| 1 |
2 |
habicht |
/**************************************************************************************************************
|
| 2 |
|
|
*
|
| 3 |
|
|
* L Z R W 1 E N C O D E R C O R E
|
| 4 |
|
|
*
|
| 5 |
|
|
* A high throughput loss less data compression core.
|
| 6 |
|
|
*
|
| 7 |
|
|
* Copyright 2012-2013 Lukas Schrittwieser (LS)
|
| 8 |
|
|
*
|
| 9 |
|
|
* This program is free software: you can redistribute it and/or modify
|
| 10 |
|
|
* it under the terms of the GNU General Public License as published by
|
| 11 |
|
|
* the Free Software Foundation, either version 2 of the License, or
|
| 12 |
|
|
* (at your option) any later version.
|
| 13 |
|
|
*
|
| 14 |
|
|
* This program is distributed in the hope that it will be useful,
|
| 15 |
|
|
* but WITHOUT ANY WARRANTY; without even the implied warranty of
|
| 16 |
|
|
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
|
| 17 |
|
|
* GNU General Public License for more details.
|
| 18 |
|
|
*
|
| 19 |
|
|
* You should have received a copy of the GNU General Public License
|
| 20 |
|
|
* along with this program; if not, write to the Free Software
|
| 21 |
|
|
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
|
| 22 |
|
|
* Or see <http://www.gnu.org/licenses/>
|
| 23 |
|
|
*
|
| 24 |
|
|
***************************************************************************************************************
|
| 25 |
|
|
*
|
| 26 |
|
|
* Change Log:
|
| 27 |
|
|
*
|
| 28 |
|
|
* Version 1.0 - 2013/04/05 - LS
|
| 29 |
|
|
* released
|
| 30 |
|
|
*
|
| 31 |
|
|
***************************************************************************************************************
|
| 32 |
|
|
*
|
| 33 |
|
|
* This program implements the same algorithm as the core written in VHDL. Moreover it can decode (decompress)
|
| 34 |
|
|
* data compressed by the core (using its testbench for example).
|
| 35 |
|
|
*
|
| 36 |
|
|
***************************************************************************************************************/
|
| 37 |
|
|
|
| 38 |
|
|
import java.io.BufferedOutputStream;
|
| 39 |
|
|
import java.io.BufferedInputStream;
|
| 40 |
|
|
import java.io.BufferedReader;
|
| 41 |
|
|
import java.io.InputStreamReader;
|
| 42 |
|
|
import java.io.FileReader;
|
| 43 |
|
|
import java.io.FileOutputStream;
|
| 44 |
|
|
import java.io.FileInputStream;
|
| 45 |
|
|
import java.io.File;
|
| 46 |
|
|
import java.io.IOException;
|
| 47 |
|
|
|
| 48 |
|
|
class LZ77
|
| 49 |
|
|
{
|
| 50 |
|
|
final static boolean DEBUG = false; // set this to true to get verbose output about the algorithm
|
| 51 |
|
|
// configure core properties
|
| 52 |
|
|
final static int HISTORY_LEN = 4096; // buffer length in bytes
|
| 53 |
|
|
final static int LOOK_AHEAD_LEN = 16;
|
| 54 |
|
|
final static int HASH_BIT_LEN = 11; // number of bits for the index in the hash table
