Some doc tweaks

[wxWidgets.git] / src / tiff / tif_fax3.c

/* $Header$ */

/*
 * 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.
 */

#include "tiffiop.h"
#ifdef CCITT_SUPPORT
/*
 * TIFF Library.
 *
 * CCITT Group 3 (T.4) and Group 4 (T.6) Compression Support.
 *
 * This file contains support for decoding and encoding TIFF
 * compression algorithms 2, 3, 4, and 32771.
 *
 * Decoder support is derived, with permission, from the code
 * in Frank Cringle's viewfax program;
 *      Copyright (C) 1990, 1995  Frank D. Cringle.
 */
#include "tif_fax3.h"
#define G3CODES
#include "t4.h"
#include <assert.h>
#include <stdio.h>

/*
 * NB: define PURIFY if you're using purify and you want
 * to avoid some harmless array bounds complaints that
 * can happen in the _TIFFFax3fillruns routine.
 */

/*
 * Compression+decompression state blocks are
 * derived from this ``base state'' block.
 */
typedef struct {
        int     mode;                   /* operating mode */
        uint32  rowbytes;               /* bytes in a decoded scanline */
        uint32  rowpixels;              /* pixels in a scanline */

        uint16  cleanfaxdata;           /* CleanFaxData tag */
        uint32  badfaxrun;              /* BadFaxRun tag */
        uint32  badfaxlines;            /* BadFaxLines tag */
        uint32  groupoptions;           /* Group 3/4 options tag */
        uint32  recvparams;             /* encoded Class 2 session params */
        char*   subaddress;             /* subaddress string */
        uint32  recvtime;               /* time spent receiving (secs) */
        TIFFVGetMethod vgetparent;      /* super-class method */
        TIFFVSetMethod vsetparent;      /* super-class method */
} Fax3BaseState;
#define Fax3State(tif)          ((Fax3BaseState*) (tif)->tif_data)

typedef struct {
        Fax3BaseState b;
        const u_char* bitmap;           /* bit reversal table */
        uint32  data;                   /* current i/o byte/word */
        int     bit;                    /* current i/o bit in byte */
        int     EOLcnt;                 /* count of EOL codes recognized */
        TIFFFaxFillFunc fill;           /* fill routine */
        uint32* runs;                   /* b&w runs for current/previous row */
        uint32* refruns;                /* runs for reference line */
        uint32* curruns;                /* runs for current line */
} Fax3DecodeState;
#define DecoderState(tif)       ((Fax3DecodeState*) Fax3State(tif))

typedef struct {
    Fax3BaseState b;
    int    data;                /* current i/o byte */
    int    bit;                 /* current i/o bit in byte */
    enum { G3_1D, G3_2D } tag;  /* encoding state */
    u_char*    refline;         /* reference line for 2d decoding */
    int    k;                   /* #rows left that can be 2d encoded */
    int    maxk;                /* max #rows that can be 2d encoded */
} Fax3EncodeState;
#define EncoderState(tif)       ((Fax3EncodeState*) Fax3State(tif))

#define is2DEncoding(sp) \
        (sp->b.groupoptions & GROUP3OPT_2DENCODING)
#define isAligned(p,t)  ((((u_long)(p)) & (sizeof (t)-1)) == 0)

/*
 * Group 3 and Group 4 Decoding.
 */

/*
 * These macros glue the TIFF library state to
 * the state expected by Frank's decoder.
 */
#define DECLARE_STATE(tif, sp, mod)                                     \
    static const char module[] = mod;                                   \
    Fax3DecodeState* sp = DecoderState(tif);                            \
    int a0;                             /* reference element */         \
    int lastx = sp->b.rowpixels;        /* last element in row */       \
    uint32 BitAcc;                      /* bit accumulator */           \
    int BitsAvail;                      /* # valid bits in BitAcc */    \
    int RunLength;                      /* length of current run */     \
    u_char* cp;                         /* next byte of input data */   \
    u_char* ep;                         /* end of input data */         \
    uint32* pa;                         /* place to stuff next run */   \
    uint32* thisrun;                    /* current row's run array */   \
    int EOLcnt;                         /* # EOL codes recognized */    \
    const u_char* bitmap = sp->bitmap;  /* input data bit reverser */   \
    const TIFFFaxTabEnt* TabEnt
#define DECLARE_STATE_2D(tif, sp, mod)                                  \
    DECLARE_STATE(tif, sp, mod);                                        \
    int b1;                             /* next change on prev line */  \
    uint32* pb                          /* next run in reference line */\
/*
 * Load any state that may be changed during decoding.
 */
#define CACHE_STATE(tif, sp) do {                                       \
    BitAcc = sp->data;                                                  \
    BitsAvail = sp->bit;                                                \
    EOLcnt = sp->EOLcnt;                                                \
    cp = (unsigned char*) tif->tif_rawcp;                               \
    ep = cp + tif->tif_rawcc;                                           \
} while (0)
/*
 * Save state possibly changed during decoding.
 */
#define UNCACHE_STATE(tif, sp) do {                                     \
    sp->bit = BitsAvail;                                                \
    sp->data = BitAcc;                                                  \
    sp->EOLcnt = EOLcnt;                                                \
    tif->tif_rawcc -= (tidata_t) cp - tif->tif_rawcp;                   \
    tif->tif_rawcp = (tidata_t) cp;                                     \
} while (0)

/*
 * Setup state for decoding a strip.
 */
static int
Fax3PreDecode(TIFF* tif, tsample_t s)
{
        Fax3DecodeState* sp = DecoderState(tif);

        (void) s;
        assert(sp != NULL);
        sp->bit = 0;                    /* force initial read */
        sp->data = 0;
        sp->EOLcnt = 0;                 /* force initial scan for EOL */
        /*
         * Decoder assumes lsb-to-msb bit order.  Note that we select
         * this here rather than in Fax3SetupState so that viewers can
         * hold the image open, fiddle with the FillOrder tag value,
         * and then re-decode the image.  Otherwise they'd need to close
         * and open the image to get the state reset.
         */
        sp->bitmap =
            TIFFGetBitRevTable(tif->tif_dir.td_fillorder != FILLORDER_LSB2MSB);
        if (sp->refruns) {              /* init reference line to white */
                sp->refruns[0] = sp->b.rowpixels;
                sp->refruns[1] = 0;
        }
        return (1);
}

/*
 * Routine for handling various errors/conditions.
 * Note how they are "glued into the decoder" by
 * overriding the definitions used by the decoder.
 */

static void LINKAGEMODE
Fax3Unexpected(const char* module, TIFF* tif, uint32 a0)
{
        TIFFError(module, "%s: Bad code word at scanline %d (x %lu)",
            tif->tif_name, tif->tif_row, (u_long) a0);
}
#define unexpected(table, a0)   Fax3Unexpected(module, tif, a0)

static void LINKAGEMODE
Fax3Extension(const char* module, TIFF* tif, uint32 a0)
{
        TIFFError(module,
            "%s: Uncompressed data (not supported) at scanline %d (x %lu)",
            tif->tif_name, tif->tif_row, (u_long) a0);
}
#define extension(a0)   Fax3Extension(module, tif, a0)

static void LINKAGEMODE
Fax3BadLength(const char* module, TIFF* tif, uint32 a0, uint32 lastx)
{
        TIFFWarning(module, "%s: %s at scanline %d (got %lu, expected %lu)",
            tif->tif_name,
            a0 < lastx ? "Premature EOL" : "Line length mismatch",
            tif->tif_row, (u_long) a0, (u_long) lastx);
}
#define badlength(a0,lastx)     Fax3BadLength(module, tif, a0, lastx)

static void LINKAGEMODE
Fax3PrematureEOF(const char* module, TIFF* tif, uint32 a0)
{
        TIFFWarning(module, "%s: Premature EOF at scanline %d (x %lu)",
            tif->tif_name, tif->tif_row, (u_long) a0);
}
#define prematureEOF(a0)        Fax3PrematureEOF(module, tif, a0)

