Texas Instruments TMS320C64X Bedienungsanleitung PDF herunterladen (Seite 125)

DSP_r4fft

4-97 C64x+ DSPLIB Reference

>>15;

x[2 * i3 + 1] = (s2 * co3−r2 *

si3)>>15;

}

ie <<= 2;

}

Special Requirements

- 4 ≤ nx ≤ 65536 (nx a power of 4)

- x is aligned on a 4*nx byte boundary for circular buffering

- Input x and coefficients w should be in different data sections or memory

spaces to eliminate memory bank hits. If this is not possible, w should be

aligned on an odd word boundary to minimize memory bank hits

- x data is stored in the order real[0], image[0], real[1], ...

- The FFT coefficients (twiddle factors) are generated using the program

tw_r4fft provided in the directory ‘support\fft’.

Implementation Notes

- Bank Conflicts: See Benchmarks.

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

- Loads input x and coefficient w as words.

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

the assembly code.

Benchmarks The performance of this function has not yet been characterized on the C64x+.

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Texas Instruments TMS320C64X Bedienungsanleitung Seite 125