text: #include "StdAfx.h"
  #include "LZARIDecoder.h"
  
  
  
  /**************************************************************
  	LZARI.C -- A Data Compression Program
  	(tab = 4 spaces)
  ***************************************************************
  	4/7/1989 Haruhiko Okumura
  	Use, distribute, and modify this program freely.
  	Please send me your improved versions.
  		PC-VAN		SCIENCE
  		NIFTY-Serve	PAF01022
  		CompuServe	74050,1022
  **************************************************************/
  #include <stdio.h>
  #include <stdlib.h>
  #include <string.h>
  #include <ctype.h>
  
  /********** Bit I/O **********/
  
  
  
  CLZARIDecoder::CLZARIDecoder(void)
  {
  	textsize = 0;
  	codesize = 0;
  	printcount = 0;
  
  	low = 0;
  	high = Q4;
  	value = 0;
  	shifts = 0;
  
  	initBuffer = false;
  }
  
  void CLZARIDecoder::Error(char *message)
  {
  	////printf("\n%s\n", message);
  	//exit(EXIT_FAILURE);
  }
  
  void CLZARIDecoder::PutBit(int bit)  /* Output one bit (bit = 0,1) */
  {
  	//static unsigned int  buffer = 0, mask = 128;
  	if (!initBuffer)
  	{
  		buffer = 0;
  		mask = 128;
  		initBuffer = true;
  	}
  	
  	if (bit) buffer |= mask;
  	if ((mask >>= 1) == 0) {
  		if (putc(buffer, outfile) == EOF) Error("Write Error");
  		buffer = 0;  mask = 128;  codesize++;
  	}
  }
  
  void CLZARIDecoder::FlushBitBuffer()  /* Send remaining bits */
  {
  	int  i;
  	
  	for (i = 0; i < 7; i++) PutBit(0);
  }
  
  int CLZARIDecoder::GetBit()  /* Get one bit (0 or 1) */
  {
  	//static unsigned int  buffer, mask = 0;
  
  	if (!initBuffer)
  	{
  		buffer = 0;
  		mask = 0;
  		initBuffer = true;
  	}
  	
  	if ((mask >>= 1) == 0) {
  		buffer = getc(infile);  mask = 128;
  	}
  	return ((buffer & mask) != 0);
  }
  
  /********** LZSS with multiple binary trees **********/
  
  
  
  
  
  void CLZARIDecoder::InitTree()  /* Initialize trees */
  {
  	int  i;
  
  	/* For i = 0 to N - 1, rson[i] and lson[i] will be the right and
  	   left children of node i.  These nodes need not be initialized.
  	   Also, dad[i] is the parent of node i.  These are initialized to
  	   NIL (= N), which stands for 'not used.'
  	   For i = 0 to 255, rson[N + i + 1] is the root of the tree
  	   for strings that begin with character i.  These are initialized
  	   to NIL.  Note there are 256 trees. */
  
  	for (i = N + 1; i <= N + 256; i++) rson[i] = NIL;	/* root */
  	for (i = 0; i < N; i++) dad[i] = NIL;	/* node */
  }
  
  void CLZARIDecoder::InsertNode(int r)
  	/* Inserts string of length F, text_buf[r..r+F-1], into one of the
  	   trees (text_buf[r]'th tree) and returns the longest-match position
  	   and length via the global variables match_position and match_length.
  	   If match_length = F, then removes the old node in favor of the new
  	   one, because the old one will be deleted sooner.
  	   Note r plays double role, as tree node and position in buffer. */
  {
  	int  i, p, cmp, temp;
  	unsigned char  *key;
  
