MDC:MULIPLE DATA COMPRESSION & DECOMPRESSION USING 6 BIT

/*SOURCE FILE TO BE COMPRESSED*/

 MY STRENGTH IS THAT I ALWAYS DO 80% OF THINGS WHAT I THINK...my weakness is this that sometimes i find myself so feelingless..so selfish...it might be good for me..I HAVE COMPLETED MDC WITH ALL 1 TO 7 BIT COMPRESSION TECHNIQUE..FOR DIFFRENT NO. OF DISTINCT CHARACTERS..I HAD ALSO COMPLETED..PROJECT USING INTERPROCESS COMMMUNICATION..FIFO PIPES SOCKETS,THREADS,,USING SYNCHRONIZATION WITH SEMAPHORES,I HAD CREATED PROJECT WITH DIFFRENT SOCKETS..THREADS..THREADS WITH PROCESSES...PROCESS WITH PIPE..SOCKETS WITH MDC...FTP USING THREADS & SOCKETS & SO ON...I HAD DONE A LONG TIME PRACTICE ON C..BOARD BRINGUP..,CHARACTER DRIVER..MAKEFILE..ARM PROCESSOR..I HAD MADE TOOLCHAIN..I AM ALSO WORKING IN  C++..I AM LEARNING PYTHON ALSO...TOUCH SCREEN DRIVER SO ON..USB DRIVER...BLOCK DRIVER...PCI DRIVER..PARRLEL PORT DRIVER....

  if((i)*(j)==24)//pending no. of bits are extracted from another byt.to make a character..but there are pending no. of bits only for j=6 & j=4..means 2nd & 3rd time ...so enter to extract pending no. of bits for these 2 vlues

                        {

                                count=read(fd,&ch,1);//read a new byt to extract pending no. of bits

                                if(count==0)

                                        break;

                                in=ch;//copy into in

                                cp=ch;//preserve tht character

                                in=in>>(i);//i=4 for j=6 & i=6 for j=4..

//4 right shift of in for 2nd character will give me 4 pending bits of 2nd character at last positions of in variable.

                                byt=byt|in;//add pending no. of bits in..in/..variable ..if any..

                                in=in^in;//again make in=0 for further use of it..

                        }

                        printf("%c",*(masterarray+byt));//now byt is full address of one character like an index..so add that index in masterarray to get exact position of that character in ur system..

                        byt=byt^byt;//make byt=0 for its again use...

                }//again go into while loop for further read of new character to decompress untill all the characters in file are decompressed....

        }

        return 0;

}

int indu(char buff)//func to index..

{

        int i=0;//i=0 initially

        if(buff == '\0')

                goto OUT;

        //i=0;

        //

        while(buff != *(masterarray+i))//WHOLE FILE TO BE COMPRESSED IS COMPAIRED TO MASTERARAY..AT WHAT VALUE OF i..character from file is matched to distinct character of masterarray..that value of i will be treated as identification of that character ...so that value of i is returned...

        {

                //printf("i=%d\n",i);

                //if(buff != *(masterarray+i))

                i++;

        }

        return i;

OUT:

        return -1;

}

              if((i)*(j)==24)//IF
ANY OF i or j is 6 or 4...only then pending bits will left ...or i can
say ..in place of 4 characters...mid two characters will have pending
no. of bits left that we get need to put those pending no. of bits in
another byt & preserve that byt for some time ....untill 1st byt is
written to file ...

                        {

                                in=ch;//put character index into the in variable

                                in=in<<i;

//make it right shift as i..i will have difference of 2 always in this condition

//j=6 i=j; i=i-2;;;will
make i=4...so j=6 i=4 means 4 left shift of in variable will give me 4
last bits of 2nd character in another byt

//j=4 i=j; i=i+2;;;will
make i=6...so j=4 i=6 means 6 left shift of in variable will give me 2
last bits of 3rd character in another byt

                        }

                        ch=ch<<2;//2 left shift will give me 6 bits of character in starting 6 positions..

// 000000 00 index=0 | 000001 00 index=1 | 000011 00 index=2

                        if(j != 8)//for 1st character...there is no right shift

                                ch=ch>>j;//0 6 4 2 ..1st char become ch=000000 00//first 6 bit will have address of character

//for 2nd character right shift is 6...become ch=000000 00//last two bits are of 2nd character in this ch...

     //for 3rd time character

                        byt=byt|ch;//2nd //

                        if(j != 8)//for 1st character only 6 bits in byt...so first time do not write into file

                        {

                                write(wfd,&byt,1);

                                printf("byt=%p\t",byt);

                                byt=byt^byt;//1st time do not make byt 0

                                byt=byt|in;//when 1st byt is written to compressed file ..make empty to file..add in to byt...tht... in... contains pending no. of bits..

                                in=in^in;//aftr adding..in..to byt..make empty to ..in...for its further use

                        }

                }

        }

        return 0;

}

int codelength(int ndc)//now we have to find codelen
{
        int i,j=0;//j will represent no. bits 6 to represent 64 distinct characters
        //printf("ndc=%d\n",ndc);
        for(i=1;i<ndc;j++)//untill i<ndc..j++ every time...
        {
                //printf("i=%d\n",i);
                i=i*2;//when i=i*2 will count power of 2..j=0 2=1*2 j=1 4=2*2 j=2 8=4*2 j=3;...so on
        }
        if(ndc==0)
                j=0;
        return j;//in this case ...we have j=6 counted...for 6 bit compression..
}

int create_masterarray(char buff)//we have to find distinct no. of characters..we have character read from the file in main send by their as a argument,..so here we have to find distinct no. of characters in from file ..& put those no. of characters in masterarray pointer..

{

        if(flag==1)//1st time flag is 1..means malloc to masterarray

        {

                masterarray=malloc(sizeof(char)*size);//bcz we have to put characters in masterarray named pointer..so we need to malloc masterarrray..

                //printf("masterarray in malloc=%p\n",masterarray+size);

                flag=0;//once masterarray is malloced then flag=0

        }

        else

        {

                //printf("master\n");

                masterarray=realloc(masterarray,sizeof(char)*size);//after making flag=0..every time ..it will not malloc the mastearray..it will realloc the masterarray..every time now...

//There is difference b/w malloc & realloc is this that..when we do malloc..a new memory from new block is provided to u..in masterarray..then realloc means ...everytime continue to memory that is malloced to u before .memory is provided to u.

                //printf("masterarray in realloc=%p\n",masterarray+size);

        }

        //printf("flag=%d\n",flag);

        if(buff != '\0')//if character that is read is not NULL...then is will send for to find distinct of characters in check function....bcz ..we do not have to increase size of our compressed file..so we will try ..not to compress this NULL character...

    ret=check(buff);//call to check function to check the distinct no. of characters & put those characters into masterarray if they are not in masterarray named pointer

        //printf("ret=%d\n",ret);

        if(ret==0)//if returned value is zero means in check function ...character was put into masterarray this time ..so increse the size...to realloc size again to put character into masterarray again...

                size++;

        return size-2;//memory in which characters are being putted is masterarray+i-1..size is 1 more i...so size-2 is returned...as no. of distinct no. of charactes...

OUT:

        return -1;

}

/*COMPRESSED FILE*/

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