src/tiff/tif_predict.c

/* $Header$ */

/*
 * Copyright (c) 1988-1997 Sam Leffler
 * Copyright (c) 1991-1997 Silicon Graphics, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software and
 * its documentation for any purpose is hereby granted without fee, provided
 * that (i) the above copyright notices and this permission notice appear in
 * all copies of the software and related documentation, and (ii) the names of
 * Sam Leffler and Silicon Graphics may not be used in any advertising or
 * publicity relating to the software without the specific, prior written
 * permission of Sam Leffler and Silicon Graphics.
 *
 * THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
 * EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
 * WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
 *
 * IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
 * ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
 * OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
 * WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
 * LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
 * OF THIS SOFTWARE.
 */

/*
 * TIFF Library.
 *
 * Predictor Tag Support (used by multiple codecs).
 */
#include "tiffiop.h"
#include "tif_predict.h"

#include <assert.h>

#define	PredictorState(tif)	((TIFFPredictorState*) (tif)->tif_data)

static	void horAcc8(TIFF*, tidata_t, tsize_t);
static	void horAcc16(TIFF*, tidata_t, tsize_t);
static	void swabHorAcc16(TIFF*, tidata_t, tsize_t);
static	void horDiff8(TIFF*, tidata_t, tsize_t);
static	void horDiff16(TIFF*, tidata_t, tsize_t);
static	int PredictorDecodeRow(TIFF*, tidata_t, tsize_t, tsample_t);
static	int PredictorDecodeTile(TIFF*, tidata_t, tsize_t, tsample_t);
static	int PredictorEncodeRow(TIFF*, tidata_t, tsize_t, tsample_t);
static	int PredictorEncodeTile(TIFF*, tidata_t, tsize_t, tsample_t);

static int
PredictorSetup(TIFF* tif)
{
	TIFFPredictorState* sp = PredictorState(tif);
	TIFFDirectory* td = &tif->tif_dir;

	if (sp->predictor == 1)		/* no differencing */
		return (1);
	if (sp->predictor != 2) {
		TIFFError(tif->tif_name, "\"Predictor\" value %d not supported",
		    sp->predictor);
		return (0);
	}
	if (td->td_bitspersample != 8 && td->td_bitspersample != 16) {
		TIFFError(tif->tif_name,
    "Horizontal differencing \"Predictor\" not supported with %d-bit samples",
		    td->td_bitspersample);
		return (0);
	}
	sp->stride = (td->td_planarconfig == PLANARCONFIG_CONTIG ?
	    td->td_samplesperpixel : 1);
	/*
	 * Calculate the scanline/tile-width size in bytes.
	 */
	if (isTiled(tif))
		sp->rowsize = TIFFTileRowSize(tif);
	else
		sp->rowsize = TIFFScanlineSize(tif);
	return (1);
}

static int
PredictorSetupDecode(TIFF* tif)
{
	TIFFPredictorState* sp = PredictorState(tif);
	TIFFDirectory* td = &tif->tif_dir;

	if (!(*sp->setupdecode)(tif) || !PredictorSetup(tif))
		return (0);
	if (sp->predictor == 2) {
		switch (td->td_bitspersample) {
		case 8:  sp->pfunc = horAcc8; break;
		case 16: sp->pfunc = horAcc16; break;
		}
		/*
		 * Override default decoding method with
		 * one that does the predictor stuff.
		 */
		sp->coderow = tif->tif_decoderow;
		tif->tif_decoderow = PredictorDecodeRow;
		sp->codestrip = tif->tif_decodestrip;
		tif->tif_decodestrip = PredictorDecodeTile;
		sp->codetile = tif->tif_decodetile;
		tif->tif_decodetile = PredictorDecodeTile;
		/*
		 * If the data is horizontally differenced
		 * 16-bit data that requires byte-swapping,
		 * then it must be byte swapped before the
		 * accumulation step.  We do this with a
		 * special-purpose routine and override the
		 * normal post decoding logic that the library
		 * setup when the directory was read.
		 */
		if (tif->tif_flags&TIFF_SWAB) {
			if (sp->pfunc == horAcc16) {
				sp->pfunc = swabHorAcc16;
				tif->tif_postdecode = _TIFFNoPostDecode;
			} /* else handle 32-bit case... */
		}
	}
	return (1);
}

