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Merge pull request dzagalskii#1 from FS-make-simple/master
1.1: added Makefile and cmdline args
2 parents c141881 + 8c743a1 commit 8c78906

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‎LICENSE‎

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Public Domain Mark 1.0
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No Copyright
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This work has been identified as being free of known restrictions
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under copyright law, including all related and neighboring rights.
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You can copy, modify, distribute and perform the work, even for
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commercial purposes, all without asking permission. See Other
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Information below.
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Other Information
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The work may not be free of known copyright restrictions in all
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jurisdictions.
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Persons may have other rights in or related to the work, such as
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patent or trademark rights, and others may have rights in how the
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work is used, such as publicity or privacy rights.
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In some jurisdictions moral rights of the author may persist beyond
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the term of copyright. These rights may include the right to be
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identified as the author and the right to object to derogatory
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treatments.
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Unless expressly stated otherwise, the person who identified the work
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makes no warranties about the work, and disclaims liability for all
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uses of the work, to the fullest extent permitted by applicable law.
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When using or citing the work, you should not imply endorsement by
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the author or the person who identified the work.

‎Makefile‎

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CC = gcc
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CFLAGS = -Wall -std=c99
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LDFLAGS = -s
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PROGS = hammingenc hammingdec
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all: $(PROGS)
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hammingenc: hammingenc.c
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$(CC) $(CFLAGS) $^ -o $@ $(LDFLAGS)
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hammingdec: hammingdec.c
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$(CC) $(CFLAGS) $^ -o $@ $(LDFLAGS)
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clean: $(PROGS)
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rm -f $^

‎README.md‎

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Familiarization with the Hamming method of error-correcting coding, which allows to detect and automatically correct errors that occur during the transmission of information.
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# HAMMING ENC/DEC
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Familiarization with the Hamming method of error-correcting coding, which allows to detect and automatically correct errors that occur during the transmission of information.
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# USAGE
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```sh
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./hammingenc input.file output.hmng [8/12/16/32/64]
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./hammingdec input.hmng output.file [8/12/16/32/64]
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```
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2019

