Category : Files from Magazines
Archive   : DDJ9405E.ZIP
Filename : HUFFC.C
#include "dflat.h"
#include "htree.h"
extern struct htree *ht;
extern int root;
extern int treect;
static int lastchar = '\n';
static void compress(FILE *, int, int);
static void outbit(FILE *fo, int bit);
static int fgetcx(FILE *fi)
{
int c;
/* ------- bypass comments ------- */
if ((c = fgetc(fi)) == ';' && lastchar == '\n')
do {
while (c != '\n' && c != EOF)
c = fgetc(fi);
} while (c == ';');
lastchar = c;
return c;
}
void main(int argc, char *argv[])
{
FILE *fi, *fo;
int c;
BYTECOUNTER bytectr = 0;
if (argc < 3) {
printf("\nusage: huffc infile outfile");
exit(1);
}
if ((fi = fopen(argv[1], "rb")) == NULL) {
printf("\nCannot open %s", argv[1]);
exit(1);
}
if ((fo = fopen(argv[2], "wb")) == NULL) {
printf("\nCannot open %s", argv[2]);
fclose(fi);
exit(1);
}
ht = calloc(256, sizeof(struct htree));
/* - read the input file and count character frequency - */
while ((c = fgetcx(fi)) != EOF) {
c &= 255;
ht[c].cnt++;
bytectr++;
}
/* ---- build the huffman tree ---- */
buildtree();
/* --- write the byte count to the output file --- */
fwrite(&bytectr, sizeof bytectr, 1, fo);
/* --- write the tree count to the output file --- */
fwrite(&treect, sizeof treect, 1, fo);
/* --- write the root offset to the output file --- */
fwrite(&root, sizeof root, 1, fo);
/* -- write the tree to the output file -- */
for (c = 256; c < treect; c++) {
int lf = ht[c].left;
int rt = ht[c].right;
fwrite(&lf, sizeof lf, 1, fo);
fwrite(&rt, sizeof rt, 1, fo);
}
/* ------ compress the file ------ */
fseek(fi, 0L, 0);
while ((c = fgetcx(fi)) != EOF)
compress(fo, (c & 255), 0);
outbit(fo, -1);
fclose(fi);
fclose(fo);
free(ht);
exit(0);
}
/* ---- compress a character value into a bit stream ---- */
static void compress(FILE *fo, int h, int child)
{
if (ht[h].parent != -1)
compress(fo, ht[h].parent, h);
if (child) {
if (child == ht[h].right)
outbit(fo, 0);
else if (child == ht[h].left)
outbit(fo, 1);
}
}
static char out8;
static int ct8;
/* -- collect and write bits to the compressed output file -- */
static void outbit(FILE *fo, int bit)
{
if (ct8 == 8 || bit == -1) {
while (ct8 < 8) {
out8 <<= 1;
ct8++;
}
fputc(out8, fo);
ct8 = 0;
}
out8 = (out8 << 1) | bit;
ct8++;
}
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This is so awesome! 😀 I’d be cool if you could download an entire archive of this at once, though.
But one thing that puzzles me is the “mtswslnkmcjklsdlsbdmMICROSOFT” string. There is an article about it here. It is definitely worth a read: http://www.os2museum.com/wp/mtswslnk/