Intermediate C Programming

440 Intermediate C Programming

freque ncies [ ind ]. freq );74

ListNode * ln = L istNod e_crea te ( tn) ;75

head = List_i nsert ( head , ln , SORTED ) ;76

ind ++;77

}78

return head ;79

}80

void List_pri n t ( L i stNode * head )81

{82

i f ( head == NULL )83

{84

return ;85

}86

Tree_pr i nt ( head -> tnptr , 0) ;87

List_pr i nt ( head -> next );88

}89

// utility .h1

#i f n d e f UTILITY_H2

#d ef in e UTILITY_ H3

#in clude < stdio .h >4

// write one bit to a file5

// whichbi t indicat e s which bit this is written to (0 means7

// leftmost , 7 means right m ost )8

// curbyte is the c u r rent byte9

//10

// if whichbit is zero , curbyte is reset and bit is put11

// to the leftmost bit12

//13

// when which bit r e a ches 7, this byte is written to the14

// file and whichbit is reset15

//16

// the functi o n returns 1 if a byte is written to the file17

// returns 0 if no byte is written18

// -1 if it tries to write and fails19

int writeBit ( FILE * fptr , unsigned char bit ,20

unsigned char * whichbit , unsigned char *21

curbyte ) ;22

// if * w hichbit is not 0, some bits of * curbyte are not used23

// fill these bits by 0 and write the byte to the file24

int padZero ( FILE * fptr , unsigned char * whichbit ,25

unsigned char * curbyte );26

int readBit ( FILE * fptr , unsigned char * bit ,28

unsigned char * whichbit ,29

unsigned char * curbyte );30

#e ndif31

// utility .c1

#in clude < stdio .h >2

Huﬀman Compression 441

#in clude " utility . h"3

int padZero ( FILE * fptr , unsigned char * whichbit ,4

unsigned char * curbyte )5

int rtv ;7

while ((* whichbit ) != 0)8

rtv = wri t eB it ( fptr , 0 , whichbit , c u r b y t e ) ;10

i f ( rtv == -1)11

{12

return -1;13

}14

}15

return rtv ;16

}17

int readBit ( FILE * fptr , unsigned char * bit ,18

unsigned char * whichbit , unsigned char * curbyte )19

{21

int ret = 1;22

i f ((* whichbit ) == 0)23

{24

// read a byte from the file25

ret = fread ( curbyte , s i z e o f ( unsigned char ) , 1, fptr );26

}27

i f ( ret != 1)28

{29

// read fail30

return -1;31

}32

// shift the bit to the correct location33

unsigned char temp = (* curbyte ) >> (7 - (* whichbit ) );34

temp = temp & 0 X01 ; // get only 1 bit , ignore the others35

// increas e by 136

* whichbit = ((* whic h bit ) + 1) % 8;37

* bit = temp ;38

return 1;39

}40

This is the Makefile for the program.

CFLAGS = -g - Wall - Wshadow1

GCC = gcc $ ( CFLAGS )2

SRCS = main .c encode .c freq .c tree .c list .c utility . c3

OBJS = $ ( SRCS :%. c =%. o)4

VALGRIND = valgrind -- leak - check = full -- tool = memcheck5

-- verbose --log - file6

code : $ ( OBJS )8

$( GCC ) $ ( OBJS ) -o code9

test1 : code11

442 Intermediate C Programming

./ code e input1 comp r ess112

$( VALGRIND )= logenc1 ./ code e input1 compr e ss113

./ code d compre s s1 output114

$( VALGRIND )= logdec1 ./ code d compres s 1 output115

echo # add a blank line16

diff input1 output117

test2 : code19

./ code e input2 comp r ess220

$( VALGRIND )= logenc2 ./ code e input2 compr e ss221

./ code d compre s s2 output222

$( VALGRIND )= logdec2 ./ code d compres s 2 output223

echo # add a blank line24

diff input2 output225

test3 : code27

./ code e input3 comp ress328

$( VALGRIND )= logenc3 ./ code e input3 compr e ss329

./ code d compre s s3 output330

$( VALGRIND )= logdec3 ./ code d compres s 3 output331

echo # add a blank line32

diff input3 output333

.c .o:35

$( GCC ) $ ( CFLAGS ) -c $ *. c36

clean :38

rm -f *. o a. out code log *39

This is the most complex program in this book. It integrates almost all topics in this

book. Please study this program carefully. It is a bridge for you from being an intermediate

programmer to becoming an advanced programmer.

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Table of Contents for Intermediate C Programming

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Intermediate C Programming