Re: CCITT Group 4 compression

Compression Scheme Configuration Support.
 */
 return (TIFFNoDecode(tif, "tile"));
}

int
_TIFFNoSeek(TIFF* tif, uint32 off)
{
 (void) off;
 TIFFError(tif->tif_name,
     "Compression algorithm does not support random access");
 return (0);
}
#include "tiffiop.h"

static int
TIFFNoEncode(TIFF* tif, char* method)
{
 const TIFFCodec* c = TIFFFindCODEC(tif->tif_dir.td_compression);

 if (c) {
   if (! strncmp(c->name, "LZW", 3) ){
     TIFFError(tif->tif_name,
        "%s %s encoding is no longer implemented due to Unisys patent
enforcement",
        c->name, method);
   } else {
     TIFFError(tif->tif_name, "%s %s encoding is not implemented",
        c->name, method);
   }
 }
 else {
  TIFFError(tif->tif_name,
     "Compression scheme %u %s encoding is not implemented",
      tif->tif_dir.td_compression, method);
 }
 return (-1);
}

int
_TIFFNoRowEncode(TIFF* tif, tidata_t pp, tsize_t cc, tsample_t s)
{
 (void) pp; (void) cc; (void) s;
 return (TIFFNoEncode(tif, "scanline"));
}

int
_TIFFNoStripEncode(TIFF* tif, tidata_t pp, tsize_t cc, tsample_t s)
{
 (void) pp; (void) cc; (void) s;
 return (TIFFNoEncode(tif, "strip"));
}

int
_TIFFNoTileEncode(TIFF* tif, tidata_t pp, tsize_t cc, tsample_t s)
{
 (void) pp; (void) cc; (void) s;
 return (TIFFNoEncode(tif, "tile"));
}

static int
TIFFNoDecode(TIFF* tif, char* method)
{
 const TIFFCodec* c = TIFFFindCODEC(tif->tif_dir.td_compression);

 if (c)
  TIFFError(tif->tif_name, "%s %s decoding is not implemented",
      c->name, method);
 else
  TIFFError(tif->tif_name,
      "Compression scheme %u %s decoding is not implemented",
      tif->tif_dir.td_compression, method);
 return (-1);
}

int
_TIFFNoRowDecode(TIFF* tif, tidata_t pp, tsize_t cc, tsample_t s)
{
 (void) pp; (void) cc; (void) s;
 return (TIFFNoDecode(tif, "scanline"));
}

int
_TIFFNoStripDecode(TIFF* tif, tidata_t pp, tsize_t cc, tsample_t s)
{
 (void) pp; (void) cc; (void) s;
 return (TIFFNoDecode(tif, "strip"));
}

int
_TIFFNoTileDecode(TIFF* tif, tidata_t pp, tsize_t cc, tsample_t s)
{
 (void) pp; (void) cc; (void) s;

int
_TIFFNoPreCode(TIFF* tif, tsample_t s)
{
 (void) tif; (void) s;
 return (1);
}

static int _TIFFtrue(TIFF* tif) { (void) tif; return (1); }
static void _TIFFvoid(TIFF* tif) { (void) tif; }

void
_TIFFSetDefaultCompressionState(TIFF* tif)
{
 tif->tif_setupdecode = _TIFFtrue;
 tif->tif_predecode = _TIFFNoPreCode;
 tif->tif_decoderow = _TIFFNoRowDecode;
 tif->tif_decodestrip = _TIFFNoStripDecode;
 tif->tif_decodetile = _TIFFNoTileDecode;
 tif->tif_setupencode = _TIFFtrue;
 tif->tif_preencode = _TIFFNoPreCode;
 tif->tif_postencode = _TIFFtrue;
 tif->tif_encoderow = _TIFFNoRowEncode;
 tif->tif_encodestrip = _TIFFNoStripEncode;
 tif->tif_encodetile = _TIFFNoTileEncode;
 tif->tif_close = _TIFFvoid;
 tif->tif_seek = _TIFFNoSeek;
 tif->tif_cleanup = _TIFFvoid;
 tif->tif_defstripsize = _TIFFDefaultStripSize;
 tif->tif_deftilesize = _TIFFDefaultTileSize;
 tif->tif_flags &= ~TIFF_NOBITREV;
}

int
TIFFSetCompressionScheme(TIFF* tif, int scheme)
{
 const TIFFCodec *c = TIFFFindCODEC((uint16) scheme);

