+ void (*float_copy)(unsigned char *destp,
+ const struct type_class_float *dest,
+ const unsigned char *srcp,
+ const struct type_class_float *src);
+ double (*double_read)(const unsigned char *ptr,
+ const struct type_class_float *src);
+ size_t (*double_write)(unsigned char *ptr,
+ const struct type_class_float *dest,
+ double v);