From: barabba <igor.sarzisartori@...>
Date: 2007-03-15T06:50:09+09:00
Subject: Re: SWIG typemap for ta-lib

On Mar 14, 11:45 am, "BENI" <rajib.chakraba...@googlemail.com> wrote:
> Thanks for your lead.
> It is lot clear now ... how to go about it.
> Still I am fuzzy on a couple of things.
> Could you pl guide....
>
>
>
> > in ruby use it as
> > closePrice = Array.new(<your data>)
> > data_inp = closePrice[0..399]
> > data_arr =  ModuleExp::TA_MA( data_inp, 30, ModuleExp::TA_MAType_SMA)
>
> So are you suggesting that i need not pass startIdx,endIdx in the
> input. But these values I understand is required .. this is to
> sometimes specify a range on which to run the function .
> What I am confused about is ...ModuleExp::TA_MAType_SMA... is this a
> constant that you are suggesting to pass along?
>
>
>
>
>
> > In .i file you should define
> > %typemap(in)(int          startIdx,
> >                    int          endIdx,
> >                    const double inReal[]
> >              )
> > {
>
> >        Check_Type($input, T_ARRAY);
>
> >     /* Get the length of the array */
> >     int size = RARRAY($input)->len;
> >     int i;
> >     $3 = (unsigned char*) malloc(size * sizeof(double));
> >     $2 = size;
> >     $1 = 0;
>
> >     // copy the ruby array in the new allocated buffer
> >     /* Get the first element in memory */
> >     VALUE *ptr = RARRAY($input)->ptr;
> >     for (i=0; i < size; i++, ptr++)
> >     {
> >         /* Convert Ruby Object Fixnum to unsigned char */
> >         $1[i]= (double)?????(*ptr); // here i don't remember the macro
> > to convert something like FIX2INT for float
> >     }
>
> here I used  $1[i]= NUM2DBL(*ptr);
> is that OK?
>
> > }
>
> > %typemap(in)(int          optInMAType,
> >                  int         *outBegIdx,
> >                    int         *outNbElement,
> >                    double       outReal[]
> >              )
> > {
> >    int out_beg_ix = 0;
> >    int out_n_ele = 0;
> >    double arr_res[400];
>
> Here I need to dimensionise the arr_res  to the size of the input
> array instead of 400. So i need to get the size variable  in the
> previous typemap declaration. But how can i use the size variable
> here... it was a local variable only.
>
>
>
>
>
> >    $1 = NUM2INT(optInMAType);
> >    $2 = &out_beg_ix;
> >    $3 = &out_n_ele;
> >    &4 = arr_res;
>
> > }
>
> > %typemap(freearg) (int          startIdx,
> >                    int          endIdx,
> >                    const double inReal[],
> >                    int          optInTimePeriod,
> >                    int          optInMAType,
> >                    int         *outBegIdx,
> >                    int         *outNbElement,
> >                    double       outReal[]) {
> >     free((double *) $1);
> > }
>
> > %typemap(out)TA_RetCode TA_MA( int          startIdx,
> >                    int          endIdx,
> >                    const double inReal[],
> >                    int          optInTimePeriod,
> >                    int          optInMAType,
> >                    int         *outBegIdx,
> >                    int         *outNbElement,
> >                    double       outReal[])
>
> I did not get this one clearly.... TA_Retcode is the output type.
> Can't i  get it in ruby?Only thing that i am getting back here is the
> outReal[] array i think.
>
> > {
>
> >        int iStartIx = *arg6;
> >        int iLen = iStartIx + *arg7;
>
> >         VALUE arr = rb_ary_new2(iLen);
>
> >         for ( int i = iStartIx; i < iLen;  i++ )
> >             rb_ary_push(arr, INT2FIX((*arg8)[i]));
> >         $result = arr;
>
> the *arg8  contains floating point number so will  INT2FIX work?
>
> > }
>
> > it is not tested but this give you the idea how to make the i file.
>
> > Regards
>
> Thanks again ..
>
> Regards

Sorry for some errors.
Your questions.
If you use TA_MAType_SMA in the C function and you want to use it
also in ruby, you have to export it.
In Ruby I like to use  all input parameters as function parameters.
Out parameters on the left side as result. If you are also interested
an TA_Retcode you have to change the typemap(out). Afterwards you can
use in ruby this:
ta_res, data_arr_out =  ModuleExp::TA_MA( data_inp, 30,
ModuleExp::TA_MAType_SMA)

in .i file:
%typemap(out)TA_RetCode TA_MA( int          startIdx,
                   int          endIdx,
                   const double inReal[],
                   int          optInTimePeriod,
                   int          optInMAType,
                   int         *outBegIdx,
                   int         *outNbElement,
                   double       outReal[]
{

       int iStartIx = *arg6;
       int iLen = iStartIx + *arg7;
       VALUE arr_results = rb_ary_new2(2) // 2 elements as result
       rb_ary_push(arr_results, INT2FIX(result)); // first is
TA_Retcode

       VALUE arr_data = rb_ary_new2(iLen); // data array

        for ( int i = iStartIx; i < iLen;  i++ )
            rb_ary_push(arr_data, rb_float_new((*arg8)[i]));

        rb_ary_push(arr_results, arr_data); // second  array of data

        $result = arr_results

}

here you are right,  INT2FIX doesn't work but rb_float_new should be.
NUM2DBL for inputs should be also ok.

If you need to pass startIdx,endIdx as input, you have to modify the
typemap(in)

 %typemap(in)(const double inReal[])
{

       Check_Type($input, T_ARRAY);

    /* Get the length of the array */
    int size = RARRAY($input)->len;
    int i;
    $1 = (unsigned char*) malloc(size * sizeof(double));

    // copy the ruby array in the new allocated buffer
    /* Get the first element in memory */
    VALUE *ptr = RARRAY($input)->ptr;
    for (i=0; i < size; i++, ptr++)
    {
        /* Convert Ruby Object Fixnum to unsigned char */
        $1[i]= (double)NUM2DBL(*ptr);
    }
}

If you don't like a maxsize for output array, like double
arr_res[MAX_OUT_DATA];
you can use:
arg8 = (unsigned char*) malloc(size * sizeof(double));
inside  %typemap(in)(const double inReal[])
I don't know if it is exact, but you can look inside the generated
code if all is set like you want (I use swig with c++ and I expect a
function called _wrap_TA_MA inside generated code).
Don't forget to free arg8 in the typemap.

Cheers
Igor