACC+=P<<PM then P=T*loc16MPYS P,T,loc16 ACC-=P<<PM then P=T*loc16ExecutionMOVP T,loc16 ACC=P<<PM T=loc16MOVA T,loc16 ACC+=P<<PM T=loc16

MOVS T,loc16 ACC-=P<<PM T=loc16Sum-of-ProductsZAPA ;ACC=P=OVC=0MOV T,@X1;T=X1MPY P,T,@A;P=A*X1MOVA T,@X2;T=X2;ACC=A*X1MPY P,T,@B;P=B*X2MOVA T,@X3 ;T=X3;ACC=A*X1+B*X2MPY P,T,@C;P=C*X3MOVA T,@X4;T=X4;ACC=A*X1+B*X2+C*X3MPY P,T,@D;P=D*X4ADDLACC,P<<PM;ACC=YMOVL@y,ACC Y=A*X1+B*X2+C*X3+D*X432x32LongMultiplicationIMPYAL P,XT,loc32 P=u(XT)*u(loc32)QMPYAL ACC,XT,loc32 ACC=(XT)*(loc32)XYXXO

*

Y0Z1Z0IMACL P,loc32,*XAR7 ACC+=P;P=u(loc32)*u(loc32)QMACL P,loc32,*XAR7 ACC+=P;P=(loc32)*(loc32)Integerlongmultiplicationu(long)=u(long)*u(long)Fractionlongmultiplication:

(long)=(long)*(long)(long)64=(long)32*(long)32Y1*X1Z3Z2AccumulatorP-registerRepeatNext:RPTFeatures:NextinstructioniteratedN+1timesSavescodespace-1word Lowoverhead-1cycleEasytouseNon-interruptibleRequiresuseof||beforenextlineMaybenestedwithinBANZloopsOptions:RPT#8bit upto256iterationsRPTloc16 location“loc16”holdscountvalueInstruction CyclesRPTBANZ14.NExample:intx[5]={0,0,0,0,0};x .usect“samp”,5 MOV AR1,#x RPT #4|| MOV *XAR1++,#0RefertoUserGuideformorerepeatableinstructionsSum-of-Products:RPT/MACXAR1++X0X1...X19MOVT,loc16ADDACC,PMPYP,T,loc16MOVAT,loc16ACC+=PT=*ARn++

P=T*(*ARn++)MAC{ZeroACC&P

Repeatsingle

Dualoperand

lastADD

ZAPA RPT #19|| MAC P,*XAR1++,*XAR7++ ADDL ACC,P<<PMx .usect“sample”,20y .usect“result”,2 .sect“coefficient”a0: .word 0x0101 .word 0x0202 ••• .word 0x2020 .sect“code”SOP: SPM 0 MOVW DP,#y MOVL XAR1,#xMOVL XAR7,#a0 MOVL @y,ACC BSOP,UNCXAR7++A0A1...A19SecondoperandmustuseXAR7ProgramControlALU/MultiplyOperationsDataMoveLogicalOperationsSpecialInstructionsDataMoveInstructionsDATA«DATA(4G«64K)DATA«PGM(4G«4M)FasterthanLoad/Store,avoidsaccumulatorAllowsaccesstoprogrammemoryOptimalwithRPT(speedandcodesize)InRPT,non-memaddressisauto-incrementedinPCMOVloc16,*(0:16bit)MOV*(0:16bit),loc1632-bitaddressmemorylocation16-bitaddressconcatenatedwith16leadingzeros .sect“.code”START: MOVL XAR5,#x MOVL XAR7,#TBL

RPT #len-1|| PREAD *XAR5++,*XAR7 ...x .usect “.samp”,4 .sect“.coeff”TBL: .word 1,2,3,4len .set $-TBLPREAD loc16,*XAR7PWRITE *XAR7,loc16pointerwitha22-bitprogrammemoryaddressConditionalMovesInstruction Execution(ifCONDismet)MOVloc16,AX,COND[loc16]=AXMOVBloc16,#8bit,COND[loc16]=8bitIfA<B,ThenB=AAccumulator00000120MOVW DP,#AMOV AL,@ACMP AL,@BExampleA.usect “var”,2,1B.set A+1.sect “code”MOV@B,AL,LT01200320DataMemoryBA0120DataMemoryBA0120BeforeAfterInstruction

Execution(ifCONDismet)MOVLloc32,ACC,COND[loc32]=AXByteOperationsMOVBAX.LSB,loc1600000000ByteAXMOVBAX.MSB,loc16ByteNochangeAXMOVBloc16,AX.MSBByteloc16NochangeMOVBloc16,AX.LSBByteloc16NochangeForloc16=*+XARn[Offset]OddOffsetEvenOffsetloc16Byte= 1.Lowbyteforregisteraddressing 2.Lowbytefordirectaddressing 3.SelectedbyteforoffsetindirectaddressingByteAddressingMOVL XAR2,#MemAMOVB *+XAR2[1],AL.LSBMOVB *+XAR2[2],AL.MSBMOVB *+XAR2[5],AH.LSBMOVB *+XAR2[6],AH.MSBAR2AH.MSBAH.LSBAL.MSBAL.LSB16bitmemory01020506123456780407000334561278MOVL XAR2,#MemAMOVBAL.LSB,*+XAR2[1]MOVBAL.MSB,*+XAR2[2]MOVBAH.LSB,*+XAR2[4]MOVBAH.MSB,*+XAR2[7]ExampleofBytePackingExampleofByteUn-PackingTestandChangeMemoryInstruction ExecutionAffectsTBIT loc16,#(0-15) ST0(TC)=loc16(bit_no) TCTSET loc16,#(0-15) Test(loc16(bit))thensetbit TCTCLR loc16,#(0-15) Test(loc16(bit))thenclrbit TCCMPB AX,#8bit

Test(AX-8bitunsigned) C,N,ZCMP AX,loc16 Test(AX–loc16) C,N,ZCMP loc16,#16b Test(loc16-#16bitsigned) C,N,ZCMPL ACC,@P Test(ACC-P<<PM) C,N,ZMIN/MAXOperations MOVL ACC,#0 MOVL XAR1,#table RPT #(table_length–1)|| MAXL ACC,*XAR1++Findthemaximum32-bitnumberinatable:

Instruction ExecutionMAX ACC,loc16 ifACC<loc16,ACC=loc16 ifACC>=loc16,donothingMIN ACC,loc16 ifACC>loc16,ACC=loc16 ifACC<=loc16,donothingMAXL ACC,loc32 ifACC<loc32,ACC=loc32 ifACC>=loc32,donothingMINL ACC,loc32 ifACC>loc32,ACC=loc32 ifACC<=loc32,donothingMAXCUL P,loc32 ifP<loc32,P=loc32(for64bitmath) ifP>=loc32,donothingMINCUL P,loc32 ifP>loc32,P=loc32(for64bitmath) ifP<=loc32,donothingRead-Modify-WriteInstructionsANDloc16,#16bORloc16,#16bXORloc16,#16bADDloc16,#16bSUBRloc16,#16bANDloc16,AXORloc16,AXXORloc16,AXADDloc16,AXSUBloc16,AXSUBRloc16,AXINCloc16DECloc16TSETloc16,#bitTCLRloc16,#bitAH,

AL16-bit

constantWorkdirectlyonmemory–bypassACCAtomicOperations–protectedfrominterruptsRead-Mod