/* $Header: /cvsroot/VTK/VTK/Utilities/vtktiff/tif_dirinfo.c,v 1.1 2004/04/28 15:49:22 king Exp $ */

/*
 * 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.
 *
 * Core Directory Tag Support.
 */
#include "tiffiop.h"
#include <stdlib.h>

/*
 * NB: NB: THIS ARRAY IS ASSUMED TO BE SORTED BY TAG.
 *     If a tag can have both LONG and SHORT types
 *     then the LONG must be placed before the SHORT for
 *     writing to work properly.
 *
 * NOTE: The second field (field_readcount) and third field (field_writecount)
 *       sometimes use the values TIFF_VARIABLE (-1), TIFF_VARIABLE2 (-3)
 *       and TIFFTAG_SPP (-2). The macros should be used but would throw off 
 *       the formatting of the code, so please interprete the -1, -2 and -3 
 *       values accordingly.
 */
#ifndef VMS
static 
#endif
const TIFFFieldInfo tiffFieldInfo[] = {
    { TIFFTAG_SUBFILETYPE,       1, 1, TIFF_LONG,       FIELD_SUBFILETYPE,
      TRUE,     FALSE,  "SubfileType" },
/* XXX SHORT for compatibility w/ old versions of the library */
    { TIFFTAG_SUBFILETYPE,       1, 1, TIFF_SHORT,      FIELD_SUBFILETYPE,
      TRUE,     FALSE,  "SubfileType" },
    { TIFFTAG_OSUBFILETYPE,      1, 1, TIFF_SHORT,      FIELD_SUBFILETYPE,
      TRUE,     FALSE,  "OldSubfileType" },
    { TIFFTAG_IMAGEWIDTH,        1, 1, TIFF_LONG,       FIELD_IMAGEDIMENSIONS,
      FALSE,    FALSE,  "ImageWidth" },
    { TIFFTAG_IMAGEWIDTH,        1, 1, TIFF_SHORT,      FIELD_IMAGEDIMENSIONS,
      FALSE,    FALSE,  "ImageWidth" },
    { TIFFTAG_IMAGELENGTH,       1, 1, TIFF_LONG,       FIELD_IMAGEDIMENSIONS,
      TRUE,     FALSE,  "ImageLength" },
    { TIFFTAG_IMAGELENGTH,       1, 1, TIFF_SHORT,      FIELD_IMAGEDIMENSIONS,
      TRUE,     FALSE,  "ImageLength" },
    { TIFFTAG_BITSPERSAMPLE,    -1,-1, TIFF_SHORT,      FIELD_BITSPERSAMPLE,
      FALSE,    FALSE,  "BitsPerSample" },
    { TIFFTAG_COMPRESSION,      -1, 1, TIFF_SHORT,      FIELD_COMPRESSION,
      FALSE,    FALSE,  "Compression" },
    { TIFFTAG_PHOTOMETRIC,       1, 1, TIFF_SHORT,      FIELD_PHOTOMETRIC,
      FALSE,    FALSE,  "PhotometricInterpretation" },
    { TIFFTAG_THRESHHOLDING,     1, 1, TIFF_SHORT,      FIELD_THRESHHOLDING,
      TRUE,     FALSE,  "Threshholding" },
    { TIFFTAG_CELLWIDTH,         1, 1, TIFF_SHORT,      FIELD_IGNORE,
      TRUE,     FALSE,  "CellWidth" },
    { TIFFTAG_CELLLENGTH,        1, 1, TIFF_SHORT,      FIELD_IGNORE,
      TRUE,     FALSE,  "CellLength" },
    { TIFFTAG_FILLORDER,         1, 1, TIFF_SHORT,      FIELD_FILLORDER,
      FALSE,    FALSE,  "FillOrder" },
    { TIFFTAG_DOCUMENTNAME,     -1,-1, TIFF_ASCII,      FIELD_DOCUMENTNAME,
      TRUE,     FALSE,  "DocumentName" },
    { TIFFTAG_IMAGEDESCRIPTION, -1,-1, TIFF_ASCII,      FIELD_IMAGEDESCRIPTION,
      TRUE,     FALSE,  "ImageDescription" },
    { TIFFTAG_MAKE,             -1,-1, TIFF_ASCII,      FIELD_MAKE,
      TRUE,     FALSE,  "Make" },