#define Nop

/*
 * Decode the requested amount of G3 1D-encoded data.
 */
static int LINKAGEMODE
Fax3Decode1D(TIFF* tif, tidata_t buf, tsize_t occ, tsample_t s)
{
        DECLARE_STATE(tif, sp, "Fax3Decode1D");

        (void) s;
        CACHE_STATE(tif, sp);
        thisrun = sp->curruns;
        while ((long)occ > 0) {
                a0 = 0;
                RunLength = 0;
                pa = thisrun;
#ifdef FAX3_DEBUG
                printf("\nBitAcc=%08X, BitsAvail = %d\n", BitAcc, BitsAvail);
                printf("-------------------- %d\n", tif->tif_row);
                fflush(stdout);
#endif
                SYNC_EOL(EOF1D);
                EXPAND1D(EOF1Da);
                (*sp->fill)(buf, thisrun, pa, lastx);
                buf += sp->b.rowbytes;
                occ -= sp->b.rowbytes;
                if (occ != 0)
                        tif->tif_row++;
                continue;
        EOF1D:                          /* premature EOF */
                CLEANUP_RUNS();
        EOF1Da:                         /* premature EOF */
                (*sp->fill)(buf, thisrun, pa, lastx);
                UNCACHE_STATE(tif, sp);
                return (-1);
        }
        UNCACHE_STATE(tif, sp);
        return (1);
}

#define SWAP(t,a,b)     { t x; x = (a); (a) = (b); (b) = x; }
/*
 * Decode the requested amount of G3 2D-encoded data.
 */
static int LINKAGEMODE
Fax3Decode2D(TIFF* tif, tidata_t buf, tsize_t occ, tsample_t s)
{
        DECLARE_STATE_2D(tif, sp, "Fax3Decode2D");
        int is1D;                       /* current line is 1d/2d-encoded */

        (void) s;
        CACHE_STATE(tif, sp);
        while ((long)occ > 0) {
                a0 = 0;
                RunLength = 0;
                pa = thisrun = sp->curruns;
#ifdef FAX3_DEBUG
                printf("\nBitAcc=%08X, BitsAvail = %d EOLcnt = %d",
                    BitAcc, BitsAvail, EOLcnt);
#endif
                SYNC_EOL(EOF2D);
                NeedBits8(1, EOF2D);
                is1D = GetBits(1);      /* 1D/2D-encoding tag bit */
                ClrBits(1);
#ifdef FAX3_DEBUG
                printf(" %s\n-------------------- %d\n",
                    is1D ? "1D" : "2D", tif->tif_row);
                fflush(stdout);
#endif
                pb = sp->refruns;
                b1 = *pb++;
                if (is1D)
                        EXPAND1D(EOF2Da);
                else
                        EXPAND2D(EOF2Da);
                (*sp->fill)(buf, thisrun, pa, lastx);
                SETVAL(0);              /* imaginary change for reference */
                SWAP(uint32*, sp->curruns, sp->refruns);
                buf += sp->b.rowbytes;
                occ -= sp->b.rowbytes;
                if (occ != 0)
                        tif->tif_row++;
                continue;
        EOF2D:                          /* premature EOF */
                CLEANUP_RUNS();
        EOF2Da:                         /* premature EOF */
                (*sp->fill)(buf, thisrun, pa, lastx);
                UNCACHE_STATE(tif, sp);
                return (-1);
        }
        UNCACHE_STATE(tif, sp);
        return (1);
}
#undef SWAP

/*
 * The ZERO & FILL macros must handle spans < 2*sizeof(long) bytes.
 * For machines with 64-bit longs this is <16 bytes; otherwise
 * this is <8 bytes.  We optimize the code here to reflect the
 * machine characteristics.
 */
#if defined(__alpha) || _MIPS_SZLONG == 64
#define FILL(n, cp)                                                         \
    switch (n) {                                                            \
    case 15:(cp)[14] = 0xff; case 14:(cp)[13] = 0xff; case 13: (cp)[12] = 0xff;\
    case 12:(cp)[11] = 0xff; case 11:(cp)[10] = 0xff; case 10: (cp)[9] = 0xff;\
    case  9: (cp)[8] = 0xff; case  8: (cp)[7] = 0xff; case  7: (cp)[6] = 0xff;\
    case  6: (cp)[5] = 0xff; case  5: (cp)[4] = 0xff; case  4: (cp)[3] = 0xff;\
    case  3: (cp)[2] = 0xff; case  2: (cp)[1] = 0xff;                         \
    case  1: (cp)[0] = 0xff; (cp) += (n); case 0:  ;                          \
    }
#define ZERO(n, cp)                                                     \
    switch (n) {                                                        \
    case 15:(cp)[14] = 0; case 14:(cp)[13] = 0; case 13: (cp)[12] = 0;  \
    case 12:(cp)[11] = 0; case 11:(cp)[10] = 0; case 10: (cp)[9] = 0;   \
    case  9: (cp)[8] = 0; case  8: (cp)[7] = 0; case  7: (cp)[6] = 0;   \
    case  6: (cp)[5] = 0; case  5: (cp)[4] = 0; case  4: (cp)[3] = 0;   \
    case  3: (cp)[2] = 0; case  2: (cp)[1] = 0;                         \
    case  1: (cp)[0] = 0; (cp) += (n); case 0:  ;                       \
    }
#else
#define FILL(n, cp)                                                         \
    switch (n) {                                                            \
    case 7: (cp)[6] = 0xff; case 6: (cp)[5] = 0xff; case 5: (cp)[4] = 0xff; \
    case 4: (cp)[3] = 0xff; case 3: (cp)[2] = 0xff; case 2: (cp)[1] = 0xff; \
    case 1: (cp)[0] = 0xff; (cp) += (n); case 0:  ;                         \
    }
#define ZERO(n, cp)                                                     \
    switch (n) {                                                        \
    case 7: (cp)[6] = 0; case 6: (cp)[5] = 0; case 5: (cp)[4] = 0;      \
    case 4: (cp)[3] = 0; case 3: (cp)[2] = 0; case 2: (cp)[1] = 0;      \
    case 1: (cp)[0] = 0; (cp) += (n); case 0:  ;                        \
    }
#endif