static int
PredictorSetupEncode(TIFF* tif)
{
	TIFFPredictorState* sp = PredictorState(tif);
	TIFFDirectory* td = &tif->tif_dir;

	if (!(*sp->setupencode)(tif) || !PredictorSetup(tif))
		return (0);
	if (sp->predictor == 2) {
		switch (td->td_bitspersample) {
		case 8:  sp->pfunc = horDiff8; break;
		case 16: sp->pfunc = horDiff16; break;
		}
		/*
		 * Override default encoding method with
		 * one that does the predictor stuff.
		 */
		sp->coderow = tif->tif_encoderow;
		tif->tif_encoderow = PredictorEncodeRow;
		sp->codestrip = tif->tif_encodestrip;
		tif->tif_encodestrip = PredictorEncodeTile;
		sp->codetile = tif->tif_encodetile;
		tif->tif_encodetile = PredictorEncodeTile;
	}
	return (1);
}

#define REPEAT4(n, op)		\
    switch (n) {		\
    default: { int i; for (i = n-4; i > 0; i--) { op; } } \
    case 4:  op;		\
    case 3:  op;		\
    case 2:  op;		\
    case 1:  op;		\
    case 0:  ;			\
    }

static void
horAcc8(TIFF* tif, tidata_t cp0, tsize_t cc)
{
	TIFFPredictorState* sp = PredictorState(tif);
	tsize_t stride = sp->stride;

	char* cp = (char*) cp0;
	if (cc > stride) {
		cc -= stride;
		/*
		 * Pipeline the most common cases.
		 */
		if (stride == 3)  {
			u_int cr = cp[0];
			u_int cg = cp[1];
			u_int cb = cp[2];
			do {
				cc -= 3, cp += 3;
				cp[0] = (char) (cr += cp[0]);
				cp[1] = (char) (cg += cp[1]);
				cp[2] = (char) (cb += cp[2]);
			} while ((int32) cc > 0);
		} else if (stride == 4)  {
			u_int cr = cp[0];
			u_int cg = cp[1];
			u_int cb = cp[2];
			u_int ca = cp[3];
			do {
				cc -= 4, cp += 4;
				cp[0] = (char) (cr += cp[0]);
				cp[1] = (char) (cg += cp[1]);
				cp[2] = (char) (cb += cp[2]);
				cp[3] = (char) (ca += cp[3]);
			} while ((int32) cc > 0);
		} else  {
			do {
				REPEAT4(stride, cp[stride] = (char) (cp[stride] + *cp); cp++)
				cc -= stride;
			} while ((int32) cc > 0);
		}
	}
}

static void
swabHorAcc16(TIFF* tif, tidata_t cp0, tsize_t cc)
{
	TIFFPredictorState* sp = PredictorState(tif);
	tsize_t stride = sp->stride;
	uint16* wp = (uint16*) cp0;
	tsize_t wc = cc / 2;

	if (wc > stride) {
		TIFFSwabArrayOfShort(wp, wc);
		wc -= stride;
		do {
			REPEAT4(stride, wp[stride] += wp[0]; wp++)
			wc -= stride;
		} while ((int32) wc > 0);
	}
}

static void
horAcc16(TIFF* tif, tidata_t cp0, tsize_t cc)
{
	tsize_t stride = PredictorState(tif)->stride;
	uint16* wp = (uint16*) cp0;
	tsize_t wc = cc / 2;

	if (wc > stride) {
		wc -= stride;
		do {
			REPEAT4(stride, wp[stride] += wp[0]; wp++)
			wc -= stride;
		} while ((int32) wc > 0);
	}
}

/*
 * Decode a scanline and apply the predictor routine.
 */
static int
PredictorDecodeRow(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s)
{
	TIFFPredictorState *sp = PredictorState(tif);

	assert(sp != NULL);
	assert(sp->coderow != NULL);
	assert(sp->pfunc != NULL);
	if ((*sp->coderow)(tif, op0, occ0, s)) {
		(*sp->pfunc)(tif, op0, occ0);
		return (1);
	} else
		return (0);
}

