libmng_read.c

Linux下的基于X11的图形开发环境。

  pBuf += sizeof (mng_chunkid);        /* adjust the buffer */
  iBuflen -= sizeof (mng_chunkid);
                                       /* determine max index of table */
  iTop = (sizeof (chunk_table) / sizeof (chunk_table [0])) - 1;

  /* binary search; with 52 chunks, worst-case is 7 comparisons */
  iLower  = 0;
  iMiddle = 11;                        /* start with the IDAT entry */
  iUpper  = iTop;
  pEntry  = 0;                         /* no goods yet! */
  pChunk  = 0;

  do                                   /* the binary search itself */
    {
      if (chunk_table [iMiddle].iChunkname < iChunkname)
        iLower = iMiddle + 1;
      else if (chunk_table [iMiddle].iChunkname > iChunkname)
        iUpper = iMiddle - 1;
      else
      {
        pEntry = &chunk_table [iMiddle];
        break;
      }

      iMiddle = (iLower + iUpper) >> 1;
    }
  while (iLower <= iUpper);

  if (!pEntry)                         /* unknown chunk ? */
    pEntry = &chunk_unknown;           /* make it so! */

  pData->iChunkname = iChunkname;      /* keep track of where we are */
  pData->iChunkseq++;

  if (pEntry->fRead)                   /* read-callback available ? */
  {
    iRetcode = pEntry->fRead (pData, pEntry, iBuflen, (mng_ptr)pBuf, &pChunk);

    if (!iRetcode)                     /* everything oke ? */
    {                                  /* remember unknown chunk's id */
      if ((pChunk) && (pEntry == &chunk_unknown))
        ((mng_chunk_headerp)pChunk)->iChunkname = iChunkname;
    }
  }
  else
    iRetcode = MNG_NOERROR;

  if (pChunk)                          /* store this chunk ? */
    add_chunk (pData, pChunk);         /* do it */

#ifdef MNG_INCLUDE_JNG                 /* implicit EOF ? */
  if ((!pData->bHasMHDR) && (!pData->bHasIHDR) && (!pData->bHasJHDR))
#else
  if ((!pData->bHasMHDR) && (!pData->bHasIHDR))
#endif
    iRetcode = process_eof (pData);    /* then do some EOF processing */

  if (iRetcode)                        /* on error bail out */
    return iRetcode;

#ifdef MNG_SUPPORT_TRACE
  MNG_TRACE (pData, MNG_FN_PROCESS_RAW_CHUNK, MNG_LC_END)
#endif

  return MNG_NOERROR;
}

/* ************************************************************************** */

mng_retcode read_chunk (mng_datap  pData)
{
  mng_uint32  iBufmax   = pData->iReadbufsize;
  mng_uint8p  pBuf      = pData->pReadbuf;
  mng_uint32  iBuflen   = 0;           /* number of bytes requested */
  mng_uint32  iRead     = 0;           /* number of bytes read */
  mng_uint32  iCrc;                    /* calculated CRC */
  mng_retcode iRetcode  = MNG_NOERROR;

#ifdef MNG_SUPPORT_TRACE
  MNG_TRACE (pData, MNG_FN_READ_CHUNK, MNG_LC_START)
#endif

#ifdef MNG_SUPPORT_DISPLAY
  if (pData->pCurraniobj)              /* processing an animation object ? */
  {
    do                                 /* process it then */
    {
      iRetcode = ((mng_object_headerp)pData->pCurraniobj)->fProcess (pData, pData->pCurraniobj);
                                       /* refresh needed ? */
/*      if ((!iRetcode) && (!pData->bTimerset) && (pData->bNeedrefresh))
        iRetcode = display_progressive_refresh (pData, 1); */
                                       /* can we advance to next object ? */
      if ((!iRetcode) && (pData->pCurraniobj) &&
          (!pData->bTimerset) && (!pData->bSectionwait))
      {
        pData->pCurraniobj = ((mng_object_headerp)pData->pCurraniobj)->pNext;
                                       /* TERM processing to be done ? */
        if ((!pData->pCurraniobj) && (pData->bHasTERM) && (!pData->bHasMHDR))
          iRetcode = process_display_mend (pData);
      }
    }                                  /* until error or a break or no more objects */
    while ((!iRetcode) && (pData->pCurraniobj) &&
           (!pData->bTimerset) && (!pData->bSectionwait) && (!pData->bFreezing));
  }
  else
  {
    if (pData->iBreakpoint)            /* do we need to finish something first ? */
    {
      switch (pData->iBreakpoint)      /* return to broken display routine */
      {
        case 1 : { iRetcode = process_display_fram2 (pData); break; }
        case 2 : { iRetcode = process_display_ihdr  (pData); break; }
        case 3 : ;                     /* same as 4 !!! */
        case 4 : { iRetcode = process_display_show  (pData); break; }
        case 5 : { iRetcode = process_display_clon2 (pData); break; }
#ifdef MNG_INCLUDE_JNG
        case 7 : { iRetcode = process_display_jhdr  (pData); break; }
#endif
        case 6 : ;                     /* same as 8 !!! */
        case 8 : { iRetcode = process_display_iend  (pData); break; }
        case 9 : { iRetcode = process_display_magn2 (pData); break; }
      }
    }
  }

