libmng_chunk_io.c

奇趣公司比较新的qt/emd版本

                                 mng_int32  iLen)
{
#ifdef MNG_USE_ZLIB_CRC
  return crc32 (iCrc, pBuf, iLen);
#else
  mng_uint32 iC = iCrc;
  mng_int32 iN;

  if (!pData->bCRCcomputed)
    make_crc_table (pData);

  for (iN = 0; iN < iLen; iN++)
    iC = pData->aCRCtable [(iC ^ pBuf [iN]) & 0xff] ^ (iC >> 8);

  return iC;
#endif
}

/* Return the CRC of the bytes buf[0..len-1]. */
mng_uint32 mng_crc (mng_datap  pData,
                    mng_uint8p pBuf,
                    mng_int32  iLen)
{
#ifdef MNG_USE_ZLIB_CRC
  return update_crc (pData, 0, pBuf, iLen);
#else
  return update_crc (pData, 0xffffffffU, pBuf, iLen) ^ 0xffffffffU;
#endif
}

/* ************************************************************************** */
/* *                                                                        * */
/* * Routines for swapping byte-order from and to graphic files             * */
/* * (This code is adapted from the libpng package)                         * */
/* *                                                                        * */
/* ************************************************************************** */

#ifndef MNG_BIGENDIAN_SUPPORTED

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

mng_uint32 mng_get_uint32 (mng_uint8p pBuf)
{
   mng_uint32 i = ((mng_uint32)(*pBuf)       << 24) +
                  ((mng_uint32)(*(pBuf + 1)) << 16) +
                  ((mng_uint32)(*(pBuf + 2)) <<  8) +
                   (mng_uint32)(*(pBuf + 3));
   return (i);
}

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

mng_int32 mng_get_int32 (mng_uint8p pBuf)
{
   mng_int32 i = ((mng_int32)(*pBuf)       << 24) +
                 ((mng_int32)(*(pBuf + 1)) << 16) +
                 ((mng_int32)(*(pBuf + 2)) <<  8) +
                  (mng_int32)(*(pBuf + 3));
   return (i);
}

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

mng_uint16 mng_get_uint16 (mng_uint8p pBuf)
{
   mng_uint16 i = (mng_uint16)(((mng_uint16)(*pBuf) << 8) +
                                (mng_uint16)(*(pBuf + 1)));
   return (i);
}

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

void mng_put_uint32 (mng_uint8p pBuf,
                     mng_uint32 i)
{
   *pBuf     = (mng_uint8)((i >> 24) & 0xff);
   *(pBuf+1) = (mng_uint8)((i >> 16) & 0xff);
   *(pBuf+2) = (mng_uint8)((i >> 8) & 0xff);
   *(pBuf+3) = (mng_uint8)(i & 0xff);
}

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

void mng_put_int32 (mng_uint8p pBuf,
                    mng_int32  i)
{
   *pBuf     = (mng_uint8)((i >> 24) & 0xff);
   *(pBuf+1) = (mng_uint8)((i >> 16) & 0xff);
   *(pBuf+2) = (mng_uint8)((i >> 8) & 0xff);
   *(pBuf+3) = (mng_uint8)(i & 0xff);
}

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

void mng_put_uint16 (mng_uint8p pBuf,
                     mng_uint16 i)
{
   *pBuf     = (mng_uint8)((i >> 8) & 0xff);
   *(pBuf+1) = (mng_uint8)(i & 0xff);
}

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

#endif /* !MNG_BIGENDIAN_SUPPORTED */

/* ************************************************************************** */
/* *                                                                        * */
/* * Helper routines to simplify chunk-data extraction                      * */
/* *                                                                        * */
/* ************************************************************************** */

#ifdef MNG_INCLUDE_READ_PROCS

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

#ifndef MNG_OPTIMIZE_CHUNKREADER
MNG_LOCAL mng_uint8p find_null (mng_uint8p pIn)
{
  mng_uint8p pOut = pIn;
  while (*pOut)                        /* the read_graphic routine has made sure there's */
    pOut++;                            /* always at least 1 zero-byte in the buffer */
  return pOut;
}
#endif

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

#if !defined(MNG_SKIPCHUNK_iCCP) || !defined(MNG_SKIPCHUNK_zTXt) || !defined(MNG_SKIPCHUNK_iTXt)
mng_retcode mng_inflate_buffer (mng_datap  pData,
                                mng_uint8p pInbuf,
                                mng_uint32 iInsize,
                                mng_uint8p *pOutbuf,
                                mng_uint32 *iOutsize,
                                mng_uint32 *iRealsize)
{
  mng_retcode iRetcode = MNG_NOERROR;

#ifdef MNG_SUPPORT_TRACE
  MNG_TRACE (pData, MNG_FN_INFLATE_BUFFER, MNG_LC_START);
#endif

  if (iInsize)                         /* anything to do ? */
  {
    *iOutsize = iInsize * 3;           /* estimate uncompressed size */
                                       /* and allocate a temporary buffer */
    MNG_ALLOC (pData, *pOutbuf, *iOutsize);

    do
    {
      mngzlib_inflateinit (pData);     /* initialize zlib */
                                       /* let zlib know where to store the output */
      pData->sZlib.next_out  = *pOutbuf;
                                       /* "size - 1" so we've got space for the
                                          zero-termination of a possible string */
      pData->sZlib.avail_out = *iOutsize - 1;
                                       /* ok; let's inflate... */
      iRetcode = mngzlib_inflatedata (pData, iInsize, pInbuf);
                                       /* determine actual output size */
      *iRealsize = (mng_uint32)pData->sZlib.total_out;

      mngzlib_inflatefree (pData);     /* zlib's done */

      if (iRetcode == MNG_BUFOVERFLOW) /* not enough space ? */
      {                                /* then get some more */
        MNG_FREEX (pData, *pOutbuf, *iOutsize);
        *iOutsize = *iOutsize + iInsize;
        MNG_ALLOC (pData, *pOutbuf, *iOutsize);
      }
    }                                  /* repeat if we didn't have enough space */
    while ((iRetcode == MNG_BUFOVERFLOW) &&
           (*iOutsize < 20 * iInsize));

    if (!iRetcode)                     /* if oke ? */
      *((*pOutbuf) + *iRealsize) = 0;  /* then put terminator zero */