|
| 55 |
|
|
|
| 56 |
|
|
/* configer the number of items (offset-length-tuples or literals) per frame */
|
| 57 |
|
|
public final int ITEMS_PER_FRAME = 8;
|
| 58 |
|
|
|
| 59 |
|
|
public static void main (String args[])
|
| 60 |
|
|
{
|
| 61 |
|
|
LZ77 compressor = new LZ77();
|
| 62 |
|
|
File dest = null;
|
| 63 |
|
|
|
| 64 |
|
|
if (args.length < 2)
|
| 65 |
|
|
{
|
| 66 |
|
|
System.err.println("Usage: LZ77 (encode|decode) in-file [out-file]");
|
| 67 |
|
|
System.err.println("Usage: LZ77 verify compressed-file clear-text-verify-file");
|
| 68 |
|
|
return;
|
| 69 |
|
|
}
|
| 70 |
|
|
|
| 71 |
|
|
if (args.length >= 3)
|
| 72 |
|
|
dest = new File(args[2]);
|
| 73 |
|
|
|
| 74 |
|
|
try
|
| 75 |
|
|
{
|
| 76 |
|
|
if (args[0].compareTo("encode") == 0)
|
| 77 |
|
|
compressor.encode(new File(args[1]), dest);
|
| 78 |
|
|
else if (args[0].compareTo("decode") == 0)
|
| 79 |
|
|
compressor.decode(new File(args[1]), dest, null);
|
| 80 |
|
|
else if (args[0].compareTo("verify") == 0)
|
| 81 |
|
|
compressor.decode(new File(args[1]), null, dest);
|
| 82 |
|
|
else
|
| 83 |
|
|
{
|
| 84 |
|
|
System.err.println("Usage: LZ77 (encode|decode) in-file [out-file]");
|
| 85 |
|
|
System.err.println("Usage: LZ77 verify compressed-file clear-text-verify-file");
|
| 86 |
|
|
}
|
| 87 |
|
|
}
|
| 88 |
|
|
catch(Exception e)
|
| 89 |
|
|
{
|
| 90 |
|
|
System.err.println("compression created exception: "+e);
|
| 91 |
|
|
e.printStackTrace();
|
| 92 |
|
|
}
|
| 93 |
|
|
}
|
| 94 |
|
|
|
| 95 |
|
|
public LZ77 ()
|
| 96 |
|
|
{
|
| 97 |
|
|
// allocate a buffer and fill it with \0
|
| 98 |
|
|
buffer = new int[HISTORY_LEN];
|
| 99 |
|
|
for (int i=0; i<buffer.length; i++)
|
| 100 |
|
|
buffer[i] = ' ';
|
| 101 |
|
|
|
| 102 |
|
|
lookAheadBuf = new int[LOOK_AHEAD_LEN];
|
| 103 |
|
|
lookAheadLen = 0;
|
| 104 |
|
|
hashTbl = new int[(int)Math.ceil(Math.pow(2,HASH_BIT_LEN))]; // does not have to be initialized
|
| 105 |
|
|
|
| 106 |
|
|
histWrInd = 0;
|
| 107 |
|
|
|
| 108 |
|
|
frameBuffer = new int[ITEMS_PER_FRAME*2];
|
| 109 |
|
|
frameBufferIndex = 0;
|
| 110 |
|
|
|
| 111 |
|
|
}
|
| 112 |
|
|
|
| 113 |
|
|
// compress a file
|
| 114 |
|
|
void encode (File source, File destination) throws IOException
|
| 115 |
|
|
{
|
| 116 |
|
|
BufferedReader br = new BufferedReader(new FileReader(source));
|
| 117 |
|
|
BufferedOutputStream bw = null;
|
| 118 |
|
|
if (destination != null)
|
| 119 |
|
|
bw = new BufferedOutputStream(new FileOutputStream(destination));
|
| 120 |
|
|
|
| 121 |
|
|
int [] cand = new int[lookAheadBuf.length];
|
| 122 |
|
|
//FileReader br = new FileReader(f);
|
| 123 |
|
|
int ch = 0;
|
| 124 |
|
|
int h;
|
| 125 |
|
|
int byteCnt = 0; // for debug purposes (better error messages)
|
| 126 |
|
|
supressCnt = 0;
|
| 127 |
|
|
histWrInd = 0;
|
| 128 |
