multiplying/dividing a positive decimal number by a positive number

[Yuri]

I doubt it's a question of format. The code works correctly for me with just "%g".

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Result
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9980.69
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ОК   
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[shankle]

        3-23-2015
My knowledge about FPU is hovering just above Zero.

    fixed dq  12.0
    n4    dq  0
    buf7  db  8 DUP (0h)
    Value db  '.043'

How do I put .043 into the ST0 FPU register
The result from Fild is incorrect

    fild D[Value] ;load Value into the ST0 register on the fpu stack
    fdiv Q[fixed] ; divide it by 12.0 directly from memory
    fstp Q[n4]    ; pop the results off the stack to memory
    invoke msvcrt:sprintf_s,addr buf7,sizeof buf7,\
                   "%g",[n4]

    invoke TextOut, [hdc],200,425,addr buf7,8
   

[jj2007]

My knowledge about FPU is hovering just above Zero.

Reading Ray's tutorials may help.

[FORTRANS]

Hi,

   FILD is to load from an integer variable.  FLD loads from a real
valued variable.

Code: [Select]

Fixed   DW      12
Real    DD      12.0

        FILD    [Fixed]
        FLD     [Real]
   Both end up with 12.0 in the FPU.  But look at a listing to see
some differences.

Regards,

Steve N.

[dedndave]

Code: [Select]

Value db  '.043'
loading it into the FPU is actually the easy part
your big problem here is converting an ASCII string into a float

now, there are a few ways to go about this
one way is to use the masm32 library StrToFloat function

Code: [Select]

    .DATA

r08Value REAL8 ?
Value db  '.043'

    .CODE

    INVOKE  StrToFloat,offset Value,offset r08Value

    fld     r08Value     ;load REAL8 into FPU ST(0)
the StrToFloat function only supports REAL8 types

i guess, for GoAsm, the "offset" syntax is a little different

[dedndave]

another way would be to convert "0.043" to a fixed-point integer of 43
load the integer and divide it by a constant real of 1000.0

still another way might be to load it using BCD math - i'm not very familiar with that
but, Ray's tutorials and libraries might help

[shankle]

So where is Ray's tutorial?
I read about the lib from 2012 and it had errors.
Have they been fixed?
I will gladly give it a read if I can find it.

[jj2007]

So where is Ray's tutorial?

Google is your friend: http://www.ray.masmcode.com/tutorial/index.html

[dedndave]

also, visit the main page - scroll down to the bottom

http://www.ray.masmcode.com/

[rrr314159]

this tutorial was my "bible" learning the FPU - thanks Raymond!

[shankle]

Thanks guys,
I should have known about this weeks ago.
In my short perusal so far I think "fpulib" is a gold mine.

BUT, FpuAtoFl shows an error for this instruction.
So I need the equivalent of Raymonds tutorial for GoAsm.
I don't think it exists. :(

And yes, Thanks Raymond

[dedndave]

FpuAtoFl sounds like one of Ray's library functions - not the same as an instruction
also - Ray's code is probably 32-bit
you may have to adapt to 64-bit code

[Yuri]

shankle
What happened to _atodbl? Did it stop working for you?

Code: [Select]

DATA SECTION

fixed dq  12.0
n4    dq  0
buf7  db  16 DUP (0h)
Value db  '.043',0

CODE SECTION

Start:
    invoke msvcrt:_atodbl, addr buf7, addr Value
    fld Q[buf7]
    fdiv Q[fixed]
    fstp Q[n4]
    invoke msvcrt:sprintf_s, addr buf7, sizeof buf7, "%g", [n4]
    invoke user32:MessageBoxA, 0, addr buf7, "Result", 0


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Result
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0.00358333
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ОК   
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[shankle]

Sorry Yuri,
Nothing wrong with atodbl. Guess I thought Ray's stuff would
replace Msvcrt. So if I understand correctly GoAsm will not
support Rays tutorial and I must use Microsofts Msvcrt:xxxxx.
Sorry for the confusion.

[Yuri]

The tutorial describes how the FPU works, so it's definitely useful. But fpu.lib is 32-bit, so you can only use it in 32-bit code, like this:

Code: [Select]

DATA SECTION

DEST_MEM8   EQU   200000h
SRC1_REAL8  EQU   20000h
SRC2_DIMM   EQU   800h
fixed dq  12.0
n4    dq  0
buf7  db  16 DUP (0h)
Value db  '.043',0

CODE SECTION

Start:
    invoke fpu.lib:FpuAtoFL, addr Value, addr buf7, DEST_MEM8
    fld Q[buf7]
    fdiv Q[fixed]
    fstp Q[n4]
    invoke fpu.lib:FpuFLtoA, addr n4, 8, addr buf7, SRC1_REAL8 | SRC2_DIMM
    invoke user32:MessageBoxA, 0, addr buf7, "Result", 0
    ret


---------------------------
Result
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 0.00358333
---------------------------
ОК   
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