‎hammingdec.c‎

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#include <stdio.h>
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#include <stdlib.h>
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void kontrolbit(int *kod, int lengh)
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{
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int i = 0, summ = 0, errorpos = 0;
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while(i < lengh)
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{
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if((i+1 == 1)||(i+1 == 2)||(i+1 == 4)||(i+1 == 8)||(i+1 == 16)||(i+1 == 32)||(i+1 == 64))
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{
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int start = i;
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while(start < lengh)
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{
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for(int g = 0; g < i + 1; g++)
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{
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if((start+g != i)&&(start+g < lengh))
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summ += kod[start+g];
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}
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start += (i + i + 2);
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}
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if(kod[i] != summ%2)
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{
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errorpos += i;
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}
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summ = 0;
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}
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i++;
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}
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kod[errorpos] = (errorpos != 0) ? !kod[errorpos] : kod[errorpos];
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}
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void invert(int *byte)
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{
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int i, t;
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for(i = 0; i < 4; i++)
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{
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t = byte[i];
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byte[i] = byte[7 - i];
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byte[7 - i] = t;
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}
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}
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void tobit(int x, int *byte)
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{
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int i;
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for(i = 0; i < 8; i++)
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{
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byte[i] = x%2;
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x >>= 1;
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}
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invert(byte);
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}
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int todec(int *byte)
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{
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int i, x = 0, st = 7;
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for(i = 0; i < 8; i++)
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{
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x += (byte[i]<<st);
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st--;
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}
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return x;
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}
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int main(int argc, char *argv[])
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{
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if (argc < 3)
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{
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printf("Usage: %s input.hmng output.file [8/12/16/32/64]\n", argv[0]);
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return 0;
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}
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FILE *f = fopen(argv[1], "rb");
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FILE *t = fopen(argv[2], "w+b");
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int byte[8];
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printf("coded: %s\n", argv[1]);
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printf("file: %s\n", argv[2]);
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int c = 8;
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if (argc > 3) c = atoi(argv[3]);
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printf("decoding length: %d\n\n", c);
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if(c == 8)
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{
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int x, kod[12], g = 0;
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x = fgetc(f);
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while(x != EOF)
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{
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tobit(x, byte);
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for(int i = 0; i < 8; i++)
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{
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if((i != 0)&&(i != 1))
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kod[g++] = byte[i];
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}
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if(g == 12)
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{
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kontrolbit(kod, 12);
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g = 0;
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for(int i = 0; i < 12; i++)
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{
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if((i+1 != 1)&&(i+1 != 2)&&(i+1 != 4)&&(i+1 != 8))
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{
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byte[g++] = kod[i];
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}
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}
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fputc(todec(byte), t);
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g = 0;
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}
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x = fgetc(f);
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}
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}
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else if(c == 12)
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{
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fprintf(stderr, "WARNIND: with coding length %d end of file is not always processed correctly\n\n", c);
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int tmp[4], x, kod[17], g = 0, flag = 0, schet = 0;
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x = fgetc(f);
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while(x != EOF)
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{
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tobit(x, byte);
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kod[g] = byte[7];
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g++;
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if(g == 17)
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{
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g = 0;
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kontrolbit(kod, 17);
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g = 0;
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if(flag == 1) //костыль
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{
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for(int i = 0; i < 4; i++)
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{
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byte[g++] = tmp[i];
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}
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flag = 0;
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}
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for(int i = 0; i < 17; i++)
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{
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if((i+1 != 1)&&(i+1 != 2)&&(i+1 != 4)&&(i+1 != 8)&&(i+1 != 16)&&(i+1 != 32)&&(i+1 != 64))
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byte[g++] = kod[i];
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if(g == 8)
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{
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fputc(todec(byte), t);
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g = 0;
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if((flag == 0)&&(schet%2 == 0)) //костыль 2
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{
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for(int i = 12; i < 17; i++)
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{
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if(i+1 != 16)
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{
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tmp[g++] = kod[i];
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}
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}
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flag = 1;
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}
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g = 0;
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}
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}
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g = 0;
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}
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schet++; //костыль 3
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x = fgetc(f);
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}
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}
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else if(c == 16)
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{
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fprintf(stderr, "WARNIND: with coding length %d end of file is not always processed correctly\n\n", c);
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int x, kod[21], g = 0;
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x = fgetc(f);
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while(x != EOF)
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{
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tobit(x, byte);
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for(int i = 0; i < 8; i++)
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{
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if(i != 0)
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kod[g++] = byte[i];
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}
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if(g == 21)
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{
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kontrolbit(kod, 21);
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g = 0;
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for(int i = 0; i < 21; i++)
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{
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if((i+1 != 1)&&(i+1 != 2)&&(i+1 != 4)&&(i+1 != 8)&&(i+1 != 16)&&(i+1 != 32)&&(i+1 != 64))
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byte[g++] = kod[i];
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if(g == 8)
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{
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fputc(todec(byte), t);
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g = 0;
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}
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}
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}
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x = fgetc(f);
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}
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}
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else if(c == 32)
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{
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fprintf(stderr, "WARNIND: with coding length %d end of file is not always processed correctly\n\n", c);
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int x, kod[38], g = 0;
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x = fgetc(f);
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while(x != EOF)
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{
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tobit(x, byte);
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for(int i = 0; i < 8; i++)
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{
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if((i == 6)||(i == 7))
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kod[g++] = byte[i];
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}
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if(g == 38)
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{
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kontrolbit(kod, 38);
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g = 0;
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for(int i = 0; i < 38; i++)
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{
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if((i+1 != 1)&&(i+1 != 2)&&(i+1 != 4)&&(i+1 != 8)&&(i+1 != 16)&&(i+1 != 32)&&(i+1 != 64))
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byte[g++] = kod[i];
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if(g == 8)
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{
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fputc(todec(byte), t);
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g = 0;
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}
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}
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}
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x = fgetc(f);
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}
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}
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else if(c == 64)
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{
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fprintf(stderr, "WARNIND: with coding length %d end of file is not always processed correctly\n\n", c);
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int x, kod[71], g = 0;
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x = fgetc(f);
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while(x != EOF)
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{
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tobit(x, byte);
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for(int i = 0; i < 8; i++)
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{
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if(i == 7)
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kod[g++] = byte[i];
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}
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if(g == 71)
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{
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kontrolbit(kod, 71);
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g = 0;
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for(int i = 0; i < 71; i++)
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{
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if((i+1 != 1)&&(i+1 != 2)&&(i+1 != 4)&&(i+1 != 8)&&(i+1 != 16)&&(i+1 != 32)&&(i+1 != 64))
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byte[g++] = kod[i];
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if(g == 8)
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{
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fputc(todec(byte), t);
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g = 0;
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}
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}
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}
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x = fgetc(f);
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}
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}
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else
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{
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fprintf(stderr, "ERROR: bad coding length %d, maybe 8/12/16/32/64\n\n", c);
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}
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fclose(f);
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fclose(t);
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return 0;
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}

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