/*
 * Bit-fill a row according to the white/black
 * runs generated during G3/G4 decoding.
 */
void
_TIFFFax3fillruns(u_char* buf, uint32* runs, uint32* erun, uint32 lastx)
{
        static const unsigned char _fillmasks[] =
            { 0x00, 0x80, 0xc0, 0xe0, 0xf0, 0xf8, 0xfc, 0xfe, 0xff };
        u_char* cp;
        uint32 x, bx, run;
        int32 n, nw;
        long* lp;

        if ((erun-runs)&1)
            *erun++ = 0;
        x = 0;
        for (; runs < erun; runs += 2) {
            run = runs[0];
            if (x+run > lastx)
                run = runs[0] = lastx - x;
            if (run) {
                cp = buf + (x>>3);
                bx = x&7;
                if (run > 8-bx) {
                    if (bx) {                   /* align to byte boundary */
                        *cp++ &= 0xff << (8-bx);
                        run -= 8-bx;
                    }
                    if( (n = run >> 3) != 0 ) { /* multiple bytes to fill */
                        if ((n/sizeof (long)) > 1) {
                            /*
                             * Align to longword boundary and fill.
                             */
                            for (; n && !isAligned(cp, long); n--)
                                    *cp++ = 0x00;
                            lp = (long*) cp;
                            nw = (int32)(n / sizeof (long));
                            n -= nw * sizeof (long);
                            do {
                                    *lp++ = 0L;
                            } while (--nw);
                            cp = (u_char*) lp;
                        }
                        ZERO(n, cp);
                        run &= 7;
                    }
#ifdef PURIFY
                    if (run)
                        cp[0] &= 0xff >> run;
#else
                    cp[0] &= 0xff >> run;
#endif
                } else
                    cp[0] &= ~(_fillmasks[run]>>bx);
                x += runs[0];
            }
            run = runs[1];
            if (x+run > lastx)
                run = runs[1] = lastx - x;
            if (run) {
                cp = buf + (x>>3);
                bx = x&7;
                if (run > 8-bx) {
                    if (bx) {                   /* align to byte boundary */
                        *cp++ |= 0xff >> bx;
                        run -= 8-bx;
                    }
                    if( (n = run>>3) != 0 ) {   /* multiple bytes to fill */
                        if ((n/sizeof (long)) > 1) {
                            /*
                             * Align to longword boundary and fill.
                             */
                            for (; n && !isAligned(cp, long); n--)
                                *cp++ = 0xff;
                            lp = (long*) cp;
                            nw = (int32)(n / sizeof (long));
                            n -= nw * sizeof (long);
                            do {
                                *lp++ = -1L;
                            } while (--nw);
                            cp = (u_char*) lp;
                        }
                        FILL(n, cp);
                        run &= 7;
                    }
#ifdef PURIFY
                    if (run)
                        cp[0] |= 0xff00 >> run;
#else
                    cp[0] |= 0xff00 >> run;
#endif
                } else
                    cp[0] |= _fillmasks[run]>>bx;
                x += runs[1];
            }
        }
        assert(x == lastx);
}
#undef  ZERO
#undef  FILL

/*
 * Setup G3/G4-related compression/decompression state
 * before data is processed.  This routine is called once
 * per image -- it sets up different state based on whether
 * or not decoding or encoding is being done and whether
 * 1D- or 2D-encoded data is involved.
 */
static int
Fax3SetupState(TIFF* tif)
{
        TIFFDirectory* td = &tif->tif_dir;
        Fax3BaseState* sp = Fax3State(tif);
        long rowbytes, rowpixels;
        int needsRefLine;

        if (td->td_bitspersample != 1) {
                TIFFError(tif->tif_name,
                    "Bits/sample must be 1 for Group 3/4 encoding/decoding");
                return (0);
        }
        /*
         * Calculate the scanline/tile widths.
         */
        if (isTiled(tif)) {
                rowbytes = TIFFTileRowSize(tif);
                rowpixels = td->td_tilewidth;
        } else {
                rowbytes = TIFFScanlineSize(tif);
                rowpixels = td->td_imagewidth;
        }
        sp->rowbytes = (uint32) rowbytes;
        sp->rowpixels = (uint32) rowpixels;
        /*
         * Allocate any additional space required for decoding/encoding.
         */
        needsRefLine = (
            (sp->groupoptions & GROUP3OPT_2DENCODING) ||
            td->td_compression == COMPRESSION_CCITTFAX4
        );
        if (tif->tif_mode == O_RDONLY) {        /* 1d/2d decoding */
                Fax3DecodeState* dsp = DecoderState(tif);
                uint32 nruns = needsRefLine ?
                     2*TIFFroundup(rowpixels,32) : rowpixels;

#if 0
                dsp->runs = (uint32*) _TIFFmalloc(nruns*sizeof (uint16));
#endif
                /* 
Problem
-------

Decoding the file frle_bug.tif causes a crash (such as with tiff2rgba). 

In particular the array dsp->runs allocated in Fax3SetupState() is overrun 
by 4-8 bytes.  This occurs when Fax3DecodeRLE() processes the first
scanline.  The EXPAND1D() macro advances "pa" to be thisrun+512 (an
alias for dsp->runs), pointing just beyond the end of the array.  Then 
the call to _TIFFFax3fillruns() does an "*erun++ = 0;" which writes beyond 
the end of the array.

In the short term I have modified the dsp->runs allocation to add eight
extra bytes to the runs buffer; however, I am only doing this because I
don't understand the algorithm well enough to change it without risking
more adverse side effects.

Frank Warmerdam (warmerda@home.com)

                */

                dsp->runs = (uint32*) _TIFFmalloc(8+nruns*sizeof (uint32));

                if (dsp->runs == NULL) {
                        TIFFError("Fax3SetupState",
                            "%s: No space for Group 3/4 run arrays",
                            tif->tif_name);
                        return (0);
                }
                dsp->curruns = dsp->runs;
                if (needsRefLine)
                        dsp->refruns = dsp->runs + (nruns>>1);
                else
                        dsp->refruns = NULL;
                if (is2DEncoding(dsp)) {        /* NB: default is 1D routine */
                        tif->tif_decoderow = Fax3Decode2D;
                        tif->tif_decodestrip = Fax3Decode2D;
                        tif->tif_decodetile = Fax3Decode2D;
                }
        } else if (needsRefLine) {              /* 2d encoding */
                Fax3EncodeState* esp = EncoderState(tif);
                /*
                 * 2d encoding requires a scanline
                 * buffer for the ``reference line''; the
                 * scanline against which delta encoding
                 * is referenced.  The reference line must
                 * be initialized to be ``white'' (done elsewhere).
                 */
                esp->refline = (u_char*) _TIFFmalloc(rowbytes);
                if (esp->refline == NULL) {
                        TIFFError("Fax3SetupState",
                            "%s: No space for Group 3/4 reference line",
                            tif->tif_name);
                        return (0);
                }
        } else                                  /* 1d encoding */
                EncoderState(tif)->refline = NULL;
        return (1);
}

/*
 * CCITT Group 3 FAX Encoding.
 */

#define Fax3FlushBits(tif, sp) {                                \
        if ((tif)->tif_rawcc >= (tif)->tif_rawdatasize)         \
                (void) TIFFFlushData1(tif);                     \
        *(tif)->tif_rawcp++ = (sp)->data;                       \
        (tif)->tif_rawcc++;                                     \
        (sp)->data = 0, (sp)->bit = 8;                          \
}
#define _FlushBits(tif) {                                       \
        if ((tif)->tif_rawcc >= (tif)->tif_rawdatasize)         \
                (void) TIFFFlushData1(tif);                     \
        *(tif)->tif_rawcp++ = data;                             \
        (tif)->tif_rawcc++;                                     \
        data = 0, bit = 8;                                      \
}
static const int _msbmask[9] =
    { 0x00, 0x01, 0x03, 0x07, 0x0f, 0x1f, 0x3f, 0x7f, 0xff };
#define _PutBits(tif, bits, length) {                           \
        while (length > bit) {                                  \
                data |= bits >> (length - bit);                 \
                length -= bit;                                  \
                _FlushBits(tif);                                \
        }                                                       \
        data |= (bits & _msbmask[length]) << (bit - length);    \
        bit -= length;                                          \
        if (bit == 0)                                           \
                _FlushBits(tif);                                \
}
        
