/* $Id: tif_fax3.h,v 1.5.2.1 2010-06-08 18:50:42 bfriesen Exp $ */

/*

 * Copyright (c) 1990-1997 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.

 */

#ifndef _FAX3_

#define	_FAX3_

/*

 * TIFF Library.

 *

 * CCITT Group 3 (T.4) and Group 4 (T.6) Decompression Support.

 *

 * Decoder support is derived, with permission, from the code

 * in Frank Cringle's viewfax program;

 *      Copyright (C) 1990, 1995  Frank D. Cringle.

 */

#include "tiff.h"

/*

 * To override the default routine used to image decoded

 * spans one can use the pseduo tag TIFFTAG_FAXFILLFUNC.

 * The routine must have the type signature given below;

 * for example:

 *

 * fillruns(unsigned char* buf, uint32* runs, uint32* erun, uint32 lastx)

 *

 * where buf is place to set the bits, runs is the array of b&w run

 * lengths (white then black), erun is the last run in the array, and

 * lastx is the width of the row in pixels.  Fill routines can assume

 * the run array has room for at least lastx runs and can overwrite

 * data in the run array as needed (e.g. to append zero runs to bring

 * the count up to a nice multiple).

 */

typedef	void (*TIFFFaxFillFunc)(unsigned char*, uint32*, uint32*, uint32);

/*

 * The default run filler; made external for other decoders.

 */

#if defined(__cplusplus)

extern "C" {

#endif

extern	void _TIFFFax3fillruns(unsigned char*, uint32*, uint32*, uint32);

#if defined(__cplusplus)

}

#endif

/* finite state machine codes */

#define S_Null		0

#define S_Pass		1

#define S_Horiz		2

#define S_V0		3

#define S_VR		4

#define S_VL		5

#define S_Ext		6

#define S_TermW		7

#define S_TermB		8

#define S_MakeUpW	9

#define S_MakeUpB	10

#define S_MakeUp	11

#define S_EOL		12

typedef struct {		/* state table entry */

	unsigned char State;	/* see above */

	unsigned char Width;	/* width of code in bits */

	uint32	Param;		/* unsigned 32-bit run length in bits */

} TIFFFaxTabEnt;

extern	const TIFFFaxTabEnt TIFFFaxMainTable[];

extern	const TIFFFaxTabEnt TIFFFaxWhiteTable[];

extern	const TIFFFaxTabEnt TIFFFaxBlackTable[];

/*

 * The following macros define the majority of the G3/G4 decoder

 * algorithm using the state tables defined elsewhere.  To build

 * a decoder you need some setup code and some glue code. Note

 * that you may also need/want to change the way the NeedBits*

 * macros get input data if, for example, you know the data to be

 * decoded is properly aligned and oriented (doing so before running

 * the decoder can be a big performance win).

 *

 * Consult the decoder in the TIFF library for an idea of what you

 * need to define and setup to make use of these definitions.

 *

 * NB: to enable a debugging version of these macros define FAX3_DEBUG

 *     before including this file.  Trace output goes to stdout.

 */

#ifndef EndOfData

#define EndOfData()	(cp >= ep)

#endif

/*

 * Need <=8 or <=16 bits of input data.  Unlike viewfax we

 * cannot use/assume a word-aligned, properly bit swizzled

 * input data set because data may come from an arbitrarily

 * aligned, read-only source such as a memory-mapped file.

 * Note also that the viewfax decoder does not check for

 * running off the end of the input data buffer.  This is

 * possible for G3-encoded data because it prescans the input

 * data to count EOL markers, but can cause problems for G4

 * data.  In any event, we don't prescan and must watch for

 * running out of data since we can't permit the library to

 * scan past the end of the input data buffer.

 *

 * Finally, note that we must handle remaindered data at the end

 * of a strip specially.  The coder asks for a fixed number of

 * bits when scanning for the next code.  This may be more bits

 * than are actually present in the data stream.  If we appear

 * to run out of data but still have some number of valid bits

 * remaining then we makeup the requested amount with zeros and

 * return successfully.  If the returned data is incorrect then

 * we should be called again and get a premature EOF error;

 * otherwise we should get the right answer.

