Texas Instruments TMS320C64X Programmer's Reference Manual page 134

DSP_fft
Special Requirements
Implementation Notes
Benchmarks
4-106
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In-place computation is not allowed.
nx must be a power of 4 and 4 ≤ nx ≤ 65536.
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Input x[ ] and output y[ ] are stored on double-word aligned boundaries.
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Input data x[ ] is stored in the order real0, img0, real1, img1, ...
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The FFT coefficients (twiddle factors) must be double-word aligned and
are generated using the program tw_fft16x16 provided in the directory
'support\fft'.
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Bank Conflicts: No bank conflicts occur.
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Interruptibility: The code is interrupt-tolerant but not interruptible.
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Loads input x[ ] and coefficient w[ ] as double words.
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Both loops j and i0 shown in the C code are placed in the inner loop of the
assembly code.
Cycles 1.25 * nx * log
Codesize 984 bytes
(nx) – 0.5 * nx + 23 * log
4
(nx) – 1
4