며칠전 질문드렸던 함수 호출에 대해서 다시 질문드려요....ㅜ.?

제가요 Qt로 프로그램을 짜는데요...
전에 질문 드렸었던거에 대한 추가적인 질문입니다....
moonzoo님하고 쿨링펜님이 답변 주셨었습니다..

=================receive.h============

#include <qradiobutton.h>
#include <qbuttongroup.h>
#include <qpushbutton.h>
#include <qlabel.h>
#include <qwidget.h>
#include <qtimer.h>
#include <qpixmap.h>
#include <qpainter.h>

#define TRUE 1

typedef struct {
	double real, imag;
} COMPLEX;

#define PI 3.141592
void fft(COMPLEX *x, int m);

class mywid:public QWidget
{
	Q_OBJECT

public:
	char buff[10];
	int fd, res, num, cat[1000], tmp, c, sta,d,i,n,j,x,type,z,t,gar;
	int res2,num2,cat2,sta2, count;
	int tmp2[1000];
	float fr[500];
	mywid();
private slots:
	void slotTimer1();
	void slotClicked1();
	void slotClicked2();
	void slotClicked3();
	void slotClicked4();
	void slotClicked5();
	void slotClicked6();
private:
	void paintEvent(QPaintEvent*);
	QButtonGroup*bg;
	QRadioButton*rb1;
	QRadioButton*rb2;
	QRadioButton*rb3;
	QTimer* timer1;
	QLabel* lab1;
	QLabel* lab2;
	QLabel* lab3;
	QLabel* lab4;
	QLabel* lab5;
	QLabel* lab6;
	QLabel* lab7;
	QPushButton* bt1;
	QPushButton* bt2;
	QPushButton* bt3;
	QPushButton* bt4;
	QPushButton* bt5;
	QPushButton* bt6;
};
 

=================receive.cpp============

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <qapplication.h>
#include <sys/signal.h>
#include <signal.h>
#include <math.h>
#include "receive.h"

#define BAUDRATE B115200
#define MODEMDEVICE "/dev/ttySA0"
#define _POSIX_SOURCE 1

int stop_flag=TRUE;

mywid::mywid()
{
	c=0,j=0,x=0,z=0,type=1,i=0,d=0,t=0,tmp2[1000],gar=0;
	struct termios oldtio, newtio;
	struct sigaction saio;
	fd = open(MODEMDEVICE, O_RDWR | O_NOCTTY | O_NONBLOCK);

	tcgetattr(fd, &oldtio);
	bzero(&newtio, sizeof(newtio));

	newtio.c_cflag = BAUDRATE | CS8 | CLOCAL | CREAD | CRTSCTS;
	newtio.c_iflag = IGNPAR;
	newtio.c_oflag = 0;
	newtio.c_lflag = 0;

	newtio.c_cc[VTIME] = 0;
	newtio.c_cc[VMIN] = 1;
	setCaption("PDA DOCTOR");

	QButtonGroup* bg = new QButtonGroup("Language", this);
	bg->setGeometry(10,5,280,50);

	rb1 = new QRadioButton("English", bg);
	rb1->move(10,15);
	rb2 = new QRadioButton("Japanese", bg);
	rb2->move(90,15);
	rb3 = new QRadioButton("Korean", bg);
	rb3->move(170,15);

	lab1 = new QLabel(this);
	lab2 = new QLabel(this);
	lab3 = new QLabel(this);
	lab4 = new QLabel(this);
	lab5 = new QLabel(this);
	lab6 = new QLabel(this);
	lab7 = new QLabel(this);
	timer1 = new QTimer(this);
	bt1 = new QPushButton("Line",this);
	bt2 = new QPushButton("Bar",this);
	bt3 = new QPushButton("Start",this);
	bt4 = new QPushButton("Stop",this);
	bt5 = new QPushButton("Reset",this);
	bt6 = new QPushButton("Result",this);

	lab1->setFrameStyle(QFrame::Panel | QFrame::Sunken);
	lab1->setLineWidth(2);
	lab1->setGeometry(10,75,100,55);

	lab2->setFrameStyle(QFrame::Panel | QFrame::Sunken);
	lab2->setLineWidth(2);
	lab2->setGeometry(10,150,100,30);

	lab3->setFrameStyle(QFrame::Panel | QFrame::Sunken);
	lab3->setLineWidth(2);
	lab3->setGeometry(120,75,170,105);

	lab4->setFrameStyle(QFrame::Panel | QFrame::Sunken);
	lab4->setLineWidth(2);
	lab4->setGeometry(120,75,170,105);
	lab4->hide();

	lab5->setText("Explanation");
	lab5->setGeometry(10,60,80,10);
	lab6->setText("Numberical Value");
	lab6->setGeometry(10,135,80,10);
	lab7->setText("Graph");
	lab7->setGeometry(120,60,80,10);

	bt1->setGeometry(45,185,30,25);
	bt2->setGeometry(80,185,30,25);
	bt3->setGeometry(10,185,30,25);
	bt4->setGeometry(115,185,30,25);
	bt5->setGeometry(150,185,30,25);
	bt6->setGeometry(185,185,30,25);

	connect(bt1, SIGNAL(clicked()), this, SLOT(slotClicked1()));
	connect(bt2, SIGNAL(clicked()), this, SLOT(slotClicked2()));
	connect(bt3, SIGNAL(clicked()), this, SLOT(slotClicked3()));
	connect(bt4, SIGNAL(clicked()), this, SLOT(slotClicked4()));
	connect(bt5, SIGNAL(clicked()), this, SLOT(slotClicked5()));
	connect(bt6, SIGNAL(clicked()), this, SLOT(slotClicked6()));
}

void mywid::paintEvent(QPaintEvent*)
{
	QPainter p(lab3);
	QPainter p1(lab4);
	sta=0,sta2=0,tmp=0;
	
