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Re: FPU Register Accuracy
Posted: Tue Nov 15, 2016 10:24 pm
by Robert
Some interesting comments above.
I did wonder if a disassembler might be a useful tool to investigate this issue.
Re: FPU Register Accuracy
Posted: Wed Nov 16, 2016 2:51 am
by DGDanforth
Robert wrote:Some interesting comments above
Robert,
I have my post order set to "Descending" so the interesting comments are "below".
Re: FPU Register Accuracy
Posted: Wed Nov 16, 2016 7:50 am
by cfbsoftware
I'm not an expert on this subject but before somebody goes too far down the path of enhancing the 80-bit x87 capabilities of BlackBox it might be worth taking a leap ahead and consider using the 128-bit capable SIMD instructions instead:
The x87 FPU instructions are executed by the so-called "math coprocessor". These instructions operate on floating-point, integer, and binary-coded decimal (BCD) operands. The main purpose of these instructions are to perform floating-point arithmetic. But nowadays we have SIMD instructions that are much faster than FPU. So, please, don't use the FPU in newly written code, because it usage is marked as outdated in Linux 64 ABI. Use SIMD instead.
http://linasm.sourceforge.net/docs/inst ... ompare_flt
However, that might have to wait for a 64-bit version of BlackBox?
Re: FPU Register Accuracy
Posted: Wed Nov 16, 2016 10:06 am
by Robert
cfbsoftware wrote:... it might be worth taking a leap ahead and consider using the 128-bit capable SIMD instructions instead:
I think this is rather a different direction.
1 - The 128-bit refers to the parallel multiple data stream path. It does not imply 128-bit accuracy, but rather doing 2 64-bit calculations in one memory fetch, or 4 32-bit calculations, or ...
2 - I think that direct
language support of multiple data streams is a big change from where we are today, and would need to be convinced that it was worth while.
3 - Writing a library to do, for example, additions of Vectors comprising 64-bit, or 32-bit REALs which itself used SIMD internally may well have uses. Such a library Module could be written today using a combination of Component Pascal and Assembler without changing the current language.
Having an assembler well integrated into the source code editor would be helpful here, but that is a different topic.
Re: FPU Register Accuracy
Posted: Fri Nov 18, 2016 10:37 am
by luowy
@Josef, are you start the work for Real80?
Re: FPU Register Accuracy
Posted: Fri Nov 18, 2016 10:45 am
by Josef Templ
luowy wrote:@Josef, are you start the work for Real80?
No.