 */

#ifndef NeedBits8

#define NeedBits8(n,eoflab) do {					\

    if (BitsAvail < (n)) {						\

	if (EndOfData()) {						\

	    if (BitsAvail == 0)			/* no valid bits */	\

		goto eoflab;						\

	    BitsAvail = (n);			/* pad with zeros */	\

	} else {							\

	    BitAcc |= ((uint32) bitmap[*cp++])<

	    BitsAvail += 8;						\

	}								\

    }									\

} while (0)

#endif

#ifndef NeedBits16

#define NeedBits16(n,eoflab) do {					\

    if (BitsAvail < (n)) {						\

	if (EndOfData()) {						\

	    if (BitsAvail == 0)			/* no valid bits */	\

		goto eoflab;						\

	    BitsAvail = (n);			/* pad with zeros */	\

	} else {							\

	    BitAcc |= ((uint32) bitmap[*cp++])<

	    if ((BitsAvail += 8) < (n)) {				\

		if (EndOfData()) {					\

		    /* NB: we know BitsAvail is non-zero here */	\

		    BitsAvail = (n);		/* pad with zeros */	\

		} else {						\

		    BitAcc |= ((uint32) bitmap[*cp++])<

		    BitsAvail += 8;					\

		}							\

	    }								\

	}								\

    }									\

} while (0)

#endif

#define GetBits(n)	(BitAcc & ((1<<(n))-1))

#define ClrBits(n) do {							\

    BitsAvail -= (n);							\

    BitAcc >>= (n);							\

} while (0)

#ifdef FAX3_DEBUG

static const char* StateNames[] = {

    "Null   ",

    "Pass   ",

    "Horiz  ",

    "V0     ",

    "VR     ",

    "VL     ",

    "Ext    ",

    "TermW  ",

    "TermB  ",

    "MakeUpW",

    "MakeUpB",

    "MakeUp ",

    "EOL    ",

};

#define DEBUG_SHOW putchar(BitAcc & (1 << t) ? '1' : '0')

#define LOOKUP8(wid,tab,eoflab) do {					\

    int t;								\

    NeedBits8(wid,eoflab);						\

    TabEnt = tab + GetBits(wid);					\

    printf("%08lX/%d: %s%5d\t", (long) BitAcc, BitsAvail,		\

	   StateNames[TabEnt->State], TabEnt->Param);			\

    for (t = 0; t < TabEnt->Width; t++)					\

	DEBUG_SHOW;							\

    putchar('\n');							\

    fflush(stdout);							\

    ClrBits(TabEnt->Width);						\

} while (0)

#define LOOKUP16(wid,tab,eoflab) do {					\

    int t;								\

    NeedBits16(wid,eoflab);						\

    TabEnt = tab + GetBits(wid);					\

    printf("%08lX/%d: %s%5d\t", (long) BitAcc, BitsAvail,		\

	   StateNames[TabEnt->State], TabEnt->Param);			\

    for (t = 0; t < TabEnt->Width; t++)					\

	DEBUG_SHOW;							\

    putchar('\n');							\

    fflush(stdout);							\

    ClrBits(TabEnt->Width);						\

} while (0)

#define SETVALUE(x) do {							\

    *pa++ = RunLength + (x);						\

    printf("SETVALUE: %d\t%d\n", RunLength + (x), a0);			\

    a0 += x;								\

    RunLength = 0;							\

} while (0)

#else

#define LOOKUP8(wid,tab,eoflab) do {					\

    NeedBits8(wid,eoflab);						\

    TabEnt = tab + GetBits(wid);					\

    ClrBits(TabEnt->Width);						\

} while (0)

#define LOOKUP16(wid,tab,eoflab) do {					\

    NeedBits16(wid,eoflab);						\

    TabEnt = tab + GetBits(wid);					\

    ClrBits(TabEnt->Width);						\

} while (0)

/*

 * Append a run to the run length array for the

 * current row and reset decoding state.

 */

#define SETVALUE(x) do {							\

    *pa++ = RunLength + (x);						\

    a0 += (x);								\

    RunLength = 0;							\

} while (0)

#endif

/*

 * Synchronize input decoding at the start of each

 * row by scanning for an EOL (if appropriate) and

 * skipping any trash data that might be present

 * after a decoding error.  Note that the decoding

 * done elsewhere that recognizes an EOL only consumes

 * 11 consecutive zero bits.  This means that if EOLcnt

 * is non-zero then we still need to scan for the final flag

 * bit that is part of the EOL code.