    { TIFFTAG_MODEL,            -1,-1, TIFF_ASCII,      FIELD_MODEL,
      TRUE,     FALSE,  "Model" },
    { TIFFTAG_STRIPOFFSETS,     -1,-1, TIFF_LONG,       FIELD_STRIPOFFSETS,
      FALSE,    FALSE,  "StripOffsets" },
    { TIFFTAG_STRIPOFFSETS,     -1,-1, TIFF_SHORT,      FIELD_STRIPOFFSETS,
      FALSE,    FALSE,  "StripOffsets" },
    { TIFFTAG_ORIENTATION,       1, 1, TIFF_SHORT,      FIELD_ORIENTATION,
      FALSE,    FALSE,  "Orientation" },
    { TIFFTAG_SAMPLESPERPIXEL,   1, 1, TIFF_SHORT,      FIELD_SAMPLESPERPIXEL,
      FALSE,    FALSE,  "SamplesPerPixel" },
    { TIFFTAG_ROWSPERSTRIP,      1, 1, TIFF_LONG,       FIELD_ROWSPERSTRIP,
      FALSE,    FALSE,  "RowsPerStrip" },
    { TIFFTAG_ROWSPERSTRIP,      1, 1, TIFF_SHORT,      FIELD_ROWSPERSTRIP,
      FALSE,    FALSE,  "RowsPerStrip" },
    { TIFFTAG_STRIPBYTECOUNTS,  -1,-1, TIFF_LONG,       FIELD_STRIPBYTECOUNTS,
      FALSE,    FALSE,  "StripByteCounts" },
    { TIFFTAG_STRIPBYTECOUNTS,  -1,-1, TIFF_SHORT,      FIELD_STRIPBYTECOUNTS,
      FALSE,    FALSE,  "StripByteCounts" },
    { TIFFTAG_MINSAMPLEVALUE,   -2,-1, TIFF_SHORT,      FIELD_MINSAMPLEVALUE,
      TRUE,     FALSE,  "MinSampleValue" },
    { TIFFTAG_MAXSAMPLEVALUE,   -2,-1, TIFF_SHORT,      FIELD_MAXSAMPLEVALUE,
      TRUE,     FALSE,  "MaxSampleValue" },
    { TIFFTAG_XRESOLUTION,       1, 1, TIFF_RATIONAL,   FIELD_RESOLUTION,
      FALSE,    FALSE,  "XResolution" },
    { TIFFTAG_YRESOLUTION,       1, 1, TIFF_RATIONAL,   FIELD_RESOLUTION,
      FALSE,    FALSE,  "YResolution" },
    { TIFFTAG_PLANARCONFIG,      1, 1, TIFF_SHORT,      FIELD_PLANARCONFIG,
      FALSE,    FALSE,  "PlanarConfiguration" },
    { TIFFTAG_PAGENAME,         -1,-1, TIFF_ASCII,      FIELD_PAGENAME,
      TRUE,     FALSE,  "PageName" },
    { TIFFTAG_XPOSITION,         1, 1, TIFF_RATIONAL,   FIELD_POSITION,
      TRUE,     FALSE,  "XPosition" },
    { TIFFTAG_YPOSITION,         1, 1, TIFF_RATIONAL,   FIELD_POSITION,
      TRUE,     FALSE,  "YPosition" },
    { TIFFTAG_FREEOFFSETS,      -1,-1, TIFF_LONG,       FIELD_IGNORE,
      FALSE,    FALSE,  "FreeOffsets" },
    { TIFFTAG_FREEBYTECOUNTS,   -1,-1, TIFF_LONG,       FIELD_IGNORE,
      FALSE,    FALSE,  "FreeByteCounts" },
    { TIFFTAG_GRAYRESPONSEUNIT,  1, 1, TIFF_SHORT,      FIELD_IGNORE,
      TRUE,     FALSE,  "GrayResponseUnit" },
    { TIFFTAG_GRAYRESPONSECURVE,-1,-1, TIFF_SHORT,      FIELD_IGNORE,
      TRUE,     FALSE,  "GrayResponseCurve" },
    { TIFFTAG_RESOLUTIONUNIT,    1, 1, TIFF_SHORT,      FIELD_RESOLUTIONUNIT,
      FALSE,    FALSE,  "ResolutionUnit" },
    { TIFFTAG_PAGENUMBER,        2, 2, TIFF_SHORT,      FIELD_PAGENUMBER,
      TRUE,     FALSE,  "PageNumber" },
    { TIFFTAG_COLORRESPONSEUNIT, 1, 1, TIFF_SHORT,      FIELD_IGNORE,
      TRUE,     FALSE,  "ColorResponseUnit" },
#ifdef COLORIMETRY_SUPPORT
    { TIFFTAG_TRANSFERFUNCTION, -1,-1, TIFF_SHORT,      FIELD_TRANSFERFUNCTION,
      TRUE,     FALSE,  "TransferFunction" },
