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Rev 2095 Rev 2102
Line 9... Line 9...
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 * OUT.LNG -> contains all language resources.
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 * OUT.LNG -> contains all language resources.
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 * OUTC.LNG -> same as OUT.LNG but with compressed strings (slower to load).
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 * OUTC.LNG -> same as OUT.LNG but with compressed strings (slower to load).
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 *
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 *
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 * === COMPRESSION ===========================================================
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 * === COMPRESSION ===========================================================
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 * The compression scheme is very simple. It is applied only to strings (ie.
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 * The compression scheme is very simple. It is applied only to strings (ie.
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 * not the dictionnary) and it is basically a stream of 16-bit values (WORDs),
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 * not the dictionnary) and it is basically a stream of 16-bit words (tokens).
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 15 
 *
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 16 
 * Token format is LLLL OOOO OOOO OOOO, where:
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 * OOOO OOOO OOOO is the back reference offset (number of bytes-1 to rewind)
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 * LLLL is the number of bytes (-1) that have to be copied from the offset.
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 19 
 *
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 20 
 * However, if LLLL is zero then the token's format is different:
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 21 
 * 0000 RRRR BBBB BBBB
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 22 
 *
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 23 
 * The above form occurs when uncompressible data is encountered:
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 24 
 * BBBB BBBB is the literal value of a byte to be copied
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 25 
 * RRRR is the number of RAW (uncompressible) WORDS that follow (possibly 0)
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 26 
 *
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 * where each WORD value contains the following bits "LLLL OOOO OOOO OOOO":
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 * where each WORD value contains the following bits "LLLL OOOO OOOO OOOO":
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 *
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 *
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 * OOOO OOOO OOOO = a backreference offset ("look that many bytes back")
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 * OOOO OOOO OOOO = a backreference offset ("look that many bytes back")
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 * LLLL = the number of bytes to copy from the backreference
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 * LLLL = the number of bytes to copy from the backreference
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 *
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 *
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 * Special case: a WORD that is smaller than 256 represents a single literal
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 * byte.
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 *
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 * To recognize a compressed lang block one has to look at the id of the block
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 * To recognize a compressed lang block one has to look at the id of the block
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 * (16-bit language id). If its highest bit is set (0x8000) then the lang block
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 * (16-bit language id). If its highest bit is set (0x8000) then the lang block
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 * is compressed.
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 * is compressed.
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 */
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 */
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static int svl_write_header(unsigned short num_strings, FILE *fd) {
 357 
static int svl_write_header(unsigned short num_strings, FILE *fd) {
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  return((fwrite("SvL\x1a", 1, 4, fd) == 4) && (fwrite(&num_strings, 1, 2, fd) == 2));
 358 
  return((fwrite("SvL\x1a", 1, 4, fd) == 4) && (fwrite(&num_strings, 1, 2, fd) == 2));
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}
 359 
}
351 
 
 360 
 
352 
 
 361 
 
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 362 
 
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 363 
/* write qlen literal bytes into dst, returns amount of "compressed" bytes */
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static unsigned short mvcomp_litqueue_dump(unsigned short **dst, const unsigned char *q, unsigned short qlen) {
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  unsigned short complen = 0;
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 366 
 
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  AGAIN:
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 368 
 
