RM0020 datasheet(42/69 Pages) STMICROELECTRONICS

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Function API

RM0020

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void main(void)

{

/******** Vertical sobel filter *********/

M = 16;

N = 12;

sobel3x3_vertical(a, b, M, N);

}

6.21

corr_frac16 - frac16 correlation function

Function call:

void corr_frac16(unsigned short N, unsigned short M, short *x,

short *y, short *r);

Arguments:

Description:

Computes the correlation of the arrays x and y. The result is written to the array r. All

data types are signed 16-bit fractional in range -1 to 1-2-15. There is used the

arithmetic with saturation so the output will never overflow.

Algorithm:

Correlation:

Equation 35

for each j = 0, 1, ..., M-1

Note: The x and y can be the same array, in that case the auto-correlation is computed.

Performance: See Section 7 and Table 52.

Example 21. corr_frac16

#include "libdsp2.h"

/* #pragma and ALIGN macros used to align to 4 bytes */

#ifdef __ghs__

#pragma alignvar (4)

#endif

Table 21.

corr_frac16 arguments(1)

The x,y,r data are in fractional 16-bit format in range -1 to 1. The arrays x,r must be word aligned,

the array y must be half-word aligned (implicit alignment of short data).

length of input vectors x and y (must be multiple of 4)

length of output vector r (must be multiple of 4, M <= N)

first input vector of length N

second input vector of length N

out

correlation of vectors x and y

out j



y0

 xj 1

y1

 ... x N 1

–

yN j

–



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