Hi, Zhongbo,
Thanks for the report of the bug. Looks like I have relied a little
too much on copy-and-paste in this case. I would like to continue to
use memcpy in cases where the internal data type matches the output
data type, and have adopted your suggestion of using std::copy for the
remaining cases.
The update source code is in SVN as revision 718. Please give it a
try and feel free to let me know if you spot any problems.
Thanks again.
John
On 5/15/14, 3:24 AM, 田忠博(Zhongbo Tian) wrote:
> Hi John and everyone,
>
> My Python extension use ibis::table::getColumnAsXXX API to retrive
> column from a fastbit table as a NumPy array. But the array is filled
> by random numbers at the end while the data is correct at the
> beginning. After examining the code, I found a possible bug in
> mensa.cpp. for example, in this snippet:
>
> array_t<signed char> tmp;
> uint64_t ival = 0;
> uint64_t irow = 0;
> for (ibis::partList::const_iterator it = parts.begin();
> it != parts.end() && irow < end; ++ it) {
> const ibis::part& dp = **it;
> if (irow + dp.nRows() > begin) {
> const ibis::column* col = dp.getColumn(cn);
> if (col == 0)
> return -3;
> if (col->getValuesArray(&tmp) < 0)
> return -4;
>
> const size_t i0 = (begin > irow ? begin - irow : 0);
> const size_t i1 = (end>=irow+dp.nRows() ? dp.nRows() :
> end-irow) - i0;
> memcpy(vals+ival, tmp.begin()+i0, i1);
> ival += i1;
> }
> irow += dp.nRows();
> }
>
> The use of memcpy is the root of the issue, memcpy is valid only when
> dest and source have the same width. I guess we should use std::copy
> here. And std::copy can avoid us all the casting troubles.
> Finally, I just do a tiny refactor to remove some duplicate code, and
> the patch is attached as following.
>
> Please review my patch, and merge it if it is the right.
>
> Thank you.
>
>
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