 */

#define	SYNC_EOL(eoflab) do {						\

    if (EOLcnt == 0) {							\

	for (;;) {							\

	    NeedBits16(11,eoflab);					\

	    if (GetBits(11) == 0)					\

		break;							\

	    ClrBits(1);							\

	}								\

    }									\

    for (;;) {								\

	NeedBits8(8,eoflab);						\

	if (GetBits(8))							\

	    break;							\

	ClrBits(8);							\

    }									\

    while (GetBits(1) == 0)						\

	ClrBits(1);							\

    ClrBits(1);				/* EOL bit */			\

    EOLcnt = 0;				/* reset EOL counter/flag */	\

} while (0)

/*

 * Cleanup the array of runs after decoding a row.

 * We adjust final runs to insure the user buffer is not

 * overwritten and/or undecoded area is white filled.

 */

#define	CLEANUP_RUNS() do {						\

    if (RunLength)							\

	SETVALUE(0);							\

    if (a0 != lastx) {							\

	badlength(a0, lastx);						\

	while (a0 > lastx && pa > thisrun)				\

	    a0 -= *--pa;						\

	if (a0 < lastx) {						\

	    if (a0 < 0)							\

		a0 = 0;							\

	    if ((pa-thisrun)&1)						\

		SETVALUE(0);						\

	    SETVALUE(lastx - a0);						\

	} else if (a0 > lastx) {					\

	    SETVALUE(lastx);						\

	    SETVALUE(0);							\

	}								\

    }									\

} while (0)

/*

 * Decode a line of 1D-encoded data.

 *

 * The line expanders are written as macros so that they can be reused

 * but still have direct access to the local variables of the "calling"

 * function.

 *

 * Note that unlike the original version we have to explicitly test for

 * a0 >= lastx after each black/white run is decoded.  This is because

 * the original code depended on the input data being zero-padded to

 * insure the decoder recognized an EOL before running out of data.

 */

#define EXPAND1D(eoflab) do {						\

    for (;;) {								\

	for (;;) {							\

	    LOOKUP16(12, TIFFFaxWhiteTable, eof1d);			\

	    switch (TabEnt->State) {					\

	    case S_EOL:							\

		EOLcnt = 1;						\

		goto done1d;						\

	    case S_TermW:						\

		SETVALUE(TabEnt->Param);					\

		goto doneWhite1d;					\

	    case S_MakeUpW:						\

	    case S_MakeUp:						\

		a0 += TabEnt->Param;					\

		RunLength += TabEnt->Param;				\

		break;							\

	    default:							\

		unexpected("WhiteTable", a0);				\

		goto done1d;						\

	    }								\

	}								\

    doneWhite1d:							\

	if (a0 >= lastx)						\

	    goto done1d;						\

	for (;;) {							\

	    LOOKUP16(13, TIFFFaxBlackTable, eof1d);			\

	    switch (TabEnt->State) {					\

	    case S_EOL:							\

		EOLcnt = 1;						\

		goto done1d;						\

	    case S_TermB:						\

		SETVALUE(TabEnt->Param);					\

		goto doneBlack1d;					\

	    case S_MakeUpB:						\

	    case S_MakeUp:						\

		a0 += TabEnt->Param;					\

		RunLength += TabEnt->Param;				\

		break;							\

	    default:							\

		unexpected("BlackTable", a0);				\

		goto done1d;						\

	    }								\

	}								\

    doneBlack1d:							\

	if (a0 >= lastx)						\

	    goto done1d;						\

        if( *(pa-1) == 0 && *(pa-2) == 0 )				\

            pa -= 2;                                                    \

    }									\

eof1d:									\

    prematureEOF(a0);							\

    CLEANUP_RUNS();							\

    goto eoflab;							\

done1d:									\

    CLEANUP_RUNS();							\

} while (0)

/*

 * Update the value of b1 using the array

 * of runs for the reference line.

 */

#define CHECK_b1 do {							\

    if (pa != thisrun) while (b1 <= a0 && b1 < lastx) {			\

	b1 += pb[0] + pb[1];						\

	pb += 2;							\

    }									\

} while (0)

/*

 * Expand a row of 2D-encoded data.