#endif
    { TIFFTAG_SOFTWARE,         -1,-1, TIFF_ASCII,      FIELD_SOFTWARE,
      TRUE,     FALSE,  "Software" },
    { TIFFTAG_DATETIME,         20,20, TIFF_ASCII,      FIELD_DATETIME,
      TRUE,     FALSE,  "DateTime" },
    { TIFFTAG_ARTIST,           -1,-1, TIFF_ASCII,      FIELD_ARTIST,
      TRUE,     FALSE,  "Artist" },
    { TIFFTAG_HOSTCOMPUTER,     -1,-1, TIFF_ASCII,      FIELD_HOSTCOMPUTER,
      TRUE,     FALSE,  "HostComputer" },
#ifdef COLORIMETRY_SUPPORT
    { TIFFTAG_WHITEPOINT,        2, 2, TIFF_RATIONAL,FIELD_WHITEPOINT,
      TRUE,     FALSE,  "WhitePoint" },
    { TIFFTAG_PRIMARYCHROMATICITIES,6,6,TIFF_RATIONAL,FIELD_PRIMARYCHROMAS,
      TRUE,     FALSE,  "PrimaryChromaticities" },
#endif
    { TIFFTAG_COLORMAP,         -1,-1, TIFF_SHORT,      FIELD_COLORMAP,
      TRUE,     FALSE,  "ColorMap" },
    { TIFFTAG_HALFTONEHINTS,     2, 2, TIFF_SHORT,      FIELD_HALFTONEHINTS,
      TRUE,     FALSE,  "HalftoneHints" },
    { TIFFTAG_TILEWIDTH,         1, 1, TIFF_LONG,       FIELD_TILEDIMENSIONS,
      FALSE,    FALSE,  "TileWidth" },
    { TIFFTAG_TILEWIDTH,         1, 1, TIFF_SHORT,      FIELD_TILEDIMENSIONS,
      FALSE,    FALSE,  "TileWidth" },
    { TIFFTAG_TILELENGTH,        1, 1, TIFF_LONG,       FIELD_TILEDIMENSIONS,
      FALSE,    FALSE,  "TileLength" },
    { TIFFTAG_TILELENGTH,        1, 1, TIFF_SHORT,      FIELD_TILEDIMENSIONS,
      FALSE,    FALSE,  "TileLength" },
    { TIFFTAG_TILEOFFSETS,      -1, 1, TIFF_LONG,       FIELD_STRIPOFFSETS,
      FALSE,    FALSE,  "TileOffsets" },
    { TIFFTAG_TILEBYTECOUNTS,   -1, 1, TIFF_LONG,       FIELD_STRIPBYTECOUNTS,
      FALSE,    FALSE,  "TileByteCounts" },
    { TIFFTAG_TILEBYTECOUNTS,   -1, 1, TIFF_SHORT,      FIELD_STRIPBYTECOUNTS,
      FALSE,    FALSE,  "TileByteCounts" },
#ifdef TIFFTAG_SUBIFD
    { TIFFTAG_SUBIFD,           -1,-1, TIFF_LONG,       FIELD_SUBIFD,
      TRUE,     TRUE,   "SubIFD" },
#endif
#ifdef CMYK_SUPPORT             /* 6.0 CMYK tags */
    { TIFFTAG_INKSET,            1, 1, TIFF_SHORT,      FIELD_INKSET,
      FALSE,    FALSE,  "InkSet" },
    { TIFFTAG_INKNAMES,         -1,-1, TIFF_ASCII,      FIELD_INKNAMES,
      TRUE,     TRUE,   "InkNames" },
    { TIFFTAG_NUMBEROFINKS,      1, 1, TIFF_SHORT,      FIELD_NUMBEROFINKS,
      TRUE,     FALSE,  "NumberOfInks" },
    { TIFFTAG_DOTRANGE,          2, 2, TIFF_SHORT,      FIELD_DOTRANGE,
      FALSE,    FALSE,  "DotRange" },
    { TIFFTAG_DOTRANGE,          2, 2, TIFF_BYTE,       FIELD_DOTRANGE,
      FALSE,    FALSE,  "DotRange" },
    { TIFFTAG_TARGETPRINTER,    -1,-1, TIFF_ASCII,      FIELD_TARGETPRINTER,
      TRUE,     FALSE,  "TargetPrinter" },
#endif
    { TIFFTAG_EXTRASAMPLES,     -1,-1, TIFF_SHORT,      FIELD_EXTRASAMPLES,
      FALSE,    FALSE,  "ExtraSamples" },
/* XXX for bogus Adobe Photoshop v2.5 files */
    { TIFFTAG_EXTRASAMPLES,     -1,-1, TIFF_BYTE,       FIELD_EXTRASAMPLES,
      FALSE,    FALSE,  "ExtraSamples" },