/*
 * Decode a tile/strip and apply the predictor routine.
 * Note that horizontal differencing must be done on a
 * row-by-row basis.  The width of a "row" has already
 * been calculated at pre-decode time according to the
 * strip/tile dimensions.
 */
static int
PredictorDecodeTile(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s)
{
	TIFFPredictorState *sp = PredictorState(tif);

	assert(sp != NULL);
	assert(sp->codetile != NULL);
	if ((*sp->codetile)(tif, op0, occ0, s)) {
		tsize_t rowsize = sp->rowsize;
		assert(rowsize > 0);
		assert(sp->pfunc != NULL);
		while ((long)occ0 > 0) {
			(*sp->pfunc)(tif, op0, (tsize_t) rowsize);
			occ0 -= rowsize;
			op0 += rowsize;
		}
		return (1);
	} else
		return (0);
}

static void
horDiff8(TIFF* tif, tidata_t cp0, tsize_t cc)
{
	TIFFPredictorState* sp = PredictorState(tif);
	tsize_t stride = sp->stride;
	char* cp = (char*) cp0;

	if (cc > stride) {
		cc -= stride;
		/*
		 * Pipeline the most common cases.
		 */
		if (stride == 3) {
			int r1, g1, b1;
			int r2 = cp[0];
			int g2 = cp[1];
			int b2 = cp[2];
			do {
				r1 = cp[3]; cp[3] = r1-r2; r2 = r1;
				g1 = cp[4]; cp[4] = g1-g2; g2 = g1;
				b1 = cp[5]; cp[5] = b1-b2; b2 = b1;
				cp += 3;
			} while ((int32)(cc -= 3) > 0);
		} else if (stride == 4) {
			int r1, g1, b1, a1;
			int r2 = cp[0];
			int g2 = cp[1];
			int b2 = cp[2];
			int a2 = cp[3];
			do {
				r1 = cp[4]; cp[4] = r1-r2; r2 = r1;
				g1 = cp[5]; cp[5] = g1-g2; g2 = g1;
				b1 = cp[6]; cp[6] = b1-b2; b2 = b1;
				a1 = cp[7]; cp[7] = a1-a2; a2 = a1;
				cp += 4;
			} while ((int32)(cc -= 4) > 0);
		} else {
			cp += cc - 1;
			do {
				REPEAT4(stride, cp[stride] -= cp[0]; cp--)
			} while ((int32)(cc -= stride) > 0);
		}
	}
}

static void
horDiff16(TIFF* tif, tidata_t cp0, tsize_t cc)
{
	TIFFPredictorState* sp = PredictorState(tif);
	tsize_t stride = sp->stride;
	int16 *wp = (int16*) cp0;
	tsize_t wc = cc/2;

	if (wc > stride) {
		wc -= stride;
		wp += wc - 1;
		do {
			REPEAT4(stride, wp[stride] -= wp[0]; wp--)
			wc -= stride;
		} while ((int32) wc > 0);
	}
}

static int
PredictorEncodeRow(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
{
	TIFFPredictorState *sp = PredictorState(tif);

	assert(sp != NULL);
	assert(sp->pfunc != NULL);
	assert(sp->coderow != NULL);
/* XXX horizontal differencing alters user's data XXX */
	(*sp->pfunc)(tif, bp, cc);
	return ((*sp->coderow)(tif, bp, cc, s));
}

static int
PredictorEncodeTile(TIFF* tif, tidata_t bp0, tsize_t cc0, tsample_t s)
{
	TIFFPredictorState *sp = PredictorState(tif);
	tsize_t cc = cc0, rowsize;
	u_char* bp = bp0;

	assert(sp != NULL);
	assert(sp->pfunc != NULL);
	assert(sp->codetile != NULL);
	rowsize = sp->rowsize;
	assert(rowsize > 0);
	while ((long)cc > 0) {
		(*sp->pfunc)(tif, bp, (tsize_t) rowsize);
		cc -= rowsize;
		bp += rowsize;
	}
	return ((*sp->codetile)(tif, bp0, cc0, s));
}

