FLD and FSTP have opcode variants that load/store 10 bytes from/to a memory address.
Downside is, of course, 10 bytes is a fairly awkward size; it is not nearly as fast as 32/64 bits to move in and out, plus it -has- to be memory (i.e. can't just borrow another register) and then the potential impacts around alignment of data structures/etc to consider.
Downside is, of course, 10 bytes is a fairly awkward size; it is not nearly as fast as 32/64 bits to move in and out, plus it -has- to be memory (i.e. can't just borrow another register) and then the potential impacts around alignment of data structures/etc to consider.