Texas Instruments TMS320C64X manual DSPneg32, Bit Vector Negate

DSP_neg32

DSP_neg32	32-Bit Vector Negate
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

4-68