File: rs01-create.c

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dvdisaster 0.79.5-10
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/*  dvdisaster: Additional error correction for optical media.
 *  Copyright (C) 2004-2015 Carsten Gnoerlich.
 *
 *  The Reed-Solomon error correction draws a lot of inspiration - and even code -
 *  from Phil Karn's excellent Reed-Solomon library: http://www.ka9q.net/code/fec/
 *
 *  Email: carsten@dvdisaster.org  -or-  cgnoerlich@fsfe.org
 *  Project homepage: http://www.dvdisaster.org
 *
 *  This file is part of dvdisaster.
 *
 *  dvdisaster is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation, either version 3 of the License, or
 *  (at your option) any later version.
 *
 *  dvdisaster is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with dvdisaster. If not, see <http://www.gnu.org/licenses/>.
 */

#include "dvdisaster.h"

#include "rs01-includes.h"

/***
 *** Interpret our redundancy settings
 ***
 * a) "normal" -> nroots=32; "high" -> nroots=64
 * b) "n"      -> nroots = n
 * c) "n%"     -> use closest nroots for given redundancy in percent
 * d) "nm"     -> choose redundancy so that .ecc file does not exceed n megabytes
 */

static guint64 ecc_file_size(guint64 sectors, int nr)
{  int nd = GF_FIELDMAX - nr;
   guint64 bytesize; 

   bytesize = 4096 + 4*sectors + 2048*nr*((sectors+nd-1)/nd);

   return (bytesize+0xfffff)/0x100000;   /* size in MiB */
}		 

static int calculate_redundancy(char *image_name)
{  int nr = 0;
   char last = 0; 
   double p;
   int ignore;
   guint64 fs,sectors,filesize;

   if(Closure->redundancy) /* get last char of redundancy parameter */
   {  int len = strlen(Closure->redundancy);

      if(len) last = Closure->redundancy[len-1];
   }

   switch(last)
   {  case '%' : p = atof(Closure->redundancy);
                 if(p<3.2 || p>64.5) Stop(_("Redundancy %4.1f%% out of useful range [3.2%%..64.5%%]"),p);
		 nr = (int)round((GF_FIELDMAX*p) / (100.0+p));
	         break;

      case 'm' : if(!LargeStat(image_name, &filesize))
  	         {  nr = 32;   /* If the image file is not present, simply return 32. */
		    break;     /* Later stages will fail anyways, but can report the error */
	         }             /* in a more meaningful context. */

	         CalcSectors(filesize, &sectors, &ignore);

	         fs = strtoll(Closure->redundancy, NULL, 10);
	         if(fs < ecc_file_size(sectors, 8) || fs > ecc_file_size(sectors, 100))
		   Stop(_("Ecc file size %lldm out of useful range [%lld .. %lld]"),
			fs, ecc_file_size(sectors, 8), ecc_file_size(sectors, 100));
		 for(nr=100; nr>8; nr--)
		   if(fs >= ecc_file_size(sectors, nr))
		     break;
	         break;

      default:
	if(!Closure->redundancy || !strcmp(Closure->redundancy, "normal")) nr = 32; 
	else if(!strcmp(Closure->redundancy, "high")) nr = 64;
	else nr = atoi(Closure->redundancy);
	break;
   }

   if(nr < 8 || nr > 100)
     Stop(_("Redundancy %d out of useful range [8..100]."),nr);

   return nr;
}

/***
 *** Remove the image file 
 ***/

static void unlink_image(GtkWidget *label)
{
   if(LargeUnlink(Closure->imageName))
   {    PrintLog(_("\nImage file %s deleted.\n"),Closure->imageName);

        if(Closure->guiMode)
	  SetLabelText(GTK_LABEL(label),
		       _("\nImage file %s deleted.\n"), Closure->imageName);
   }
   else 
   {    if(!Closure->guiMode)
	  PrintLog("\n");

        ModalWarning(GTK_MESSAGE_ERROR, GTK_BUTTONS_OK, NULL,
		     _("Image file %s not deleted: %s\n"),
		     Closure->imageName, strerror(errno));
   }
}

