/*  dvdisaster: Additional error correction for optical media.
 *  Copyright (C) 2004-2010 Carsten Gnoerlich.
 *  Project home page: http://www.dvdisaster.com
 *  Email: carsten@dvdisaster.com  -or-  cgnoerlich@fsfe.org
 *
 *  This program 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 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program 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 this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA,
 *  or direct your browser at http://www.gnu.org.
 */

#include "dvdisaster.h"

#include "rs03-includes.h"


/***
 *** Read one or more image sectors from the .iso file.
 ***/

void RS03ReadSectors(LargeFile *file, RS03Layout *lay, unsigned char *buf, 
		     gint64 layer, gint64 layer_sector, gint64 how_many, int flags)
{  gint64 start_sector=0;
   gint64 stop_sector=0;
   gint64 byte_size = how_many * 2048;
   gint64 n;

   if(layer < 0 || layer > 255) 
      Stop("RS03ReadSectors: layer %lld out of range 0 .. 255\n", layer);
   if(layer_sector < 0 || layer_sector >= lay->sectorsPerLayer) 
      Stop("RS03ReadSectors: offset %lld out of range 0 .. %lld)\n",
	   layer_sector, lay->sectorsPerLayer-1);

   /* Read out of the data layer */

   if(layer < lay->ndata-1)
   {  if(!(flags & RS03_READ_DATA))
	 Stop("RS03ReadSectors: trying to read data layer, but flag not set\n");
      
      start_sector = layer*lay->sectorsPerLayer + layer_sector;
      stop_sector  = start_sector + how_many - 1;

      if(stop_sector >= (layer+1)*lay->sectorsPerLayer)
	Stop("RS03ReadSectors: range %lld..%lld crosses layer boundary\n",
	     start_sector, stop_sector);

      /* Padding sectors are virtual in ecc file case.
         Create them in memory; shorten read range accordingly */

      if(lay->target == ECC_FILE)
      {  unsigned char *bufptr = buf;

	 for(n=start_sector; n<=stop_sector; n++)
	 {  
	    if(n>=lay->dataSectors)
	    {  CreatePaddingSector(bufptr, n, lay->eh->mediumFP, FINGERPRINT_SECTOR);
	       byte_size -= 2048;
	    }
	    bufptr += 2048;
	 }
      }
   }

   /* Read out of the crc layer */

   if(layer == lay->ndata-1)
   {  if(!(flags & RS03_READ_CRC))
	 Stop("RS03ReadSectors: trying to read crc layer, but flag not set\n");

      start_sector = lay->firstCrcPos + layer_sector;
      stop_sector  = start_sector + how_many - 1;
   }

   /*** Read out of the ecc layers */

   if(layer >= lay->ndata)
   {  if(!(flags & RS03_READ_ECC))
	 Stop("RS03ReadSectors: trying to read ecc layer, but flag not set\n");

      start_sector = lay->firstEccPos + (layer-lay->ndata)*lay->sectorsPerLayer + layer_sector;
      stop_sector  = start_sector + how_many - 1;
   }

   /* All sectors are consecutively readable in image case */

   if(!LargeSeek(file, (gint64)(2048*start_sector)))
      Stop(_("Failed seeking to sector %lld in image: %s"),
	   start_sector, strerror(errno));

   n = LargeRead(file, buf, byte_size);
   if(n != byte_size)
      Stop(_("Failed reading sector %lld in image: %s"),
	   start_sector, strerror(errno));
}

/***
 *** Calculate position of n-th sector of the given layer in the image.
 ***/

gint64 RS03SectorIndex(RS03Layout *lay, gint64 layer, gint64 n)
{  
   if(lay->target == ECC_IMAGE)
      return layer*lay->sectorsPerLayer+n;

   /* Image portion in ecc file case */

   if(layer < lay->ndata-1)
      return layer*lay->sectorsPerLayer+n;

   /* Layers located in the ecc file */

   if(layer == lay->ndata-1) /* CRC layer */
      return lay->firstCrcPos + n;

   /* Ecc layers */

   return lay->firstEccPos + (layer-lay->ndata)*lay->sectorsPerLayer + n;
}


/***
 *** Calculation of the image layout
 ***/

static int get_roots(gint64 data_sectors, gint64 medium_capacity)
{  gint64 sectors_per_layer = medium_capacity/GF_FIELDMAX;
   int ndata = (data_sectors + 2 +sectors_per_layer - 1) / sectors_per_layer;

   return GF_FIELDMAX - ndata - 1;
}

static gint64 ecc_file_size(gint64 sectors, int nr)
{  int nd = GF_FIELDMAX - nr;
   gint64 bytesize; 

