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RM0020

Function API

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Algorithm:

Equation 25

for each k = 0,1,...N-1

where x denotes complex multiplication.

Note: There must be 16 bytes of readable memory behind x and w buffers.

Performance: See Section 7 and Table 42.

Example 11. window_apply_complex_float

#include "libdsp2.h"

float x[2*64+4];

/* +4 to ensure there is 16 bytes of readable

memory behind buffer, must be aligned to 8 bytes */

float w[2*64+4];

/* +4 to ensure there is 16 bytes of readable

memory behind buffer, must be aligned to 8 bytes */

void main(void)

{

unsigned int i, N;

/* length of complex vectors is 64 */

N = 64;

/* prepare example input data */

for (i = 0; i < 2*N; i++) x[i] = i+1;

for (i = 0; i < 2*N; i++) w[i] = i+2*N;

/* windowing function on complex float data, x[i] = x[i]*w[i] */

window_apply_complex_float(N, x, x, w);

}

6.12

Complex frac16 windowing function

Function call:

void window_apply_complex_frac16(unsigned int N, short *x, short *y,

short *w);

Arguments:

Description:

Windowing function for complex frac16 data. All the data are handled as signed

fractional 16-bit (range -1 to 1-2^-15). Input data are stored in x vector, output data



 wk





Table 12.

window_apply_complex_frac16 arguments

length of complex vectors, must be multiple of 4

x(1)

All vectors must be word aligned. All vectors have the following memory layout:

re(0) im(0) re(1) im(1)... re(N-1) im(N-1), where re is real part and im is imaginary part.

pointer to the input vector of length 2*N

y(1)

out

pointer to the output vector of length 2*N, y vector can be the same

as x vector (in-place windowing).

w(1)

pointer to the window vector of length 2*N

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