/***
 *** Create parity information for the medium sectors.
 ***/

/*
 * Local data package used during encoding
 */

typedef struct
{  Method *self;
   RS01Widgets *wl;
   GaloisTables *gt;
   ReedSolomonTables *rt;
   Image *image;
   int earlyTermination;
   unsigned char *data;
   unsigned char *parity;
   char *msg;
   GTimer *timer;
} ecc_closure;

static void ecc_cleanup(gpointer data)
{  ecc_closure *ec = (ecc_closure*)data;

   UnregisterCleanup();

   if(Closure->guiMode)
   {  if(ec->earlyTermination)
        SetLabelText(GTK_LABEL(ec->wl->encFootline),
		     _("<span %s>Aborted by unrecoverable error.</span>"),
		     Closure->redMarkup); 
      AllowActions(TRUE);
   }

   /** Clean up */

   if(ec->gt) FreeGaloisTables(ec->gt);
   if(ec->rt) FreeReedSolomonTables(ec->rt);
   if(ec->data) g_free(ec->data);
   if(ec->parity) g_free(ec->parity);

   if(ec->image) CloseImage(ec->image);
   if(ec->msg)   g_free(ec->msg);
   if(ec->timer) g_timer_destroy(ec->timer);

   if(Closure->enableCurveSwitch)
   {  Closure->enableCurveSwitch = FALSE;
      RS01ShowCurveButton(ec->self);
   }

   g_free(ec);

   if(Closure->guiMode)
      g_thread_exit(0);
}

/*
 * Create the parity file.
 */

enum { NORMAL, HIGH, GENERIC };

void RS01Create(void)
{  Method *self = FindMethod("RS01");
   RS01Widgets *wl = (RS01Widgets*)self->widgetList;
   GaloisTables *gt;
   ReedSolomonTables *rt;
   ecc_closure *ec = g_malloc0(sizeof(ecc_closure));
   struct MD5Context md5Ctxt;
   EccHeader *eh;
   Image *image;
   guint64 block_idx[256];  /* must be >= ndata */
   guint64 s,si,n;
   int i;
   int percent = 0,max_percent,progress = 0, last_percent = -1;
   guint64 n_parity_blocks,n_layer_sectors;
   guint64 n_parity_bytes,n_layer_bytes;
   guint64 chunk;
   int layer;
   int loop_type = GENERIC;
   gint32 nroots;         /* These are copied to increase performance. */
   gint32 ndata;
   gint32 *gf_index_of;
   gint32 *enc_alpha_to;
   gint32 *rs_gpoly;

   /*** Register the cleanup procedure for GUI mode */

   ec->self = self;
   ec->wl = wl;
   ec->earlyTermination = TRUE;
   RegisterCleanup(_("Error correction file creation aborted"), ecc_cleanup, ec);

   /*** Set up the Galois field arithmetic */

   /* Calculate number of roots (= max. number of erasures)
      and number of data bytes from redundancy setting */

   if(!Closure->redundancy || !strcmp(Closure->redundancy, "normal")) 
	                                          loop_type = NORMAL;
   else if(!strcmp(Closure->redundancy, "high"))  loop_type = HIGH;

   i  = calculate_redundancy(Closure->imageName);
   gt = ec->gt = CreateGaloisTables(RS_GENERATOR_POLY);
   rt = ec->rt = CreateReedSolomonTables(gt, RS_FIRST_ROOT, RS_PRIM_ELEM, i);

   nroots       = rt->nroots;
   ndata        = rt->ndata;
   rs_gpoly     = rt->gpoly;
   enc_alpha_to = gt->encAlphaTo;
   gf_index_of  = gt->indexOf;

   /*** Announce what we are going to do */

   ec->msg = g_strdup_printf(_("Encoding with Method RS01: %d roots, %4.1f%% redundancy."),
			     nroots,
			     ((double)nroots*100.0)/(double)ndata);

   if(Closure->guiMode)
     SetLabelText(GTK_LABEL(wl->encHeadline),
		  _("<big>Creating the error correction file.</big>\n<i>%s</i>"), ec->msg);

   /*** Test the image file and create the CRC sums */

   /* Get rid of old ecc file (if any exists) */

   if(LargeStat(Closure->eccName, &n))
   {  
      if(ConfirmEccDeletion(Closure->eccName))
	 LargeUnlink(Closure->eccName);
      else
      {  SetLabelText(GTK_LABEL(ec->wl->encFootline),
		      _("<span %s>Aborted to keep existing ecc file.</span>"),
		      Closure->redMarkup); 
	 ec->earlyTermination = FALSE;
	 goto terminate;
      }
   }

