/*************************************************************************/
/* fir.c
/*************************************************************************/
#include <stdio.h>
#include <malloc.h>
#include "math.h"
#include "fir.h"
#include "firdecim.h"

/*************************************************************************/
/* Global Variables
/*************************************************************************/
int FDfilter(struct _sFIRDECIM *pObj, float *pX, float *pY, int len)
{
	int len2, i, firLen, kL;
	float *pSxt, *pBt, sum;

	kL = pObj->kL;
	firLen = pObj->firLen;

	pBt  = &pObj->pB[0];
	pSxt = &pObj->pX[0];
	len2 = 0;
	while (len >= kL)
	{

        for (i = firLen-1; i >= kL; i--)
		{
            pObj->pX[i] = pObj->pX[i- kL];
        }

        for (i = kL-1; i >= 0; i--)
		{
			pObj->pX[i] = *(pX++);
        }
		len -= kL;
		
		sum = 0.0;

		for (i=0; i < firLen; i++)
			sum += pObj->pX[i] * pObj->pB[i];

		*(pY++) = sum;
		len2++;
	}
	return len2;
}

void FDinit(struct _sFIRDECIM *pObj, int kL, int nCoefPerPhase)
{
	int n;
	pObj->kL = kL;

	pObj->firLen = kL*nCoefPerPhase;
	pObj->nCoefPerPhase = nCoefPerPhase;

	if ((pObj->firLen%2) == 0)
		pObj->firLen++;

	pObj->pB = (float*)malloc(pObj->firLen*sizeof(float));
	pObj->pX = (float*)malloc(pObj->firLen*sizeof(float));


	for(n=0; n < pObj->firLen; n++)
	{
		pObj->pX[n] = 0;
	}

	Sinc(pObj->pB, kL, 1.f/kL, 1.f/kL, pObj->firLen);

}

void FDfree(struct _sFIRDECIM *pObj)
{
	free(pObj->pB);
	free(pObj->pX);
}