Re: floating point asm

Article View: borland.public.cppbuilder.language.basm

Article #40

Back to borland.public.cppbuilder.language.basm Previous Next

#40

From: Michael
Date: Sat, 12 Jan 2008 09:50

35 lines
1995 bytes

Spine wrote:
> Hi,
> 
> I am just trying a bit around using assembler, and run into problems.
> 
> just multiplying integers a and b to res as result. this works fine.
>  int a = 2,b = 3,res;
>  for (int i=0;i<100;i++) {
>   __asm{
>    mov eax, a
>    mov ecx, b
>    mul ecx
>    mov res, eax
>   } }
> 
> then why does this not work? that is, it works fine for 4 iterations or so, 
> then it comes up with illegal flaoting point operation. even if I only have 
> "fld d_a" it throws the error.
>  double d_a = 1.1, d_b = 1.2, d_res;
>  for (int i=0;i<100;i++) {
>   __asm{
>    fld d_a
>    fmul d_b
>    fst d_res
>   } }
> 
> Sipke 


Remember that x86 floating point assembler works on a stack, and stacks 
can overflow.  The code you have is pushing values onto the floating 
point stack, but never popping them back off.  Try changing the "fst" to 
an "fstp", and see if it works.

- Michael

Technical Details

Message-ID: <47888da3$1@newsgroups.borland.com>

Path:

arc1-ca.pugleaf.net!g2news1.google.com!news3.google.com!feeder3.cambrium.nl!feeder2.cambrium.nl!feeder6.cambrium.nl!feed.tweaknews.nl!news.astraweb.com!newsrouter-eu.astraweb.com!newsfeed2.ip.tiscali.net!tiscali!newsfeed1.ip.tiscali.net!newsfeed00.sul.t-online.de!newsfeed01.sul.t-online.de!t-online.de!newsgroups.borland.com!not-for-mail

References: <46dfc4ba$1@newsgroups.borland.com>

Show Full Headers

Complete Article Headers

X-Google-Thread: 107b11,2ff544b33be6fabc
X-Google-Attributes: gid107b11,public,usenet
X-Google-Language: ENGLISH,ASCII-7-bit
Date: Sat, 12 Jan 2008 02:50:33 -0700
From: Michael <zrax@comcast.net>
User-Agent: Thunderbird 2.0.0.9 (Windows/20071031)
MIME-Version: 1.0
Newsgroups: borland.public.cppbuilder.language.basm
Subject: Re: floating point asm
References: <46dfc4ba$1@newsgroups.borland.com>
In-Reply-To: <46dfc4ba$1@newsgroups.borland.com>
Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Content-Transfer-Encoding: 7bit
NNTP-Posting-Host: 76.113.93.105
Message-ID: <47888da3$1@newsgroups.borland.com>
X-Trace: newsgroups.borland.com 1200131491 76.113.93.105 (12 Jan 2008 01:51:31 -0700)
Lines: 35
Path: arc1-ca.pugleaf.net!g2news1.google.com!news3.google.com!feeder3.cambrium.nl!feeder2.cambrium.nl!feeder6.cambrium.nl!feed.tweaknews.nl!news.astraweb.com!newsrouter-eu.astraweb.com!newsfeed2.ip.tiscali.net!tiscali!newsfeed1.ip.tiscali.net!newsfeed00.sul.t-online.de!newsfeed01.sul.t-online.de!t-online.de!newsgroups.borland.com!not-for-mail

Reply to Parent Message