#define	FIELD_PREDICTOR	(FIELD_CODEC+0)		/* XXX */

static const TIFFFieldInfo predictFieldInfo[] = {
    { TIFFTAG_PREDICTOR,	 1, 1, TIFF_SHORT,	FIELD_PREDICTOR,
      FALSE,	FALSE,	"Predictor" },
};
#define	N(a)	(sizeof (a) / sizeof (a[0]))

static int
PredictorVSetField(TIFF* tif, ttag_t tag, va_list ap)
{
	TIFFPredictorState *sp = PredictorState(tif);

	switch (tag) {
	case TIFFTAG_PREDICTOR:
		sp->predictor = (uint16) va_arg(ap, int);
		TIFFSetFieldBit(tif, FIELD_PREDICTOR);
		break;
	default:
		return (*sp->vsetparent)(tif, tag, ap);
	}
	tif->tif_flags |= TIFF_DIRTYDIRECT;
	return (1);
}

static int
PredictorVGetField(TIFF* tif, ttag_t tag, va_list ap)
{
	TIFFPredictorState *sp = PredictorState(tif);

	switch (tag) {
	case TIFFTAG_PREDICTOR:
		*va_arg(ap, uint16*) = sp->predictor;
		break;
	default:
		return (*sp->vgetparent)(tif, tag, ap);
	}
	return (1);
}

static void
PredictorPrintDir(TIFF* tif, FILE* fd, long flags)
{
	TIFFPredictorState* sp = PredictorState(tif);

	(void) flags;
	if (TIFFFieldSet(tif,FIELD_PREDICTOR)) {
		fprintf(fd, "  Predictor: ");
		switch (sp->predictor) {
		case 1: fprintf(fd, "none "); break;
		case 2: fprintf(fd, "horizontal differencing "); break;
		}
		fprintf(fd, "%u (0x%x)\n", sp->predictor, sp->predictor);
	}
	if (sp->printdir)
		(*sp->printdir)(tif, fd, flags);
}

int
TIFFPredictorInit(TIFF* tif)
{
	TIFFPredictorState* sp = PredictorState(tif);

	/*
	 * Merge codec-specific tag information and
	 * override parent get/set field methods.
	 */
	_TIFFMergeFieldInfo(tif, predictFieldInfo, N(predictFieldInfo));
	sp->vgetparent = tif->tif_tagmethods.vgetfield;
	tif->tif_tagmethods.vgetfield =
            PredictorVGetField;/* hook for predictor tag */
	sp->vsetparent = tif->tif_tagmethods.vsetfield;
	tif->tif_tagmethods.vsetfield =
            PredictorVSetField;/* hook for predictor tag */
	sp->printdir = tif->tif_tagmethods.printdir;
	tif->tif_tagmethods.printdir =
            PredictorPrintDir;	/* hook for predictor tag */

	sp->setupdecode = tif->tif_setupdecode;
	tif->tif_setupdecode = PredictorSetupDecode;
	sp->setupencode = tif->tif_setupencode;
	tif->tif_setupencode = PredictorSetupEncode;