  }
  else
  {
    *pOutbuf   = 0;                    /* nothing to do; then there's no output */
    *iOutsize  = 0;
    *iRealsize = 0;
  }

#ifdef MNG_SUPPORT_TRACE
  MNG_TRACE (pData, MNG_FN_INFLATE_BUFFER, MNG_LC_END);
#endif

  return iRetcode;
}
#endif

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

#endif /* MNG_INCLUDE_READ_PROCS */

/* ************************************************************************** */
/* *                                                                        * */
/* * Helper routines to simplify chunk writing                              * */
/* *                                                                        * */
/* ************************************************************************** */
#ifdef MNG_INCLUDE_WRITE_PROCS
/* ************************************************************************** */

#if !defined(MNG_SKIPCHUNK_iCCP) || !defined(MNG_SKIPCHUNK_zTXt) || !defined(MNG_SKIPCHUNK_iTXt)
MNG_LOCAL mng_retcode deflate_buffer (mng_datap  pData,
                                      mng_uint8p pInbuf,
                                      mng_uint32 iInsize,
                                      mng_uint8p *pOutbuf,
                                      mng_uint32 *iOutsize,
                                      mng_uint32 *iRealsize)
{
  mng_retcode iRetcode = MNG_NOERROR;

#ifdef MNG_SUPPORT_TRACE
  MNG_TRACE (pData, MNG_FN_DEFLATE_BUFFER, MNG_LC_START);
#endif

  if (iInsize)                         /* anything to do ? */
  {
    *iOutsize = (iInsize * 5) >> 2;    /* estimate compressed size */
                                       /* and allocate a temporary buffer */
    MNG_ALLOC (pData, *pOutbuf, *iOutsize);

    do
    {
      mngzlib_deflateinit (pData);     /* initialize zlib */
                                       /* let zlib know where to store the output */
      pData->sZlib.next_out  = *pOutbuf;
      pData->sZlib.avail_out = *iOutsize;
                                       /* ok; let's deflate... */
      iRetcode = mngzlib_deflatedata (pData, iInsize, pInbuf);
                                       /* determine actual output size */
      *iRealsize = pData->sZlib.total_out;

      mngzlib_deflatefree (pData);     /* zlib's done */

      if (iRetcode == MNG_BUFOVERFLOW) /* not enough space ? */
      {                                /* then get some more */
        MNG_FREEX (pData, *pOutbuf, *iOutsize);
        *iOutsize = *iOutsize + (iInsize >> 1);
        MNG_ALLOC (pData, *pOutbuf, *iOutsize);
      }
    }                                  /* repeat if we didn't have enough space */
    while (iRetcode == MNG_BUFOVERFLOW);
  }
  else
  {
    *pOutbuf   = 0;                    /* nothing to do; then there's no output */
    *iOutsize  = 0;
    *iRealsize = 0;
  }

#ifdef MNG_SUPPORT_TRACE
  MNG_TRACE (pData, MNG_FN_DEFLATE_BUFFER, MNG_LC_END);
#endif

  return iRetcode;
}
#endif

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

MNG_LOCAL mng_retcode write_raw_chunk (mng_datap   pData,
                                       mng_chunkid iChunkname,
                                       mng_uint32  iRawlen,
                                       mng_uint8p  pRawdata)
{
  mng_uint32 iCrc;
  mng_uint32 iWritten;

#ifdef MNG_SUPPORT_TRACE
  MNG_TRACE (pData, MNG_FN_WRITE_RAW_CHUNK, MNG_LC_START);
#endif
                                       /* temporary buffer ? */
  if ((pRawdata != 0) && (pRawdata != pData->pWritebuf+8))
  {                                    /* store length & chunktype in default buffer */
    mng_put_uint32 (pData->pWritebuf,   iRawlen);
    mng_put_uint32 (pData->pWritebuf+4, (mng_uint32)iChunkname);

    if (pData->iCrcmode & MNG_CRC_OUTPUT)
    {
      if ((pData->iCrcmode & MNG_CRC_OUTPUT) == MNG_CRC_OUTPUT_GENERATE)
      {                                /* calculate the crc */
        iCrc = update_crc (pData, 0xffffffffL, pData->pWritebuf+4, 4);
        iCrc = update_crc (pData, iCrc, pRawdata, iRawlen) ^ 0xffffffffL;
      } else {
        iCrc = 0;                      /* dummy crc */
      }                                /* store in default buffer */
      mng_put_uint32 (pData->pWritebuf+8, iCrc);
    }
                                       /* write the length & chunktype */
    if (!pData->fWritedata ((mng_handle)pData, pData->pWritebuf, 8, &iWritten))
      MNG_ERROR (pData, MNG_APPIOERROR);

    if (iWritten != 8)                 /* disk full ? */