//Эта часть должна быть в библиотеке:
struct xml_struct
{
    short       level; //XML element level
    char        tag[32]; //tag name
    short       data_type; //output data type
    char*       data; //pointer of the memory, to store data
    (int*)(char* buf); //some function to process the data
}
... processing functions, data and similar library things

//А эта часть уже будет в нашем коде, используя ф-ции библиотеки
    xml_struct CtrlDataRsp[] =
    {
        {0, "some tag", STR,    SomeVarToStoredata,   NULL},
            {1, "some subtag", LONG,    SomeVarToStoredata,   SomeConversionFunction},
        {0, "/some tag", STR,    SomeVarToStoredata,   NULL},
        {NULL}
    };

void main()
{
    char buf[1024]={0};
    //some code to receiva data int buf variable
    parse(CtrlDataRsp, buf); //let's get data from the xml structure to the variables
    let's process data
}

<control data response>
        <controllers>1</controllers>
  	<controller info>
    		<name>ZX1</name>
     		<port>COM1</port>
  	</controller info>
</control data response>

typedef struct xml_struct
{
    short       level;
    char        tag[32];
    short       type;
    short       data_type;
    char*       data;
    int            p_cnv_function(char*);
}xml_struct;

    short ctrlcnt;
    char    name[16];
    char    port[8];

xml_struct rsp_descr[]=
{
   {0, "control data response", OPNTAG, NULL, NULL, NULL},
   {1, "controllers", DATATAG, FLDSHRT, (char*) &ctrlcnt, NULL},
   {1, "controller info", OPNTAG, NULL, NULL, NULL},
   {2, "name", DATATAG, FLDSTR, name, NULL},
   {2, "port", DATATAG, FLDSTR, port, NULL},
   {1, "controller info", CLOSETAG, NULL, NULL, NULL},
   {0, "control data response", CLOSETAG, NULL, NULL, NULL},
   {NULL}
}

parse(xmldatabuffer,  rsp_descr);