Texas Instruments TMS320C64X manual Adaptive Filtering, DSPfirlms2

DSP_firlms2

4.1 Adaptive Filtering

DSP_firlms2	LMS FIR
Function		long DSP_firlms2(short * restrict h, const short * restrict x, short b, int nh)
Arguments		h[nh]	Coefficient Array
		x[nh+1]	Input Array
		b	Error from previous FIR
		nh	Number of coefficients. Must be multiple of 4.
		return long	Return value
Description		The Least Mean Square Adaptive Filter computes an update of all nh
		coefficients by adding the weighted error times the inputs to the original
		coefficients. The input array includes the last nh inputs followed by a new
		single sample input. The coefficient array includes 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.
		long DSP_firlms2(short h[ ],short x[ ], short b,
		int nh)
	{
		int	i;
		long	r = 0;

for (i = 0; i < nh; i++) { h[i] += (x[i] * b) >> 15; r += x[i + 1] * h[i];

}

return r;

}

Special Requirements

-This routine assumes 16-bit input and output.

-The number of coefficients nh must be a multiple of 4.

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