/*
 * Write a variable-length bit-value to
 * the output stream.  Values are
 * assumed to be at most 16 bits.
 */
static void LINKAGEMODE
Fax3PutBits(TIFF* tif, u_int bits, u_int length)
{
        Fax3EncodeState* sp = EncoderState(tif);
        int bit = sp->bit;
        int data = sp->data;

        _PutBits(tif, bits, length);

        sp->data = data;
        sp->bit = bit;
}

/*
 * Write a code to the output stream.
 */
#define putcode(tif, te)        Fax3PutBits(tif, (te)->code, (te)->length)

#ifdef FAX3_DEBUG
#define DEBUG_COLOR(w) (tab == TIFFFaxWhiteCodes ? w "W" : w "B")
#define DEBUG_PRINT(what,len) {                                         \
    int t;                                                              \
    printf("%08X/%-2d: %s%5d\t", data, bit, DEBUG_COLOR(what), len);    \
    for (t = length-1; t >= 0; t--)                                     \
        putchar(code & (1<<t) ? '1' : '0');                             \
    putchar('\n');                                                      \
}
#endif

/*
 * Write the sequence of codes that describes
 * the specified span of zero's or one's.  The
 * appropriate table that holds the make-up and
 * terminating codes is supplied.
 */
static void LINKAGEMODE
putspan(TIFF* tif, int32 span, const tableentry* tab)
{
        Fax3EncodeState* sp = EncoderState(tif);
        int bit = sp->bit;
        int data = sp->data;
        u_int code, length;

        while (span >= 2624) {
                const tableentry* te = &tab[63 + (2560>>6)];
                code = te->code, length = te->length;
#ifdef FAX3_DEBUG
                DEBUG_PRINT("MakeUp", te->runlen);
#endif
                _PutBits(tif, code, length);
                span -= te->runlen;
        }
        if (span >= 64) {
                const tableentry* te = &tab[63 + (span>>6)];
                assert(te->runlen == 64*(span>>6));
                code = te->code, length = te->length;
#ifdef FAX3_DEBUG
                DEBUG_PRINT("MakeUp", te->runlen);
#endif
                _PutBits(tif, code, length);
                span -= te->runlen;
        }
        code = tab[span].code, length = tab[span].length;
#ifdef FAX3_DEBUG
        DEBUG_PRINT("  Term", tab[span].runlen);
#endif
        _PutBits(tif, code, length);

        sp->data = data;
        sp->bit = bit;
}

/*
 * Write an EOL code to the output stream.  The zero-fill
 * logic for byte-aligning encoded scanlines is handled
 * here.  We also handle writing the tag bit for the next
 * scanline when doing 2d encoding.
 */
static void LINKAGEMODE
Fax3PutEOL(TIFF* tif)
{
        Fax3EncodeState* sp = EncoderState(tif);
        int bit = sp->bit;
        int data = sp->data;
        u_int code, length;

        if (sp->b.groupoptions & GROUP3OPT_FILLBITS) {
                /*
                 * Force bit alignment so EOL will terminate on
                 * a byte boundary.  That is, force the bit alignment
                 * to 16-12 = 4 before putting out the EOL code.
                 */
                int align = 8 - 4;
                if (align != sp->bit) {
                        if (align > sp->bit)
                                align = sp->bit + (8 - align);
                        else
                                align = sp->bit - align;
                        code = 0;
                        _PutBits(tif, 0, align);
                }
        }
        code = EOL, length = 12;
        if (is2DEncoding(sp))
#if defined(__VISAGECPP30__)
/* VA 3.0 is just plain wierd. */
                code = (code<<1) | (sp->tag == Fax3EncodeState::G3_1D), length++;
#else
                code = (code<<1) | (sp->tag == G3_1D), length++;
#endif
        _PutBits(tif, code, length);

        sp->data = data;
        sp->bit = bit;
}

/*
 * Reset encoding state at the start of a strip.
 */
static int
Fax3PreEncode(TIFF* tif, tsample_t s)
{
        Fax3EncodeState* sp = EncoderState(tif);

        (void) s;
        assert(sp != NULL);
        sp->bit = 8;
        sp->data = 0;
#if defined(__VISAGECPP30__)
/* VA 3.0 is just plain wierd. */
        sp->tag = Fax3EncodeState::G3_1D;
#else
        sp->tag = G3_1D;
#endif
        /*
         * This is necessary for Group 4; otherwise it isn't
         * needed because the first scanline of each strip ends
         * up being copied into the refline.
         */
        if (sp->refline)
                _TIFFmemset(sp->refline, 0x00, sp->b.rowbytes);
        if (is2DEncoding(sp)) {
                float res = tif->tif_dir.td_yresolution;
                /*
                 * The CCITT spec says that when doing 2d encoding, you
                 * should only do it on K consecutive scanlines, where K
                 * depends on the resolution of the image being encoded
                 * (2 for <= 200 lpi, 4 for > 200 lpi).  Since the directory
                 * code initializes td_yresolution to 0, this code will
                 * select a K of 2 unless the YResolution tag is set
                 * appropriately.  (Note also that we fudge a little here
                 * and use 150 lpi to avoid problems with units conversion.)
                 */
                if (tif->tif_dir.td_resolutionunit == RESUNIT_CENTIMETER)
                        res *= 2.54f;           /* convert to inches */
                sp->maxk = (res > 150 ? 4 : 2);
                sp->k = sp->maxk-1;
        } else
                sp->k = sp->maxk = 0;
        return (1);
}

static const u_char zeroruns[256] = {
    8, 7, 6, 6, 5, 5, 5, 5, 4, 4, 4, 4, 4, 4, 4, 4,     /* 0x00 - 0x0f */
    3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,     /* 0x10 - 0x1f */
    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,     /* 0x20 - 0x2f */
    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,     /* 0x30 - 0x3f */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,     /* 0x40 - 0x4f */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,     /* 0x50 - 0x5f */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,     /* 0x60 - 0x6f */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,     /* 0x70 - 0x7f */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0x80 - 0x8f */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0x90 - 0x9f */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0xa0 - 0xaf */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0xb0 - 0xbf */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0xc0 - 0xcf */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0xd0 - 0xdf */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0xe0 - 0xef */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0xf0 - 0xff */
};
static const u_char oneruns[256] = {
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0x00 - 0x0f */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0x10 - 0x1f */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0x20 - 0x2f */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0x30 - 0x3f */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0x40 - 0x4f */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0x50 - 0x5f */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0x60 - 0x6f */
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,     /* 0x70 - 0x7f */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,     /* 0x80 - 0x8f */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,     /* 0x90 - 0x9f */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,     /* 0xa0 - 0xaf */
    1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1,     /* 0xb0 - 0xbf */
    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,     /* 0xc0 - 0xcf */
    2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2,     /* 0xd0 - 0xdf */
    3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3, 3,     /* 0xe0 - 0xef */
    4, 4, 4, 4, 4, 4, 4, 4, 5, 5, 5, 5, 6, 6, 7, 8,     /* 0xf0 - 0xff */
};

/*
 * On certain systems it pays to inline
 * the routines that find pixel spans.
 */
#ifdef VAXC
static  int32 find0span(u_char*, int32, int32);
static  int32 find1span(u_char*, int32, int32);
#pragma inline(find0span,find1span)
#endif

