Texas Instruments TMS320C64X Manuel d'utilisateur télécharger pdf (Page 134)

DSP_fft

4-106

Special Requirements

- In-place computation is not allowed.

- nx must be a power of 4 and 4 ≤ nx ≤ 65536.

- Input x[ ] and output y[ ] are stored on double-word aligned boundaries.

- Input data x[ ] is stored in the order real0, img0, real1, img1, ...

- The FFT coefficients (twiddle factors) must be double-word aligned and

are generated using the program tw_fft16x16 provided in the directory

‘support\fft’.

Implementation Notes

- Bank Conflicts: No bank conflicts occur.

- Interruptibility: The code is interrupt-tolerant but not interruptible.

- Loads input x[ ] and coefficient w[ ] as double words.

- Both loops j and i0 shown in the C code are placed in the inner loop of the

assembly code.

Benchmarks Cycles 1.25 * nx * log

(nx) – 0.5 * nx + 23 * log

(nx) – 1

Codesize 984 bytes

1 2 ... 129 130 131 132 133 134 135 136 137 138 139 ... 168 169

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Texas Instruments TMS320C64X Manuel d'utilisateur Page 134