"TMS320C55x DSP Library DSPLIB Programmer's Reference"

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and16Overflow Handling MethodologyNo scaling implemented for overflow prevention.Special Requirements No special requirements.Implementation Notes Rand16() is written so that it can be called from a C program. Prior to callingrand16(), rand16i() can be called to initialize the random number generatorseed value. The C routine passes two parameters to rand16(): A pointer to therandom number array *r and the count of random numbers (nr) desired. Therandom numbers are declared as short or 16 bit values. Two constantsRNDMULT and RNDINC are defined in the function. The algorithm is sensitiveto the choice of RNDMULT and RNDINC so exercise caution when changingthese.MThis value is based on the system that the routine runs. Thisroutine returns a random number from 0 to 65536 (64K) andis NOT internally bounded. If you need a min/max limit, thismust be coded externally to this routine.RNDSEEDRNDMULTAn arbitrary constant that can be any value between 0 and64K. If 0 (zero) is chosen, then RNDINC should be somevalue greater than 1. Otherwise, the first two values will be 0and 1. To change the set of random numbers generated bythis routine, change the RNDSEED value. In this routine,RNDSEED is initialized to 21845, which is 65536/3.Should be chosen such that the last three digits fall in thepattern even_digit–2–1 such as xx821, xx421 etc.RNDMULT = 31821 is used in this routine.RNDINCIn general, this constant can be any prime number related toM. Research shows that RNDINC (the increment value)should be chosen by the following formula:RNDINC = ((1/2 – (1/6 * SQRT(3))) * M). Using M=65536,RNDINC was picked as 13849.The random seed initialized in rand16i() is used to generate the first randomnumber. Each random number generated is used to generate the next numberin the series. The random number is generated in the accumulator (32 bits) byusing the multiply-accumulate (MAC) unit to do the computation. In the courseof the algorithm if there is intermediate overflow, the overflow flag bit in statusregister is set. At the end of the algorithm, the overflow flag is tested for anyintermediate overflow conditions.ExampleSee examples/rand16 subdirectory4-82
and16initBenchmarksCycles Core: 13 + nr*2Overhead: 10Code size(in bytes)49C54x Benchmark for ComparisonCycles Core: 10 + nr*4Overhead: 16Code size(in bytes)56rand16initFunctionArgumentsDescriptionAlgorithmRandom Number Generation Initializationvoid rand16init(void)noneInitializes seed for 16-bit random number generator.Not applicableOverflow Handling MethodologyNo scaling implemented for overflow prevention.Special Requirements Allocation of .bss section is required in linker command file.Implementation Notes This function initializes a global variable rndseed in global memory to be usedfor the 16 bit random number generation routine (rand16)ExampleSee examples/rand16i subdirectoryBenchmarksCycles 6Code size(in bytes)9C54x Benchmark for ComparisonCycles 7Code size(in bytes)10Function Descriptions4-83
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TMS320C55x DSP LibraryProgrammer’
Page 3 and 4:
PrefaceRead This FirstAbout This Ma
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Contentsatan16 . . . . . . . . . .
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DSP Routines1.1 DSP RoutinesThe TI
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DSPLIB Content / How to Install DSP
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Chapter 3Using DSPLIBThis chapter d
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Calling a DSPLIB Function from C3.2
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Calling a DSPLIB Function from Asse
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How DSPLIB Deals with Overflow and
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Chapter 4Function DescriptionsThis
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DSPLIB Functions4.2 DSPLIB Function
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DSPLIB FunctionsTable 4-2. Summary
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acorracorrFunctionArgumentsAutocorr
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addCycles †Code size(in bytes)Aub
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atan16Description This function cal
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expbexpFunctionBlock Exponent Imple
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cfftBenchmarks(preliminary)Cycles
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cfirCFFT - NOSCALEFFT Size Cycles
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cfirImplementation Notes The first
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cifftcifftFunctionInverse Complex F
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convolCIFFT - NOSCALEFFT Size Cycle
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convol1Figure 4-6. h Array in Memor
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convol2Figure 4-8. r Array in Memor
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convol2Figure 4-10. x Array in Memo
Page 51 and 52: dlmsImplementation NotesSpecial deb
Page 53 and 54: expnImplementation NotesDelayed ver
Page 55 and 56: firr[nx]Pointer to output vector of
Page 57 and 58: fir2Figure 4-14. x Array in Memoryo
Page 59 and 60: fir2Special Requirementsnh must be
Page 61 and 62: firdecr[nx/D]dbuffer[nh+1]nxnhDofla
Page 63 and 64: firinterpIoflagInterpolation factor
Page 65 and 66: firlatpbuffer [nh]nxnhoflagDelay bu
Page 67 and 68: firsnh2oflagHalf the number of coef
Page 69 and 70: fltoq15Figure 4-21. r Array in Memo
Page 71 and 72: hilb16dbuffer[nh + 2] Pointer to de
Page 73 and 74: iir32Figure 4-23. x Array in Memory
Page 75 and 76: iir32In the case of multiple-buffer
Page 77 and 78: iircas4nxoflagNumber of elements of
Page 79 and 80: iircas51This function retains the a
Page 81 and 82: iirlatBenchmarks(preliminary)Cycles
Page 83 and 84: ldiv16ldiv16Function32-bit by 16-bi
Page 85 and 86: log_10Special Requirements noneImpl
Page 87 and 88: lognThe coefficients Bi used in the
Page 89 and 90: maxidxmaxidxFunctionIndex of the Ma
Page 91 and 92: maxvecDescription Returns the maxim
Page 93 and 94: minvecminvalFunctionMinimum Value o
Page 95 and 96: mmulDescriptionAlgorithmThis functi
Page 97 and 98: negr[nx]Pointer to output data vect
Page 99 and 100: powernxoflagNumber of elements of i
Page 101: and16AlgorithmNot applicableOverflo
Page 105 and 106: fftThe initial estimate can be obta
Page 107 and 108: ifftrifftFunctionInverse Real FFT (
Page 109 and 110: sqrt_16DescriptionComputes the sine
Page 111 and 112: subr[nx]nxscaleoflagPointer to outp
Page 113 and 114: What DSPLIB Benchmarks are Provided
Page 115 and 116: DSPLIB Software Updates6.1 DSPLIB S
Page 117 and 118: Q3.12 Format / Q.15 Format / Q.31 F
Page 119 and 120: Calculating the Reciprocal of a Q15
Page 121 and 122: IndexIndex16-bit reciprocal functio
Page 123: Indexmmul 4-74mtrans 4-76mul32 4-76
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