Hi Andrew, I'm looking at the cases where the reciprocal is near the boundary between finite and infinite or between normal and denormal. Are you trying to get the boundaries approximately right?

I've PRed a full definition of these instructions. Please sanity-check my work:

I always understood fixpoint to have an implicit denominator that was restricted to a positive (integer) power of 2 (which could be fixed, or could be configured). Arbitrary denominators mean that

Nick, Thank you for your response and proposed clarification. This proposal for how to use the numbers fundamentally realigns our interpretation of how this would be used. This is much closer to the

Hi Coheen, Thanks for the discussion on the fixed-point vector instructions. Most of Chapter 13 predates my involvement with the Task Group, but I think I am able to address one of your

perhaps i am not upto date on this topic. but addresses are fixed point. (integers). and you need vector support for vector loads using the vector accumulators.(indexs). the math, other than

Andy, Thank you for your response. The concern I'm raising is less about "How do I avoid overflow?" and more about "Why are we avoiding the specification of saturating instructions, or an overflow

Perhaps, it is important to understand the history of why fixed point is utilized. Historically, fixed point was the alternative for expensive floating point implementations/operations, or was the

| Thank you for the response, Andrew. | Given that these operations are intended to be conveniences, in the first place (hence: vector), the | addition of a required macro for inclusion could be

Date: 2020/8/7 Task Group: Vector Extension Chair: Krste Asanovic Co-Chair: Roger Espasa Number of Attendees: ~22 Current issues on github: https://github.com/riscv/riscv-v-spec Issues

Apologies for delay in sending these out. When doing this week's minutes, I realized I hadn't sent out previous week's. Krste Date: 2020/7/31 Task Group: Vector Extension Chair: Krste

For extended precision arithmetic, e.g. such as is often performed in cryptography, 2X widening multiply accumulate is the best that I have found. (And as far as I know other members

Thank you for the response, Andrew. Given that these operations are intended to be conveniences, in the first place (hence: vector), the addition of a required macro for inclusion could be considered

Having implemented these instructions recently, I can say they weren’t unduly onerous to provide, and the HW cost increase wasn’t that great (the rounding and clipping logic are new; the rest

Would be mostly redundant with vadd.vi, since the immediate operand is signed. (Same reason the scalar ISA doesn’t provide a subi instruction.)

Is the point of vrsub.vi to provide negation? From a compiler/user perspective, completing the vsub pattern with vsub.vi (even as a virtual instruction) may be a usability enhancement to consider.

Vector-widening multiply & accumulate instructions: These instructions, signed or unsigned, will quickly overflow in even simple cases. Given absence of flagging (e.g. OVERFLOW), a saturating version

The definition of the numeric range (at the beginning of section 13) matches the definition of an integer, not of a fixed-point number. For example, the range specified is the range of an integer,

great! again this is meant as informational for when this goes to vote. this should be discussable now in email with questions and comments. please include this in the ratification materials (place in

I filled out the RISC-V Policy: Change and Extension Rationale as best I could for the issue #427. I believe it is accessible by all. But I will also paste the contents below.