f * f -> f asm

.686
.model flat
public _fmf
.data

.code
_fmf PROC
    push ebp
    mov ebp, esp
    push esi
    push edi
    push ebx

    mov esi, [ebp + 8] ; a
    mov edi, [ebp + 12] ; b

    mov eax, esi ; wykl a
    mov ebx, esi ; mant a
    mov ecx, edi ; wykl b
    mov edx, edi ; mant b

    and eax, 7F800000h
    rol eax, 9
    sub eax, 127

    and ebx, 007FFFFFh

    and ecx, 7F800000h
    rol ecx, 9
    sub ecx, 127

    and edx, 007FFFFFh

    add eax, ecx
    add eax, 127
    mov esi, eax

    mov eax, ebx
    bts eax, 23
    bts edx, 23
    mul edx

    bt edx, 15
    jnc ptl
    inc esi
ptl:
    shl eax, 1
    rcl edx, 1
    jnc ptl

    shr edx, 9
    mov eax, 0
    mov eax, esi
    shl eax, 23
    or eax, edx

    push eax
    fld dword ptr [esp]
    add esp, 4




    pop ebx
    pop edi
    pop esi
    pop ebp
    ret
_fmf ENDP

END