Esempio n. 1
0
/*
 * Finish off an encoded strip by flushing the last
 * string and tacking on an End Of Information code.
 */
static int
LZWPostEncode(TIFF* tif)
{
  register LZWCodecState *sp = EncoderState(tif);
  uint8* op = tif->tif_rawcp;
  long nextbits = sp->lzw_nextbits;
  long nextdata = sp->lzw_nextdata;
  long outcount = sp->enc_outcount;
  int nbits = sp->lzw_nbits;

  if (op > sp->enc_rawlimit) {
    tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
    TIFFFlushData1(tif);
    op = tif->tif_rawdata;
  }
  if (sp->enc_oldcode != (hcode_t) -1) {
    PutNextCode(op, sp->enc_oldcode);
    sp->enc_oldcode = (hcode_t) -1;
  }
  PutNextCode(op, CODE_EOI);
  if (nextbits > 0)
    *op++ = (unsigned char)(nextdata << (8-nextbits));
  tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
  return (1);
}
Esempio n. 2
0
/*
 * Finish off an encoded strip by flushing the last
 * string and tacking on an End Of Information code.
 */
static int
LZWPostEncode(TIFF* tif)
{
	register LZWCodecState *sp = EncoderState(tif);
	uint8* op = tif->tif_rawcp;
	long nextbits = sp->lzw_nextbits;
	unsigned long nextdata = sp->lzw_nextdata;
	long outcount = sp->enc_outcount;
	int nbits = sp->lzw_nbits;

	if (op > sp->enc_rawlimit) {
		tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
		if( !TIFFFlushData1(tif) )
                    return 0;
		op = tif->tif_rawdata;
	}
	if (sp->enc_oldcode != (hcode_t) -1) {
		PutNextCode(op, sp->enc_oldcode);
		sp->enc_oldcode = (hcode_t) -1;
	}
	PutNextCode(op, CODE_EOI);
        /* Explicit 0xff masking to make icc -check=conversions happy */
	if (nextbits > 0) 
		*op++ = (unsigned char)((nextdata << (8-nextbits))&0xff);
	tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
	return (1);
}
Esempio n. 3
0
/*
 * Finish off an encoded strip by flushing the last
 * string and tacking on an End Of Information code.
 */
static int
LZWPostEncode(TIFF* tif)
{
	register LZWCodecState *sp = EncoderState(tif);
	uint8* op = tif->tif_rawcp;
	long nextbits = sp->lzw_nextbits;
	unsigned long nextdata = sp->lzw_nextdata;
	long outcount = sp->enc_outcount;
	int nbits = sp->lzw_nbits;

	if (op > sp->enc_rawlimit) {
		tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
		if( !TIFFFlushData1(tif) )
                    return 0;
		op = tif->tif_rawdata;
	}
	if (sp->enc_oldcode != (hcode_t) -1) {
                int free_ent = sp->lzw_free_ent;

		PutNextCode(op, sp->enc_oldcode);
		sp->enc_oldcode = (hcode_t) -1;
                free_ent ++;

                if (free_ent == CODE_MAX-1) {
                        /* table is full, emit clear code and reset */
                        outcount = 0;
                        PutNextCode(op, CODE_CLEAR);
                        nbits = BITS_MIN;
                } else {
                        /*
                        * If the next entry is going to be too big for
                        * the code size, then increase it, if possible.
                        */
                        if (free_ent > sp->lzw_maxcode) {
                                nbits++;
                                assert(nbits <= BITS_MAX);
                        }
                }
	}
	PutNextCode(op, CODE_EOI);
        /* Explicit 0xff masking to make icc -check=conversions happy */
	if (nextbits > 0) 
		*op++ = (unsigned char)((nextdata << (8-nextbits))&0xff);
	tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
	return (1);
}
Esempio n. 4
0
/*
 * Encode a chunk of pixels.
 *
 * Uses an open addressing double hashing (no chaining) on the 
 * prefix code/next character combination.  We do a variant of
 * Knuth's algorithm D (vol. 3, sec. 6.4) along with G. Knott's
 * relatively-prime secondary probe.  Here, the modular division
 * first probe is gives way to a faster exclusive-or manipulation. 
 * Also do block compression with an adaptive reset, whereby the
 * code table is cleared when the compression ratio decreases,
 * but after the table fills.  The variable-length output codes
 * are re-sized at this point, and a CODE_CLEAR is generated
 * for the decoder. 
 */
static int
LZWEncode(TIFF* tif, uint8* bp, tmsize_t cc, uint16 s)
{
	register LZWCodecState *sp = EncoderState(tif);
	register long fcode;
	register hash_t *hp;
	register int h, c;
	hcode_t ent;
	long disp;
	long incount, outcount, checkpoint;
	unsigned long nextdata;
        long nextbits;
	int free_ent, maxcode, nbits;
	uint8* op;
	uint8* limit;

