68 lines
1.6 KiB
C
68 lines
1.6 KiB
C
#include <stdio.h>
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#include <stdlib.h>
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#include <arpa/inet.h>
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// FILE format is: 'header', then 2023 skipped bytes, then the number of interest
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#define OURINT 1426915328
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#define OFFSETTODATA 2023
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int writeToFile(){
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FILE* fp = fopen("toReadLater.txt","w+");
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char c = 'h';
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fwrite(&c, sizeof(char), 1, fp);
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c = 'e';
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fwrite(&c, sizeof(char), 1, fp);
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c = 'a';
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fwrite(&c, sizeof(char), 1, fp);
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c = 'd';
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fwrite(&c, sizeof(char), 1, fp);
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c = 'e';
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fwrite(&c, sizeof(char), 1, fp);
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c = 'r';
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fwrite(&c, sizeof(char), 1, fp);
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unsigned int buf = OFFSETTODATA;
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fwrite(&buf, sizeof(int), 1, fp);
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fseek(fp, OFFSETTODATA, SEEK_CUR);
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buf = OURINT;
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fwrite(&buf, sizeof(int), 1, fp);
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fclose(fp);
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}
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int readFromFile(){
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FILE *fp = fopen("toReadLater.txt", "r+");
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fseek(fp, 6 , SEEK_SET);
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int skip = 0;
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fread(&skip, sizeof(int), 1, fp);
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// NOTE, in HW, the size of the section is a value in
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// Big-Endian format, it will actually need conversion
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fseek(fp, skip, SEEK_CUR);
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unsigned int qBe = 0;
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unsigned int qLe = 0;
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int i;
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unsigned char *c = (char *)(&qBe);
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unsigned char *d = (char *)(&qLe);
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for (i = 0; i < 4; i++)
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{
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c[i] = getc(fp);
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printf("Byte %i: %i %x\n",i, c[i], c[i]);
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}
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for (i = 0; i < 4; i++)
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{
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d[4-i-1] = c[i];
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}
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printf("Translated using swapping the bytes order: %i\n", qLe);
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qLe = ntohl(qBe);
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printf("Translated using ntohl: %i\n", qLe);
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fclose(fp);
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}
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int main (int argc, char** argv){
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unsigned int wantToRead;
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writeToFile();
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printf("Sizeof (int) is:%li\n", sizeof(unsigned int));
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readFromFile();
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return 0;
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} |