   /* Open image and ecc files */

   PrintLog(_("\nOpening %s"), Closure->imageName);

   image = OpenImageFromFile(Closure->imageName, O_RDONLY, IMG_PERMS);
   ec->image = image;
   if(!image)
   {  PrintLog(": %s.\n", strerror(errno));
      Stop(_("Image file %s: %s."),Closure->imageName, strerror(errno));
   }
   if(image->inLast == 2048)
        PrintLog(_(": %lld medium sectors.\n"), image->sectorSize);
   else PrintLog(_(": %lld medium sectors and %d bytes.\n"), 
		   image->sectorSize-1, image->inLast);

   if(!Closure->eccName || !strlen(Closure->eccName))
     Stop(_("No error correction file specified!\n"));

   image->eccFile = LargeOpen(Closure->eccName, O_RDWR | O_CREAT, IMG_PERMS);
   if(!image->eccFile)
      Stop(_("Can't open %s:\n%s"),Closure->eccName,strerror(errno));

   ec->timer   = g_timer_new();

   if(Closure->crcCache)   /* use CRC values created during last read */
   {  guint32 crc_idx;
      int percent, last_percent = 0;
      char *msg = _("Writing sector checksums: %3d%%");

      if(Closure->guiMode)
	SetLabelText(GTK_LABEL(wl->encLabel1),
		     _("<b>1. Writing image sector checksums:</b>"));

      memcpy(image->mediumSum, Closure->md5Cache, 16);
      MD5Init(&md5Ctxt);    /*  md5sum of CRC portion of ecc file */

      /* Write out the cached CRC sectors */

      if(!LargeSeek(image->eccFile, (gint64)sizeof(EccHeader)))
         Stop(_("Failed skipping the ecc header: %s"),strerror(errno));

      for(crc_idx=0; crc_idx<image->sectorSize; crc_idx+=1024)
      {  int ci,n,size; 
	 guint32 *crcbuf;

	 if(crc_idx + 1024 > image->sectorSize)
	       ci = image->sectorSize - crc_idx;
	 else  ci = 1024;

	 size   = ci*sizeof(guint32);
	 crcbuf = &Closure->crcCache[crc_idx];

	 n = LargeWrite(image->eccFile, crcbuf, size);
	 MD5Update(&md5Ctxt, (unsigned char*)crcbuf, size);

	 if(size != n)
	   Stop(_("Error writing CRC information: %s"), strerror(errno));

         percent = (100*crc_idx)/image->sectorSize;
         if(last_percent != percent) 
         {  PrintProgress(msg,percent);

            if(Closure->guiMode)
	      SetProgress(wl->encPBar1, percent, 100);

	    last_percent = percent;
	 }
      }	    

      PrintProgress(msg, 100);
   }
   else   /* Scan image for missing sectors and calculate the checksums */
   {  if(Closure->guiMode)
       SetLabelText(GTK_LABEL(wl->encLabel1),
		    _("<b>1. Calculating image sector checksums:</b>"));

      RS01ScanImage(self, image, &md5Ctxt, CREATE_CRC);

      if(image->sectorsMissing)
      {  LargeClose(image->eccFile); /* Will be deleted anyways; no need to test for errors */
	 image->eccFile = NULL;

	 LargeUnlink(Closure->eccName);  /* Do not leave a CRC-only .ecc file behind */

	 if(Closure->stopActions)   
	 {
	    if(Closure->stopActions == STOP_CURRENT_ACTION) /* suppress memleak warning when closing window */
	       SetLabelText(GTK_LABEL(wl->encFootline), 
			    _("<span %s>Aborted by user request!</span> (partial error correction file removed)"),
			    Closure->redMarkup); 
	   ec->earlyTermination = FALSE;  /* suppress respective error message */
	   goto terminate;
	 }
	 else 
	 {  if(Closure->guiMode)
	     SetProgress(wl->encPBar1, 100, 100);

	    Stop(_("%lld sectors unread or missing due to errors.\n"), image->sectorsMissing);
	 }
      }
   }