 _TIFFSetDefaultCompressionState(tif);
 /*
  * Don't treat an unknown compression scheme as an error.
  * This permits applications to open files with data that
  * the library does not have builtin support for, but which
  * may still be meaningful.
  */
 return (c ? (*c->init)(tif, scheme) : 1);
}

/*
 * Other compression schemes may be registered.  Registered
 * schemes can also override the builtin versions provided
 * by this library.
 */
typedef struct _codec {
 struct _codec* next;
 TIFFCodec* info;
} codec_t;
static codec_t* registeredCODECS = NULL;

const TIFFCodec*
TIFFFindCODEC(uint16 scheme)
{
 const TIFFCodec* c;
 codec_t* cd;

 for (cd = registeredCODECS; cd; cd = cd->next)
  if (cd->info->scheme == scheme)
   return ((const TIFFCodec*) cd->info);
 for (c = _TIFFBuiltinCODECS; c->name; c++)
  if (c->scheme == scheme)
   return (c);
 return ((const TIFFCodec*) 0);
}

TIFFCodec*
TIFFRegisterCODEC(uint16 scheme, const char* name, TIFFInitMethod init)
{
 codec_t* cd = (codec_t*)
     _TIFFmalloc(sizeof (codec_t) + sizeof (TIFFCodec) + strlen(name)+1);

 if (cd != NULL) {
  cd->info = (TIFFCodec*) ((tidata_t) cd + sizeof (codec_t));
  cd->info->name = (char*)
      ((tidata_t) cd->info + sizeof (TIFFCodec));
  strcpy(cd->info->name, name);
  cd->info->scheme = scheme;
  cd->info->init = init;
  cd->next = registeredCODECS;
  registeredCODECS = cd;
 } else
  TIFFError("TIFFRegisterCODEC",
      "No space to register compression scheme %s", name);
 return (cd->info);
}

void
TIFFUnRegisterCODEC(TIFFCodec* c)
{
 codec_t* cd;
 codec_t** pcd;

 for (pcd = &registeredCODECS; (cd = *pcd); pcd = &cd->next)
  if (cd->info == c) {
   *pcd = cd->next;
   _TIFFfree(cd);
   return;
  }
 TIFFError("TIFFUnRegisterCODEC",
     "Cannot remove compression scheme %s; not registered", c->name);
}



"Hall, Philip" wrote:

> Post the C code you're having an issue with, a number of us know C as well
> as MI...
>
> --phil
>
> -----Original Message-----
> From: Harry Williams
> Sent: Fri 12/14/2001 11:46 PM
> To: mi400@midrange.com
> Cc:
> Subject: Re: [MI400] CCITT Group 4 compression
>
> No,
> I do not understand the C side that well. This is in C, I was trying to
> translate it to MI.
> Harry
>
> Steve Richter wrote:
>
> > Harry,
> >
> > You are coding these routines in MI ?  You are having coding problems with
>
> > the MI bit instructions ?
> >
> > Steve Richter
> >
> > ----- Original Message -----
> > From: "Harry Williams" <planesmart@teleteam.com>
> > To: <MI400@midrange.com>
> > Sent: Thursday, December 13, 2001 10:27 AM
> > Subject: [MI400] CCITT Group 4 compression
> >
> > > Does anyone have algorithms for the CCITT Group 4 compression or
> > > decompression? I find it for C but I am having trouble in translating
> > > the bit mask.
> > > Harry
> > >
> > > _______________________________________________
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> .
> > >
> > >
> >
> > _______________________________________________
> > This is the MI Programming on the AS400 / iSeries (MI400) mailing list
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>
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