  	cmp = 1;  key = &text_buf[r];  p = N + 1 + key[0];
  	rson[r] = lson[r] = NIL;  match_length = 0;
  	for ( ; ; ) {
  		if (cmp >= 0) {
  			if (rson[p] != NIL) p = rson[p];
  			else {  rson[p] = r;  dad[r] = p;  return;  }
  		} else {
  			if (lson[p] != NIL) p = lson[p];
  			else {  lson[p] = r;  dad[r] = p;  return;  }
  		}
  		for (i = 1; i < F; i++)
  			if ((cmp = key[i] - text_buf[p + i]) != 0)  break;
  		if (i > THRESHOLD) {
  			if (i > match_length) {
  				match_position = (r - p) & (N - 1);
  				if ((match_length = i) >= F) break;
  			} else if (i == match_length) {
  				if ((temp = (r - p) & (N - 1)) < match_position)
  					match_position = temp;
  			}
  		}
  	}
  	dad[r] = dad[p];  lson[r] = lson[p];  rson[r] = rson[p];
  	dad[lson[p]] = r;  dad[rson[p]] = r;
  	if (rson[dad[p]] == p) rson[dad[p]] = r;
  	else                   lson[dad[p]] = r;
  	dad[p] = NIL;  /* remove p */
  }
  
  void CLZARIDecoder::DeleteNode(int p)  /* Delete node p from tree */
  {
  	int  q;
  	
  	if (dad[p] == NIL) return;  /* not in tree */
  	if (rson[p] == NIL) q = lson[p];
  	else if (lson[p] == NIL) q = rson[p];
  	else {
  		q = lson[p];
  		if (rson[q] != NIL) {
  			do {  q = rson[q];  } while (rson[q] != NIL);
  			rson[dad[q]] = lson[q];  dad[lson[q]] = dad[q];
  			lson[q] = lson[p];  dad[lson[p]] = q;
  		}
  		rson[q] = rson[p];  dad[rson[p]] = q;
  	}
  	dad[q] = dad[p];
  	if (rson[dad[p]] == p) rson[dad[p]] = q;
  	else                   lson[dad[p]] = q;
  	dad[p] = NIL;
  }
  
  
  
  
  
  void CLZARIDecoder::StartModel()  /* Initialize model */
  {
  	int ch, sym, i;
  	
  	sym_cum[N_CHAR] = 0;
  	for (sym = N_CHAR; sym >= 1; sym--) {
  		ch = sym - 1;
  		char_to_sym[ch] = sym;  sym_to_char[sym] = ch;
  		sym_freq[sym] = 1;
  		sym_cum[sym - 1] = sym_cum[sym] + sym_freq[sym];
  	}
  	sym_freq[0] = 0;  /* sentinel (!= sym_freq[1]) */
  	position_cum[N] = 0;
  	for (i = N; i >= 1; i--)
  		position_cum[i - 1] = position_cum[i] + 10000 / (i + 200);
  			/* empirical distribution function (quite tentative) */
  			/* Please devise a better mechanism! */
  }
  
  void CLZARIDecoder::UpdateModel(int sym)
  {
  	int i, c, ch_i, ch_sym;
  	
  	if (sym_cum[0] >= MAX_CUM) {
  		c = 0;
  		for (i = N_CHAR; i > 0; i--) {
  			sym_cum[i] = c;
  			c += (sym_freq[i] = (sym_freq[i] + 1) >> 1);
  		}
  		sym_cum[0] = c;
  	}
  	for (i = sym; sym_freq[i] == sym_freq[i - 1]; i--) ;
  	if (i < sym) {
  		ch_i = sym_to_char[i];    ch_sym = sym_to_char[sym];
  		sym_to_char[i] = ch_sym;  sym_to_char[sym] = ch_i;
  		char_to_sym[ch_i] = sym;  char_to_sym[ch_sym] = i;
  	}
  	sym_freq[i]++;
  	while (--i >= 0) sym_cum[i]++;
  }
  
  void CLZARIDecoder::Output(int bit)  /* Output 1 bit, followed by its complements */
  {
  	PutBit(bit);
  	for ( ; shifts > 0; shifts--) PutBit(! bit);
  }
  
  void CLZARIDecoder::EncodeChar(int ch)
  {
  	int  sym;
  	unsigned long int  range;
  
  	sym = char_to_sym[ch];
  	range = high - low;
  	high = low + (range * sym_cum[sym - 1]) / sym_cum[0];
  	low +=       (range * sym_cum[sym    ]) / sym_cum[0];
  	for ( ; ; ) {
  		if (high <= Q2) Output(0);
  		else if (low >= Q2) {
  			Output(1);  low -= Q2;  high -= Q2;
  		} else if (low >= Q1 && high <= Q3) {
  			shifts++;  low -= Q1;  high -= Q1;
  		} else break;
  		low += low;  high += high;
  	}
  	UpdateModel(sym);
  }
  
