Averaging floating value in assembly

I have to get average. In C++ since I don't pass it the length of the array I don't know how to divide it by that.

Here's how I'm passing my values in C++

extern "C" double Average (long [6]); 

        _Average proc


        finit
        mov  ecx, 6  ; number of elements
        mov  ebx, [esp + 4] ; address of the array
        fldz

   L1: 
        fld REAL4 PTR [ebx]  ; get elements of array
        fadd
        add ebx, 4

        loop L1
        fdiv DWORD PTR [esp + 4]

        fwait 

开发者_Go百科        ret   

       _Average endp

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Then pass the length. Or, since it's a fixed-sized array of length 6, just assume it's 6.

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You already know that it's six elements long, since you're using that as your loop count (in ecx) and it is specified in the prototype. The only alternative is to pass another parameter with the length (as you would have to do in pure C++ anyway).

You also need to use fild instead of fld to load a long, since it is not a floating point variable, as well as changing REAL4 PTR to DWORD PTR. Alternatively, change long to float. (Another alternative is changing long to double, though this changes the size of the data type which will require more modifications.)