FSTCW / FNSTCW

FSTCW / FNSTCW

Usage: FSTCW src                                           Modifies flags: None

          FNSTCW src

Stores the current value of the FPU control word at the specified destination in memory. The FSTCW instruction checks for and handles pending unmasked floating-point exceptions before storing the control word; the FNSTCW instruction does not.

Store Floating-Point Control Word

FSTCW mem16                   ; 9B D9 /7             [8086,FPU]

FNSTCW mem16                  ; D9 /7                [8086,FPU]

FSTCW stores the FPU control word (governing things like the rounding mode, the precision, and the exception masks) into a 2-byte memory area. See also FLDCW.

FNSTCW does the same thing as FSTCW, without first waiting for pending floating-point exceptions to clear.

EXAMPLE:

fstcw

fnstcw

FSTCW / FNSTCW

FSTCW / FNSTCW

Usage: FSTCW src                                           Modifies flags: None

          FNSTCW src

Stores the current value of the FPU control word at the specified destination in memory. The FSTCW instruction checks for and handles pending unmasked floating-point exceptions before storing the control word; the FNSTCW instruction does not.

Store Floating-Point Control Word

FSTCW mem16                   ; 9B D9 /7             [8086,FPU]

FNSTCW mem16                  ; D9 /7                [8086,FPU]

FSTCW stores the FPU control word (governing things like the rounding mode, the precision, and the exception masks) into a 2-byte memory area. See also FLDCW.

FNSTCW does the same thing as FSTCW, without first waiting for pending floating-point exceptions to clear.

EXAMPLE:

fstcw

fnstcw