/**********************************************************************
* _E00ReadTestOpen()
*
* Given a pre-initialized E00ReadPtr, this function will make sure
* that the file is really a E00 file, and also establish if it is
* compressed or not... setting the structure members by the same way.
*
* Returns NULL (and destroys the E00ReadPtr) if the file does not
* appear to be a valid E00 file.
**********************************************************************/
static E00ReadPtr _E00ReadTestOpen(E00ReadPtr psInfo)
{
/* Check that the file is in E00 format.
*/
_ReadNextSourceLine(psInfo);
if (!psInfo->bEOF && strncmp(psInfo->szInBuf, "EXP ", 4) == 0)
{
/* We should be in presence of a valid E00 file...
* Is the file compressed or not?
*
* Note: we cannot really rely on the number that follows the EXP to
* establish if the file is compressed since we sometimes encounter
* uncompressed files that start with a "EXP 1" line!!!
*
* The best test is to read the first non-empty line: if the file is
* compressed, the first line of data should be 79 or 80 characters
* long and contain several '~' characters.
*/
do
{
_ReadNextSourceLine(psInfo);
}while(!psInfo->bEOF &&
(psInfo->szInBuf[0] == '\0' || isspace(psInfo->szInBuf[0])) );
if (!psInfo->bEOF &&
(strlen(psInfo->szInBuf)==79 || strlen(psInfo->szInBuf)==80) &&
strchr(psInfo->szInBuf, '~') != NULL )
psInfo->bIsCompressed = 1;
/* Move the Read ptr ready to read at the beginning of the file
*/
E00ReadRewind(psInfo);
}
else
{
CPLFree(psInfo);
psInfo = NULL;
}
return psInfo;
}
CPLErr E00GRIDRasterBand::IReadBlock( CPL_UNUSED int nBlockXOff,
int nBlockYOff,
void * pImage )
{
E00GRIDDataset *poGDS = (E00GRIDDataset *) poDS;
char szVal[E00_FLOAT_SIZE+1];
szVal[E00_FLOAT_SIZE] = 0;
float* pafImage = (float*)pImage;
int* panImage = (int*)pImage;
const float fNoData = static_cast<float>(poGDS->dfNoData);
/* A new data line begins on a new text line. So if the xsize */
/* is not a multiple of VALS_PER_LINE, there are padding values */
/* that must be ignored */
const int nRoundedBlockXSize = ((nBlockXSize + VALS_PER_LINE - 1) /
VALS_PER_LINE) * VALS_PER_LINE;
if (poGDS->e00ReadPtr)
{
if (poGDS->nLastYOff < 0)
{
E00ReadRewind(poGDS->e00ReadPtr);
for(int i=0;i<6;i++)
E00ReadNextLine(poGDS->e00ReadPtr);
}
if (nBlockYOff == poGDS->nLastYOff + 1)
{
}
else if (nBlockYOff <= poGDS->nMaxYOffset)
{
//CPLDebug("E00GRID", "Skip to %d from %d", nBlockYOff, poGDS->nLastYOff);
VSIFSeekL(poGDS->fp, poGDS->panOffsets[nBlockYOff], SEEK_SET);
poGDS->nPosBeforeReadLine = poGDS->panOffsets[nBlockYOff];
poGDS->e00ReadPtr->iInBufPtr = 0;
poGDS->e00ReadPtr->szInBuf[0] = '\0';
}
else if (nBlockYOff > poGDS->nLastYOff + 1)
{
//CPLDebug("E00GRID", "Forward skip to %d from %d", nBlockYOff, poGDS->nLastYOff);
for(int i=poGDS->nLastYOff + 1; i < nBlockYOff;i++)
IReadBlock(0, i, pImage);
}
if (nBlockYOff > poGDS->nMaxYOffset)
{
poGDS->panOffsets[nBlockYOff] = poGDS->nPosBeforeReadLine +
poGDS->e00ReadPtr->iInBufPtr;
poGDS->nMaxYOffset = nBlockYOff;
}
const char* pszLine = NULL;
for(int i=0;i<nBlockXSize;i++)
{
if ((i % VALS_PER_LINE) == 0)
{
pszLine = E00ReadNextLine(poGDS->e00ReadPtr);
if (pszLine == NULL || strlen(pszLine) < 5 * E00_FLOAT_SIZE)
return CE_Failure;
}
if (eDataType == GDT_Float32)
{
pafImage[i] = (float) CPLAtof(pszLine + (i%VALS_PER_LINE) * E00_FLOAT_SIZE);
/* Workaround single vs double precision problems */
if (fNoData != 0 && fabs((pafImage[i] - fNoData)/fNoData) < 1e-6)
pafImage[i] = fNoData;
}
else
{
panImage[i] = atoi(pszLine + (i%VALS_PER_LINE) * E00_FLOAT_SIZE);
}
}
poGDS->nLastYOff = nBlockYOff;
return CE_None;
}
vsi_l_offset nValsToSkip = (vsi_l_offset)nBlockYOff * nRoundedBlockXSize;
vsi_l_offset nLinesToSkip = nValsToSkip / VALS_PER_LINE;
int nBytesPerLine = VALS_PER_LINE * E00_FLOAT_SIZE + poGDS->nBytesEOL;
vsi_l_offset nPos = poGDS->nDataStart + nLinesToSkip * nBytesPerLine;
VSIFSeekL(poGDS->fp, nPos, SEEK_SET);
for(int i=0;i<nBlockXSize;i++)
{
if (VSIFReadL(szVal, E00_FLOAT_SIZE, 1, poGDS->fp) != 1)
return CE_Failure;
if (eDataType == GDT_Float32)
{
pafImage[i] = (float) CPLAtof(szVal);
/* Workaround single vs double precision problems */
if (fNoData != 0 && fabs((pafImage[i] - fNoData)/fNoData) < 1e-6)
pafImage[i] = fNoData;
}
else
{
panImage[i] = atoi(szVal);
}
if (((i+1) % VALS_PER_LINE) == 0)
VSIFReadL(szVal, poGDS->nBytesEOL, 1, poGDS->fp);
}
return CE_None;
}
