C Tutorial Part 2[1]

8/8/2019 C Tutorial Part 2[1]

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C Tutorial: Part 2

Dr. Charalampos Tsimenidis

Newcastle University

School of Electrical, Electronic and Computer Engineering

September 2010

Dr. Charalampos Tsimenidis C Tutorial: Part 2
http://find/http://goback/


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Loops: for

Example: ex_p2_1.c

1 int n, N=100;

2 float fc=1000.0; //Carrier frequency in Hz

3 float fs=48000.0; //Sampling frequency

4 float t, Ts, wc, xc;

5

6 Ts=1.0/fs; //Sampling time

7

wc=2.0*M_PI*fc;8

9 //Generate cosine signal

10 for (n=0;n data.txt

http://goforward/http://find/http://goback/


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Loops: while

Example: ex_p2_2.c

1 int n=0, N=100;2 float fc=1000.0; //Carrier frequency in Hz



5


7 wc=2.0*M_PI*fc;8


10 while (n


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Loops: do

Example: ex_p2_2.c

1 int n=0, N=100;2 float fc=1000.0; //Carrier frequency in Hz



5


7 wc=2.0*M_PI*fc;8


10 do

11 {

12 t=n*Ts;

13 xc=cosf(wc*t);

14 printf("%+.7f, %+.7f\n",t,xc);

15 }

16 while(++n


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Structures: struct

Definition 1:

1 struct cmplx

2 {

3 float real;

4 float imag;

5 };

Example: ex_p2_4.c

1 struct cmplx x;

2

3

x.real=1.0;4 x.imag=1.0;

5 printf("Real-Imaginary form: x=%f+j*%f\n",x.real,x.imag);



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Structures: struct, typedef

Definition 2:

1 typedef struct

2 {

3 float real;

4 float imag;

5 }cmplx;

Example: ex_p2_5.c

1 cmplx x;

2

3

x.real=1.0;4 x.imag=1.0;

5 printf("Real-Imaginary form: x=%f+j*%f\n",x.real,x.imag);



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Arrays (1)

Definitions: ex_p2_6.c

1 float x[1000];

2 float y[]={1.0,1.0, 1.0};

3 float z[1000]={1.0};

4 int adc[1024];5 char text[]="C is cool!";

Array index limits for an array with N elements:

Lower index limit: 0

Upper index limit: N-1



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Arrays (2)

Example: ex_p2_7.c

1 int n, N=100;

2 float fc=1000.0; //Carrier frequency in Hz


4 float t, Ts, wc, xc[N];

5

6 Ts=1.0/fs; //Sampling time7 wc=2.0*M_PI*fc;

8


10 for (n=0;n


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Two Dimensional Arrays

Example: ex_p2_8.c1 float X[3][3];

2 float Y[3][3]={{1.0, 0.0, 0.0},

3 {0.0, 1.0, 0.0},

4 {0.0, 0.0, 1.0}};

5 int m, n;

6

7 for (m=0;m


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Functions (1)

Definition: ex_p2_9.c

1 typedef struct

2 {

3 float real;

4 float imag;

5 float mag;

6 }cmplx;7

8 float mag(cmplx x)

9 {

10 float y;

11 y=sqrtf(x.real*x.real+x.imag*x.imag);

12

13 return y;

14 }


F i (2)


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Functions (2)

Example: ex_p2_9.c

1 cmplx x;

2

3 x.real=1.0;

4 x.imag=1.0;

5

6 x.mag=mag(x);

7 printf("The magnitude of x = %+.3f %+.3f * j is %f\n",x.real

,x.imag,x.mag);


F ti (3)


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Functions (3)

Functions with array input variables: ex_p2_10.c

1 float mean(float x[], unsigned long N)

2 {

3 int n;

4 float avg=0;

5

6 for (n=0;n


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Functions (4)

Functions using global variables: ex_p2_11.c

1 // x[] and N are globally defined (above the main function)

2 float mean()

3 {

4

5 int n;6 float avg=0;

7

8 for (n=0;n


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Pointers

Pointer is a variable that points to or references a memorylocation where data are stored

Pointer declarations examples: ex_p2_12.c

1 float *p1, *p2;

2 int *p3;

Address operator: &1 float *p1, *p2;

2 float num1=10.0, num2=0.0;

3

4 p1=&num1; //p1 points to the address of num1

5 p2=p1; //p2 point to the same address as p16 num2=*p1; //Equivalent to num2=num1;

7

8 printf("num2 = %f\n",num2);

9 printf("*p2 = %f\n",*p2);


Pointer and Arrays


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Pointer and Arrays

Example: ex_p2_13.c

1 float *p1=NULL, x[5]={0.1, 0.2, 0.3, 0.4, 0.5}, y1, y2;

2 p1=&x[0]; // point p1 to the first element of x[]

3

y1=*(p1+3); // Equivalent to y1=x[3];4 y2=p1[3]; // Equivalent to y2=x[3];

5

6 printf("y1 = %f\n",y1);

7 printf("y2 = %f\n",y2);


Bitwise Operators (1)


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Memory Range Data Type

Logical Operators bitwise complement ~bitwise AND &

bitwise OR |bitwise XOR ^

Shift Operators left shift >




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Example 1: ex_p2_14.c1 unsigned int a=0, b=3;

2

3 //Left and right shift

4 printf("a=%u\n",a); // a=0

5 a=b=1; // or a=a>>1

8 printf("a=%u\n",a); // a=6

Example 2: ex_p2_15.c1 unsigned short int a=1, b=5;

2

3 //Bitwise operations4 printf("~a = %hu\n",~a); //Complement:

5 printf("a & b = %u\n",a&b); //AND

6 printf("a | b = %u\n",a|b); //OR

7 printf("a ^ b = %u\n",a^b); //XOR


Review Exercise 3


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Review Exercise 3

Write a program that generates in an array and prints a linearfrequency modulated chirp with the following parameters:

Start frequency: f0=1 kHzStop frequency: f1=2 kHzSampling frequency: fs=48 kHz

Duration: Td=50 msThe chirp formula is given as:

y(t) = cos

2

f0t+

f1 f02Td

t2

Plot the generated signal in MatlabUse both for, while, as well as the do approaches


Review Exercise 4


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Review Exercise 4

Extend the structure for the complex numbers to include thephase argument of a complex number

Write a function, cphi, that computes phase argument ofcomplex number

Write 4 functions that implement addition, subtraction,

multiplication and division for complex numbers with namescadd, csub, cmul, and cdiv. Test the developed functions forz1=-1+j and z2=2-j. Check the results using matlab.

Create your own complex-number library by including all the

developed functions and cmplx structure itself in a header filecmplx.h. Re-write the previous program to use#include "cmplx.h"


C Tutorial Part 2[1]

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