	sp->predictor = 1;			/* default value */
	sp->pfunc = NULL;			/* no predictor routine */
	return (1);
}
Commit	Line	Data
	1	/* $Header$ */
	2
	3	/*
	4	* Copyright (c) 1988-1997 Sam Leffler
	5	* Copyright (c) 1991-1997 Silicon Graphics, Inc.
	6	*
	7	* Permission to use, copy, modify, distribute, and sell this software and
	8	* its documentation for any purpose is hereby granted without fee, provided
	9	* that (i) the above copyright notices and this permission notice appear in
	10	* all copies of the software and related documentation, and (ii) the names of
	11	* Sam Leffler and Silicon Graphics may not be used in any advertising or
	12	* publicity relating to the software without the specific, prior written
	13	* permission of Sam Leffler and Silicon Graphics.
	14	*
	15	* THE SOFTWARE IS PROVIDED "AS-IS" AND WITHOUT WARRANTY OF ANY KIND,
	16	* EXPRESS, IMPLIED OR OTHERWISE, INCLUDING WITHOUT LIMITATION, ANY
	17	* WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
	18	*
	19	* IN NO EVENT SHALL SAM LEFFLER OR SILICON GRAPHICS BE LIABLE FOR
	20	* ANY SPECIAL, INCIDENTAL, INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND,
	21	* OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS,
	22	* WHETHER OR NOT ADVISED OF THE POSSIBILITY OF DAMAGE, AND ON ANY THEORY OF
	23	* LIABILITY, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE
	24	* OF THIS SOFTWARE.
	25	*/
	26
	27	/*
	28	* TIFF Library.
	29	*
	30	* Predictor Tag Support (used by multiple codecs).
	31	*/
	32	#include "tiffiop.h"
	33	#include "tif_predict.h"
	34
	35	#include <assert.h>
	36
	37	#define PredictorState(tif) ((TIFFPredictorState*) (tif)->tif_data)
	38
	39	static void horAcc8(TIFF*, tidata_t, tsize_t);
	40	static void horAcc16(TIFF*, tidata_t, tsize_t);
	41	static void swabHorAcc16(TIFF*, tidata_t, tsize_t);
	42	static void horDiff8(TIFF*, tidata_t, tsize_t);
	43	static void horDiff16(TIFF*, tidata_t, tsize_t);
	44	static int PredictorDecodeRow(TIFF*, tidata_t, tsize_t, tsample_t);
	45	static int PredictorDecodeTile(TIFF*, tidata_t, tsize_t, tsample_t);
	46	static int PredictorEncodeRow(TIFF*, tidata_t, tsize_t, tsample_t);
	47	static int PredictorEncodeTile(TIFF*, tidata_t, tsize_t, tsample_t);
	48
	49	static int
	50	PredictorSetup(TIFF* tif)
	51	{
	52	TIFFPredictorState* sp = PredictorState(tif);
	53	TIFFDirectory* td = &tif->tif_dir;
	54
	55	if (sp->predictor == 1) /* no differencing */
	56	return (1);
	57	if (sp->predictor != 2) {
	58	TIFFError(tif->tif_name, "\"Predictor\" value %d not supported",
	59	sp->predictor);
	60	return (0);
	61	}
	62	if (td->td_bitspersample != 8 && td->td_bitspersample != 16) {
	63	TIFFError(tif->tif_name,
	64	"Horizontal differencing \"Predictor\" not supported with %d-bit samples",
	65	td->td_bitspersample);
	66	return (0);
	67	}
	68	sp->stride = (td->td_planarconfig == PLANARCONFIG_CONTIG ?
	69	td->td_samplesperpixel : 1);
	70	/*
	71	* Calculate the scanline/tile-width size in bytes.
	72	*/
	73	if (isTiled(tif))
	74	sp->rowsize = TIFFTileRowSize(tif);
	75	else
	76	sp->rowsize = TIFFScanlineSize(tif);
	77	return (1);
	78	}
	79
	80	static int
	81	PredictorSetupDecode(TIFF* tif)
	82	{
	83	TIFFPredictorState* sp = PredictorState(tif);
	84	TIFFDirectory* td = &tif->tif_dir;
	85
	86	if (!(*sp->setupdecode)(tif) \|\| !PredictorSetup(tif))
	87	return (0);
	88	if (sp->predictor == 2) {
	89	switch (td->td_bitspersample) {
