Texas Instruments TMS320C64X DSPfirr4, FIR Filter when the number of coefficients is a multiple

DSP_fir_r4

DSP_fir_r4	FIR Filter (when the number of coefficients is a multiple of 4)
Function
		void DSP_fir_r4 (const short * restrict x, const short * restrict h, short * restrict
		r, int nh, int nr)
Arguments		x[nr+nh−1]	Pointer to input array of size nr + nh – 1.
		h[nh]	Pointer to coefficient array of size nh (coefficients must be in
			reverse order).
		r[nr]	Pointer to output array of size nr.
		nh	Number of coefficients. Must be multiple of 4 and ≥8.
		nr	Number of samples to calculate. Must be multiple of 4.
Description		Computes a real FIR filter (direct-form) using coefficients stored in vector h[ ].
		The real data input is stored in vector x[ ]. The filter output result is stored in
		vector r[ ]. This FIR operates on 16-bit data with a 32-bit accumulate. The filter
		calculates nr output samples using nh coefficients.
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_fir_r4(short *x, short *h, short *r, int nh, int nr)

{

int i, j, sum;

for (j = 0; j < nr; j++) { sum = 0;

for (i = 0; i < nh; i++) sum += x[i + j] * h[i];

r[j] = sum >> 15;

}

}

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