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Old 27 November 2022, 15:25   #121
Samurai_Crow
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Quote:
Originally Posted by Thomas Richter View Post
Sorry, I'm completely confused on what you are proposing here. First, you say "coprocessor circuits present in the 68020 and 68030 were offloaded to an external chip on the 68040 and 68060". Nothing was "offloaded to an external chip" there. Actually, nothing was offloaded to external hardware. The missing opcodes are offloaded to external software (the fpsp.resource). So do you want to say "I plan an external chip that replaces the fpsp.resource"? If so, softIEEE has no role here. This process works (a bit) different compared to SoftIEEE, and it would need to go through a CPU library, or lacking this, an fpsp.resource.



What has Gunnar to do with all this? Even if you disable the FPU on his design, the FPU remains active for elementary math and would continue to process data for such elementary operations in only 56 bits rather than the full precision offered by SoftIEEE. Thus, at best you can offload some transcendental functions to an external chip, but whether it makes sense to go through the emulator trap rather than his "millicode" I cannot judge.



Third, what has all this to do with a vector unit, and how does SoftIEEE plays in here? As said, going through an emulator trap does not make sense, it would be only slower than scalar math operations carried out multiple times, so as a software interface to an external chip it makes little sense. I



If you propose to use SoftIEEE as some kind of "prototype system" where you catch (lacking hardware) the instructions by software - well, you can do that as of today. It would make sense there as temporary solution just to test the chip until the full interface becomes available in silicon. Just implement a softieee.library. Will I do that? No - that's not the purpose of the project, but the interface is open and documented, so it is doable, and I can help you to understand how the interface works.



If you plan to do that as an external chip for the 68LC040 to provide an FPU - that is possible, though again not exactly fast, so I'm not sure how competitive such a design could be.



If you plan that as an external chip for Gunnar's 68EC080, I guess you better talk to Gunnar to get it linked to the system as some sort of coprocessor interface. Good luck with that. The chip currently lacks the ability to re-route all FPU instructions, and even if you can re-route the transcendental functions as a subset to an external chip, it would likely not perform very well, but that's not my problem at all.



Last but not least, I doubt any soft of FPU can be implemented on a CPLD, these chips are much too tiny for such complex operations. You can probably implement a CORDIC logic in an FPGA to get the missing functions, but you would still need to find a way how to interface this chip to either a Mot chip, or Gunnar's EC080. For the 68040 and related chips, there is no coprocessor interface, thus some software layer is necessary. Yes, SoftIEEE can do that (minus vector instructions), and the answer is that you then need the right softieee.library. Doable, read the documentation, then ask me in case you have additional questions.



Thus, to conclude: Please write a concise project proposal of what exactly you are attempting to do. I cannot really make much sense of what you have written so far - sorry.
Thanks for your suggestions. I won't waste any more of your thread.
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Old 28 November 2022, 13:26   #122
OldB0y
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Originally Posted by alenppc View Post
You can grab the NovaCoder's softfloat version (posted in the Quake thread) and it should be slightly faster, although the 3660 is an awful card so probably not by much.
Cool, can you point me in the direction of this thread - I can't seem to locate it with the search function. Cheers!
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Old 28 November 2022, 13:38   #123
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Cool, can you point me in the direction of this thread - I can't seem to locate it with the search function. Cheers!
https://eab.abime.net/showthread.php?t=64697
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Old 28 November 2022, 15:59   #124
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Originally Posted by OldB0y View Post
Cool, can you point me in the direction of this thread - I can't seem to locate it with the search function. Cheers!

Specifically this post:



https://eab.abime.net/showpost.php?p...&postcount=287


Keep in mind that an integer version of Quake source exists as well, but it has not been ported onto the Amiga. That one would make a major difference in performance.
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Old 29 November 2022, 09:22   #125
Reynolds
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Quote:
Originally Posted by alenppc View Post
Specifically this post:



https://eab.abime.net/showpost.php?p...&postcount=287


Keep in mind that an integer version of Quake source exists as well, but it has not been ported onto the Amiga. That one would make a major difference in performance.
AFAIK Quake can be started with disabling FPU routines. At least the frontend I use has a tickbox with that function. (Can't recall if it really works or not, though)
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Old 04 December 2022, 06:11   #126
Dynamic_Computi
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Brilliant as always, @Thomas Richter - I am installing a new BFG in my Amiga 3000 tomorrow for a review and look forward to trying this out with my 68LC060. I am sure it will be slow, but it will mean I don't have to remove and reinstall my FPU aware software like Art Department and ImageFX!
I will report back with my findings if I run into any issues.
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