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

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


RS03Layout *CalcRS03Layout(gint64 data_sectors, EccHeader *eh, int target)
{  RS03Layout *lay = g_malloc0(sizeof(RS03Layout));

   lay->eh = eh;
   lay->target = target;

   /* We are going to create an error correction file */

   if(target == ECC_FILE)
   {  gint64 filesize;
      int n_roots = 0;
      char last = 0;

      if(eh)  /* Header given; get number of roots from there */
      {  n_roots = eh->eccBytes;
	 lay->dataSectors = uchar_to_gint64(eh->sectors);
	 lay->inLast = eh->inLast;
      }
      else    /* Calculate number of roots */
      {
	 /* Calculate image size in sectors */

	 if(!LargeStat(Closure->imageName, &filesize))
	    Stop(_("Image file %s not present."),Closure->imageName);

	 CalcSectors(filesize, (gint64*)&lay->dataSectors, &lay->inLast);

	 /* Calculate wanted redundancy from Closure->redundancy */

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

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

	 switch(last)
	 {  case '%': 
	    {  double p = atof(Closure->redundancy);

	       if(p<3.2 || p>200.0)
		  Stop(_("Redundancy %4.1f%% out of useful range [3.2%%..200%%]"),p);
	       n_roots = (int)round((GF_FIELDMAX*p) / (100.0+p));
	       break;
	    }
	    case 'm': 
	    {  gint64 ecc_size;

	       ecc_size = strtoll(Closure->redundancy, NULL, 10);
	       if(   ecc_size < ecc_file_size(lay->dataSectors, 8) 
		  || ecc_size > ecc_file_size(lay->dataSectors, 170))
		  Stop(_("Ecc file size %lldm out of useful range [%lld .. %lld]"),
		       ecc_size, 
		       ecc_file_size(lay->dataSectors, 8), 
		       ecc_file_size(lay->dataSectors, 170));

	       for(n_roots=170; n_roots>8; n_roots--)
		  if(ecc_size >= ecc_file_size(lay->dataSectors, n_roots))
		     break;
	       break;
	    }

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

      if(n_roots < 8 || n_roots > 170)
	 Stop(_("Redundancy %d out of useful range [8..170]."),n_roots);

      /* Now we have settled for the number of roots,
	 so calculate the layout. */

      lay->dataPadding = 0; /* always zero for ecc files */
      lay->nroots = n_roots;
      lay->ndata = GF_FIELDMAX - n_roots;

      lay->sectorsPerLayer = (lay->dataSectors + lay->ndata - 2)/(lay->ndata-1);
      lay->totalSectors = 2 + (lay->nroots+1)*lay->sectorsPerLayer;

      lay->mediumCapacity   = 0;  /* unused for ecc files */
      lay->eccHeaderPos     = 0;
      lay->firstCrcPos      = 2;
      lay->firstEccPos      = lay->firstCrcPos + lay->sectorsPerLayer;
      lay->redundancy = ((double)lay->nroots*100.0)/(double)lay->ndata;
   }

   /* We are going to augment an image file */

   if(target == ECC_IMAGE)         
   {
      /* Determine smallest possible medium format which
	 can hold the image plus at least 8 roots for ecc.
	 Overriding the medium size via --debug is not recommended
	 as it may render the image irrecoverable in the error case. */

      if(!eh)
      { 
	 if(Closure->debugMode && Closure->mediumSize)
	    lay->mediumCapacity = Closure->mediumSize;
	 else
	 {  if(get_roots(data_sectors, CDR_SIZE) >= 8)
	       lay->mediumCapacity = CDR_SIZE;          /* CDR */
	    else if(get_roots(data_sectors, DVD_SL_SIZE) >= 8)
	       lay->mediumCapacity = DVD_SL_SIZE;       /* Single layered DVD */
	    else if(get_roots(data_sectors, DVD_DL_SIZE) >= 8)
	       lay->mediumCapacity = DVD_DL_SIZE;       /* Double layered DVD */
	    else if(get_roots(data_sectors, BD_SL_SIZE) >= 8)
	       lay->mediumCapacity = BD_SL_SIZE;        /* Single layered BD */
	    else  lay->mediumCapacity = BD_DL_SIZE;     /* Double layered BD */
	 }
      }