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  /* are we done? (also take care of guys calling me in for jokes) */
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  if (qlen == 0) return(complen);
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  qlen--; /* now it's between 0 and 30 */
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  /* write the length and first char */
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  **dst = ((qlen / 2) << 8) | q[0];
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  *dst += 1;
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  q++;
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 377 
  complen += 2;
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  /* anything left? */
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  if (qlen == 0) return(complen);
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  /* write the pending words */
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 383 
  if (qlen > 1) {
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    memcpy(*dst, q, (qlen/2)*2);
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    *dst += qlen / 2;
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    q += (qlen / 2) * 2;
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    complen += (qlen / 2) * 2;
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    qlen -= (qlen / 2) * 2;
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 389 
  }
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 391 
  /* one byte might still be left if it did not fit inside a word */
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  goto AGAIN;
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}
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353 
/* mvcomp applies the MV-COMPRESSION algorithm to data and returns the compressed size */
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/* mvcomp applies the MV-COMPRESSION algorithm to data and returns the compressed size */
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static unsigned short mvcomp(char *dstbuf, const char *src, unsigned short len) {
 397 
static unsigned short mvcomp(char *dstbuf, const char *src, unsigned short len) {
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  unsigned short complen = 0;
 398 
  unsigned short complen = 0;
356 
  unsigned short *dst = (void *)dstbuf;
 399 
  unsigned short *dst = (void *)dstbuf;
357 
  unsigned short bytesprocessed = 0;
 400 
  unsigned short bytesprocessed = 0;
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 401 
  unsigned char litqueue[32];
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 402 
  unsigned char litqueuelen = 0;
358 
 
 403 
 
359 
  /* read src byte by byte, len times, each time look for a match of 15,14,13..2 chars in the back buffer */
 404 
  /* read src byte by byte, len times, each time look for a match of 15,14,13..2 chars in the back buffer */
360 
  while (len > 0) {
 405 
  while (len > 0) {
361 
    unsigned short matchlen;
 406 
    unsigned short matchlen;
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    unsigned short offset;
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    unsigned short offset;
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374 
          goto FOUND;
 419 
          goto FOUND;
375 
        }
 420 
        }
376 
      }
 421 
      }
377 
    }
 422 
    }
378 
 
 423 
 
379 
    /* if here: no match found, write a literal byte */
 424 
    /* if here: no match found, write a literal byte to queue */
380 
    *dst = *src;
 425 
    litqueue[litqueuelen++] = *src;
381 
    dst++;
 - 
 
382 
    src++;
 426 
    src++;
383 
    bytesprocessed++;
 427 
    bytesprocessed++;
384 
    len--;
 428 
    len--;
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 429 
 
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 430 
    /* dump literal queue to dst if max length reached */
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 431 
    if (litqueuelen == 31) {
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 432 
      complen += mvcomp_litqueue_dump(&dst, litqueue, litqueuelen);
385 
    complen += 2;
 433 
      litqueuelen = 0;
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 434 
    }
386 
    continue;
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    continue;
387 
 
 436 
 
388 
    FOUND: /* found a match of matchlen bytes at -offset */
 437 
    FOUND: /* found a match of matchlen bytes at -offset */
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 438 
 
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 439 
    /* dump awaiting literal queue to dst first */
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 440 
    if (litqueuelen != 0) {
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 441 
      complen += mvcomp_litqueue_dump(&dst, litqueue, litqueuelen);
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 442 
      litqueuelen = 0;
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 443 
    }
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 444 
 
389 
    *dst = ((matchlen - 1) << 12) | (offset - 1);
 445 
    *dst = ((matchlen - 1) << 12) | (offset - 1);
390 
    dst++;
 446 
    dst++;
391 
    src += matchlen;
 447 
    src += matchlen;
392 
    bytesprocessed += matchlen;
 448 
    bytesprocessed += matchlen;
393 
    len -= matchlen;
 449 
    len -= matchlen;
394 
    complen += 2;
 450 
    complen += 2;
395 
  }
 451 
  }
396 
 
 452 
 
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 453 
  /* dump awaiting literal queue to dst first */
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 454 
  if (litqueuelen != 0) {
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 455 
    complen += mvcomp_litqueue_dump(&dst, litqueue, litqueuelen);
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 456 
    litqueuelen = 0;
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 457 
  }
- 
 
 458 
 
397 
  return(complen);
 459 
  return(complen);
398 
}
 460 
}
399 
 
 461 
 
400 
 
 462 
 
401 
/* write the language block (id, dict, strings) into the LNG file.
463 
/* write the language block (id, dict, strings) into the LNG file.