Intel 80286, 80287 manual Fsubrp / /destination/source

PROGRAMMING NUMERIC APPLICATIONS

The normal subtraction instructions (subtract real, subtract real and pop, integer subtract) subtract the source operand from the destination and return the difference to the destination.

REVERSED SUBTRACTION

FSUBR / /source/destination, source

FSUBRP / /destination/source

FISUBR source

The reversed subtraction instructions (subtract real reversed, subtract real reversed and pop, integer subtract reversed) subtract the destination from the source and return the difference to the destination.

MULTIPLICATION

FMUL / /source/destination, source

FMULP destination, source

FIMUL source

The multiplication instructions (multiply real, multiply real and pop, integer mUltiply) multiply the source and destination operands and return the product to the destination. Coding FMUL ST,ST(O) squares the content of the stack top.

NORMAL DIVISION

FDIV / /source/destination,source

FDIVP destination, source

FIDIV source

The normal division instructions (divide real, divide real and pop, integer divide) divide the destination by the source and return the quotient to the destination.

REVERSED DIVISION

FDIVR / /source/destination, source

FDIVRP destination, source

FIDIVR source

The reversed division instructions (divide real reversed, divide real reversed and pop, integer divide reversed) divide the source operand by the destination and return the quotient to the destination.

FSQRT

FSQRT (square root) replaces the content of the top stack element with its square root. (Note: The square root of -0 is defined to be -0.)

FSCALE

FSCALE (scale) interprets the value contained in ST(l) as an integer and adds this value to the exponent of the number in ST. This is equivalent to

ST ~ST. 2ST(I)

Thus, FSCALE provides rapid multiplication or division by integral powers of 2. It is particularly useful for scaling the elements of a vector.

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