Performing Floating-point Operations in DirectDraw

DirectDraw driver callback functions must perform all floating-point operations between calls to the GDI-supplied EngSaveFloatingPointState and EngRestoreFloatingPointState functions. That is, the driver's callback functions must save the floating-point state prior to performing a floating-point operation and must restore the floating-point state when the floating-point operation completes. For more information about floating-point operations, see Floating-Point Operations in Graphics Driver Functions.