  if (iRetcode)                        /* on error bail out */
    return iRetcode;

#endif /* MNG_SUPPORT_DISPLAY */
                                       /* can we continue processing now, or do we */
                                       /* need to wait for the timer to finish (again) ? */
#ifdef MNG_SUPPORT_DISPLAY
  if ((!pData->bTimerset) && (!pData->bSectionwait) && (!pData->bEOF))
#else
  if (!pData->bEOF)
#endif
  {                                    /* freezing in progress ? */
    if ((pData->bFreezing) && (pData->iSuspendpoint == 0))
      pData->bRunning = MNG_FALSE;     /* then this is the right moment to do it */

    if (pData->iSuspendpoint <= 2)
    {
      iBuflen  = sizeof (mng_uint32);  /* read length */
      iRetcode = read_databuffer (pData, pBuf, iBuflen, &iRead);

      if (iRetcode)                    /* bail on errors */
        return iRetcode;

      if (pData->bSuspended)           /* suspended ? */
        pData->iSuspendpoint = 2;
      else                             /* save the length */
        pData->iChunklen = mng_get_uint32 (pBuf);

    }

    if (!pData->bSuspended)            /* still going ? */
    {                                  /* previously suspended or not eof ? */
      if ((pData->iSuspendpoint > 2) || (iRead == iBuflen))
      {                                /* determine length chunkname + data + crc */
        iBuflen = pData->iChunklen + (mng_uint32)(sizeof (mng_chunkid) + sizeof (iCrc));

        if (iBuflen < iBufmax)         /* does it fit in default buffer ? */
        {                              /* note that we don't use the full size
                                          so there's always a zero-byte at the
                                          very end !!! */
          iRetcode = read_databuffer (pData, pBuf, iBuflen, &iRead);

          if (iRetcode)                /* bail on errors */
            return iRetcode;

          if (pData->bSuspended)       /* suspended ? */
            pData->iSuspendpoint = 3;
          else
          {
            if (iRead != iBuflen)      /* did we get all the data ? */
              iRetcode = MNG_UNEXPECTEDEOF;
            else
            {
              mng_uint32 iL = iBuflen - (mng_uint32)(sizeof (iCrc));
                                       /* calculate the crc */
              iCrc = crc (pData, pBuf, iL);
                                       /* and check it */
              if (!(iCrc == mng_get_uint32 (pBuf + iL)))
                iRetcode = MNG_INVALIDCRC;
              else
                iRetcode = process_raw_chunk (pData, pBuf, iL);
            }
          }
        }
        else
        {
          if (!pData->iSuspendpoint)   /* create additional large buffer ? */
          {                            /* again reserve space for the last zero-byte */
            pData->iLargebufsize = iBuflen + 1;
            MNG_ALLOC (pData, pData->pLargebuf, pData->iLargebufsize)
          }

          iRetcode = read_databuffer (pData, pData->pLargebuf, iBuflen, &iRead);

          if (iRetcode)
            return iRetcode;

          if (pData->bSuspended)       /* suspended ? */
            pData->iSuspendpoint = 4;
          else
          {
            if (iRead != iBuflen)      /* did we get all the data ? */
              iRetcode = MNG_UNEXPECTEDEOF;
            else
            {
              mng_uint32 iL = iBuflen - (mng_uint32)(sizeof (iCrc));
                                       /* calculate the crc */
              iCrc = crc (pData, pData->pLargebuf, iL);
                                       /* and check it */
              if (!(iCrc == mng_get_uint32 (pData->pLargebuf + iL)))
                iRetcode = MNG_INVALIDCRC;
              else
                iRetcode = process_raw_chunk (pData, pData->pLargebuf, iL);
            }
                                       /* cleanup additional large buffer */
            MNG_FREE (pData, pData->pLargebuf, pData->iLargebufsize)
          }  
        }

        if (iRetcode)                  /* on error bail out */
          return iRetcode;