	90	case 8: sp->pfunc = horAcc8; break;
	91	case 16: sp->pfunc = horAcc16; break;
	92	}
	93	/*
	94	* Override default decoding method with
	95	* one that does the predictor stuff.
	96	*/
	97	sp->coderow = tif->tif_decoderow;
	98	tif->tif_decoderow = PredictorDecodeRow;
	99	sp->codestrip = tif->tif_decodestrip;
	100	tif->tif_decodestrip = PredictorDecodeTile;
	101	sp->codetile = tif->tif_decodetile;
	102	tif->tif_decodetile = PredictorDecodeTile;
	103	/*
	104	* If the data is horizontally differenced
	105	* 16-bit data that requires byte-swapping,
	106	* then it must be byte swapped before the
	107	* accumulation step. We do this with a
	108	* special-purpose routine and override the
	109	* normal post decoding logic that the library
	110	* setup when the directory was read.
	111	*/
	112	if (tif->tif_flags&TIFF_SWAB) {
	113	if (sp->pfunc == horAcc16) {
	114	sp->pfunc = swabHorAcc16;
	115	tif->tif_postdecode = _TIFFNoPostDecode;
	116	} /* else handle 32-bit case... */
	117	}
	118	}
	119	return (1);
	120	}
	121
	122	static int
	123	PredictorSetupEncode(TIFF* tif)
	124	{
	125	TIFFPredictorState* sp = PredictorState(tif);
	126	TIFFDirectory* td = &tif->tif_dir;
	127
	128	if (!(*sp->setupencode)(tif) \|\| !PredictorSetup(tif))
	129	return (0);
	130	if (sp->predictor == 2) {
	131	switch (td->td_bitspersample) {
	132	case 8: sp->pfunc = horDiff8; break;
	133	case 16: sp->pfunc = horDiff16; break;
	134	}
	135	/*
	136	* Override default encoding method with
	137	* one that does the predictor stuff.
	138	*/
	139	sp->coderow = tif->tif_encoderow;
	140	tif->tif_encoderow = PredictorEncodeRow;
	141	sp->codestrip = tif->tif_encodestrip;
	142	tif->tif_encodestrip = PredictorEncodeTile;
	143	sp->codetile = tif->tif_encodetile;
	144	tif->tif_encodetile = PredictorEncodeTile;
	145	}
	146	return (1);
	147	}
	148
	149	#define REPEAT4(n, op) \
	150	switch (n) { \
	151	default: { int i; for (i = n-4; i > 0; i--) { op; } } \
	152	case 4: op; \
	153	case 3: op; \
	154	case 2: op; \
	155	case 1: op; \
	156	case 0: ; \
	157	}
	158
	159	static void
	160	horAcc8(TIFF* tif, tidata_t cp0, tsize_t cc)
	161	{
	162	TIFFPredictorState* sp = PredictorState(tif);
	163	tsize_t stride = sp->stride;
	164
	165	char* cp = (char*) cp0;
	166	if (cc > stride) {
	167	cc -= stride;
	168	/*
	169	* Pipeline the most common cases.
	170	*/
	171	if (stride == 3) {
	172	u_int cr = cp[0];
	173	u_int cg = cp[1];
	174	u_int cb = cp[2];
	175	do {
	176	cc -= 3, cp += 3;
	177	cp[0] = (char) (cr += cp[0]);
	178	cp[1] = (char) (cg += cp[1]);
	179	cp[2] = (char) (cb += cp[2]);
	180	} while ((int32) cc > 0);
	181	} else if (stride == 4) {
	182	u_int cr = cp[0];
	183	u_int cg = cp[1];
	184	u_int cb = cp[2];
	185	u_int ca = cp[3];
	186	do {
	187	cc -= 4, cp += 4;
	188	cp[0] = (char) (cr += cp[0]);
	189	cp[1] = (char) (cg += cp[1]);
	190	cp[2] = (char) (cb += cp[2]);
	191	cp[3] = (char) (ca += cp[3]);
	192	} while ((int32) cc > 0);
	193	} else {
	194	do {
	195	REPEAT4(stride, cp[stride] = (char) (cp[stride] + *cp); cp++)
	196	cc -= stride;
	197	} while ((int32) cc > 0);
	198	}
	199	}
	200	}
	201
	202	static void
	203	swabHorAcc16(TIFF* tif, tidata_t cp0, tsize_t cc)
	204	{
	205	TIFFPredictorState* sp = PredictorState(tif);
	206	tsize_t stride = sp->stride;
	207	uint16* wp = (uint16*) cp0;
	208	tsize_t wc = cc / 2;
	209
	210	if (wc > stride) {
	211	TIFFSwabArrayOfShort(wp, wc);
	212	wc -= stride;
	213	do {