	(void) s;
	if (sp == NULL)
		return (0);

        assert(sp->enc_hashtab != NULL);

	/*
	 * Load local state.
	 */
	incount = sp->enc_incount;
	outcount = sp->enc_outcount;
	checkpoint = sp->enc_checkpoint;
	nextdata = sp->lzw_nextdata;
	nextbits = sp->lzw_nextbits;
	free_ent = sp->lzw_free_ent;
	maxcode = sp->lzw_maxcode;
	nbits = sp->lzw_nbits;
	op = tif->tif_rawcp;
	limit = sp->enc_rawlimit;
	ent = (hcode_t)sp->enc_oldcode;

	if (ent == (hcode_t) -1 && cc > 0) {
		/*
		 * NB: This is safe because it can only happen
		 *     at the start of a strip where we know there
		 *     is space in the data buffer.
		 */
		PutNextCode(op, CODE_CLEAR);
		ent = *bp++; cc--; incount++;
	}
	while (cc > 0) {
		c = *bp++; cc--; incount++;
		fcode = ((long)c << BITS_MAX) + ent;
		h = (c << HSHIFT) ^ ent;	/* xor hashing */
#ifdef _WINDOWS
		/*
		 * Check hash index for an overflow.
		 */
		if (h >= HSIZE)
			h -= HSIZE;
#endif
		hp = &sp->enc_hashtab[h];
		if (hp->hash == fcode) {
			ent = hp->code;
			continue;
		}
		if (hp->hash >= 0) {
			/*
			 * Primary hash failed, check secondary hash.
			 */
			disp = HSIZE - h;
			if (h == 0)
				disp = 1;
			do {
				/*
				 * Avoid pointer arithmetic because of
				 * wraparound problems with segments.
				 */
				if ((h -= disp) < 0)
					h += HSIZE;
				hp = &sp->enc_hashtab[h];
				if (hp->hash == fcode) {
					ent = hp->code;
					goto hit;
				}
			} while (hp->hash >= 0);
		}
		/*
		 * New entry, emit code and add to table.
		 */
		/*
		 * Verify there is space in the buffer for the code
		 * and any potential Clear code that might be emitted
		 * below.  The value of limit is setup so that there
		 * are at least 4 bytes free--room for 2 codes.
		 */
		if (op > limit) {
			tif->tif_rawcc = (tmsize_t)(op - tif->tif_rawdata);
			if( !TIFFFlushData1(tif) )
                            return 0;
			op = tif->tif_rawdata;
		}
		PutNextCode(op, ent);
		ent = (hcode_t)c;
		hp->code = (hcode_t)(free_ent++);
		hp->hash = fcode;
		if (free_ent == CODE_MAX-1) {
			/* table is full, emit clear code and reset */
			cl_hash(sp);
			sp->enc_ratio = 0;
			incount = 0;
			outcount = 0;
			free_ent = CODE_FIRST;
			PutNextCode(op, CODE_CLEAR);
			nbits = BITS_MIN;
			maxcode = MAXCODE(BITS_MIN);
		} else {
			/*
			 * If the next entry is going to be too big for
			 * the code size, then increase it, if possible.
			 */
			if (free_ent > maxcode) {
				nbits++;
				assert(nbits <= BITS_MAX);
				maxcode = (int) MAXCODE(nbits);
			} else if (incount >= checkpoint) {
				long rat;
				/*
				 * Check compression ratio and, if things seem
				 * to be slipping, clear the hash table and
				 * reset state.  The compression ratio is a
				 * 24+8-bit fractional number.
				 */
				checkpoint = incount+CHECK_GAP;
				CALCRATIO(sp, rat);
				if (rat <= sp->enc_ratio) {
					cl_hash(sp);
					sp->enc_ratio = 0;
					incount = 0;
					outcount = 0;
					free_ent = CODE_FIRST;
					PutNextCode(op, CODE_CLEAR);
					nbits = BITS_MIN;
					maxcode = MAXCODE(BITS_MIN);
				} else
					sp->enc_ratio = rat;
			}
		}
	hit:
		;
	}

	/*
	 * Restore global state.
	 */
	sp->enc_incount = incount;
	sp->enc_outcount = outcount;
	sp->enc_checkpoint = checkpoint;
	sp->enc_oldcode = ent;
	sp->lzw_nextdata = nextdata;
	sp->lzw_nextbits = nextbits;
	sp->lzw_free_ent = (unsigned short)free_ent;
	sp->lzw_maxcode = (unsigned short)maxcode;
	sp->lzw_nbits = (unsigned short)nbits;
	tif->tif_rawcp = op;
	return (1);
}