"TMS320C55x DSP Library DSPLIB Programmer's Reference"

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hilb16nh must be a minimum value of 6. For smaller filters, zero pad the H[] array.Implementation Notes The first element in the dbuffer array (index = 0) is the entry index for the inputhistory. It is treated as an unsigned 16-bit value by the function even thoughit has been declared as signed in C. The value of the entry index is equal tothe index – 1 of the oldest input entry in the array. The remaining elementsmake up the input history. Figure 4–22 shows the array in memory with anentry index of 2. The newest entry in the dbuffer is denoted by x(j–0), whichin this case would occupy index = 3 in the array. The next newest entry isx(j–1), and so on. It is assumed that all x() entries were placed into the arrayby the previous invocation of the function in a multiple-buffering scheme.The dbuffer array actually contains one more history value than is needed toimplement this filter. The value x(j–nh) does not enter into the calculations forfor the output r(j). However, this value is required in other <strong>DSP</strong>LIB filter functionsthat utilize the dual-MAC units on the C55x, such as FIR2. Including thisextra location ensures compatibility across all filter functions in the C55x<strong>DSP</strong>LIB.Figure 4–22, Figure 4–23, and Figure 4–24 show the dbuffer, x, and r arraysas they appear in memory.Figure 4–22. dbuffer Array in Memory at Time joldest x( ) entrynewest x( ) entryentry index = 2x(j–nh–2)x(j–nh–1)x(j–nh)x(j–0)x(j–1)x(j–2)•x(j–nh–5)x(j–nh–4)x(j–nh–3)lowest memory addresshighest memory address4-52
iir32Figure 4–23. x Array in Memoryoldest x( ) entrynewest x( ) entryx(0)x(1)•x(nx–2)x(nx–1)lowest memory addresshighest memory addressFigure 4–24. r Array in Memoryoldest x( ) entrynewest x( ) entryr(0)r(1)•r(nx–2)r(nx–1)lowest memory addresshighest memory addressExampleBenchmarksSee examples/hilb16 subdirectory(preliminary)Cycles Core: nx*(2+nh/2)Overhead: 28Code size(in bytes)108iir32FunctionDouble-precision IIR Filterushort oflag = iir32 (DATA *x, LDATA *h, DATA *r, LDATA *dbuffer, ushort nbiq,ushort nr)(defined in iir32.asm)Argumentsx [nr]h[5*nbiq]Pointer to input data vector of size nrPointer to the 32-bit filter coefficient vector with thefollowing format. For example for nbiq= 2, h is equalto:Function Descriptions4-53
Page 1 and 2:
TMS320C55x DSP LibraryProgrammer’
Page 3 and 4:
PrefaceRead This FirstAbout This Ma
Page 5:
Contentsatan16 . . . . . . . . . .
Page 9 and 10:
DSP Routines1.1 DSP RoutinesThe TI
Page 11 and 12:
DSPLIB Content / How to Install DSP
Page 13 and 14:
Chapter 3Using DSPLIBThis chapter d
Page 15 and 16:
Calling a DSPLIB Function from C3.2
Page 17 and 18:
Calling a DSPLIB Function from Asse
Page 19 and 20:
How DSPLIB Deals with Overflow and
Page 21 and 22: Chapter 4Function DescriptionsThis
Page 23 and 24: DSPLIB Functions4.2 DSPLIB Function
Page 25 and 26: DSPLIB FunctionsTable 4-2. Summary
Page 27 and 28: acorracorrFunctionArgumentsAutocorr
Page 29 and 30: addCycles †Code size(in bytes)Aub
Page 31 and 32: atan16Description This function cal
Page 33 and 34: expbexpFunctionBlock Exponent Imple
Page 35 and 36: cfftBenchmarks(preliminary)Cycles
Page 37 and 38: cfirCFFT - NOSCALEFFT Size Cycles
Page 39 and 40: cfirImplementation Notes The first
Page 41 and 42: cifftcifftFunctionInverse Complex F
Page 43 and 44: convolCIFFT - NOSCALEFFT Size Cycle
Page 45 and 46: convol1Figure 4-6. h Array in Memor
Page 47 and 48: convol2Figure 4-8. r Array in Memor
Page 49 and 50: 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: hilb16dbuffer[nh + 2] Pointer to de
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 and 102: and16AlgorithmNot applicableOverflo
Page 103 and 104: and16initBenchmarksCycles Core: 13
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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