 */

#define EXPAND2D(eoflab) do {						\

    while (a0 < lastx) {						\

	LOOKUP8(7, TIFFFaxMainTable, eof2d);				\

	switch (TabEnt->State) {					\

	case S_Pass:							\

	    CHECK_b1;							\

	    b1 += *pb++;						\

	    RunLength += b1 - a0;					\

	    a0 = b1;							\

	    b1 += *pb++;						\

	    break;							\

	case S_Horiz:							\

	    if ((pa-thisrun)&1) {					\

		for (;;) {	/* black first */			\

		    LOOKUP16(13, TIFFFaxBlackTable, eof2d);		\

		    switch (TabEnt->State) {				\

		    case S_TermB:					\

			SETVALUE(TabEnt->Param);				\

			goto doneWhite2da;				\

		    case S_MakeUpB:					\

		    case S_MakeUp:					\

			a0 += TabEnt->Param;				\

			RunLength += TabEnt->Param;			\

			break;						\

		    default:						\

			goto badBlack2d;				\

		    }							\

		}							\

	    doneWhite2da:;						\

		for (;;) {	/* then white */			\

		    LOOKUP16(12, TIFFFaxWhiteTable, eof2d);		\

		    switch (TabEnt->State) {				\

		    case S_TermW:					\

			SETVALUE(TabEnt->Param);				\

			goto doneBlack2da;				\

		    case S_MakeUpW:					\

		    case S_MakeUp:					\

			a0 += TabEnt->Param;				\

			RunLength += TabEnt->Param;			\

			break;						\

		    default:						\

			goto badWhite2d;				\

		    }							\

		}							\

	    doneBlack2da:;						\

	    } else {							\

		for (;;) {	/* white first */			\

		    LOOKUP16(12, TIFFFaxWhiteTable, eof2d);		\

		    switch (TabEnt->State) {				\

		    case S_TermW:					\

			SETVALUE(TabEnt->Param);				\

			goto doneWhite2db;				\

		    case S_MakeUpW:					\

		    case S_MakeUp:					\

			a0 += TabEnt->Param;				\

			RunLength += TabEnt->Param;			\

			break;						\

		    default:						\

			goto badWhite2d;				\

		    }							\

		}							\

	    doneWhite2db:;						\

		for (;;) {	/* then black */			\

		    LOOKUP16(13, TIFFFaxBlackTable, eof2d);		\

		    switch (TabEnt->State) {				\

		    case S_TermB:					\

			SETVALUE(TabEnt->Param);				\

			goto doneBlack2db;				\

		    case S_MakeUpB:					\

		    case S_MakeUp:					\

			a0 += TabEnt->Param;				\

			RunLength += TabEnt->Param;			\

			break;						\

		    default:						\

			goto badBlack2d;				\

		    }							\

		}							\

	    doneBlack2db:;						\

	    }								\

	    CHECK_b1;							\

	    break;							\

	case S_V0:							\

	    CHECK_b1;							\

	    SETVALUE(b1 - a0);						\

	    b1 += *pb++;						\

	    break;							\

	case S_VR:							\

	    CHECK_b1;							\

	    SETVALUE(b1 - a0 + TabEnt->Param);				\

	    b1 += *pb++;						\

	    break;							\

	case S_VL:							\

	    CHECK_b1;							\

	    SETVALUE(b1 - a0 - TabEnt->Param);				\

	    b1 -= *--pb;						\

	    break;							\

	case S_Ext:							\

	    *pa++ = lastx - a0;						\

	    extension(a0);						\

	    goto eol2d;							\

	case S_EOL:							\

	    *pa++ = lastx - a0;						\

	    NeedBits8(4,eof2d);						\

	    if (GetBits(4))						\

		unexpected("EOL", a0);					\

            ClrBits(4);                                                 \

	    EOLcnt = 1;							\

	    goto eol2d;							\

	default:							\

	badMain2d:							\

	    unexpected("MainTable", a0);				\

	    goto eol2d;							\

	badBlack2d:							\

	    unexpected("BlackTable", a0);				\

	    goto eol2d;							\

	badWhite2d:							\

	    unexpected("WhiteTable", a0);				\

	    goto eol2d;							\

	eof2d:								\

	    prematureEOF(a0);						\

	    CLEANUP_RUNS();						\

	    goto eoflab;						\

	}								\

    }									\

    if (RunLength) {							\

	if (RunLength + a0 < lastx) {					\

	    /* expect a final V0 */					\

	    NeedBits8(1,eof2d);						\

	    if (!GetBits(1))						\

		goto badMain2d;						\

	    ClrBits(1);							\

	}								\

	SETVALUE(0);							\

    }									\

eol2d:									\

    CLEANUP_RUNS();							\

} while (0)

#endif /* _FAX3_ */

/*

 * Local Variables:

 * mode: c

 * c-basic-offset: 8

 * fill-column: 78

 * End:

 */