Re: Fast copy of buffer data into a matrix

[John Swensen]

Muthiah Annamalai wrote:
> I think theres something like a 
>
> double *val = ret_img.fortran_vec(); // in this case for Matrix,
> what I gather from looking at liboctave/Marray2.cc|h &
> liboctave/MArray-defs.h (where operator macros live).
>
> -Muthiah
>
>   
> > I have searched around a bit, but can't find a way of just doing a 
> > memcpy into the Matrix object, rather than my slow existing 
> > implementation.  Any suggestions?
> >
> > John Swensen
> > _______________________________________________
> > Help-octave mailing list
> > address@hidden
> > https://www.cae.wisc.edu/mailman/listinfo/help-octave
> >     
FYI, here is how I ended up copying a unsigned char buffer into a Matrix 
of type uint8.  It ended up taking about 50% of the time of doing it 
element by element.

static Matrix m1(settings.width, settings.height);
static uint8NDArray m = octave_value(m1).uint8_array_value();
static octave_uint8* tmp = m.fortran_vec();
memcpy( tmp, capturebuffer, settings.height*settings.width );
return octave_value(m.transpose());   

As a side note, when using mkoctfile with the -p option, is there any 
way to get a complete list of all the include flags and all the ld 
flags?  I need to link with a static library and mkoctfile won't allow 
me to specify a 'libfoo.a' file in the list of object files.  So, I need 
to build the link up and would like to use 'mkoctfile -p', but don't 
want to have it start looking like 'mkoctfile -p LDFLAGS LD_CXX 
LD_STATIC_FLAG LIBS LFLAGS LIBCRUFT LIBOCTAVE LIBOCTINTERP ETC'

John Swensen