/*
 * Find a span of ones or zeros using the supplied
 * table.  The ``base'' of the bit string is supplied
 * along with the start+end bit indices.
 */
INLINE static int32 LINKAGEMODE
find0span(u_char* bp, int32 bs, int32 be)
{
        int32 bits = be - bs;
        int32 n, span;

        bp += bs>>3;
        /*
         * Check partial byte on lhs.
         */
        if (bits > 0 && (n = (bs & 7))) {
                span = zeroruns[(*bp << n) & 0xff];
                if (span > 8-n)         /* table value too generous */
                        span = 8-n;
                if (span > bits)        /* constrain span to bit range */
                        span = bits;
                if (n+span < 8)         /* doesn't extend to edge of byte */
                        return (span);
                bits -= span;
                bp++;
        } else
                span = 0;
        if (bits >= 2*8*sizeof (long)) {
                long* lp;
                /*
                 * Align to longword boundary and check longwords.
                 */
                while (!isAligned(bp, long)) {
                        if (*bp != 0x00)
                                return (span + zeroruns[*bp]);
                        span += 8, bits -= 8;
                        bp++;
                }
                lp = (long*) bp;
                while (bits >= 8*sizeof (long) && *lp == 0) {
                        span += 8*sizeof (long), bits -= 8*sizeof (long);
                        lp++;
                }
                bp = (u_char*) lp;
        }
        /*
         * Scan full bytes for all 0's.
         */
        while (bits >= 8) {
                if (*bp != 0x00)        /* end of run */
                        return (span + zeroruns[*bp]);
                span += 8, bits -= 8;
                bp++;
        }
        /*
         * Check partial byte on rhs.
         */
        if (bits > 0) {
                n = zeroruns[*bp];
                span += (n > bits ? bits : n);
        }
        return (span);
}

INLINE static int32 LINKAGEMODE
find1span(u_char* bp, int32 bs, int32 be)
{
        int32 bits = be - bs;
        int32 n, span;

        bp += bs>>3;
        /*
         * Check partial byte on lhs.
         */
        if (bits > 0 && (n = (bs & 7))) {
                span = oneruns[(*bp << n) & 0xff];
                if (span > 8-n)         /* table value too generous */
                        span = 8-n;
                if (span > bits)        /* constrain span to bit range */
                        span = bits;
                if (n+span < 8)         /* doesn't extend to edge of byte */
                        return (span);
                bits -= span;
                bp++;
        } else
                span = 0;
        if (bits >= 2*8*sizeof (long)) {
                long* lp;
                /*
                 * Align to longword boundary and check longwords.
                 */
                while (!isAligned(bp, long)) {
                        if (*bp != 0xff)
                                return (span + oneruns[*bp]);
                        span += 8, bits -= 8;
                        bp++;
                }
                lp = (long*) bp;
                while (bits >= 8*sizeof (long) && *lp == ~0) {
                        span += 8*sizeof (long), bits -= 8*sizeof (long);
                        lp++;
                }
                bp = (u_char*) lp;
        }
        /*
         * Scan full bytes for all 1's.
         */
        while (bits >= 8) {
                if (*bp != 0xff)        /* end of run */
                        return (span + oneruns[*bp]);
                span += 8, bits -= 8;
                bp++;
        }
        /*
         * Check partial byte on rhs.
         */
        if (bits > 0) {
                n = oneruns[*bp];
                span += (n > bits ? bits : n);
        }
        return (span);
}

/*
 * Return the offset of the next bit in the range
 * [bs..be] that is different from the specified
 * color.  The end, be, is returned if no such bit
 * exists.
 */
#define finddiff(_cp, _bs, _be, _color) \
        (_bs + (_color ? find1span(_cp,_bs,_be) : find0span(_cp,_bs,_be)))
/*
 * Like finddiff, but also check the starting bit
 * against the end in case start > end.
 */
#define finddiff2(_cp, _bs, _be, _color) \
        (_bs < _be ? finddiff(_cp,_bs,_be,_color) : _be)

/*
 * 1d-encode a row of pixels.  The encoding is
 * a sequence of all-white or all-black spans
 * of pixels encoded with Huffman codes.
 */
static int LINKAGEMODE
Fax3Encode1DRow(TIFF* tif, u_char* bp, uint32 bits)
{
        Fax3EncodeState* sp = EncoderState(tif);
        int32 bs = 0, span;

        for (;;) {
                span = find0span(bp, bs, bits);         /* white span */
                putspan(tif, span, TIFFFaxWhiteCodes);
                bs += span;
                if (bs >= bits)
                        break;
                span = find1span(bp, bs, bits);         /* black span */
                putspan(tif, span, TIFFFaxBlackCodes);
                bs += span;
                if (bs >= bits)
                        break;
        }
        if (sp->b.mode & (FAXMODE_BYTEALIGN|FAXMODE_WORDALIGN)) {
                if (sp->bit != 8)                       /* byte-align */
                        Fax3FlushBits(tif, sp);
                if ((sp->b.mode&FAXMODE_WORDALIGN) &&
                    !isAligned(tif->tif_rawcp, uint16))
                        Fax3FlushBits(tif, sp);
        }
        return (1);
}

static const tableentry horizcode =
    { 3, 0x1 };         /* 001 */
static const tableentry passcode =
    { 4, 0x1 };         /* 0001 */
static const tableentry vcodes[7] = {
    { 7, 0x03 },        /* 0000 011 */
    { 6, 0x03 },        /* 0000 11 */
    { 3, 0x03 },        /* 011 */
    { 1, 0x1 },         /* 1 */
    { 3, 0x2 },         /* 010 */
    { 6, 0x02 },        /* 0000 10 */
    { 7, 0x02 }         /* 0000 010 */
};

/*
 * 2d-encode a row of pixels.  Consult the CCITT
 * documentation for the algorithm.
 */
static int LINKAGEMODE
Fax3Encode2DRow(TIFF* tif, u_char* bp, u_char* rp, uint32 bits)
{
#define PIXEL(buf,ix)   ((((buf)[(ix)>>3]) >> (7-((ix)&7))) & 1)
        int32 a0 = 0;
        int32 a1 = (PIXEL(bp, 0) != 0 ? 0 : finddiff(bp, 0, bits, 0));
        int32 b1 = (PIXEL(rp, 0) != 0 ? 0 : finddiff(rp, 0, bits, 0));
        int32 a2, b2;

        for (;;) {
                b2 = finddiff2(rp, b1, bits, PIXEL(rp,b1));
                if (b2 >= a1) {
                        int32 d = b1 - a1;
                        if (!(-3 <= d && d <= 3)) {     /* horizontal mode */
                                a2 = finddiff2(bp, a1, bits, PIXEL(bp,a1));
                                putcode(tif, &horizcode);
                                if (a0+a1 == 0 || PIXEL(bp, a0) == 0) {
                                        putspan(tif, a1-a0, TIFFFaxWhiteCodes);
                                        putspan(tif, a2-a1, TIFFFaxBlackCodes);
                                } else {
                                        putspan(tif, a1-a0, TIFFFaxBlackCodes);
                                        putspan(tif, a2-a1, TIFFFaxWhiteCodes);
                                }
                                a0 = a2;
                        } else {                        /* vertical mode */
                                putcode(tif, &vcodes[d+3]);
                                a0 = a1;
                        }
                } else {                                /* pass mode */
                        putcode(tif, &passcode);
                        a0 = b2;
                }
                if (a0 >= bits)
                        break;
                a1 = finddiff(bp, a0, bits, PIXEL(bp,a0));
                b1 = finddiff(rp, a0, bits, !PIXEL(bp,a0));
                b1 = finddiff(rp, b1, bits, PIXEL(bp,a0));
        }
        return (1);
#undef PIXEL
}

