FADD            Add real                             Exceptions: I D O U P
FADDP           Add real and pop                     C3 C2 C1 C0: ? ? * ?

FADD [[destination,] source]
FADDP [destination, ST]

        Logic   ; FADD source                   ; FADD and FADDP
                ST ← ST + source                ST(1) ← ST(1) + ST
                                                pop ST

                ; FADD dest, source             ; FADDP dest, ST
                ST(dest) ← ST(dest) + ST(src)   ST(dest) ← ST(dest) + ST
                                                pop ST

    FADD/FADDP add the source operand to the destination operand.

    The one-operand form of FADD adds a (single or double real) memory
    operand to ST.
    The two-operand form of FADD adds two register operands (ST must
    be one of these) and stores the sum in the destination register.
    FADDP works like the two-operand FADD but requires ST to be the
    source operand; it also pops the stack.
    The no-operand forms FADD and FADDP equal 'FADDP ST(1), ST'.


    Opcode      Format
    D8 /0       FADD m32
    DC /0       FADD m64
    D8 C0 + i   FADD ST,ST(i)
    DC C0 + i   FADD ST(i),ST
    DE C0 + i   FADDP ST(i),ST
    DE C1       FADD
    DE C1       FADDP


    Timing
    Variations/
    operand       8087         287        387      486     Pentium
    fadd         70-100       70-100     23-34     8-20    3/1     FX
    fadd m32     90-120+EA    90-120     24-32     8-20    3/1     FX
    fadd m64     95-125+EA    95-125     29-37     8-20    3/1     FX
    faddp        75-105       75-105     23-31     8-20    3/1     FX