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
6
// 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
27
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
{6
int rtv ;7
while ((* whichbit ) != 0)8
{9
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
20
{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
7
code : $ ( OBJS )8
$( GCC ) $ ( OBJS ) -o code9
10
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
18
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
26
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
34
.c .o:35
$( GCC ) $ ( CFLAGS ) -c $ *. c36
37
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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