/*
 * Encode a buffer of pixels.
 */
static int LINKAGEMODE
Fax3Encode(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
{
        Fax3EncodeState* sp = EncoderState(tif);

        (void) s;
        while ((long)cc > 0) {
                if ((sp->b.mode & FAXMODE_NOEOL) == 0)
                        Fax3PutEOL(tif);
                if (is2DEncoding(sp)) {
#if defined(__VISAGECPP30__)
/* VA 3.0 is just plain wierd. */
                        if (sp->tag == Fax3EncodeState::G3_1D) {
#else
                        if (sp->tag == G3_1D) {
#endif
                                if (!Fax3Encode1DRow(tif, bp, sp->b.rowpixels))
                                        return (0);
#if defined(__VISAGECPP30__)
/* VA 3.0 is just plain wierd. */
                                sp->tag = Fax3EncodeState::G3_2D;
#else
                                sp->tag = G3_2D;
#endif
                        } else {
                                if (!Fax3Encode2DRow(tif, bp, sp->refline, sp->b.rowpixels))
                                        return (0);
                                sp->k--;
                        }
                        if (sp->k == 0) {
#if defined(__VISAGECPP30__)
/* VA 3.0 is just plain wierd. */
                                sp->tag = Fax3EncodeState::G3_1D;
#else
                                sp->tag = G3_1D;
#endif
                                sp->k = sp->maxk-1;
                        } else
                                _TIFFmemcpy(sp->refline, bp, sp->b.rowbytes);
                } else {
                        if (!Fax3Encode1DRow(tif, bp, sp->b.rowpixels))
                                return (0);
                }
                bp += sp->b.rowbytes;
                cc -= sp->b.rowbytes;
                if (cc != 0)
                        tif->tif_row++;
        }
        return (1);
}

static int
Fax3PostEncode(TIFF* tif)
{
        Fax3EncodeState* sp = EncoderState(tif);

        if (sp->bit != 8)
                Fax3FlushBits(tif, sp);
        return (1);
}

static void
Fax3Close(TIFF* tif)
{
        if ((Fax3State(tif)->mode & FAXMODE_NORTC) == 0) {
                Fax3EncodeState* sp = EncoderState(tif);
                u_int code = EOL;
                u_int length = 12;
                int i;

                if (is2DEncoding(sp))
#if defined(__VISAGECPP30__)
/* VA 3.0 is just plain wierd. */
                        code = (code<<1) | (sp->tag == Fax3EncodeState::G3_1D), length++;
#else
                        code = (code<<1) | (sp->tag == G3_1D), length++;
#endif
                for (i = 0; i < 6; i++)
                        Fax3PutBits(tif, code, length);
                Fax3FlushBits(tif, sp);
        }
}

static void
Fax3Cleanup(TIFF* tif)
{
        if (tif->tif_data) {
                if (tif->tif_mode == O_RDONLY) {
                        Fax3DecodeState* sp = DecoderState(tif);
                        if (sp->runs)
                                _TIFFfree(sp->runs);
                } else {
                        Fax3EncodeState* sp = EncoderState(tif);
                        if (sp->refline)
                                _TIFFfree(sp->refline);
                }
                if (Fax3State(tif)->subaddress)
                        _TIFFfree(Fax3State(tif)->subaddress);
                _TIFFfree(tif->tif_data);
                tif->tif_data = NULL;
        }
}

#define FIELD_BADFAXLINES       (FIELD_CODEC+0)
#define FIELD_CLEANFAXDATA      (FIELD_CODEC+1)
#define FIELD_BADFAXRUN         (FIELD_CODEC+2)
#define FIELD_RECVPARAMS        (FIELD_CODEC+3)
#define FIELD_SUBADDRESS        (FIELD_CODEC+4)
#define FIELD_RECVTIME          (FIELD_CODEC+5)

#define FIELD_OPTIONS           (FIELD_CODEC+6)

static const TIFFFieldInfo faxFieldInfo[] = {
    { TIFFTAG_FAXMODE,           0, 0,  TIFF_ANY,       FIELD_PSEUDO,
      FALSE,    FALSE,  "FaxMode" },
    { TIFFTAG_FAXFILLFUNC,       0, 0,  TIFF_ANY,       FIELD_PSEUDO,
      FALSE,    FALSE,  "FaxFillFunc" },
    { TIFFTAG_BADFAXLINES,       1, 1,  TIFF_LONG,      FIELD_BADFAXLINES,
      TRUE,     FALSE,  "BadFaxLines" },
    { TIFFTAG_BADFAXLINES,       1, 1,  TIFF_SHORT,     FIELD_BADFAXLINES,
      TRUE,     FALSE,  "BadFaxLines" },
    { TIFFTAG_CLEANFAXDATA,      1, 1,  TIFF_SHORT,     FIELD_CLEANFAXDATA,
      TRUE,     FALSE,  "CleanFaxData" },
    { TIFFTAG_CONSECUTIVEBADFAXLINES,1,1, TIFF_LONG,    FIELD_BADFAXRUN,
      TRUE,     FALSE,  "ConsecutiveBadFaxLines" },
    { TIFFTAG_CONSECUTIVEBADFAXLINES,1,1, TIFF_SHORT,   FIELD_BADFAXRUN,
      TRUE,     FALSE,  "ConsecutiveBadFaxLines" },
    { TIFFTAG_FAXRECVPARAMS,     1, 1, TIFF_LONG,       FIELD_RECVPARAMS,
      TRUE,     FALSE,  "FaxRecvParams" },
    { TIFFTAG_FAXSUBADDRESS,    -1,-1, TIFF_ASCII,      FIELD_SUBADDRESS,
      TRUE,     FALSE,  "FaxSubAddress" },
    { TIFFTAG_FAXRECVTIME,       1, 1, TIFF_LONG,       FIELD_RECVTIME,
      TRUE,     FALSE,  "FaxRecvTime" },
};
static const TIFFFieldInfo fax3FieldInfo[] = {
    { TIFFTAG_GROUP3OPTIONS,     1, 1,  TIFF_LONG,      FIELD_OPTIONS,
      FALSE,    FALSE,  "Group3Options" },
};
static const TIFFFieldInfo fax4FieldInfo[] = {
    { TIFFTAG_GROUP4OPTIONS,     1, 1,  TIFF_LONG,      FIELD_OPTIONS,
      FALSE,    FALSE,  "Group4Options" },
};
#define N(a)    (sizeof (a) / sizeof (a[0]))

static int
Fax3VSetField(TIFF* tif, ttag_t tag, va_list ap)
{
        Fax3BaseState* sp = Fax3State(tif);