      }
      else
      {                                /* that's final */
        iRetcode = process_eof (pData);

        if (iRetcode)                  /* on error bail out */
          return iRetcode;

        if ((iRead != 0) ||            /* did we get an unexpected eof ? */
#ifdef MNG_INCLUDE_JNG
            (pData->bHasIHDR || pData->bHasMHDR || pData->bHasJHDR))
#else
            (pData->bHasIHDR || pData->bHasMHDR))
#endif
          MNG_ERROR (pData, MNG_UNEXPECTEDEOF);
      } 
    }
  }

#ifdef MNG_SUPPORT_DISPLAY             /* refresh needed ? */
  if ((!pData->bTimerset) && (!pData->bSuspended) && (pData->bNeedrefresh))
  {
    iRetcode = display_progressive_refresh (pData, 1);

    if (iRetcode)                      /* on error bail out */
      return iRetcode;
  }
#endif

#ifdef MNG_SUPPORT_TRACE
  MNG_TRACE (pData, MNG_FN_READ_CHUNK, MNG_LC_END)
#endif

  return MNG_NOERROR;
}

/* ************************************************************************** */

mng_retcode read_graphic (mng_datap pData)
{
  mng_uint32  iBuflen;                 /* number of bytes requested */
  mng_uint32  iRead;                   /* number of bytes read */
  mng_retcode iRetcode;                /* temporary error-code */

#ifdef MNG_SUPPORT_TRACE
  MNG_TRACE (pData, MNG_FN_READ_GRAPHIC, MNG_LC_START)
#endif

  if (!pData->pReadbuf)                /* buffer allocated ? */
  {
    pData->iReadbufsize = 4200;        /* allocate a default read buffer */
    MNG_ALLOC (pData, pData->pReadbuf, pData->iReadbufsize)
  }
                                       /* haven't processed the signature ? */
  if ((!pData->bHavesig) || (pData->iSuspendpoint == 1))
  {
    iBuflen = 2 * sizeof (mng_uint32); /* read signature */

    iRetcode = read_databuffer (pData, pData->pReadbuf, iBuflen, &iRead);

    if (iRetcode)
      return iRetcode;

    if (pData->bSuspended)             /* input suspension ? */
      pData->iSuspendpoint = 1;
    else
    {
      if (iRead != iBuflen)            /* full signature received ? */
        MNG_ERROR (pData, MNG_UNEXPECTEDEOF);
                                       /* is it a valid signature ? */
      if (mng_get_uint32 (pData->pReadbuf) == PNG_SIG)
        pData->eSigtype = mng_it_png;
      else
      if (mng_get_uint32 (pData->pReadbuf) == JNG_SIG)
        pData->eSigtype = mng_it_jng;
      else
      if (mng_get_uint32 (pData->pReadbuf) == MNG_SIG)
        pData->eSigtype = mng_it_mng;
      else
        MNG_ERROR (pData, MNG_INVALIDSIG);
                                       /* all of it ? */
      if (mng_get_uint32 (pData->pReadbuf+4) != POST_SIG)
        MNG_ERROR (pData, MNG_INVALIDSIG);

      pData->bHavesig = MNG_TRUE;
    }
  }

  if (!pData->bSuspended)              /* still going ? */
  {
    do
    {
      iRetcode = read_chunk (pData);   /* process a chunk */

      if (iRetcode)                    /* on error bail out */
        return iRetcode;
    }
#ifdef MNG_SUPPORT_DISPLAY             /* until EOF or a break-request */
    while (((!pData->bEOF) || (pData->pCurraniobj)) && (!pData->bSuspended) &&
           (!pData->bTimerset) && (!pData->bSectionwait));
#else
    while ((!pData->bEOF) && (!pData->bSuspended));
#endif
  }

#ifdef MNG_SUPPORT_TRACE
  MNG_TRACE (pData, MNG_FN_READ_GRAPHIC, MNG_LC_END)
#endif

  return MNG_NOERROR;
}

/* ************************************************************************** */

#endif /* MNG_INCLUDE_READ_PROCS */

/* ************************************************************************** */
/* * end of file                                                            * */
/* ************************************************************************** */