_IO_JUMPS_FUNC
# define JUMP0(FUNC, THIS) _IO_JUMPS_FUNC(THIS)->FUNC.pfn (THIS)
# define JUMP1(FUNC, THIS, X1) _IO_JUMPS_FUNC(THIS)->FUNC.pfn (THIS, X1)
# define JUMP2(FUNC, THIS, X1, X2) _IO_JUMPS_FUNC(THIS)->FUNC.pfn (THIS, X1, X2)
# define JUMP3(FUNC, THIS, X1,X2,X3) _IO_JUMPS_FUNC(THIS)->FUNC.pfn (THIS, X1,X2,X3)
#define JUMP0(FUNC, THIS) (_IO_JUMPS_FUNC(THIS)->FUNC) (THIS)
#define JUMP1(FUNC, THIS, X1) (_IO_JUMPS_FUNC(THIS)->FUNC) (THIS, X1)
#define JUMP2(FUNC, THIS, X1, X2) (_IO_JUMPS_FUNC(THIS)->FUNC) (THIS, X1, X2)
#define JUMP3(FUNC, THIS, X1,X2,X3) (_IO_JUMPS_FUNC(THIS)->FUNC) (THIS, X1,X2, X3)