|
|
frameItemCnt = 0;
|
| 129 |
|
|
frameBufferIndex = 0;
|
| 130 |
|
|
validBufferLen = 0;
|
| 131 |
|
|
|
| 132 |
|
|
// fill the lookahead buffer with data
|
| 133 |
|
|
do
|
| 134 |
|
|
{
|
| 135 |
|
|
ch = br.read();
|
| 136 |
|
|
if (ch != -1)
|
| 137 |
|
|
{
|
| 138 |
|
|
//buffer[histWrInd++] = ch;
|
| 139 |
|
|
lookAheadBuf[lookAheadLen] = ch;
|
| 140 |
|
|
lookAheadLen++;
|
| 141 |
|
|
insertIntoHistBuf(ch); // Note: the front the of the history buffer holds a copy of the lookahead buffer
|
| 142 |
|
|
}
|
| 143 |
|
|
} while ((ch != -1) && (lookAheadLen < lookAheadBuf.length-1));
|
| 144 |
|
|
|
| 145 |
|
|
while ((ch != -1) || (lookAheadLen > 0))
|
| 146 |
|
|
{
|
| 147 |
|
|
|
| 148 |
|
|
ch = br.read();
|
| 149 |
|
|
if (ch != -1)
|
| 150 |
|
|
{
|
| 151 |
|
|
// enter this char into the stream history buffer
|
| 152 |
|
|
insertIntoHistBuf(ch);
|
| 153 |
|
|
// store it in look ahead shift register
|
| 154 |
|
|
lookAheadBuf[lookAheadLen] = ch;
|
| 155 |
|
|
lookAheadLen++;
|
| 156 |
|
|
}
|
| 157 |
|
|
if (DEBUG)
|
| 158 |
|
|
System.out.println("lookAheadLen: "+lookAheadLen);
|
| 159 |
|
|
|
| 160 |
|
|
byteCnt++;
|
| 161 |
|
|
if (DEBUG)
|
| 162 |
|
|
System.out.println("processing byte number "+byteCnt);
|
| 163 |
|
|
dbgPrint();
|
| 164 |
|
|
|
| 165 |
|
|
// get the hash for the current look ahead buffer
|
| 166 |
|
|
h = hash(lookAheadBuf[0], lookAheadBuf[1], lookAheadBuf[2]);
|
| 167 |
|
|
// get match candidate index from table
|
| 168 |
|
|
int cInd = hashTbl[h];
|
| 169 |
|
|
// save new pointer in hash table
|
| 170 |
|
|
int x = histWrInd - lookAheadLen; //
|
| 171 |
|
|
if (x < 0)
|
| 172 |
|
|
x += buffer.length;
|
| 173 |
|
|
hashTbl[h] = x;
|
| 174 |
|
|
//System.out.println("h: "+h+" cInd: "+cInd+" histWrInd: "+histWrInd);
|
| 175 |
|
|
// load the candidate from the stream history buffer
|
| 176 |
|
|
for (int i=0; i<lookAheadLen; i++)
|
| 177 |
|
|
{
|
| 178 |
|
|
int ind = cInd + i;
|
| 179 |
|
|
if (ind >= buffer.length)
|
| 180 |
|
|
ind -= buffer.length;
|
| 181 |
|
|
cand[i] = buffer[ind];
|
| 182 |
|
|
}
|
| 183 |
|
|
if (DEBUG)
|
| 184 |
|
|
{
|
| 185 |
|
|
System.out.print("candidate: <");
|
| 186 |
|
|
for (int i=0; i<lookAheadLen; i++)
|
| 187 |
|
|
{
|
| 188 |
|
|
if (cand[i] != '\n')
|
| 189 |
|
|
System.out.print(((char)cand[i]));
|
| 190 |
|
|
else
|
| 191 |
|
|
System.out.print("\\n");
|
| 192 |
|
|
}
|
| 193 |
|
|
System.out.println("> len:"+lookAheadLen);
|
| 194 |
|
|
}
|
| 195 |
|
|
|
| 196 |
|
|
int mLen = checkCandidate(cand);
|
| 197 |
|
|
|
| 198 |
|
|
// the hardware has a limitation on the candidate length depending on the candidate address, we model this here
|
| 199 |
|
|
int maxLen=0;
|
| 200 |
|
|
if (lookAheadLen == 16)
|
| 201 |
|
|
maxLen = lookAheadLen - (cInd&0x03);
|
| 202 |
|
|
else
|
| 203 |
|
|
maxLen = lookAheadLen;
