RM0020 datasheet(30/69 Pages) STMICROELECTRONICS

30 / 69 page

Function API

RM0020

30/69

are written into y vector. The y vector can be the same as x vector (in-place

windowing).

The output scaling is configurable by constant definition in the function source file:

.set

SCALING,

#/* 0 - off, 1 - on (output

divided by 2) */

By default it is turned on. The scaling is performed by dividing output data by 2.

Algorithm:

Equation 26

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

where x denotes complex multiplication. The output value

is divided by 2 when

SCALING == 1.

Note: There must be 8 bytes of readable memory behind x and w buffers.

If SCALING == 1, then w array mustn't have any value equal to -1 (-32768) since

there is used integer multiplication for fractional data.

Performance: See Section 7 and Table 43.

Example 12. window_apply_complex_frac16

#include "libdsp2.h"

short x[2*64+4];

/* +4 to ensure there is 8 bytes of readable

memory behind buffer, must be aligned to 4 bytes */

short w[2*64+4];

/* +4 to ensure there is 8 bytes of readable

memory behind buffer, must be aligned to 4 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)<<5;

for (i = 0; i < 2*N; i++) w[i] = (i+2*N)<<5;

/* windowing function on complex frac16 data, x[i] = x[i]*w[i]

window_apply_complex_frac16(N, x, x, w);

}

6.13

Real float windowing function

Function call:

void window_apply_real_float(unsigned int N, float *x, float *y,

float *w);



 wk







RM0020 데이터시트(PDF) 30 Page - STMicroelectronics

RM0020 데이터시트(HTML) 30 Page - STMicroelectronics

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69

데이터시트 다운로드

링크 URL