    { TIFFTAG_SAMPLEFORMAT,     -1,-1, TIFF_SHORT,      FIELD_SAMPLEFORMAT,
      FALSE,    FALSE,  "SampleFormat" },
    { TIFFTAG_SMINSAMPLEVALUE,  -2,-1, TIFF_ANY,        FIELD_SMINSAMPLEVALUE,
      TRUE,     FALSE,  "SMinSampleValue" },
    { TIFFTAG_SMAXSAMPLEVALUE,  -2,-1, TIFF_ANY,        FIELD_SMAXSAMPLEVALUE,
      TRUE,     FALSE,  "SMaxSampleValue" },
#ifdef YCBCR_SUPPORT            /* 6.0 YCbCr tags */
    { TIFFTAG_YCBCRCOEFFICIENTS, 3, 3, TIFF_RATIONAL,   FIELD_YCBCRCOEFFICIENTS,
      FALSE,    FALSE,  "YCbCrCoefficients" },
    { TIFFTAG_YCBCRSUBSAMPLING,  2, 2, TIFF_SHORT,      FIELD_YCBCRSUBSAMPLING,
      FALSE,    FALSE,  "YCbCrSubsampling" },
    { TIFFTAG_YCBCRPOSITIONING,  1, 1, TIFF_SHORT,      FIELD_YCBCRPOSITIONING,
      FALSE,    FALSE,  "YCbCrPositioning" },
#endif
#ifdef COLORIMETRY_SUPPORT
    { TIFFTAG_REFERENCEBLACKWHITE,6,6,TIFF_RATIONAL,    FIELD_REFBLACKWHITE,
      TRUE,     FALSE,  "ReferenceBlackWhite" },
/* XXX temporarily accept LONG for backwards compatibility */
    { TIFFTAG_REFERENCEBLACKWHITE,6,6,TIFF_LONG,        FIELD_REFBLACKWHITE,
      TRUE,     FALSE,  "ReferenceBlackWhite" },
#endif
/* begin SGI tags */
    { TIFFTAG_MATTEING,          1, 1, TIFF_SHORT,      FIELD_EXTRASAMPLES,
      FALSE,    FALSE,  "Matteing" },
    { TIFFTAG_DATATYPE,         -2,-1, TIFF_SHORT,      FIELD_SAMPLEFORMAT,
      FALSE,    FALSE,  "DataType" },
    { TIFFTAG_IMAGEDEPTH,        1, 1, TIFF_LONG,       FIELD_IMAGEDEPTH,
      FALSE,    FALSE,  "ImageDepth" },
    { TIFFTAG_IMAGEDEPTH,        1, 1, TIFF_SHORT,      FIELD_IMAGEDEPTH,
      FALSE,    FALSE,  "ImageDepth" },
    { TIFFTAG_TILEDEPTH,         1, 1, TIFF_LONG,       FIELD_TILEDEPTH,
      FALSE,    FALSE,  "TileDepth" },
    { TIFFTAG_TILEDEPTH,         1, 1, TIFF_SHORT,      FIELD_TILEDEPTH,
      FALSE,    FALSE,  "TileDepth" },
/* end SGI tags */
/* begin Pixar tags */
    { TIFFTAG_PIXAR_IMAGEFULLWIDTH,  1, 1, TIFF_LONG,   FIELD_IMAGEFULLWIDTH,
      TRUE,     FALSE,  "ImageFullWidth" },
    { TIFFTAG_PIXAR_IMAGEFULLLENGTH, 1, 1, TIFF_LONG,   FIELD_IMAGEFULLLENGTH,
      TRUE,     FALSE,  "ImageFullLength" },
    { TIFFTAG_PIXAR_TEXTUREFORMAT,  -1,-1, TIFF_ASCII,  FIELD_TEXTUREFORMAT,
      TRUE,     FALSE,  "TextureFormat" },
    { TIFFTAG_PIXAR_WRAPMODES,      -1,-1, TIFF_ASCII,  FIELD_WRAPMODES,
      TRUE,     FALSE,  "TextureWrapModes" },
    { TIFFTAG_PIXAR_FOVCOT,          1, 1, TIFF_FLOAT,  FIELD_FOVCOT,
      TRUE,     FALSE,  "FieldOfViewCotan" },
    { TIFFTAG_PIXAR_MATRIX_WORLDTOSCREEN,       16,16,  TIFF_FLOAT,
      FIELD_MATRIX_WORLDTOSCREEN,       TRUE,   FALSE,  "MatrixWorldToScreen" },
    { TIFFTAG_PIXAR_MATRIX_WORLDTOCAMERA,       16,16,  TIFF_FLOAT,
       FIELD_MATRIX_WORLDTOCAMERA,      TRUE,   FALSE,  "MatrixWorldToCamera" },
    { TIFFTAG_COPYRIGHT,        -1,-1, TIFF_ASCII,      FIELD_COPYRIGHT,
      TRUE,     FALSE,  "Copyright" },
/* end Pixar tags */