   PrintTimeToLog(ec->timer, "for CRC writing/generation.\n");

   if(Closure->guiMode)
   {  SetProgress(wl->encPBar1, 100, 100);
      ShowWidget(wl->encPBar2);
      ShowWidget(wl->encLabel2);
   }

   if(!Closure->guiMode)
     PrintLog("%s\n",ec->msg);

   /*** Prepare Ecc file header.
        The .eccSum will be filled in after all ecc blocks have been created. */

   image->eccFileHeader = eh = g_malloc0(sizeof(EccHeader));
   memcpy(eh->cookie, "*dvdisaster*", 12);
   memcpy(eh->method, "RS01", 4);
   eh->methodFlags[0] = 1;
   gint64_to_uchar(eh->sectors, image->sectorSize);
   eh->dataBytes       = ndata;
   eh->eccBytes        = nroots;

   eh->creatorVersion  = Closure->version;
   eh->fpSector        = FINGERPRINT_SECTOR;
   eh->inLast          = image->inLast;

   /* dvdisaster 0.66 brings some extensions which are not compatible with
      prior versions. These are:
      - If the methodFlags contains any other bits set than methodFlags[0] == 1,
        prior versions will incorrectly reject ecc files as being produced by
	version 0.40.7 due to a bug in the version processing code.
	So ecc files tagged with -devel or -rc status will not work with prior
	versions. But they are experimental versions available only through CVS, 
	so this issue is not as big as it appears.
      - Version 0.66 records the inLast value in the ecc file to facilitate
        processing non-image files. Previous versions do not use this field
	and may round up file length to the next multiple of 2048 when doing
	error correction.
   */

   if(image->inLast != 2048)
        eh->neededVersion = 6600;
   else eh->neededVersion = 5500;

   memcpy(eh->mediumFP, image->imageFP, 16);
   memcpy(eh->mediumSum, image->mediumSum, 16);

   if(!LargeSeek(image->eccFile, (gint64)sizeof(EccHeader) + image->sectorSize*sizeof(guint32)))
	Stop(_("Failed skipping ecc+crc header: %s"),strerror(errno));

   /*** Allocate buffers for the parity calculation and image data caching. 

        The algorithm builds the parity file consecutively in chunks of n_parity_blocks.
        We use all the amount of memory allowed by cacheMiB for caching the parity blocks. */

   n_parity_blocks = ((guint64)Closure->cacheMiB<<20) / (guint64)nroots;
   n_parity_blocks &= ~0x7ff;                   /* round down to multiple of 2048 */
   n_parity_bytes  = (guint64)nroots * n_parity_blocks;

   /* Each chunk of parity blocks is built iteratively by processing the data in layers
      (first all bytes at pos 0, then pos 1, until ndata layers have been processed).
      So one buffer of n_layer_bytes = n_parity_blocks needs to be buffered.
      For practical reasons we require that the layer size is a multiple of the
      medium sector size of 2048 bytes. */

   n_layer_bytes   = n_parity_blocks;
   n_layer_sectors = n_parity_blocks/2048;

   if(n_layer_sectors*2048 != n_parity_blocks)
     Stop("Internal error: parity blocks are not a multiple of sector size.\n");

   ec->parity = g_try_malloc(n_parity_bytes);
   ec->data   = g_try_malloc(n_layer_bytes);

   if(!ec->parity || !ec->data)
      Stop(_("Failed allocating memory for I/O cache.\n"
	     "Cache size is currently %d MiB.\n"
	     "Try reducing it.\n"),
	   Closure->cacheMiB);

   /*** Setup the block counters for mapping medium sectors to ecc blocks 
        The image is divided into ndata sections;
        with each section spanning s sectors. */

   s = (image->sectorSize+ndata-1)/ndata;

   for(si=0, i=0; i<ndata; si+=s, i++)
     block_idx[i] = si;

   /*** Create ecc information for the medium image. */ 

   max_percent = ndata * ((s / n_layer_sectors) + 1);
   g_timer_start(ec->timer);

   /* Process the image.
      From each section a chunk of n_layer_sectors is read in at once.
      So after (s/n_layer_sectors)+1 iterations the whole image has been processed. */

   for(chunk=0; chunk<s; chunk+=n_layer_sectors) 
   {  guint64 actual_layer_bytes,actual_layer_sectors;

      /* Prepare the parity data for the next chunk. */

      memset(ec->parity, 0, n_parity_bytes);

