micropython-printf-ffi-test.c

#include "ffi.h"

STATIC mp_obj_t example_printf(size_t n_args, const mp_obj_t *args) {
    ffi_cif cif;
    ffi_type **types = alloca(n_args * sizeof(ffi_type *));
    ffi_raw *values = alloca(n_args * sizeof(ffi_raw));
    void **arg_values = alloca(n_args * sizeof(void *));

    ffi_arg result;

    size_t i;
    for (i = 0; i < n_args; i++) {
        if (mp_obj_get_int_maybe(args[i], (mp_int_t *)&values[i].sint)) {
            types[i] = &ffi_type_sint;
        } else if (mp_obj_get_float_maybe(args[i], (mp_float_t *)&values[i].flt)) {
            types[i] = &ffi_type_double;
        } else if (mp_obj_is_str(args[i])) {
            types[i] = &ffi_type_pointer;
            values[i].ptr = (void *)mp_obj_str_get_str(args[i]);
        } else {
            // ERROR
            mp_raise_TypeError(MP_ERROR_TEXT("not supported type is specified"));
        }
        arg_values[i] = &values[i];
    }

    ffi_prep_cif_var(&cif, FFI_DEFAULT_ABI, 1, n_args, &ffi_type_sint, types);
    ffi_call(&cif, FFI_FN(printf), &result, arg_values);

    return mp_obj_new_int(result);
}

STATIC MP_DEFINE_CONST_FUN_OBJ_VAR(example_printf_obj, 1, example_printf);