        switch (tag) {
        case TIFFTAG_FAXMODE:
                sp->mode = va_arg(ap, int);
                return (1);                     /* NB: pseudo tag */
        case TIFFTAG_FAXFILLFUNC:
                if (tif->tif_mode == O_RDONLY)
                        DecoderState(tif)->fill = va_arg(ap, TIFFFaxFillFunc);
                return (1);                     /* NB: pseudo tag */
        case TIFFTAG_GROUP3OPTIONS:
        case TIFFTAG_GROUP4OPTIONS:
                sp->groupoptions = va_arg(ap, uint32);
                break;
        case TIFFTAG_BADFAXLINES:
                sp->badfaxlines = va_arg(ap, uint32);
                break;
        case TIFFTAG_CLEANFAXDATA:
                sp->cleanfaxdata = (uint16) va_arg(ap, int);
                break;
        case TIFFTAG_CONSECUTIVEBADFAXLINES:
                sp->badfaxrun = va_arg(ap, uint32);
                break;
        case TIFFTAG_FAXRECVPARAMS:
                sp->recvparams = va_arg(ap, uint32);
                break;
        case TIFFTAG_FAXSUBADDRESS:
                _TIFFsetString(&sp->subaddress, va_arg(ap, char*));
                break;
        case TIFFTAG_FAXRECVTIME:
                sp->recvtime = va_arg(ap, uint32);
                break;
        default:
                return (*sp->vsetparent)(tif, tag, ap);
        }
        TIFFSetFieldBit(tif, _TIFFFieldWithTag(tif, tag)->field_bit);
        tif->tif_flags |= TIFF_DIRTYDIRECT;
        return (1);
}

static int
Fax3VGetField(TIFF* tif, ttag_t tag, va_list ap)
{
        Fax3BaseState* sp = Fax3State(tif);

        switch (tag) {
        case TIFFTAG_FAXMODE:
                *va_arg(ap, int*) = sp->mode;
                break;
        case TIFFTAG_FAXFILLFUNC:
                if (tif->tif_mode == O_RDONLY)
                        *va_arg(ap, TIFFFaxFillFunc*) = DecoderState(tif)->fill;
                break;
        case TIFFTAG_GROUP3OPTIONS:
        case TIFFTAG_GROUP4OPTIONS:
                *va_arg(ap, uint32*) = sp->groupoptions;
                break;
        case TIFFTAG_BADFAXLINES:
                *va_arg(ap, uint32*) = sp->badfaxlines;
                break;
        case TIFFTAG_CLEANFAXDATA:
                *va_arg(ap, uint16*) = sp->cleanfaxdata;
                break;
        case TIFFTAG_CONSECUTIVEBADFAXLINES:
                *va_arg(ap, uint32*) = sp->badfaxrun;
                break;
        case TIFFTAG_FAXRECVPARAMS:
                *va_arg(ap, uint32*) = sp->recvparams;
                break;
        case TIFFTAG_FAXSUBADDRESS:
                *va_arg(ap, char**) = sp->subaddress;
                break;
        case TIFFTAG_FAXRECVTIME:
                *va_arg(ap, uint32*) = sp->recvtime;
                break;
        default:
                return (*sp->vgetparent)(tif, tag, ap);
        }
        return (1);
}

static void LINKAGEMODE
Fax3PrintDir(TIFF* tif, FILE* fd, long flags)
{
        Fax3BaseState* sp = Fax3State(tif);

        (void) flags;
        if (TIFFFieldSet(tif,FIELD_OPTIONS)) {
                const char* sep = " ";
                if (tif->tif_dir.td_compression == COMPRESSION_CCITTFAX4) {
                        fprintf(fd, "  Group 4 Options:");
                        if (sp->groupoptions & GROUP4OPT_UNCOMPRESSED)
                                fprintf(fd, "%suncompressed data", sep);
                } else {

                        fprintf(fd, "  Group 3 Options:");
                        if (sp->groupoptions & GROUP3OPT_2DENCODING)
                                fprintf(fd, "%s2-d encoding", sep), sep = "+";
                        if (sp->groupoptions & GROUP3OPT_FILLBITS)
                                fprintf(fd, "%sEOL padding", sep), sep = "+";
                        if (sp->groupoptions & GROUP3OPT_UNCOMPRESSED)
                                fprintf(fd, "%suncompressed data", sep);
                }
                fprintf(fd, " (%lu = 0x%lx)\n",
                    (u_long) sp->groupoptions, (u_long) sp->groupoptions);
        }
        if (TIFFFieldSet(tif,FIELD_CLEANFAXDATA)) {
                fprintf(fd, "  Fax Data:");
                switch (sp->cleanfaxdata) {
                case CLEANFAXDATA_CLEAN:
                        fprintf(fd, " clean");
                        break;
                case CLEANFAXDATA_REGENERATED:
                        fprintf(fd, " receiver regenerated");
                        break;
                case CLEANFAXDATA_UNCLEAN:
                        fprintf(fd, " uncorrected errors");
                        break;
                }
                fprintf(fd, " (%u = 0x%x)\n",
                    sp->cleanfaxdata, sp->cleanfaxdata);
        }
        if (TIFFFieldSet(tif,FIELD_BADFAXLINES))
                fprintf(fd, "  Bad Fax Lines: %lu\n", (u_long) sp->badfaxlines);
        if (TIFFFieldSet(tif,FIELD_BADFAXRUN))
                fprintf(fd, "  Consecutive Bad Fax Lines: %lu\n",
                    (u_long) sp->badfaxrun);
        if (TIFFFieldSet(tif,FIELD_RECVPARAMS))
                fprintf(fd, "  Fax Receive Parameters: %08lx\n",
                   (u_long) sp->recvparams);
        if (TIFFFieldSet(tif,FIELD_SUBADDRESS))
                fprintf(fd, "  Fax SubAddress: %s\n", sp->subaddress);
        if (TIFFFieldSet(tif,FIELD_RECVTIME))
                fprintf(fd, "  Fax Receive Time: %lu secs\n",
                    (u_long) sp->recvtime);
}

static int LINKAGEMODE
InitCCITTFax3(TIFF* tif)
{
        Fax3BaseState* sp;

        /*
         * Allocate state block so tag methods have storage to record values.
         */
        if (tif->tif_mode == O_RDONLY)
#if defined(__VISAGECPP__)
                tif->tif_data = (tidata_t)_TIFFmalloc(sizeof (Fax3DecodeState));
        else
                tif->tif_data = (tidata_t)_TIFFmalloc(sizeof (Fax3EncodeState));
#else
                tif->tif_data = _TIFFmalloc(sizeof (Fax3DecodeState));
        else
                tif->tif_data = _TIFFmalloc(sizeof (Fax3EncodeState));
#endif
        if (tif->tif_data == NULL) {
                TIFFError("TIFFInitCCITTFax3",
                    "%s: No space for state block", tif->tif_name);
                return (0);
        }
        sp = Fax3State(tif);

        /*
         * Merge codec-specific tag information and
         * override parent get/set field methods.
         */
        _TIFFMergeFieldInfo(tif, faxFieldInfo, N(faxFieldInfo));
        sp->vgetparent = tif->tif_vgetfield;
        tif->tif_vgetfield = Fax3VGetField;     /* hook for codec tags */
        sp->vsetparent = tif->tif_vsetfield;
        tif->tif_vsetfield = Fax3VSetField;     /* hook for codec tags */
        tif->tif_printdir = Fax3PrintDir;       /* hook for codec tags */
        sp->groupoptions = 0;   
        sp->recvparams = 0;
        sp->subaddress = NULL;

        if (tif->tif_mode == O_RDONLY) {
                tif->tif_flags |= TIFF_NOBITREV;/* decoder does bit reversal */
                DecoderState(tif)->runs = NULL;
                TIFFSetField(tif, TIFFTAG_FAXFILLFUNC, _TIFFFax3fillruns);
        } else
                EncoderState(tif)->refline = NULL;