      /* The last chunk may contain fewer sectors. */

      if(chunk+n_layer_sectors < s)
           actual_layer_sectors = n_layer_sectors;
      else actual_layer_sectors = s-chunk;

      actual_layer_bytes   = 2048*actual_layer_sectors;

      /* Work each of the ndata data layers 
	 into the parity data of the current chunk. */

      switch(loop_type)
      { case NORMAL:  /* Inner loop unrolled for nroots = 32. */
	{int sp=1;    /* sp==1 makes sure sp==0 after ndata bytes [since (223+1) mod 32 = 0]*/
  
         for(layer=0; layer<ndata; layer++)
	 {  int offset = 0;
            unsigned char *par_idx = ec->parity;

	    if(Closure->stopActions) /* User hit the Stop button */
	    {  if(Closure->stopActions == STOP_CURRENT_ACTION) /* suppress memleak warning when closing window */
		  SetLabelText(GTK_LABEL(wl->encFootline), 
			       _("<span %s>Aborted by user request!</span> (partial error correction file removed)"),
			       Closure->redMarkup); 
	       ec->earlyTermination = FALSE;  /* suppress respective error message */
	       LargeClose(image->eccFile);
	       image->eccFile = NULL;
	       LargeUnlink(Closure->eccName); /* Do not leave partial .ecc file behind */
	       goto terminate;
	    }

	    /* Read the next data sectors of this layer. */

	    for(si=0; si<actual_layer_sectors; si++)
	    {  RS01ReadSector(image, ec->data+offset, block_idx[layer]);
	       block_idx[layer]++;
	       offset += 2048;
	    }

	    /* Now process the data bytes of the current layer. */

	    for(si=0; si<actual_layer_bytes; si++)
	    {  register int feedback;

	       feedback = gf_index_of[ec->data[si] ^ par_idx[sp]];

	       if(feedback != GF_ALPHA0) /* non-zero feedback term */
	       {  register int spk = sp;

                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback + 249];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  59];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  66];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +   4];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  43];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback + 126];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback + 251];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  97];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  30];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +   3];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback + 213];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  50];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  66];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback + 170];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +   5];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  24];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +   5];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback + 170];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  66];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  50];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback + 213];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +   3];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  30];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  97];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback + 251];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback + 126];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  43];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +   4];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  66];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback +  59];
                  par_idx[((++spk)&31)] ^= enc_alpha_to[feedback + 249];

		  par_idx[sp] = enc_alpha_to[feedback];  /* feedback + 0 */
	       }
	       else                   /* zero feedback term */
		 par_idx[sp] = 0;

	       par_idx += nroots;
	    }

	    sp = (sp+1) & 31;         /* shift */

	    /* Report progress */

	    progress++;
	    percent = (1000*progress)/max_percent;
	    if(last_percent != percent) 
	    {  if(Closure->guiMode)
	          SetProgress(wl->encPBar2, percent, 1000);
	       else
	          PrintProgress(_("Ecc generation: %3d.%1d%%"), percent/10, percent%10);
	       last_percent = percent;
	    }
	 }
	}
	break;

        case HIGH: /* Inner loop is unrolled for nroots = 64. */
	{int sp=1; /* sp==1 makes sure sp==0 after ndata bytes [since (191+1) mod 64 = 0] */
         for(layer=0; layer<ndata; layer++)
	 {  int offset = 0;
	    unsigned char *par_idx = ec->parity;

	    if(Closure->stopActions) /* User hit the Stop button */
	    {  if(Closure->stopActions == STOP_CURRENT_ACTION) /* suppress memleak warning when closing window */
		  SetLabelText(GTK_LABEL(wl->encFootline), 
			       _("<span %s>Aborted by user request!</span> (partial error correction file removed)"),
			       Closure->redMarkup); 
	       ec->earlyTermination = FALSE;   /* suppress respective error message */
	       LargeClose(image->eccFile);
	       image->eccFile = NULL;
	       LargeUnlink(Closure->eccName);  /* Do not leave partial .ecc file behind */
	       goto terminate;
	    }

	    /* Read the next data sectors of this layer. */

	    for(si=0; si<actual_layer_sectors; si++)
	    {  RS01ReadSector(image, ec->data+offset, block_idx[layer]);
	       block_idx[layer]++;
	       offset += 2048;
	    }

