optical/NxFuncs/stadc/filter.c

#define _IN_FILTER_C
#include "filter.h"

//------------------------------------------------------
// һ<><D2BB><EFBFBD>ͺ<EFBFBD><CDBA>˲<EFBFBD><CBB2><EFBFBD>
#if (1)

int LPF1st(LPF1stData * pLpf1st, int newData)
{
	int data = 0;
	if (pLpf1st != NULL)
	{
		if (pLpf1st->f1value < 0)
		{
			pLpf1st->f1value = newData;
		}

		// һ<><D2BB><EFBFBD>ͺ<EFBFBD><CDBA>˲<EFBFBD>
		pLpf1st->f1value = newData * pLpf1st->lowpassxs + pLpf1st->f1value * (1-pLpf1st->lowpassxs);
		data = pLpf1st->f1value;
	}

	return data;
}

#endif

// <20><><EFBFBD><EFBFBD>IIR<49>˲<EFBFBD><CBB2><EFBFBD>
#if (1)

//------------------------------------------------------

int LPF2nd(LPF2ndData * pLpf2nd, int newData)
{
	int data = 0;

	if (pLpf2nd != NULL)
	{
		if (pLpf2nd->f2value < 0)
		{
			pLpf2nd->preout = newData;
			pLpf2nd->lastout = newData;
		}

		// <20><><EFBFBD>ڶ<EFBFBD><DAB6><EFBFBD>IIR<49>˲<EFBFBD><CBB2><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ʽ:Y<><59>n)= b0*xn + b1*xn-1 + b2*xn-2 - (a1*xn-1 + a2*xn-2)

		// <20>˴<EFBFBD><CBB4><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>b1 * xn-1 + b2 * xn-2 <20><>b1<62><31>b2<62><32>ϵ<EFBFBD><CFB5>Ϊ0
		pLpf2nd->f2value = (newData * pLpf2nd->b0)+ (pLpf2nd->lastout * pLpf2nd->a1) - (pLpf2nd->preout * pLpf2nd->a2);

		// <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֵ<EFBFBD><D6B5><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>´<EFBFBD><C2B4><EFBFBD><EFBFBD><EFBFBD>
		pLpf2nd->preout = pLpf2nd->lastout;
		pLpf2nd->lastout = pLpf2nd->f2value;
		data = pLpf2nd->lastout;
	}

	return data;
}

#endif

//------------------------------------------------------

// <20><>Ȩ<EFBFBD><C8A8><EFBFBD><EFBFBD>ƽ<EFBFBD><C6BD><EFBFBD>˲<EFBFBD><CBB2><EFBFBD>
#if (1)

// <20><><EFBFBD><EFBFBD>Ȩֵ
int WRAFilter(int * pBuff, int len)
{
	float value = 0;
	int i;
	int coe, coesum;

	if (pBuff == NULL || len <= 0)
	{
		return 0;
	}

	coe = 1;	// Ȩֵ<C8A8><D6B5>1<EFBFBD><31>ʼ
	coesum = 0;
	for (i = 0; i < len; i++)
	{
		value += *pBuff++ * coe;	// <20><>Ȩ<EFBFBD><C8A8><EFBFBD><EFBFBD>
		coesum += coe;
		coe++;		// Ȩֵ<C8A8><D6B5><EFBFBD>ӣ<EFBFBD><D3A3><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Ȩֵ<C8A8><D6B5>
	}
	value /= coesum;	// <20><>Ȩƽ<C8A8><C6BD>ֵ

	return value;
}

#endif

//------------------------------------------------------

// <20><>λֵƽ<D6B5><C6BD><EFBFBD>˲<EFBFBD><CBB2><EFBFBD>
#if (1)

int MAFilter(int * pBuff, int len)
{
	int i;
	s32 value = 0;

	if (pBuff == NULL || len <= 0)
	{
		return 0;
	}

	if (len <= 5)		// <20><><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>٣<EFBFBD>ֱ<EFBFBD><D6B1>ȡƽ<C8A1><C6BD>ֵ
	{
		// ȡƽ<C8A1><C6BD><EFBFBD><EFBFBD>
		for (i = 0; i < len; i++)
		{
			value += *pBuff++;
		}
		value /= len;
	}
	else
	{
		s32 min, max, temp;
		min = max = *pBuff;		// <20><>һ<EFBFBD><D2BB>ֵ

		// ȡ<><C8A1><EFBFBD><EFBFBD><EFBFBD><EFBFBD>ֵ<EFBFBD><D6B5><EFBFBD>ۼӺͲ<D3BA><CDB2>õ<EFBFBD><C3B5><EFBFBD><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Сֵ
		for (i = 0; i < len; i++)
		{
			temp = *pBuff++;
			value += temp;		// <20><><EFBFBD>ϵ<EFBFBD>ǰֵ
			if (min > temp)
			{
				min = temp;
			}
			if (max < temp)
			{
				max = temp;
			}
		}

		// <20>ۼӺͼ<D3BA>ȥ<EFBFBD><C8A5><EFBFBD><EFBFBD><EFBFBD><EFBFBD>Сֵ
		value -= min;
		value -= max;

		// ʣ<><CAA3><EFBFBD><EFBFBD><EFBFBD>ݵ<EFBFBD>ƽ<EFBFBD><C6BD>ֵ
		value /= (len-2);
	}

	return value;
}

#endif


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