|
| 204 |
|
|
|
| 205 |
|
|
if (mLen > maxLen)
|
| 206 |
|
|
mLen = maxLen;
|
| 207 |
|
|
if (DEBUG)
|
| 208 |
|
|
System.out.println("mLen: "+mLen+" maxLen: "+maxLen);
|
| 209 |
|
|
|
| 210 |
|
|
int lit = lookAheadBuf[0];
|
| 211 |
|
|
shiftLookAhead(1);
|
| 212 |
|
|
lookAheadLen--;
|
| 213 |
|
|
|
| 214 |
|
|
if (supressCnt > 0)
|
| 215 |
|
|
{
|
| 216 |
|
|
// this byte has already been encoded. Discard it
|
| 217 |
|
|
supressCnt--;
|
| 218 |
|
|
if (DEBUG)
|
| 219 |
|
|
System.out.println("data output supressed");
|
| 220 |
|
|
continue;
|
| 221 |
|
|
}
|
| 222 |
|
|
|
| 223 |
|
|
if (mLen < 3)
|
| 224 |
|
|
{
|
| 225 |
|
|
// we have no mtach, simply output a literal
|
| 226 |
|
|
output(bw, 0,1,lit);
|
| 227 |
|
|
continue;
|
| 228 |
|
|
}
|
| 229 |
|
|
|
| 230 |
|
|
// we have a match, calculate the offset
|
| 231 |
|
|
if (DEBUG)
|
| 232 |
|
|
{
|
| 233 |
|
|
System.out.println("wrInd: "+histWrInd+" lookAheadLen: "+lookAheadLen+ " cInd: "+cInd);
|
| 234 |
|
|
}
|
| 235 |
|
|
int offset = histWrInd - (lookAheadLen+1) - cInd - 1;
|
| 236 |
|
|
if (offset < 0)
|
| 237 |
|
|
offset += buffer.length ;
|
| 238 |
|
|
// check offset
|
| 239 |
|
|
if (offset >= (validBufferLen))
|
| 240 |
|
|
{
|
| 241 |
|
|
System.out.println("offset "+offset+" is too old");
|
| 242 |
|
|
// this match is too old and therefore not valid (we have already overwritten this data with the lookAhead data)
|
| 243 |
|
|
output(bw, 0,1,lit);
|
| 244 |
|
|
continue;
|
| 245 |
|
|
}
|
| 246 |
|
|
|
| 247 |
|
|
if (offset < 0)
|
| 248 |
|
|
{
|
| 249 |
|
|
System.out.println("offset "+offset+" is negative!");
|
| 250 |
|
|
output(bw, 0,1,lit);
|
| 251 |
|
|
continue;
|
| 252 |
|
|
}
|
| 253 |
|
|
output(bw, offset, mLen-1, 0); // take length -1 to save one bit (we can't have length 0 but 16 becomes 15)
|
| 254 |
|
|
supressCnt = mLen-1; // supress output for the next mLen-1 bytes (as we already encoded them)
|
| 255 |
|
|
}
|
| 256 |
|
|
br.close();
|
| 257 |
|
|
|
| 258 |
|
|
// create 'end of data' flag
|
| 259 |
|
|
output(bw, 0, 0, 0);
|
| 260 |
|
|
|
| 261 |
|
|
if (bw != null)
|
| 262 |
|
|
bw.close();
|
| 263 |
|
|
}
|
| 264 |
|
|
|
| 265 |
|
|
|
| 266 |
|
|
void decode (File source, File destination, File verify) throws IOException
|
| 267 |
|
|
{
|
| 268 |
|
|
BufferedInputStream bi = new BufferedInputStream(new FileInputStream(source));
|
| 269 |
|
|
BufferedInputStream verifyStream = null;
|
| 270 |
|
|
BufferedOutputStream bo = null;
|
| 271 |
|
|
if (destination != null)
|
| 272 |
|
|
bo = new BufferedOutputStream(new FileOutputStream(destination));
|
| 273 |
|
|
if (verify != null)
|
| 274 |
|
|
verifyStream = new BufferedInputStream(new FileInputStream(verify));
|
| 275 |
|
|
|
| 276 |
|
|
int ch = 0;
|
| 277 |
|
|
int flags = 0;
|
| 278 |
|
|
int highByte = 0;
|
| 279 |
|
|
