From: BENI <rajib.chakrabarti@...>
Date: 2007-03-14T19:50:21+09:00
Subject: Re: SWIG typemap for ta-lib

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