From: BENI <rajib.chakrabarti@...>
Date: 2007-03-13T17:25:07+09:00
Subject: extending ta-lib using SWIG

ta-lib (http://ta-lib.org/) is a package availiable which has port for
perl,python?,excel etc.

I needed it in ruby... since no port is availiable (AFAIK) ... i
thought of building a port.

i have read along the pickaxe book of extending ruby....

after evaluating all the options i thought i will give SWIG a shot...

given  the header like

=================================================
TA_RetCode TA_MA( int           START_IDX,
                  int           END_IDX,
                  const double *IN_ARRAY /* inReal */,
                  int           OPT_INT /* optInTimePeriod */, /* From
1 to 100000 */
                  TA_MAType     OPT_MATYPE /* optInMAType */,
                  int          *BEG_IDX,
                  int          *OUT_SIZE,
                  double       *OUT_ARRAY /* outReal */ );
==================================================

in C it can be called like
=====================
TA_Real    closePrice[400];
TA_Real    out[400];
TA_Integer outBeg;
TA_Integer outNbElement;

/* ... initialize your closing price here... */

retCode = TA_MA( 0, 399,
&closePrice[0],
30,TA_MAType_SMA,
&outBeg, &outNbElement, &out[0] );

/* The output is displayed here */
for( i=0; i < outNbElement; i++ )
   printf( "Day %d = %f\n", outBeg+i, out[i] );

=======================
*********************************************
could any one give me a lead how should the typemap for *IN_ARRAY look
like?

for python the typemap for *IN_ARRAY  looks like
=====================================
%typemap(in) const double *IN_ARRAY
{
    int array_size = endIdx2 + 1;

    $1 = ($1_ltype) calloc(array_size, sizeof($*1_ltype));
    if (!convert_darray($input, $1, array_size))  goto fail;
}
=======================================

cheers

Rajib