Texas Instruments TMS320C64X manual Miscellaneous, DSPbexp, Block Exponent Implementation

DSP_bexp

4.7 Miscellaneous

DSP_bexp	Block Exponent Implementation
Function		short DSP_bexp(const int *x, short nx)
Arguments		x[nx]	Pointer to input vector of size nx. Must be double-word
			aligned.
		nx	Number of elements in input vector. Must be multiple of 8.
		return short	Return value is the maximum exponent that may be used in
			scaling.
Description		Computes the exponents (number of extra sign bits) of all values in the input
		vector x[ ] and returns the minimum exponent. This will be useful in
		determining the maximum shift value that may be used in scaling a block of
		data.
Algorithm		This is the C equivalent of the assembly code without restrictions. Note that
		the assembly code is hand optimized and restrictions may apply.
		short DSP_bexp(const int *x, short nx)
	{
		int	min_val =_norm(x[0]);
		short	n;
		int	i;

for(i=1;i<nx;i++)

{

n =_norm(x[i]); /* _norm(x) = number of */ /* redundant sign bits */

if(n<min_val) min_val=n;

}

return min_val;

}

Special Requirements

-nx must be a multiple of 8.

-The input vector x[ ] must be double-word aligned.

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