	214	REPEAT4(stride, wp[stride] += wp[0]; wp++)
	215	wc -= stride;
	216	} while ((int32) wc > 0);
	217	}
	218	}
	219
	220	static void
	221	horAcc16(TIFF* tif, tidata_t cp0, tsize_t cc)
	222	{
	223	tsize_t stride = PredictorState(tif)->stride;
	224	uint16* wp = (uint16*) cp0;
	225	tsize_t wc = cc / 2;
	226
	227	if (wc > stride) {
	228	wc -= stride;
	229	do {
	230	REPEAT4(stride, wp[stride] += wp[0]; wp++)
	231	wc -= stride;
	232	} while ((int32) wc > 0);
	233	}
	234	}
	235
	236	/*
	237	* Decode a scanline and apply the predictor routine.
	238	*/
	239	static int
	240	PredictorDecodeRow(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s)
	241	{
	242	TIFFPredictorState *sp = PredictorState(tif);
	243
	244	assert(sp != NULL);
	245	assert(sp->coderow != NULL);
	246	assert(sp->pfunc != NULL);
	247	if ((*sp->coderow)(tif, op0, occ0, s)) {
	248	(*sp->pfunc)(tif, op0, occ0);
	249	return (1);
	250	} else
	251	return (0);
	252	}
	253
	254	/*
	255	* Decode a tile/strip and apply the predictor routine.
	256	* Note that horizontal differencing must be done on a
	257	* row-by-row basis. The width of a "row" has already
	258	* been calculated at pre-decode time according to the
	259	* strip/tile dimensions.
	260	*/
	261	static int
	262	PredictorDecodeTile(TIFF* tif, tidata_t op0, tsize_t occ0, tsample_t s)
	263	{
	264	TIFFPredictorState *sp = PredictorState(tif);
	265
	266	assert(sp != NULL);
	267	assert(sp->codetile != NULL);
	268	if ((*sp->codetile)(tif, op0, occ0, s)) {
	269	tsize_t rowsize = sp->rowsize;
	270	assert(rowsize > 0);
	271	assert(sp->pfunc != NULL);
	272	while ((long)occ0 > 0) {
	273	(*sp->pfunc)(tif, op0, (tsize_t) rowsize);
	274	occ0 -= rowsize;
	275	op0 += rowsize;
	276	}
	277	return (1);
	278	} else
	279	return (0);
	280	}
	281
	282	static void
	283	horDiff8(TIFF* tif, tidata_t cp0, tsize_t cc)
	284	{
	285	TIFFPredictorState* sp = PredictorState(tif);
	286	tsize_t stride = sp->stride;
	287	char* cp = (char*) cp0;
	288
	289	if (cc > stride) {
	290	cc -= stride;
	291	/*
	292	* Pipeline the most common cases.
	293	*/
	294	if (stride == 3) {
	295	int r1, g1, b1;
	296	int r2 = cp[0];
	297	int g2 = cp[1];
	298	int b2 = cp[2];
	299	do {
	300	r1 = cp[3]; cp[3] = r1-r2; r2 = r1;
	301	g1 = cp[4]; cp[4] = g1-g2; g2 = g1;
	302	b1 = cp[5]; cp[5] = b1-b2; b2 = b1;
	303	cp += 3;
	304	} while ((int32)(cc -= 3) > 0);
	305	} else if (stride == 4) {
	306	int r1, g1, b1, a1;
	307	int r2 = cp[0];
	308	int g2 = cp[1];
	309	int b2 = cp[2];
	310	int a2 = cp[3];
	311	do {
	312	r1 = cp[4]; cp[4] = r1-r2; r2 = r1;
	313	g1 = cp[5]; cp[5] = g1-g2; g2 = g1;
	314	b1 = cp[6]; cp[6] = b1-b2; b2 = b1;
	315	a1 = cp[7]; cp[7] = a1-a2; a2 = a1;
	316	cp += 4;
	317	} while ((int32)(cc -= 4) > 0);
	318	} else {
	319	cp += cc - 1;
	320	do {
	321	REPEAT4(stride, cp[stride] -= cp[0]; cp--)
	322	} while ((int32)(cc -= stride) > 0);
	323	}
	324	}
	325	}
	326
	327	static void
	328	horDiff16(TIFF* tif, tidata_t cp0, tsize_t cc)
	329	{
	330	TIFFPredictorState* sp = PredictorState(tif);
	331	tsize_t stride = sp->stride;
	332	int16 wp = (int16) cp0;
	333	tsize_t wc = cc/2;
	334
	335	if (wc > stride) {
	336	wc -= stride;
	337	wp += wc - 1;
	338	do {
	339	REPEAT4(stride, wp[stride] -= wp[0]; wp--)
	340	wc -= stride;
	341	} while ((int32) wc > 0);
	342	}
	343	}
	344
	345	static int
	346	PredictorEncodeRow(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
	347	{