      /* Calculate the image layout */

      if(eh) lay->sectorsPerLayer = eh->sectorsPerLayer;
      else   lay->sectorsPerLayer = lay->mediumCapacity/GF_FIELDMAX;
      lay->dataSectors      = data_sectors;
      lay->totalSectors     = GF_FIELDMAX*lay->sectorsPerLayer;
      
      lay->ndata       = (data_sectors + 2 + lay->sectorsPerLayer - 1) / lay->sectorsPerLayer;
      if(lay->ndata < 84) /* we clip redundancy at 170 roots */
      {  Verbose("Redundancy clipped from %d to %d\n", lay->ndata, 84);
	 lay->ndata = 84;
      }	 
      lay->dataPadding = lay->ndata * lay->sectorsPerLayer - lay->dataSectors - 2;
      lay->ndata++;    /* CRC layer is also protected and counted as part of the data portion */
      lay->nroots      = GF_FIELDMAX-lay->ndata; 
      lay->redundancy = ((double)lay->nroots*100.0)/(double)lay->ndata;
      
      lay->eccHeaderPos     = lay->dataSectors;
      lay->firstCrcPos      = (lay->ndata-1)*lay->sectorsPerLayer;
      lay->firstEccPos      = lay->firstCrcPos + lay->sectorsPerLayer;
   }

   /* Debugging output */

   if(target == ECC_FILE)
        Verbose("Calculated layout for RS03 file:\n");
   else Verbose("Calculated layout for RS03 image:\n");
   
   Verbose("data sectors      = %lld\n", lay->dataSectors);
   Verbose("data padding      = %lld\n", lay->dataPadding);
   Verbose("layer size        = %lld\n", lay->sectorsPerLayer);
   Verbose("total sectors     = %lld\n", lay->totalSectors);
   Verbose("medium capacity   = %lld\n", lay->mediumCapacity);
   Verbose("header position   = %lld\n", lay->eccHeaderPos);
   Verbose("first CRC sector  = %lld\n", lay->firstCrcPos);
   Verbose("first ECC sector  = %lld\n", lay->firstEccPos);
   Verbose("ndata             = %d\n", lay->ndata);
   Verbose("nroots            = %d (%4.1f%%)\n", lay->nroots, lay->redundancy);
   Verbose("\n");

   return lay;
}

/***
 *** Write the RS03 header into the image.
 ***/

void WriteRS03Header(LargeFile *file, RS03Layout *lay, EccHeader *eh)
{  int n;

   if(!LargeSeek(file, 2048*lay->eccHeaderPos))
     Stop(_("Failed seeking to ecc header at %lld: %s\n"), lay->eccHeaderPos, strerror(errno));
   
   n = LargeWrite(file, eh, sizeof(EccHeader));
   if(n != sizeof(EccHeader))
     Stop(_("Failed writing ecc header at %lld: %s\n"), lay->eccHeaderPos, strerror(errno));
}

/***
 *** Reconstruct the RS03 header from a CRC block 
 ***/

void ReconstructRS03Header(EccHeader *eh, CrcBlock *cb)
{  int i;

   memset(eh, 0, sizeof(EccHeader));

   memcpy(eh->cookie, "*dvdisaster*", 12);
   memcpy(eh->method, "RS03", 4);
   for(i=0; i<4; i++)
      eh->methodFlags[i] = cb->methodFlags[i];
   memcpy(eh->mediumFP, cb->mediumFP, 16);
   memcpy(eh->mediumSum, cb->mediumSum, 16);
   gint64_to_uchar(eh->sectors, cb->dataSectors);
   eh->dataBytes = cb->dataBytes;
   eh->eccBytes = cb->eccBytes;
   eh->creatorVersion = cb->creatorVersion;
   eh->neededVersion = cb->neededVersion;
   eh->fpSector = cb->fpSector;
   eh->inLast = cb->inLast;
   eh->sectorsPerLayer = cb->sectorsPerLayer;

   eh->selfCRC = 0x4c5047;

#ifdef HAVE_BIG_ENDIAN
   SwapEccHeaderBytes(eh);
   eh->selfCRC = 0x47504c00;
#endif

   eh->selfCRC = Crc32((unsigned char*)eh, 4096);
}