  void CLZARIDecoder::EncodePosition(int position)
  {
  	unsigned long int  range;
  
  	range = high - low;
  	high = low + (range * position_cum[position    ]) / position_cum[0];
  	low +=       (range * position_cum[position + 1]) / position_cum[0];
  	for ( ; ; ) {
  		if (high <= Q2) Output(0);
  		else if (low >= Q2) {
  			Output(1);  low -= Q2;  high -= Q2;
  		} else if (low >= Q1 && high <= Q3) {
  			shifts++;  low -= Q1;  high -= Q1;
  		} else break;
  		low += low;  high += high;
  	}
  }
  
  void CLZARIDecoder::EncodeEnd()
  {
  	shifts++;
  	if (low < Q1) Output(0);  else Output(1);
  	FlushBitBuffer();  /* flush bits remaining in buffer */
  }
  
  int CLZARIDecoder::BinarySearchSym(unsigned int x)
  	/* 1      if x >= sym_cum[1],
  	   N_CHAR if sym_cum[N_CHAR] > x,
  	   i such that sym_cum[i - 1] > x >= sym_cum[i] otherwise */
  {
  	int i, j, k;
  	
  	i = 1;  j = N_CHAR;
  	while (i < j) {
  		k = (i + j) / 2;
  		if (sym_cum[k] > x) i = k + 1;  else j = k;
  	}
  	return i;
  }
  
  int CLZARIDecoder::BinarySearchPos(unsigned int x)
  	/* 0 if x >= position_cum[1],
  	   N - 1 if position_cum[N] > x,
  	   i such that position_cum[i] > x >= position_cum[i + 1] otherwise */
  {
  	int i, j, k;
  	
  	i = 1;  j = N;
  	while (i < j) {
  		k = (i + j) / 2;
  		if (position_cum[k] > x) i = k + 1;  else j = k;
  	}
  	return i - 1;
  }
  
  void CLZARIDecoder::StartDecode()
  {
  	int i;
  
  	for (i = 0; i < M + 2; i++)
  		value = 2 * value + GetBit();
  }
  
  int CLZARIDecoder::DecodeChar()
  {
  	int	 sym, ch;
  	unsigned long int  range;
  	
  	range = high - low;
  	sym = BinarySearchSym((unsigned int)
  		(((value - low + 1) * sym_cum[0] - 1) / range));
  	high = low + (range * sym_cum[sym - 1]) / sym_cum[0];
  	low +=       (range * sym_cum[sym    ]) / sym_cum[0];
  	for ( ; ; ) {
  		if (low >= Q2) {
  			value -= Q2;  low -= Q2;  high -= Q2;
  		} else if (low >= Q1 && high <= Q3) {
  			value -= Q1;  low -= Q1;  high -= Q1;
  		} else if (high > Q2) break;
  		low += low;  high += high;
  		value = 2 * value + GetBit();
  	}
  	ch = sym_to_char[sym];
  	UpdateModel(sym);
  	return ch;
  }
  
  int CLZARIDecoder::DecodePosition()
  {
  	int position;
  	unsigned long int  range;
  	
  	range = high - low;
  	position = BinarySearchPos((unsigned int)
  		(((value - low + 1) * position_cum[0] - 1) / range));
  	high = low + (range * position_cum[position    ]) / position_cum[0];
  	low +=       (range * position_cum[position + 1]) / position_cum[0];
  	for ( ; ; ) {
  		if (low >= Q2) {
  			value -= Q2;  low -= Q2;  high -= Q2;
  		} else if (low >= Q1 && high <= Q3) {
  			value -= Q1;  low -= Q1;  high -= Q1;
  		} else if (high > Q2) break;
  		low += low;  high += high;
  		value = 2 * value + GetBit();
  	}
  	return position;
  }
  