boolean isPair = false;
|
| 280 |
|
|
histWrInd = 0;
|
| 281 |
|
|
frameItemCnt = 0;
|
| 282 |
|
|
boolean verifyFailed = false;
|
| 283 |
|
|
|
| 284 |
|
|
// we keep a statistic of the match length values we encounter during decoding
|
| 285 |
|
|
int [] mLenCnt = new int[16];
|
| 286 |
|
|
for (int i=0; i<mLenCnt.length; i++)
|
| 287 |
|
|
mLenCnt[0] = 0;
|
| 288 |
|
|
|
| 289 |
|
|
while (ch != -1)
|
| 290 |
|
|
{
|
| 291 |
|
|
ch = bi.read();
|
| 292 |
|
|
|
| 293 |
|
|
if (ch == -1)
|
| 294 |
|
|
{
|
| 295 |
|
|
System.err.println("corrupt file: EOF without an end of data marker");
|
| 296 |
|
|
break;
|
| 297 |
|
|
}
|
| 298 |
|
|
|
| 299 |
|
|
if (isPair)
|
| 300 |
|
|
{
|
| 301 |
|
|
// this is the second byte of a length-distance pair, processes it
|
| 302 |
|
|
isPair = false;
|
| 303 |
|
|
int len = (highByte>>4) & 0x0f;
|
| 304 |
|
|
int offset = ((highByte<<8)&0x0f00) + (ch&0xff);
|
| 305 |
|
|
// increment the counter for this match length
|
| 306 |
|
|
mLenCnt[len]++;
|
| 307 |
|
|
|
| 308 |
|
|
// check for the end of data signal
|
| 309 |
|
|
if ((len==0) && (offset==0))
|
| 310 |
|
|
{
|
| 311 |
|
|
if (DEBUG)
|
| 312 |
|
|
System.out.println("found end of data");
|
| 313 |
|
|
while((ch=bi.read()) != -1)
|
| 314 |
|
|
{
|
| 315 |
|
|
System.err.printf("found extra byte: '%c'=%02x\n",ch,ch);
|
| 316 |
|
|
verifyFailed = true;
|
| 317 |
|
|
}
|
| 318 |
|
|
break;
|
| 319 |
|
|
}
|
| 320 |
|
|
if (DEBUG)
|
| 321 |
|
|
System.out.print("copy o="+offset+" l="+len+": ");
|
| 322 |
|
|
for (int i=0; i<=len; i++)
|
| 323 |
|
|
{
|
| 324 |
|
|
// load the byte from the history buffer
|
| 325 |
|
|
int ind = histWrInd-offset-1;
|
| 326 |
|
|
if (ind < 0)
|
| 327 |
|
|
ind += HISTORY_LEN;
|
| 328 |
|
|
if (ind < 0)
|
| 329 |
|
|
{
|
| 330 |
|
|
// index is still zero, this is error in the encoded data
|
| 331 |
|
|
System.err.println("Error in encoded data, offset is too long");
|
| 332 |
|
|
verifyFailed = true;
|
| 333 |
|
|
return;
|
| 334 |
|
|
}
|
| 335 |
|
|
ch = buffer[ind];
|
| 336 |
|
|
|
| 337 |
|
|
if (DEBUG)
|
| 338 |
|
|
System.out.printf(" '%c'=%x",ch,ch);
|
| 339 |
|
|
if (bo != null)
|
| 340 |
|
|
bo.write(ch);
|
| 341 |
|
|
// save this byte in the history buffer
|
| 342 |
|
|
buffer[histWrInd++] = ch;
|
| 343 |
|
|
if (histWrInd >= buffer.length)
|
| 344 |
|
|
histWrInd = 0;
|
| 345 |
|
|
|
| 346 |
|
|
// check with verify file
|
| 347 |
|
|
if (verifyStream != null)
|
| 348 |
|
|
{
|
| 349 |
|
|
int vCh = verifyStream.read();
|
| 350 |
|
|
if (vCh < 0)
|
| 351 |
|
|
{
|
| 352 |
|
|
System.err.printf("verify failed: decoded '%c'=%02x, verify file is empty\n", ch, ch);
|
| 353 |
|
|
verifyFailed = true;
|
| 354 |
|
|
}
|
| 355 |
|
|
else if (vCh != ch)
|
| 356 |
|
|
{
|
| 357 |
|
|
System.err.printf("verify failed: decoded '%c'=%02x, expected '%c'=%02x\n", ch, ch, vCh, vCh);
