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6a00



Joined: 11 Sep 2009
Posts: 5
6a00
Who knows how convert string like this '-35.027' into floating point number and reverse?
Post 04 Nov 2009, 15:45
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rugxulo



Joined: 09 Aug 2005
Posts: 2341
Location: Usono (aka, USA)
rugxulo
Quote:

`FILD' loads an integer out of a memory location, converts it to a
real, and pushes it on the FPU register stack. `FIST' converts `ST0'
to an integer and stores that in memory; `FISTP' does the same as
`FIST', but pops the register stack afterwards.
Post 04 Nov 2009, 18:10
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windwakr



Joined: 30 Jun 2004
Posts: 827
Location: Michigan, USA
windwakr
rugxulo wrote:
Quote:

`FILD' loads an integer out of a memory location, converts it to a
real, and pushes it on the FPU register stack. `FIST' converts `ST0'
to an integer and stores that in memory; `FISTP' does the same as
`FIST', but pops the register stack afterwards.

He wants to take a string and turn it into a Floating point number.



If you are programming for windows, I think there is a function for this. If not(or if there is no function), you would need to parse the string yourself.

EDIT: There's another topic on this subject here:
http://board.flatassembler.net/topic.php?t=9338

EDIT 2: http://board.flatassembler.net/topic.php?t=7717

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Last edited by windwakr on 04 Nov 2009, 20:37; edited 2 times in total
Post 04 Nov 2009, 18:19
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kohlrak



Joined: 21 Jul 2006
Posts: 1421
Location: Uncle Sam's Pad
kohlrak
If you ask me, windwakr, unless he understand BCD, that link has very, very little to work with.

anyway, 6a00, i ended up giving up on this a long, long time ago and most people do. The FPU is such a painful subject (you'll find it's slow and SSE is faster but still painful to use), so really most people don't use it unless they have functions already available for it like atof and ftoa.
Post 04 Nov 2009, 20:11
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6a00



Joined: 11 Sep 2009
Posts: 5
6a00
I found that my code gives inaccurate result
Code:
proc _ascii2float           ;in edi pointer to data in ecx number of characters
    push ebx edx eax

          xor eax,eax
          push word[edi]
          ffree st7
          ffree st6
          ffree st5
          fld1
          fldz
          fldz

.loop:    dec ecx
          js .endloop
          mov al,byte[edi]
          inc edi
          cmp al,'.'
          je .loop2
          xor al,30h
          cmp al,9
          jg .loop
          mov [_tmp],ax
          fimul word[_ten]
          fiadd word[_tmp]
          jmp .loop

.loop2:   dec ecx
          js .endloop
          mov al,byte[edi]
          inc edi
          xor al,30h
          cmp al,9
          jg .loop2
          mov [_tmp],ax
          fxch st2
          ;st0 = 1
          fidiv word[_ten] ;there is problem
          ;st0 =0.1000000000000000056
          fxch st2
          fxch st1
          fincstp
          ffree st7
          fldz
          fiadd word[_tmp]
          fmul st,st2
          fxch st1
          fadd st,st1
          jmp .loop2

.endloop: fstp st1
          fstp st1
          pop cx
          cmp cl,'-'
          jnz @f
          fchs

@@: pop eax edx ebx
ret
_ten dw 10
_tmp dw 0
endp 
    
Post 05 Nov 2009, 19:44
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farrier



Joined: 26 Aug 2004
Posts: 274
Location: North Central Mississippi
farrier
6a00,

Raymong Filiatreault has a site:

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

with libraries and tutorials on using the FPU and BCD numbers. In the FPU library are routines to convert from decimal to FPU and FPU to decimal. Very robust but not necessarily optimized for speed. For my own use I converted--with Raymond's permission--his library to a DLL. The code is in Masm but easy to understand +/or use.

hth,

farrier

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Post 05 Nov 2009, 20:12
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vid
Verbosity in development


Joined: 05 Sep 2003
Posts: 7105
Location: Slovakia
vid
I also posted (unpublished) FASNMLIB code for ascii2float (with all sorts of input and range checking) sometime ago on this board.
Post 06 Nov 2009, 11:57
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