masm FPU to fasm FPU cannot translate and it does not work

Question

I have this code in masm to deal with the FPU and it works great

in this code I get a number from 2 different textboxes and then divide them and then output the results to another textbox

this is the data that is local

LOCAL variable1 :QWORD
LOCAL variable2 :QWORD
LOCAL variable3 :QWORD

LOCAL string1[20]:BYTE
LOCAL string2[20]:BYTE
LOCAL string3[20]:BYTE

this is the code

invoke GetDlgItemText,hWin,textbox1,addr string1,9
invoke StrToFloat,addr string1,addr variable1

invoke GetDlgItemText,hWin,textbox2,addr string2,9
invoke StrToFloat,addr string2,addr variable2

finit
fld variable1
fld variable2
fdiv
fstp variable3

invoke FloatToStr,variable3,addr string3
invoke SetDlgItemText,hWin,textbox3,addr string3

I am trying to convert the code to fasm

this is what I have so far but it is not working the textbox3 just says 0

this is the data (this is not local data because I have not learned how to do that in fasm yet)

v1 dq ?
v2 dq ?
v3 dd ?
v4 rb 20

this is the code

invoke GetDlgItemTextA,[hWin],textbox1,addr v1,100 
invoke GetDlgItemTextA,[hWin],textbox2,addr v2,100 

finit
fld qword [v1]
fld qword [v2]
fdivp
fstp qword [v3]

cinvoke wsprintfA,addr v4,"%u",[v3]
invoke SetDlgItemTextA,[hWin],textbox3,addr v4

I know this code is not right because I am not converting the text to float at the begining but i do not know how to

I also tried a simpler version and it did not work either

mov [v1],5.3
mov [v2],7.1

finit
fld [v1]
fld [v2]
fdivp
fstp [v3]

cinvoke wsprintfA,addr v4,"%u",[v3]
invoke SetDlgItemTextA,[hWin],maximumoutputpowertext,addr v4

so my question is can someone please show me how to read a number from 2 different textboxes and then divide them and the return the result to another textbox using fasm code

thank you

Answer 1

There are several problems in the demonstrated code.

At first, it is not clear what StrToFloat procedure is? Is it imported from some DLL or it is part of the code, or some other library?

If this procedure is imported, it has to be imported in the FASM program as well. Else it can be written from scratch or ported in source form from the MASM program.

The immediate show stopper here is mov [v1], FLOAT_CONSTANT instruction. The reason is that v1 is qword variable, but mov can moves only dword immediate values (even in 64bit environment).

mov dword [v1], 5.0 works fine, but of course it is not what the OP needs. Floating qword constants can be defined immediately in compile time as well: v1 dq 3.2

If we really want to set some qword floating constant in run time, we have to make it in two instructions following way:

    a = 5.3

    mov  dword [var], (a and $ffffffff)
    mov  dword [var+4], (a shr 32)

    var dq ?

The original FPU code in FASM syntax will be:

    finit
    fld  [variable1]
    fdiv [variable2]
    fstp [variable3]