	348	TIFFPredictorState *sp = PredictorState(tif);
	349
	350	assert(sp != NULL);
	351	assert(sp->pfunc != NULL);
	352	assert(sp->coderow != NULL);
	353	/* XXX horizontal differencing alters user's data XXX */
	354	(*sp->pfunc)(tif, bp, cc);
	355	return ((*sp->coderow)(tif, bp, cc, s));
	356	}
	357
	358	static int
	359	PredictorEncodeTile(TIFF* tif, tidata_t bp0, tsize_t cc0, tsample_t s)
	360	{
	361	TIFFPredictorState *sp = PredictorState(tif);
	362	tsize_t cc = cc0, rowsize;
	363	u_char* bp = bp0;
	364
	365	assert(sp != NULL);
	366	assert(sp->pfunc != NULL);
	367	assert(sp->codetile != NULL);
	368	rowsize = sp->rowsize;
	369	assert(rowsize > 0);
	370	while ((long)cc > 0) {
	371	(*sp->pfunc)(tif, bp, (tsize_t) rowsize);
	372	cc -= rowsize;
	373	bp += rowsize;
	374	}
	375	return ((*sp->codetile)(tif, bp0, cc0, s));
	376	}
	377
	378	#define FIELD_PREDICTOR (FIELD_CODEC+0) /* XXX */
	379
	380	static const TIFFFieldInfo predictFieldInfo[] = {
	381	{ TIFFTAG_PREDICTOR, 1, 1, TIFF_SHORT, FIELD_PREDICTOR,
	382	FALSE, FALSE, "Predictor" },
	383	};
	384	#define N(a) (sizeof (a) / sizeof (a[0]))
	385
	386	static int
	387	PredictorVSetField(TIFF* tif, ttag_t tag, va_list ap)
	388	{
	389	TIFFPredictorState *sp = PredictorState(tif);
	390
	391	switch (tag) {
	392	case TIFFTAG_PREDICTOR:
	393	sp->predictor = (uint16) va_arg(ap, int);
	394	TIFFSetFieldBit(tif, FIELD_PREDICTOR);
	395	break;
	396	default:
	397	return (*sp->vsetparent)(tif, tag, ap);
	398	}
	399	tif->tif_flags \|= TIFF_DIRTYDIRECT;
	400	return (1);
	401	}
	402
	403	static int
	404	PredictorVGetField(TIFF* tif, ttag_t tag, va_list ap)
	405	{
	406	TIFFPredictorState *sp = PredictorState(tif);
	407
	408	switch (tag) {
	409	case TIFFTAG_PREDICTOR:
	410	va_arg(ap, uint16) = sp->predictor;
	411	break;
	412	default:
	413	return (*sp->vgetparent)(tif, tag, ap);
	414	}
	415	return (1);
	416	}
	417
	418	static void
	419	PredictorPrintDir(TIFF* tif, FILE* fd, long flags)
	420	{
	421	TIFFPredictorState* sp = PredictorState(tif);
	422
	423	(void) flags;
	424	if (TIFFFieldSet(tif,FIELD_PREDICTOR)) {
	425	fprintf(fd, " Predictor: ");
	426	switch (sp->predictor) {
	427	case 1: fprintf(fd, "none "); break;
	428	case 2: fprintf(fd, "horizontal differencing "); break;
	429	}
	430	fprintf(fd, "%u (0x%x)\n", sp->predictor, sp->predictor);
	431	}
	432	if (sp->printdir)
	433	(*sp->printdir)(tif, fd, flags);
	434	}
	435
	436	int
	437	TIFFPredictorInit(TIFF* tif)
	438	{
	439	TIFFPredictorState* sp = PredictorState(tif);
	440
	441	/*
	442	* Merge codec-specific tag information and
	443	* override parent get/set field methods.
	444	*/
	445	_TIFFMergeFieldInfo(tif, predictFieldInfo, N(predictFieldInfo));
	446	sp->vgetparent = tif->tif_tagmethods.vgetfield;
	447	tif->tif_tagmethods.vgetfield =
	448	PredictorVGetField;/* hook for predictor tag */
	449	sp->vsetparent = tif->tif_tagmethods.vsetfield;
	450	tif->tif_tagmethods.vsetfield =
	451	PredictorVSetField;/* hook for predictor tag */
	452	sp->printdir = tif->tif_tagmethods.printdir;
	453	tif->tif_tagmethods.printdir =
	454	PredictorPrintDir; /* hook for predictor tag */
	455
	456	sp->setupdecode = tif->tif_setupdecode;
	457	tif->tif_setupdecode = PredictorSetupDecode;
	458	sp->setupencode = tif->tif_setupencode;
	459	tif->tif_setupencode = PredictorSetupEncode;
	460
	461	sp->predictor = 1; /* default value */
	462	sp->pfunc = NULL; /* no predictor routine */
	463	return (1);
	464	}