Calling COBOL from C with variable arguments

gistfile1.c

#include <stdio.h>
#include <stdarg.h>

/*
COBOL will be calling the function like this:

    CALL "calling_c" USING BY REFERENCE
        "d" & x"00"
        "FOO" & x"00" WS-DEPTH-1 *> ws-depth-1 and ws-depth-2 are PIC 9(4) COMP-5
        "BAR" & x"00" WS-DEPTH-2
        x"00".
*/

#define PRINT( fmt, ... ) \
    printf( "%s:%d ==> " fmt "\n", __FUNCTION__ , __LINE__  , ## __VA_ARGS__ )

int calling_c( void * arg );

int calling_c( char * data_type, ... )
{
    va_list         ap;
    char *          key;
    unsigned short  depth;
    int             i = 0;

    PRINT( "Hello from %s", __FUNCTION__ );

    PRINT( "data_type = %s", data_type );

    va_start( ap, data_type );

    do {
        key = va_arg( ap, char *);
        if( key [0] != 0 ) {
            depth = * ( va_arg( ap, unsigned short *) );

            PRINT( "key = %s; depth = %d", key,  depth );

            i+= 2;
        }
    } while( key[ 0 ] != 0 );

    return 0;
}