RM0020 datasheet(44/69 Pages) STMICROELECTRONICS

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Function API

RM0020

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Algorithm:

Equation 36

for each n from 0 to N-1

Note: The filter coefficients must be stored in reversed order.

Performance: See Section 7 and Table 53.

Example 22. fir_float

#include "libdsp2.h"

/* #pragma and ALIGN macros used to align to 8 bytes */

#ifdef __ghs__

#pragma alignvar (8)

#endif

ALIGN_DCC(8)

float x[288/*+2*/] ALIGN_MWERKS(8); /* +2 to ensure there are 8

bytes of readable memory behind x */

#ifdef __ghs__

#pragma alignvar (8)

#endif

ALIGN_DCC(8)

float y [256] ALIGN_MWERKS(8);

#ifdef __ghs__

#pragma alignvar (8)

#endif

ALIGN_DCC(8)

float hr[33/*+2*/] ALIGN_MWERKS(8) = { /* +2 to ensure there are 8

bytes of readable memory behind hr */

-0.0015288448F,-0.0019041377F,-0.0025120102F,-0.0031517229F,-

0.0033815748F,-

0.0025689987F,0.0000000000F,0.0049703708F,0.0127558533F,0.023399631

1F,0.0364901802F,0.0511553726F,0.0661431077F,0.0799794722F,0.091179

2726F,0.0984722196F,0.1010036179F,0.0984722196F,0.0911792726F,0.079

9794722F,0.0661431077F,0.0511553726F,0.0364901802F,0.0233996311F,0.

0127558533F,0.0049703708F,0.0000000000F,-0.0025689987F,-

0.0033815748F,-0.0031517229F,-0.0025120102F,-0.0019041377F,-

0.0015288448F,

};

unsigned short N, ntaps;

void main(void)

{

/* filter the samples in x with FIR filter of 32nd order, */

/* write result into y, hr are filter coefficients stored */

/* in reversed order */

N = 256;



 xn k

–





ntaps

–



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