    { TIFFTAG_UIC2TAG, -1,-3, TIFF_RATIONAL,   FIELD_UIC2TAG, 
      FALSE,    TRUE,   "UIC2Tag" },

#ifdef IPTC_SUPPORT
#ifdef PHOTOSHOP_SUPPORT
    { TIFFTAG_RICHTIFFIPTC, -1,-1, TIFF_LONG,   FIELD_RICHTIFFIPTC, 
      FALSE,    TRUE,   "RichTIFFIPTC" },
#else
    { TIFFTAG_RICHTIFFIPTC, -1,-3, TIFF_UNDEFINED, FIELD_RICHTIFFIPTC, 
      FALSE,    TRUE,   "RichTIFFIPTC" },
#endif
#endif

    { TIFFTAG_CZ_LSMINFO,       -1,-3, TIFF_BYTE,       FIELD_CZ_LSMINFO,
      FALSE,       TRUE,       "LSM Info" },

#ifdef PHOTOSHOP_SUPPORT
    { TIFFTAG_PHOTOSHOP,    -1,-3, TIFF_BYTE,   FIELD_PHOTOSHOP, 
      FALSE,    TRUE,   "Photoshop" },
#endif
#ifdef ICC_SUPPORT
    { TIFFTAG_ICCPROFILE,       -1,-3, TIFF_UNDEFINED,  FIELD_ICCPROFILE,
      FALSE,    TRUE,   "ICC Profile" },
#endif
    { TIFFTAG_STONITS,           1, 1, TIFF_DOUBLE,     FIELD_STONITS,
      FALSE,    FALSE,  "StoNits" },
};
#define N(a)    (sizeof (a) / sizeof (a[0]))

void
_TIFFSetupFieldInfo(TIFF* tif)
{
        if (tif->tif_fieldinfo) {
                _TIFFfree(tif->tif_fieldinfo);
                tif->tif_nfields = 0;
        }
        _TIFFMergeFieldInfo(tif, tiffFieldInfo, N(tiffFieldInfo));
}

static int
tagCompare(const void* a, const void* b)
{
        const TIFFFieldInfo* ta = *(const TIFFFieldInfo**) a;
        const TIFFFieldInfo* tb = *(const TIFFFieldInfo**) b;
        /* NB: be careful of return values for 16-bit platforms */
        if (ta->field_tag != tb->field_tag)
                return (ta->field_tag < tb->field_tag ? -1 : 1);
        else
                return (tb->field_type < ta->field_type ? -1 : 1);
}

void
_TIFFMergeFieldInfo(TIFF* tif, const TIFFFieldInfo info[], int n)
{
        TIFFFieldInfo** tp;
        int i;

