Texas Instruments TMS320C64X Manual de usuario descargar pdf (Pagina 96)

DSP_neg32

4-68

32-Bit Vector Negate

DSP_neg32

Function void DSP_neg32(int *x, int *r, short nx)

Arguments x[nx] Pointer to input data vector 1 of size nx with 32-bit elements.

Must be double-word aligned.

r[nx] Pointer to output data vector of size nx with 32-bit elements.

Must be double-word aligned.

nx Number of elements of input and output vectors. Must be a

multiple of 4 and ≥8.

Description This function negates the elements of a vector (32-bit elements). The input and

output arrays must not be overlapped except for where the input and output

pointers are exactly equal.

Algorithm This is the C equivalent of the assembly code without restrictions. Note that

the assembly code is hand optimized and restrictions may apply.

void DSP_neg32(int *x, int *r, short nx)

{

short i;

for(i=nx; i>0; i−−)

*(r++)=−*(x++);

}

Special Requirements

- nx must be a multiple of 4 and greater than or equal to 8.

- The arrays x[ ] and r[ ] must be double-word aligned.

Implementation Notes

- Bank Conflicts: No bank conflicts occur.

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

- The loop is unrolled twice and pipelined.

Benchmarks Cycles nx/2 + 19

Codesize 124 bytes

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Texas Instruments TMS320C64X Manual de usuario Pagina 96