PlexSheep
/
c-basic
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

removed bad occurences algorithm huffman

This commit is contained in:
Christoph J. Scherr 2022-11-26 01:03:37 +01:00
parent 8cdc34f119
commit 7acfb7b20c
1 changed files with 14 additions and 84 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

98
huffman/huffman.c
View File

@ -8,6 +8,8 @@
#include <sys/types.h>
#include <unistd.h>
// stolen from stackoverflow
// https://stackoverflow.com/questions/8236/how-do-you-determine-the-size-of-a-file-in-c
off_t fsize(const char *filename) {
struct stat st;
@ -33,7 +35,7 @@ int main(int argc, char *argv[]) {
bool verbose = false;
bool debug = false;
char *filestring = NULL;
uint64_t filelen;
off_t filelen;
FILE *fptrR = NULL; // file pointer for reading
FILE *fptrW = NULL; // file pointer for writing
@ -73,17 +75,15 @@ int main(int argc, char *argv[]) {
if (filestring) {
if(debug)
printf("[DEBUG]processing given file argument.\n");
// open the given file in binary mode, I want this to work with any files,
// not just textfiles.
// open the given file in binary mode
fptrR = fopen(filestring, "rb");
if (fptrR == NULL) {
fprintf(stderr, "The given file does not exist or is unavailable.\n");
exit(EXIT_FAILURE);
}
// causes bugs.
fseek(fptrR, 0L, SEEK_END);
filelen = ftell(fptrR);
fseek(fptrR, 0L, SEEK_SET);
filelen = fsize(filestring);
if(verbose)
printf("filesize: %ldB\n", filelen);
}
else {
// empty filestring or filestring is NULL
@ -91,10 +91,6 @@ int main(int argc, char *argv[]) {
exit(EXIT_FAILURE);
}
// TODO check file size and spit a "what the heck im not a 10x dev, do a
if(verbose)
printf("filesize: %ldB\n", filelen);
if (extract_mode) {
printf("extracting is not yet implemented.\n");
// decompress the file
@ -126,81 +122,15 @@ int main(int argc, char *argv[]) {
}
}
uint64_t occurences[256];
for(int i=0;i<256;i++){
occurences[i]=0;
}
// FIXME doesnt loop through full file! only 50% for larger files
// Backup occurence counting algorithm
/*
while(!feof(fptrR)){
fseek(fptrR, 512, SEEK_CUR);
if(fread(buf, 1, 512, fptrR)){
for(int i=0;i<512;i++){
occurences[buf[i]]++;
}
}
else{
fprintf(stderr, "Error when processing file.\n");
exit(EXIT_FAILURE);
}
uint64_t occurences[256] = { 0 };
// advance filepointer 512 bytes foreward. If not possible, set endOfFile flag.
// FIXME
offset += 512;
}
*/
// backup
while(1){
fseek(fptrR, 512, SEEK_CUR); // this line seems the be making the most problems
// not needed
// for(int i=0;i<256;i++){
// occurences[i]=0;
// }
// On success, fread() and fwri)te() return the number of items read or written.
// This number equals the number of bytes transferred only when size is
// 1. If an error occurs, or the end of the file is reached, the return value is a short item count (or zero).
// fread() does not distinguish between end-of-file and error, and callers must use feof(3) and ferror(3) to determine which occurred.
// FIXME )This is a buggy mess
if(512 == fread(buf, 1, 512, fptrR)){
for(int i=0;i<512;i++){
occurences[buf[i]]++;
}
}
else if(0 == fread(buf, 1, 512, fptrR)){
if(debug)
printf("[DEBUG]fread returned 0! ftell for current position is %lu\n", ftell(fptrR));
break;
}
else{
fprintf(stderr, "Error when processing file: %lu, At offset %lu\n",fread(buf, 1, 512, fptrR), ftell(fptrR));
exit(EXIT_FAILURE);
}
if(ftell(fptrR) > filelen) {
// ??? unknown error
fprintf(stderr, "tried reading further than the file is long somehow?\n");
exit(EXIT_FAILURE);
}
}
// ALMOST WORKS! ~200 bytes lost for a 10M file!!!
uint8_t bufMini[1];
// while(1){
// if(fread(bufMini, 1, 1, fptrR)){
// occurences[buf[0]]++;
// }
// else{
// if(ferror(fptrR)){
// fprintf(stderr, "encountered error when reading file.\n");
// exit(EXIT_FAILURE);
// }
// }
// fseek(fptrR, 1, SEEK_SET);
// if(ferror(fptrR)){
// fprintf(stderr, "encountered error when reading file.\n");
// exit(EXIT_FAILURE);
// }
// else if(feof(fptrR)){
// break;
// }
// }
// TODO calculate occurences
if(debug){
printf("Occurences (Hex):\n");
for(int i=0;i<256;i++){