With this method, I got the compiler warning about breaking the strict aliasing rule:

uint8_t bytes[4] = {12, 34, 56, 78};

float f = *(float*)bytes;

This is my code, and for now, it is working properly. But I am not sure if this is an efficient way or not.

typedef struct _xsensparse

{

    t_object x_obj;

    uint8_t wrd[4];

    t_float o;

    t_outlet *f1_out, *f2_out;

} t_xsensparse;

static void xsensparse_list(t_xsensparse *x, t_symbol *s, int argc, t_atom *argv)

{

    for(int i=0; i<argc; i++) {

    x->wrd[i]=(uint8_t)atom_getfloat(argv+3-i);

    memcpy(&x->o, &x->wrd, 4);

    }

    post("%f",  x->o);

    outlet_float(x->f1_out, x->o);

}