|
| 358 |
|
|
verifyFailed = true;
|
| 359 |
|
|
}
|
| 360 |
|
|
}
|
| 361 |
|
|
}
|
| 362 |
|
|
if (DEBUG)
|
| 363 |
|
|
System.out.println(" ");
|
| 364 |
|
|
|
| 365 |
|
|
continue;
|
| 366 |
|
|
}
|
| 367 |
|
|
|
| 368 |
|
|
// check whether we have a new header
|
| 369 |
|
|
if (frameItemCnt==0)
|
| 370 |
|
|
{
|
| 371 |
|
|
flags = ch;
|
| 372 |
|
|
if (DEBUG)
|
| 373 |
|
|
System.out.printf("found header: %02x\n",ch);
|
| 374 |
|
|
frameItemCnt = 8;
|
| 375 |
|
|
continue;
|
| 376 |
|
|
}
|
| 377 |
|
|
|
| 378 |
|
|
if ((flags&0x01) == 1)
|
| 379 |
|
|
{
|
| 380 |
|
|
// this is a length-offset pair, save first byte for later processing
|
| 381 |
|
|
highByte = ch;
|
| 382 |
|
|
isPair = true;
|
| 383 |
|
|
}
|
| 384 |
|
|
else
|
| 385 |
|
|
{
|
| 386 |
|
|
isPair = false;
|
| 387 |
|
|
// this is a literal
|
| 388 |
|
|
if (DEBUG)
|
| 389 |
|
|
System.out.printf("lit: '%c'=%02x\n",ch,ch);
|
| 390 |
|
|
if (bo != null)
|
| 391 |
|
|
bo.write(ch);
|
| 392 |
|
|
// count this as a literal in the frequency counter for the statistics
|
| 393 |
|
|
mLenCnt[0]++;
|
| 394 |
|
|
// save this byte in the history buffer
|
| 395 |
|
|
buffer[histWrInd++] = ch;
|
| 396 |
|
|
if (histWrInd >= buffer.length)
|
| 397 |
|
|
histWrInd = 0;
|
| 398 |
|
|
// check with verify file
|
| 399 |
|
|
if (verifyStream != null)
|
| 400 |
|
|
{
|
| 401 |
|
|
int vCh = verifyStream.read();
|
| 402 |
|
|
if (vCh < 0)
|
| 403 |
|
|
{
|
| 404 |
|
|
System.err.printf("verify failed: decoded '%c'=%02x, verify file is empty\n", ch, ch);
|
| 405 |
|
|
verifyFailed = true;
|
| 406 |
|
|
}
|
| 407 |
|
|
else if (vCh != ch)
|
| 408 |
|
|
{
|
| 409 |
|
|
System.err.printf("verify failed: decoded '%c'=%02x, expected '%c'=%02x\n", ch, ch, vCh, vCh);
|
| 410 |
|
|
verifyFailed = true;
|
| 411 |
|
|
}
|
| 412 |
|
|
}
|
| 413 |
|
|
}
|
| 414 |
|
|
// shift header for next byte
|
| 415 |
|
|
frameItemCnt--;
|
| 416 |
|
|
flags >>= 1;
|
| 417 |
|
|
}
|
| 418 |
|
|
|
| 419 |
|
|
bi.close();
|
| 420 |
|
|
|
| 421 |
|
|
if (bo != null)
|
| 422 |
|
|
bo.close();
|
| 423 |
|
|
|
| 424 |
|
|
// print some statistics
|
| 425 |
|
|
System.out.println("Percentages of different match lengths:");
|
| 426 |
|
|
int total = 0;
|
| 427 |
|
|
for (int i=0; i<mLenCnt.length; i++)
|
| 428 |
|
|
total += mLenCnt[i];
|
| 429 |
|
|
for (int i=0; i<mLenCnt.length; i++)
|
| 430 |
|
|
System.out.println("match len "+(i+1)+": \t"+(mLenCnt[i]/(float)total));
|
| 431 |
|
|
|
| 432 |
|
|
if (verifyStream != null)
|
| 433 |
|
|
{
|
| 434 |
|
|
while((ch=verifyStream.read()) != -1)
|
| 435 |
|
|
{
|
| 436 |
|
|
verifyFailed = true;
|
| 437 |
|
|
System.err.printf("found extra byte in verify file: '%c'=%02x\n",ch,ch);
|
| 438 |
|
|
}
|
| 439 |
|
|
verifyStream.close();
|
| 440 |
|
|
if (verifyFailed)
|
| 441 |
|
|
