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/* FreeDOS Edit Help Compiler
Part of the FreeDOS Project
Originally part of D-Flat, by Dr. Dobbs Journal
Modified by Joe Cosentino 2002.
*/
/* I N C L U D E S /////////////////////////////////////////////////////// */
#include "dflat.h"
#include "htree.h"
/* G L O B A L S ///////////////////////////////////////////////////////// */
extern struct htree *ht;
extern int root;
extern int treect;
static int lastchar='\n';
static int ct8;
static char out8;
/* P R O T O T Y P E S /////////////////////////////////////////////////// */
static void compress(FILE *, int, int);
static void outbit(FILE *, int);
/* F U N C T I O N S ///////////////////////////////////////////////////// */
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;
}
/* 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);
}
}
/* 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++;
}
void main(int argc, char *argv[])
{
FILE *fi, *fo;
int c;
BYTECOUNTER bytectr = 0;
if (argc < 3)
{
printf("Syntax: HUFFC infile outfile\n");
exit(1);
}
if ((fi = fopen(argv[1], "rb")) == NULL)
{
printf("Cannot open %s\n", argv[1]);
exit(1);
}
if ((fo = fopen(argv[2], "wb")) == NULL)
{
printf("Cannot open %s\n", 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,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);
}
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