        /*
         * Install codec methods.
         */
        tif->tif_setupdecode = Fax3SetupState;
        tif->tif_predecode = Fax3PreDecode;
        tif->tif_decoderow = Fax3Decode1D;
        tif->tif_decodestrip = Fax3Decode1D;
        tif->tif_decodetile = Fax3Decode1D;
        tif->tif_setupencode = Fax3SetupState;
        tif->tif_preencode = Fax3PreEncode;
        tif->tif_postencode = Fax3PostEncode;
        tif->tif_encoderow = Fax3Encode;
        tif->tif_encodestrip = Fax3Encode;
        tif->tif_encodetile = Fax3Encode;
        tif->tif_close = Fax3Close;
        tif->tif_cleanup = Fax3Cleanup;

        return (1);
}

int
TIFFInitCCITTFax3(TIFF* tif, int scheme)
{
        if (InitCCITTFax3(tif)) {
                _TIFFMergeFieldInfo(tif, fax3FieldInfo, N(fax3FieldInfo));

                /*
                 * The default format is Class/F-style w/o RTC.
                 */
                return TIFFSetField(tif, TIFFTAG_FAXMODE, FAXMODE_CLASSF);
        } else
                return (0);
}

/*
 * CCITT Group 4 (T.6) Facsimile-compatible
 * Compression Scheme Support.
 */

#define SWAP(t,a,b)     { t x; x = (a); (a) = (b); (b) = x; }
/*
 * Decode the requested amount of G4-encoded data.
 */
static int LINKAGEMODE
Fax4Decode(TIFF* tif, tidata_t buf, tsize_t occ, tsample_t s)
{
        DECLARE_STATE_2D(tif, sp, "Fax4Decode");

        (void) s;
        CACHE_STATE(tif, sp);
        while ((long)occ > 0) {
                a0 = 0;
                RunLength = 0;
                pa = thisrun = sp->curruns;
                pb = sp->refruns;
                b1 = *pb++;
#ifdef FAX3_DEBUG
                printf("\nBitAcc=%08X, BitsAvail = %d\n", BitAcc, BitsAvail);
                printf("-------------------- %d\n", tif->tif_row);
                fflush(stdout);
#endif
                EXPAND2D(EOFG4);
                (*sp->fill)(buf, thisrun, pa, lastx);
                SETVAL(0);              /* imaginary change for reference */
                SWAP(uint32*, sp->curruns, sp->refruns);
                buf += sp->b.rowbytes;
                occ -= sp->b.rowbytes;
                if (occ != 0)
                        tif->tif_row++;
                continue;
        EOFG4:
                (*sp->fill)(buf, thisrun, pa, lastx);
                UNCACHE_STATE(tif, sp);
                return (-1);
        }
        UNCACHE_STATE(tif, sp);
        return (1);
}
#undef  SWAP

/*
 * Encode the requested amount of data.
 */
static int LINKAGEMODE
Fax4Encode(TIFF* tif, tidata_t bp, tsize_t cc, tsample_t s)
{
        Fax3EncodeState *sp = EncoderState(tif);

        (void) s;
        while ((long)cc > 0) {
                if (!Fax3Encode2DRow(tif, bp, sp->refline, sp->b.rowpixels))
                        return (0);
                _TIFFmemcpy(sp->refline, bp, sp->b.rowbytes);
                bp += sp->b.rowbytes;
                cc -= sp->b.rowbytes;
                if (cc != 0)
                        tif->tif_row++;
        }
        return (1);
}

static int
Fax4PostEncode(TIFF* tif)
{
        Fax3EncodeState *sp = EncoderState(tif);

        /* terminate strip w/ EOFB */
        Fax3PutBits(tif, EOL, 12);
        Fax3PutBits(tif, EOL, 12);
        if (sp->bit != 8)
                Fax3FlushBits(tif, sp);
        return (1);
}

int
TIFFInitCCITTFax4(TIFF* tif, int scheme)
{
        if (InitCCITTFax3(tif)) {               /* reuse G3 support */
                _TIFFMergeFieldInfo(tif, fax4FieldInfo, N(fax4FieldInfo));

                tif->tif_decoderow = Fax4Decode;
                tif->tif_decodestrip = Fax4Decode;
                tif->tif_decodetile = Fax4Decode;
                tif->tif_encoderow = Fax4Encode;
                tif->tif_encodestrip = Fax4Encode;
                tif->tif_encodetile = Fax4Encode;
                tif->tif_postencode = Fax4PostEncode;
                /*
                 * Suppress RTC at the end of each strip.
                 */
                return TIFFSetField(tif, TIFFTAG_FAXMODE, FAXMODE_NORTC);
        } else
                return (0);
}

/*
 * CCITT Group 3 1-D Modified Huffman RLE Compression Support.
 * (Compression algorithms 2 and 32771)
 */

/*
 * Decode the requested amount of RLE-encoded data.
 */
static int LINKAGEMODE
Fax3DecodeRLE(TIFF* tif, tidata_t buf, tsize_t occ, tsample_t s)
{
        DECLARE_STATE(tif, sp, "Fax3DecodeRLE");
        int mode = sp->b.mode;

        (void) s;
        CACHE_STATE(tif, sp);
        thisrun = sp->curruns;
        while ((long)occ > 0) {
                a0 = 0;
                RunLength = 0;
                pa = thisrun;
#ifdef FAX3_DEBUG
                printf("\nBitAcc=%08X, BitsAvail = %d\n", BitAcc, BitsAvail);
                printf("-------------------- %d\n", tif->tif_row);
                fflush(stdout);
#endif
                EXPAND1D(EOFRLE);
                (*sp->fill)(buf, thisrun, pa, lastx);
                /*
                 * Cleanup at the end of the row.
                 */
                if (mode & FAXMODE_BYTEALIGN) {
                        int n = BitsAvail - (BitsAvail &~ 7);
                        ClrBits(n);
                } else if (mode & FAXMODE_WORDALIGN) {
                        int n = BitsAvail - (BitsAvail &~ 15);
                        ClrBits(n);
                        if (BitsAvail == 0 && !isAligned(cp, uint16))
                            cp++;
                }
                buf += sp->b.rowbytes;
                occ -= sp->b.rowbytes;
                if (occ != 0)
                        tif->tif_row++;
                continue;
        EOFRLE:                         /* premature EOF */
                (*sp->fill)(buf, thisrun, pa, lastx);
                UNCACHE_STATE(tif, sp);
                return (-1);
        }
        UNCACHE_STATE(tif, sp);
        return (1);
}

int
TIFFInitCCITTRLE(TIFF* tif, int scheme)
{
        if (InitCCITTFax3(tif)) {               /* reuse G3 support */
                tif->tif_decoderow = Fax3DecodeRLE;
                tif->tif_decodestrip = Fax3DecodeRLE;
                tif->tif_decodetile = Fax3DecodeRLE;
                /*
                 * Suppress RTC+EOLs when encoding and byte-align data.
                 */
                return TIFFSetField(tif, TIFFTAG_FAXMODE,
                    FAXMODE_NORTC|FAXMODE_NOEOL|FAXMODE_BYTEALIGN);
        } else
                return (0);
}

int
TIFFInitCCITTRLEW(TIFF* tif, int scheme)
{
        if (InitCCITTFax3(tif)) {               /* reuse G3 support */
                tif->tif_decoderow = Fax3DecodeRLE;
                tif->tif_decodestrip = Fax3DecodeRLE;
                tif->tif_decodetile = Fax3DecodeRLE;
                /*
                 * Suppress RTC+EOLs when encoding and word-align data.
                 */
                return TIFFSetField(tif, TIFFTAG_FAXMODE,
                    FAXMODE_NORTC|FAXMODE_NOEOL|FAXMODE_WORDALIGN);
        } else
                return (0);
}
#endif /* CCITT_SUPPORT */