System.err.println("verify failed");
|
| 442 |
|
|
else
|
| 443 |
|
|
System.err.println("verify passed");
|
| 444 |
|
|
}
|
| 445 |
|
|
|
| 446 |
|
|
|
| 447 |
|
|
}
|
| 448 |
|
|
|
| 449 |
|
|
private void insertIntoHistBuf (int ch)
|
| 450 |
|
|
{
|
| 451 |
|
|
buffer[histWrInd++] = ch;
|
| 452 |
|
|
if (histWrInd >= buffer.length)
|
| 453 |
|
|
histWrInd = 0;
|
| 454 |
|
|
// count the number of valid bytes in the histroy buffer
|
| 455 |
|
|
if (validBufferLen < (HISTORY_LEN - LOOK_AHEAD_LEN))
|
| 456 |
|
|
validBufferLen++;
|
| 457 |
|
|
}
|
| 458 |
|
|
|
| 459 |
|
|
/* checks a candidate to look ahead buffer
|
| 460 |
|
|
returns the length of the match in bytes (0 means no match)*/
|
| 461 |
|
|
private int checkCandidate(int [] cand)
|
| 462 |
|
|
{
|
| 463 |
|
|
int i;
|
| 464 |
|
|
for (i=0; i<lookAheadLen; i++)
|
| 465 |
|
|
{
|
| 466 |
|
|
if (cand[i] != lookAheadBuf[i])
|
| 467 |
|
|
return i;
|
| 468 |
|
|
}
|
| 469 |
|
|
return lookAheadLen; // all chars matched
|
| 470 |
|
|
}
|
| 471 |
|
|
|
| 472 |
|
|
// look ahead is implemented as shift to left register
|
| 473 |
|
|
private void shiftLookAhead(int cnt)
|
| 474 |
|
|
{
|
| 475 |
|
|
for (int i=0; i<(LOOK_AHEAD_LEN-cnt); i++)
|
| 476 |
|
|
lookAheadBuf[i] = lookAheadBuf[i+cnt];
|
| 477 |
|
|
}
|
| 478 |
|
|
|
| 479 |
|
|
private int hash(int k0, int k1, int k2)
|
| 480 |
|
|
{
|
| 481 |
|
|
int mask = 0;
|
| 482 |
|
|
for (int i=0; i<HASH_BIT_LEN; i++)
|
| 483 |
|
|
{
|
| 484 |
|
|
mask <<= 1;
|
| 485 |
|
|
mask |= 1;
|
| 486 |
|
|
}
|
| 487 |
|
|
//System.out.println("mask: "+mask);
|
| 488 |
|
|
// original hash function as used by LZRW
|
| 489 |
|
|
return ( (40543*((((k0<<4)^k1)<<4)^k2)) >>4 ) & mask;
|
| 490 |
|
|
}
|
| 491 |
|
|
|
| 492 |
|
|
private void dbgPrint()
|
| 493 |
|
|
{
|
| 494 |
|
|
if (DEBUG)
|
| 495 |
|
|
{
|
| 496 |
|
|
int ind = histWrInd;
|
| 497 |
|
|
System.out.print('|');
|
| 498 |
|
|
for (int i=0; i<buffer.length; i++)
|
| 499 |
|
|
{
|
| 500 |
|
|
char c = (char)buffer[ind++];
|
| 501 |
|
|
if (c == '\n')
|
| 502 |
|
|
System.out.print("\\n");
|
| 503 |
|
|
else
|
| 504 |
|
|
System.out.print(c);
|
| 505 |
|
|
// System.out.print(" ");
|
| 506 |
|
|
if (ind >= buffer.length)
|
| 507 |
|
|
ind = 0;
|
| 508 |
|
|
}
|
| 509 |
|
|
System.out.print("| |");
|
| 510 |
|
|
for (int i=0; i<lookAheadLen; i++)
|
| 511 |
|
|
{
|
| 512 |
|
|
char c = (char)lookAheadBuf[i];
|
| 513 |
|
|
if (c == '\n')
|
| 514 |
|
|
System.out.print("\\n");
|
| 515 |
|
|
else
|
| 516 |
|
|
System.out.print(c);
|
| 517 |
|
|
// System.out.print(" ");
|
| 518 |
|
|
}
|
| 519 |
|
|
System.out.println("|");
|
| 520 |
|
|
}
|
| 521 |
|
|
}
|
| 522 |
|
|
|
| 523 |
|
|
private void output (BufferedOutputStream bw, int offset, int len, int ch) throws IOException
|
| 524 |
|
|
{
|
| 525 |
|
|
if (DEBUG)
|
| 526 |
|
|
{
|
| 527 |