	QBrush brush1(green,SolidPattern);
	QBrush brush2(red,SolidPattern);
	QBrush brush3(yellow,SolidPattern);
	
	if(stop_flag==FALSE)
	{
		res2=read(fd, buff, 10);
		tmp2[t] = atoi(buff);
		for(z=0;z<=i;z++)
		{
			if(type==2){
				if(tmp2[z]>80){d=2;}
				else if(tmp2[z]<60){d=3;}
				else{d=1;}
				switch(d){
					case 1: p1.fillRect(sta2,105-tmp2[z], 2, 105, brush1);
					sta2 = sta2+2;break;

					case 2: p1.fillRect(sta2, 105-tmp2[z], 2, 105, brush2);
					sta2 = sta2+2;break;

					case 3: p1.fillRect(sta2, 105-tmp2[z], 2, 105, brush3);
					sta2 = sta2+2;break;
				}
			}

			else{
				p.drawLine(sta, 105-tmp, sta+2, 105-tmp2[z]);
				tmp = tmp2[z];
				sta = sta+2;
			}
		}
		i++;
		t++;
	}
}

void mywid::slotTimer1()
{
	repaint();
} 

void mywid::slotClicked1()
{
	type = 1;
	lab4->hide();
	stop_flag=FALSE;
	lab3->show();
	repaint();
}

void mywid::slotClicked2()
{
	type = 2;
	lab3->hide();
	stop_flag=FALSE;
	lab4->show();
	repaint();
}

void mywid::slotClicked3()
{
	stop_flag=FALSE;
	timer1->start(1000,false);
	connect(timer1, SIGNAL(timeout()), this, SLOT(slotTimer1()));
}

void mywid::slotClicked4()
{
	stop_flag=TRUE;
	timer1->stop();
}

void mywid::slotClicked5()
{
	mywid();
}

void mywid::slotClicked6()
{

}

void fft(COMPLEX *x, int m)
{
	static COMPLEX *w;
	static int mstore = 0;
	static int n = 1;

	COMPLEX u,temp,tm;
	COMPLEX *xi,*xip,*xj,*wptr;
	int i,j,k,l,le,windex;
	double arg,w_real,w_imag,wrecur_real,wrecur_imag,wtemp_real;

	if(m != mstore) {
		if(mstore != 0) free(w);
		mstore = m;
		if(m == 0) return;
		n = 1 << m; 
		le = n/2;
		w = (COMPLEX *) calloc(le-1,sizeof(COMPLEX));
		if(!w) {
			printf("\nUnable to allocate complex W array\n");
			exit(1);
		}
		arg = PI/le;
		wrecur_real = w_real = cos(arg);
		wrecur_imag = w_imag = -sin(arg);
		xj = w;
		for (j = 1 ; j < le ; j++) {
			xj->real = (double)wrecur_real;
			xj->imag = (double)wrecur_imag;
			xj++;
			wtemp_real = wrecur_real*w_real - wrecur_imag*w_imag;
			wrecur_imag = wrecur_real*w_imag + wrecur_imag*w_real;
			wrecur_real = wtemp_real;
		}
	}
	le = n;
	windex = 1;
	for (l = 0 ; l < m ; l++) {
		le = le/2;
		for(i = 0 ; i < n ; i = i + 2*le) {
			xi = x + i;
			xip = xi + le;
			temp.real = xi->real + xip->real;
			temp.imag = xi->imag + xip->imag;
			xip->real = xi->real - xip->real;
			xip->imag = xi->imag - xip->imag;
			*xi = temp;
		}
		wptr = w + windex - 1;
		for (j = 1 ; j < le ; j++) {
			u = *wptr;
			for (i = j ; i < n ; i = i + 2*le) {
				xi = x + i;
				xip = xi + le;
				temp.real = xi->real + xip->real;
				temp.imag = xi->imag + xip->imag;
				tm.real = xi->real - xip->real;
				tm.imag = xi->imag - xip->imag; 
				xip->real = tm.real*u.real - tm.imag*u.imag;
				xip->imag = tm.real*u.imag + tm.imag*u.real;
				*xi = temp;
			}
			wptr = wptr + windex;
		}
		windex = 2*windex;
	} 
	j = 0;
	for (i = 1 ; i < (n-1) ; i++) {
			k = n/2;
		while(k <= j) {
			j = j - k;
			k = k/2;
		}
		j = j + k;
		if (i < j) {
			xi = x + i;
			xj = x + j;
			temp = *xj;
			*xj = *xi;
			*xi = temp;
		}
	}
} 

소스 보시기 정신없으실텐데요......
위에 코드 보시면요....
시리얼을 통해서 데이터가 들어오면
그 데이터를 tmp2라는 배열에
차례대로 저장하게 되는데요....
버튼 6을 누르면 fft함수를 호출해서
푸리에 변환을 시키는 건데요....
tmp2배열에 저장되어 있는 값을
fft함수에 어떻게 적용해야할지 몰라서요...ㅜ.ㅜ