        if (tif->tif_nfields > 0) {
                tif->tif_fieldinfo = (TIFFFieldInfo**)
                    _TIFFrealloc(tif->tif_fieldinfo,
                        (tif->tif_nfields+n) * sizeof (TIFFFieldInfo*));
        } else {
                tif->tif_fieldinfo = (TIFFFieldInfo**)
                    _TIFFmalloc(n * sizeof (TIFFFieldInfo*));
        }
        tp = &tif->tif_fieldinfo[tif->tif_nfields];
        for (i = 0; i < n; i++)
                tp[i] = (TIFFFieldInfo*) &info[i];      /* XXX */
        /*
         * NB: the core tags are presumed sorted correctly.
         */
        if (tif->tif_nfields > 0)
                qsort(tif->tif_fieldinfo, (size_t) (tif->tif_nfields += n),
                    sizeof (TIFFFieldInfo*), tagCompare);
        else
                tif->tif_nfields += n;
}

void
_TIFFPrintFieldInfo(TIFF* tif, FILE* fd)
{
        int i;

        fprintf(fd, "%s: \n", tif->tif_name);
        for (i = 0; i < tif->tif_nfields; i++) {
                const TIFFFieldInfo* fip = tif->tif_fieldinfo[i];
                fprintf(fd, "field[%2d] %5lu, %2d, %2d, %d, %2d, %5s, %5s, %s\n"
                        , i
                        , (unsigned long) fip->field_tag
                        , fip->field_readcount, fip->field_writecount
                        , fip->field_type
                        , fip->field_bit
                        , fip->field_oktochange ? "TRUE" : "FALSE"
                        , fip->field_passcount ? "TRUE" : "FALSE"
                        , fip->field_name
                );
        }
}

const int tiffDataWidth[] = {
    1,  /* nothing */
    1,  /* TIFF_BYTE */
    1,  /* TIFF_ASCII */
    2,  /* TIFF_SHORT */
    4,  /* TIFF_LONG */
    8,  /* TIFF_RATIONAL */
    1,  /* TIFF_SBYTE */
    1,  /* TIFF_UNDEFINED */
    2,  /* TIFF_SSHORT */
    4,  /* TIFF_SLONG */
    8,  /* TIFF_SRATIONAL */
    4,  /* TIFF_FLOAT */
    8,  /* TIFF_DOUBLE */
};

/*
 * Return nearest TIFFDataType to the sample type of an image.
 */
TIFFDataType
_TIFFSampleToTagType(TIFF* tif)
{
        int bps = (int) TIFFhowmany(tif->tif_dir.td_bitspersample, 8);

        switch (tif->tif_dir.td_sampleformat) {
        case SAMPLEFORMAT_IEEEFP:
                return (bps == 4 ? TIFF_FLOAT : TIFF_DOUBLE);
        case SAMPLEFORMAT_INT:
                return (bps <= 1 ? TIFF_SBYTE :
                    bps <= 2 ? TIFF_SSHORT : TIFF_SLONG);
        case SAMPLEFORMAT_UINT:
                return (bps <= 1 ? TIFF_BYTE :
                    bps <= 2 ? TIFF_SHORT : TIFF_LONG);
        case SAMPLEFORMAT_VOID:
                return (TIFF_UNDEFINED);
        }
        /*NOTREACHED*/
        return (TIFF_UNDEFINED);
}

const TIFFFieldInfo*
_TIFFFindFieldInfo(TIFF* tif, ttag_t tag, TIFFDataType dt)
{
        static const TIFFFieldInfo *last = NULL;
        int i, n;

        if (last && last->field_tag == tag &&
            (dt == TIFF_ANY || dt == last->field_type))
                return (last);
        /* NB: if table gets big, use sorted search (e.g. binary search) */
        for (i = 0, n = tif->tif_nfields; i < n; i++) {
                const TIFFFieldInfo* fip = tif->tif_fieldinfo[i];
                if (fip->field_tag == tag &&
                    (dt == TIFF_ANY || fip->field_type == dt))
                        return (last = fip);
        }
        return ((const TIFFFieldInfo *)0);
}

#include <assert.h>
#include <stdio.h>

const TIFFFieldInfo*
_TIFFFieldWithTag(TIFF* tif, ttag_t tag)
{
        const TIFFFieldInfo* fip = _TIFFFindFieldInfo(tif, tag, TIFF_ANY);
        if (!fip) {
                TIFFError("TIFFFieldWithTag",
                    "Internal error, unknown tag 0x%x", (u_int) tag);
                assert(fip != NULL);
                /*NOTREACHED*/
        }
        return (fip);
}