|
|
if (len<=1)
|
| 528 |
|
|
{
|
| 529 |
|
|
System.out.print("lit: '");
|
| 530 |
|
|
if (ch == '\n')
|
| 531 |
|
|
System.out.print("\\n");
|
| 532 |
|
|
else
|
| 533 |
|
|
System.out.print((char)ch);
|
| 534 |
|
|
System.out.println("'");
|
| 535 |
|
|
|
| 536 |
|
|
}
|
| 537 |
|
|
else
|
| 538 |
|
|
System.out.println("off: "+offset+"\t len:"+len);
|
| 539 |
|
|
if (len == 0)
|
| 540 |
|
|
System.out.println("creating EOD");
|
| 541 |
|
|
}
|
| 542 |
|
|
|
| 543 |
|
|
if (bw != null)
|
| 544 |
|
|
{
|
| 545 |
|
|
assert(len < 16);
|
| 546 |
|
|
assert(len >= 0);
|
| 547 |
|
|
assert(ch >= 0);
|
| 548 |
|
|
assert(ch <= 255);
|
| 549 |
|
|
|
| 550 |
|
|
if (len == 1)
|
| 551 |
|
|
{
|
| 552 |
|
|
// output a string literal
|
| 553 |
|
|
header &= (~(1<<frameItemCnt)); // clear flag bit in header to indicate a literal
|
| 554 |
|
|
frameBuffer[frameBufferIndex++] = ch; // copy literal to buffer
|
| 555 |
|
|
}
|
| 556 |
|
|
|
| 557 |
|
|
if (len >= 2)
|
| 558 |
|
|
{
|
| 559 |
|
|
header |= (1<<frameItemCnt); // set flag bit in header to indicate a pair
|
| 560 |
|
|
int code = (len<<12) | offset;
|
| 561 |
|
|
// we use big endian encoding
|
| 562 |
|
|
frameBuffer[frameBufferIndex++] = (code>>8) & 0xff;
|
| 563 |
|
|
frameBuffer[frameBufferIndex++] = (code & 0xff);
|
| 564 |
|
|
}
|
| 565 |
|
|
|
| 566 |
|
|
if (len == 0)
|
| 567 |
|
|
{
|
| 568 |
|
|
// create an end of data code (pair with length of zero)
|
| 569 |
|
|
header |= (1<<frameItemCnt); // set flag bit in header to indicate a pair
|
| 570 |
|
|
frameBuffer[frameBufferIndex++] = 0;
|
| 571 |
|
|
frameBuffer[frameBufferIndex++] = 0;
|
| 572 |
|
|
}
|
| 573 |
|
|
|
| 574 |
|
|
frameItemCnt++;
|
| 575 |
|
|
//if (DEBUG)
|
| 576 |
|
|
// System.out.println("frame item cnt: "+frameItemCnt);
|
| 577 |
|
|
|
| 578 |
|
|
// send the buffer if the frame is full or if we have to send an end of data signal
|
| 579 |
|
|
if ((frameItemCnt==8) || (len==0))
|
| 580 |
|
|
{
|
| 581 |
|
|
header &= 0xff;
|
| 582 |
|
|
bw.write(header);
|
| 583 |
|
|
for (int i=0; i<frameBufferIndex; i++)
|
| 584 |
|
|
bw.write(frameBuffer[i] & 0xff);
|
| 585 |
|
|
frameBufferIndex = 0;
|
| 586 |
|
|
frameItemCnt = 0;
|
| 587 |
|
|
/*header = 0;
|
| 588 |
|
|
bw.flush();
|
| 589 |
|
|
BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
|
| 590 |
|
|
in.readLine();*/
|
| 591 |
|
|
}
|
| 592 |
|
|
}
|
| 593 |
|
|
}
|
| 594 |
|
|
|
| 595 |
|
|
int [] buffer;
|
| 596 |
|
|
int validBufferLen;
|
| 597 |
|
|
int [] hashTbl;
|
| 598 |
|
|
int [] lookAheadBuf;
|
| 599 |
|
|
int lookAheadLen;
|
| 600 |
|
|
int histWrInd;
|
| 601 |
|
|
int supressCnt;
|
| 602 |
|
|
int header;
|
| 603 |
|
|
int frameItemCnt;
|
| 604 |
|
|
int [] frameBuffer;
|
| 605 |
|
|
int frameBufferIndex;
|
| 606 |
|
|
|
| 607 |
|
|
|
| 608 |
|
|
}
|
| 609 |
|
|
|
| 610 |
|
|
|
