/* huffenc.c - Don Yang (uguu.org)

   09/13/01
                                                                           */

#include<sys/types.h>
#include<sys/stat.h>
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include"hufftree.h"


struct
{
   unsigned char bit[HUFFMAN_TREE_DEPTH];
   int length;
} Table[256];

static void HuffmanEncode(FILE *infile, FILE *outfile, int size);
static void InitTable(void);
static void InitTableEntries(int index, char *string);
static void SetEntry(int index, char *string, int length);

/******************************************************************** main */
int main(int argc, char **argv)
{
   FILE *infile, *outfile;
   struct stat info;
   int size;

   InitTable();
   if( argc < 3 )
      return printf("%s <infile> <outfile>\n", *argv);

   if( stat(argv[1], &info) )
      return printf("Can not stat %s\n", argv[1]);
   size = (int)info.st_size;
   if( (infile = fopen(argv[1], "rb")) == NULL )
      return printf("Can not open %s\n", argv[1]);
   if( (outfile = fopen(argv[2], "wb+")) == NULL )
   {
      fclose(infile);
      return printf("Can not create %s\n", argv[2]);
   }

   fwrite(&size, sizeof(int), 1, outfile);
   HuffmanEncode(infile, outfile, size);
   fclose(infile);
   fclose(outfile);

   return 0;

} /* main() */

/*********************************************************** HuffmanEncode */
static void HuffmanEncode(FILE *infile, FILE *outfile, int size)
{
   int bit, byte, c, i, j;

   for(i = bit = byte = 0; i < size && (c = fgetc(infile)) != EOF; i++)
   {
      for(j = 0; j < Table[c].length; j++)
      {
         byte |= ((unsigned)Table[c].bit[j]) << (bit++);
         if( bit > 7 )
         {
            fputc(byte, outfile);
            bit = byte = 0;
         }
      }
   }

   if( bit > 0 )
      fputc(byte, outfile);

} /* HuffmanEncode() */

/*************************************************************** InitTable */
static void InitTable(void)
{
   char string[HUFFMAN_TREE_DEPTH];

   string[0] = 0;
   InitTableEntries(0, string);

} /* InitTable() */

/******************************************************** InitTableEntries */
static void InitTableEntries(int index, char *string)
{
   size_t x;
   int i;

   x = strlen(string);
   string[x] = 1;
   string[x + 1] = 0;
   if( (i = Left[index]) <= 0 )  SetEntry(-i, string, x + 1);
   else                          InitTableEntries(i, string);

   string[x] = 2;
   if( (i = Right[index]) <= 0 ) SetEntry(-i, string, x + 1);
   else                          InitTableEntries(i, string);

   string[x] = 0;

} /* InitTableEntries() */

/**************************************************************** SetEntry */
static void SetEntry(int index, char *string, int length)
{
   int i;

   Table[index].length = length;
   for(i = 0; i < length; i++)
      Table[index].bit[i] = (unsigned char)(string[i] - 1);

} /* SetEntry() */