	    /* Now process the data bytes of the current layer. */

	    for(si=0; si<actual_layer_bytes; si++)
	    {  register int feedback;

	       feedback = gf_index_of[ec->data[si] ^ par_idx[sp]];

	       if(feedback != GF_ALPHA0) /* non-zero feedback term */
	       {  register int spk = sp;

                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  98];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 247];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 160];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  15];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  96];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  27];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  87];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 175];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  64];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 170];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  53];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  39];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 236];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  39];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  58];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  82];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  44];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  89];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  97];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 182];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  80];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 120];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  40];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 104];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  73];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  73];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  12];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 152];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 205];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  96];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  50];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  21];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 147];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  35];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 241];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  30];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 242];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 145];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 242];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 115];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 148];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  70];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 127];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  71];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  83];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 172];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 224];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 104];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 177];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +   0];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  39];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 194];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  50];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +   9];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +   0];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 208];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 217];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 254];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 165];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 181];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback + 168];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  97];
                  par_idx[((++spk)&63)] ^= enc_alpha_to[feedback +  45];

                  par_idx[sp] = enc_alpha_to[feedback +  44];
	       }
	       else                   /* zero feedback term */
		 par_idx[sp] = 0;

	       par_idx += nroots;
	    }

	    sp = (sp+1) & 63;         /* shift */

	    /* Report progress */

	    progress++;
	    percent = (1000*progress)/max_percent;
	    if(last_percent != percent) 
	    {  if(Closure->guiMode)
	          SetProgress(wl->encPBar2, percent, 1000);
	       else
	          PrintProgress(_("Ecc generation: %3d.%1d%%"), percent/10, percent%10);
	       last_percent = percent;
	    }
	 }
	}
	break;

        default:   /* general case for nroots other than 32 or 64 */
	{int sp = nroots - ndata % nroots; /* => (ndata + sp) mod nroots = 0 so that parity */
	                                   /* is aligned at sp=0 after ndata iterations */
      	 if(sp==nroots) sp=0;

	 for(layer=0; layer<ndata; layer++)
	 {  int offset = 0;
            unsigned char *par_idx = ec->parity;

	    if(Closure->stopActions) /* User hit the Stop button */
	    {  if(Closure->stopActions == STOP_CURRENT_ACTION) /* suppress memleak warning when closing window */
		  SetLabelText(GTK_LABEL(wl->encFootline), 
			       _("<span %s>Aborted by user request!</span>"),
			       Closure->redMarkup); 
	       ec->earlyTermination = FALSE;   /* suppress respective error message */
	       LargeClose(image->eccFile);
	       image->eccFile = NULL;
	       LargeUnlink(Closure->eccName);  /* Do not leave partial .ecc file behind */
	       goto terminate;
	    }

            /* Read the next data sectors of this layer. */

   	    for(si=0; si<actual_layer_sectors; si++)
	    {  RS01ReadSector(image, ec->data+offset, block_idx[layer]);
	       block_idx[layer]++;
	       offset += 2048;
	    }

	    /* Now process the data bytes of the current layer. */

	    for(si=0; si<actual_layer_bytes; si++)
	    {  register int feedback;

	       feedback = gf_index_of[ec->data[si] ^ par_idx[sp]];

	       if(feedback != GF_ALPHA0) /* non-zero feedback term */
	       {  register int spk = sp+1;
		  register int *gpoly = rs_gpoly + nroots;

		  switch(nroots-spk)
		  {  
		    case 110: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 109: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 108: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 107: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 106: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 105: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 104: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 103: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 102: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 101: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 100: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 99: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 98: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 97: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 96: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 95: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 94: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 93: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 92: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 91: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 90: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 89: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 88: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 87: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 86: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 85: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 84: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 83: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 82: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 81: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 80: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 79: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 78: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 77: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 76: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 75: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 74: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 73: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 72: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 71: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 70: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 69: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 68: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 67: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 66: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 65: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 64: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 63: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 62: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 61: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 60: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 59: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 58: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 57: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 56: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 55: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 54: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 53: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 52: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 51: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 50: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 49: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 48: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 47: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 46: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 45: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 44: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 43: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 42: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 41: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 40: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 39: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 38: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 37: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 36: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 35: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 34: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 33: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 32: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 31: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 30: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 29: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 28: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 27: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 26: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 25: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 24: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 23: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 22: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 21: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 20: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 19: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 18: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 17: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 16: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 15: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 14: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 13: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 12: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 11: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 10: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  9: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  8: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  7: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  6: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  5: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  4: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  3: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  2: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  1: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		  }