  /********** Encode and Decode **********/
  
  void CLZARIDecoder::Encode()
  {
  	int  i, c, len, r, s, last_match_length;
  	
  	fseek(infile, 0L, SEEK_END);
  	textsize = ftell(infile);
  	if (fwrite(&textsize, sizeof textsize, 1, outfile) < 1)
  		Error("Write Error");  /* output size of text */
  	codesize += sizeof textsize;
  	if (textsize == 0) return;
  	rewind(infile);  textsize = 0;
  	StartModel();  InitTree();
  	s = 0;  r = N - F;
  	for (i = s; i < r; i++) text_buf[i] = ' ';
  	for (len = 0; len < F && (c = getc(infile)) != EOF; len++)
  		text_buf[r + len] = c;
  	textsize = len;
  	for (i = 1; i <= F; i++) InsertNode(r - i);
  	InsertNode(r);
  	do {
  		if (match_length > len) match_length = len;
  		if (match_length <= THRESHOLD) {
  			match_length = 1;  EncodeChar(text_buf[r]);
  		} else {
  			EncodeChar(255 - THRESHOLD + match_length);
  			EncodePosition(match_position - 1);
  		}
  		last_match_length = match_length;
  		for (i = 0; i < last_match_length &&
  				(c = getc(infile)) != EOF; i++) {
  			DeleteNode(s);  text_buf[s] = c;
  			if (s < F - 1) text_buf[s + N] = c;
  			s = (s + 1) & (N - 1);
  			r = (r + 1) & (N - 1);
  			InsertNode(r);
  		}
  		if ((textsize += i) > printcount) {
  			//printf("%12ld\r", textsize);  printcount += 1024;
  		}
  		while (i++ < last_match_length) {
  			DeleteNode(s);
  			s = (s + 1) & (N - 1);
  			r = (r + 1) & (N - 1);
  			if (--len) InsertNode(r);
  		}
  	} while (len > 0);
  	EncodeEnd();
  	//printf("In : %lu bytes\n", textsize);
  	//printf("Out: %lu bytes\n", codesize);
  	//printf("Out/In: %.3f\n", (double)codesize / textsize);
  }
  
  void CLZARIDecoder::Decode()
  {
  	int  i, j, k, r, c;
  	unsigned long int  count;
  
  	if (fread(&textsize, sizeof textsize, 1, infile) < 1)
  		Error("Read Error");  /* read size of text */
  	if (textsize == 0) return;
  	StartDecode();  StartModel();
  	for (i = 0; i < N - F; i++) text_buf[i] = ' ';
  	r = N - F;
  	for (count = 0; count < textsize; ) {
  		c = DecodeChar();
  		if (c < 256) {
  			putc(c, outfile);  text_buf[r++] = c;
  			r &= (N - 1);  count++;
  		} else {
  			i = (r - DecodePosition() - 1) & (N - 1);
  			j = c - 255 + THRESHOLD;
  			for (k = 0; k < j; k++) {
  				c = text_buf[(i + k) & (N - 1)];
  				putc(c, outfile);  text_buf[r++] = c;
  				r &= (N - 1);  count++;
  			}
  		}
  		if (count > printcount) {
  			//printf("%12lu\r", count);  printcount += 1024;
  		}
  	}
  	//printf("%12lu\n", count);
  }
  
  /*int main(int argc, char *argv[])
  {
  	char  *s;
  	
  	if (argc != 4) {
  		//printf("'lzari e file1 file2' encodes file1 into file2.\n"
  			   "'lzari d file2 file1' decodes file2 into file1.\n");
  		return EXIT_FAILURE;
  	}
  	if ((s = argv[1], s[1] || strpbrk(s, "DEde") == NULL)
  	 || (s = argv[2], (infile  = fopen(s, "rb")) == NULL)
  	 || (s = argv[3], (outfile = fopen(s, "wb")) == NULL)) {
  		//printf("??? %s\n", s);  return EXIT_FAILURE;
  	}
  	if (toupper(*argv[1]) == 'E') Encode();  else Decode();
  	fclose(infile);  fclose(outfile);
  	return EXIT_SUCCESS;
  }*/