Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > comp.lang.forth > #135016
| From | Krishna Myneni <krishna.myneni@ccreweb.org> |
|---|---|
| Newsgroups | comp.lang.forth |
| Subject | Re: GNU Forth has a floating point floor word, but not floating point ceiling word? |
| Date | 2026-04-29 08:30 -0500 |
| Organization | A noiseless patient Spider |
| Message-ID | <10st150$3uddf$1@dont-email.me> (permalink) |
| References | (1 earlier) <69eac411$1@news.ausics.net> <10sooig$2o6bk$1@dont-email.me> <20260428134002.000057e7@tin.it> <10srj60$3htnj$1@dont-email.me> <69f15ce7$1@news.ausics.net> |
On 4/28/26 8:20 PM, dxf wrote:
> On 29/04/2026 10:25 am, Krishna Myneni wrote:
>> On 4/28/26 6:40 AM, peter wrote:
>>> On Mon, 27 Apr 2026 17:39:11 -0500
>>> Krishna Myneni <krishna.myneni@ccreweb.org> wrote:
>>>
>> ...
>>>>
>>>> \ Testing F= for positive and negative special values
>>>> t{ +INF -INF F= -> false }t
>>>> t{ +NAN -NAN F= -> true }t
>>>> t{ F=ZERO F=-ZERO F= -> true }t
>>>
>>> How is your F= defined?
>>> I see that it returns true for comparing two nans.
>>> Shouldn't that return false in IEEE fp math?
>>>
>>> BR
>>> Peter
>> I was just looking for my IEEE 754 documentation, but I think you are correct that +NAN should not equal itself or -NAN, since the equality comparison is not valid for NANs.
>>
>> I am using the x87 FCOMP instruction, which I expected to have IEEE-compatible behavior. Will need to look closer at this.
>
> I used FCOMP and got the expected results.
>
> \ fsp points to separate f/p stack in memory
> label tst
> addr fsp ) di mov
> qword 1 floats [di] fld qword 0 [di] fld fcompp
> ax fstsw st(0) fstp 2 floats # addr fsp ) add
> 41 # ah and bx bx sub cl ah cmp 1 $ jnz bx dec
> 1 $: bx push next
> end-code
>
> code F< ( r1 r2 -- flag ) 00 # cl mov tst ju end-code
> code F> ( r1 r2 -- flag ) 01 # cl mov tst ju end-code
> code F= ( r1 r2 -- flag ) 40 # cl mov tst ju end-code
>
> +NAN +NAN F= . 0 ok
> +NAN -NAN F= . 0 ok
>
>
Thank you. There is likely a mistake in handling the flags from FCOMP
for this case.
--
Krishna
Back to comp.lang.forth | Previous | Next — Previous in thread | Next in thread | Find similar
GNU Forth has a floating point floor word, but not floating point ceiling word? Buzz McCool <buzz_mccool@yahoo.com> - 2026-04-23 16:11 -0700
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? dxf <dxforth@gmail.com> - 2026-04-24 11:14 +1000
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? Buzz McCool <buzz_mccool@yahoo.com> - 2026-04-24 08:29 -0700
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-27 17:39 -0500
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? peter <peter.noreply@tin.it> - 2026-04-28 13:40 +0200
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? minforth <minforth@gmx.net> - 2026-04-28 14:01 +0200
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-28 19:25 -0500
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? dxf <dxforth@gmail.com> - 2026-04-29 11:20 +1000
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-29 08:30 -0500
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-29 20:15 -0500
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-05-02 15:56 -0500
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? dxf <dxforth@gmail.com> - 2026-04-29 11:47 +1000
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-30 04:40 -0500
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-30 05:37 -0500
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? peter <peter.noreply@tin.it> - 2026-04-30 15:55 +0200
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-04-30 20:49 -0500
Special memory access words (was: GNU Forth has a ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-01 06:16 +0000
Re: Special memory access words (was: GNU Forth has a ...) peter <peter.noreply@tin.it> - 2026-05-01 10:22 +0200
Re: Special memory access words (was: GNU Forth has a ...) anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-01 08:57 +0000
Re: Special memory access words Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-05-01 10:19 -0500
Re: Special memory access words anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-01 15:35 +0000
Re: Special memory access words Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-05-01 13:28 -0500
Re: Special memory access words Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-05-01 13:30 -0500
Re: Special memory access words anton@mips.complang.tuwien.ac.at (Anton Ertl) - 2026-05-02 05:54 +0000
Re: Special memory access words Krishna Myneni <krishna.myneni@ccreweb.org> - 2026-05-02 15:49 -0500
Re: Special memory access words Hans Bezemer <the.beez.speaks@gmail.com> - 2026-05-01 13:28 +0200
Re: GNU Forth has a floating point floor word, but not floating point ceiling word? peter <peter.noreply@tin.it> - 2026-05-01 10:18 +0200
csiph-web