		  spk = 0;
		  
		  switch(sp)
		  {
                    case 110: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 109: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 108: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 107: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 106: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 105: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 104: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 103: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 102: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 101: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		    case 100: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 99: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 98: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 97: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 96: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 95: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 94: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 93: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 92: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 91: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 90: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 89: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 88: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 87: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 86: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 85: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 84: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 83: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 82: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 81: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 80: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 79: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 78: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 77: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 76: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 75: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 74: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 73: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 72: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 71: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 70: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 69: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 68: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 67: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 66: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 65: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 64: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 63: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 62: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 61: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 60: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 59: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 58: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 57: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 56: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 55: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 54: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 53: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 52: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 51: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 50: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 49: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 48: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 47: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 46: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 45: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 44: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 43: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 42: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 41: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 40: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 39: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 38: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 37: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 36: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 35: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 34: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 33: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 32: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 31: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 30: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 29: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 28: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 27: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 26: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 25: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 24: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 23: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 22: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 21: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 20: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 19: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 18: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 17: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 16: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 15: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 14: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 13: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 12: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 11: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case 10: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  9: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  8: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  7: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  6: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  5: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  4: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  3: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  2: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		     case  1: par_idx[spk++] ^= enc_alpha_to[feedback + *--gpoly];
		  }

		  par_idx[sp] = enc_alpha_to[feedback + rs_gpoly[0]];
	       }
	       else                   /* zero feedback term */
		 par_idx[sp] = 0;

	       par_idx += nroots;
	    }

	    if(++sp>=nroots) sp=0;   /* shift */

	    /* Report progress */

	    progress++;
	    percent = (1000*progress)/max_percent;
	    if(last_percent != percent) 
	    {  if(Closure->guiMode)
	          SetProgress(wl->encPBar2, percent, 1000);
	       else
	          PrintProgress(_("Ecc generation: %3d.%1d%%"), percent/10, percent%10);
	       last_percent = percent;
	    }
	 }
	}
	break;
      }

      /* Write the nroots bytes of parity information */

      n = LargeWrite(image->eccFile, ec->parity, nroots*actual_layer_bytes);

      if(n != nroots*actual_layer_bytes)
        Stop(_("could not write to ecc file \"%s\":\n%s"),Closure->eccName,strerror(errno));

      MD5Update(&md5Ctxt, ec->parity, nroots*actual_layer_bytes);
   }

   /*** Complete the ecc header and write it out */

   MD5Final(eh->eccSum, &md5Ctxt);

   LargeSeek(image->eccFile, 0);
#ifdef HAVE_BIG_ENDIAN
   SwapEccHeaderBytes(eh);
#endif
   n = LargeWrite(image->eccFile, eh, sizeof(EccHeader));
   if(n != sizeof(EccHeader))
     Stop(_("Can't write ecc header:\n%s"),strerror(errno));

   if(!LargeClose(image->eccFile))
     Stop(_("Error closing error correction file:\n%s"), strerror(errno));
   image->eccFile = NULL;

   PrintTimeToLog(ec->timer, "for ECC generation.\n");

   PrintProgress(_("Ecc generation: 100.0%%\n"));
   PrintLog(_("Error correction file \"%s\" created.\n"
	       "Make sure to keep this file on a reliable medium.\n"),
	     Closure->eccName);
   
   if(Closure->guiMode)
   {  SetProgress(wl->encPBar2, 100, 100);

      SetLabelText(GTK_LABEL(wl->encFootline), 
		   _("The error correction file has been successfully created.\n"
		     "Make sure to keep this file on a reliable medium.")); 
   }

   /*** If the --unlink option or respective GUI switch is set, 
	unlink the image. */

   if(Closure->unlinkImage)
   {  if(ec->image) CloseImage(ec->image);
      ec->image = NULL;
      unlink_image(Closure->guiMode ? wl->encFootline2 : NULL);
   }

   /*** Clean up */

   ec->earlyTermination = FALSE;

terminate:
   ecc_cleanup((gpointer)ec);
}