FISUBR
Usage: FISUBR dest,src Modifies flags: See below
Subtracts the 'src' operand from the 'dest' and stores the difference in the 'dest' location. The 'dest' operand is always an FPU data register; the 'src' operand can be a register or a memory location.
Floating-Point/Integer Subtraction
FISUB mem16 ; DE /4 [8086,FPU]
FISUB mem32 ; DA /4 [8086,FPU]
FISUBR mem16 ; DE /5 [8086,FPU]
FISUBR mem32 ; DA /5 [8086,FPU]
FISUB subtracts the 16-bit or 32-bit integer stored in the given memory location from ST0, and stores the result in ST0. FISUBR does the subtraction the other way round, i.e. it subtracts ST0 from the given integer, but still stores the result in ST0.
Source operands in memory can be in single-precision or double-precision floating-point format or in word or doubleword integer format.
FPU Flags Affected C1 Set to 0 if stack underflow occurred. Set if result was rounded up; cleared otherwise. C0, C2, C3 Undefined.
EXAMPLE:
fisubr Label | fisub Label