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It would be nice to add the 64- and 128-bit DFP (Decimal Floating Point) support to this. The Intel DFP library can be dropped in, similar to how SoftFP was use
by apaprocki 10y ago
It would be nice to add the 64- and 128-bit DFP (Decimal Floating Point) support to this. The Intel DFP library can be dropped in, similar to how SoftFP was used for floating point: https://software.intel.com/en-us/articles/intel-decimal-floating-point-math-library https://software.intel.com/en-us/articles/intel-decimal-floa...
The RISC-V spec mentions it supports this in the “L” Standard Extension for Decimal Floating-Point.
- kobeya 10y agoThere's no actual spec. Although there is discussion about creating one if you want to join the ISA-dev mailing list.
- ajross 10y agoThere certainly is: https://riscv.org/specifications/ https://riscv.org/specifications/ I read it about a year ago and found it straightforward and clean. Are you making a technical point about stuff missing?
- baobrien 10y agoI think they mean that the decimal floating point extension ('L') isn't in the spec. Check out the user ISA v2.1. The 'L' name is reserved, but it's not fleshed out.
- kobeya 10y agoI'll wait while you go and actually read the "L" section of the spec you linked to.
- ajross 10y agoGot it. You were indeed making a technical point and chose snark over clarity. Thanks.
- Dylan16807 10y agoI thought it was clear that "there's no actual spec" referred to decimal and not risc-v as a whole. It's an important non-nitpick point.
- nitrogen 10y agoI don't [edit: think] "there is no spec [for the CPU]" was an unreasonable interpretation for that comment, even if "[for decimal floating point]" was the intended meaning.
- Dylan16807 10y agoThere was some ambiguity, and the interpretation is understandable. Dismissing it as a "technical point" and implying that kobeya never should have commented is not.
- nitrogen 10y agoYes, that is also true.
- apaprocki 10y agoAh interesting.. I just assumed it was actually spec'd out-of-document, so shame on me :)
- kobeya 10y agoWell if you are interested in making it happen I encourage you to join the ISA dev mailing list. There are others discussing informal proposals for the L spec as recently as the last few days. Helping craft a spec and reference implementation would make actual silicon implementations a near term prospect.