
Re: Fixed Point (Chapter 13): Clarification Request
I like the new definition of fixed point. Its quite crisp.
Building on the definition we can now argue that any integer number representation is: integer value/2^N
With N being a positive
I like the new definition of fixed point. Its quite crisp.
Building on the definition we can now argue that any integer number representation is: integer value/2^N
With N being a positive

By
Mikael <mikael.mortensen@...>
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#334
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Re: VFRECIP/VFRSQRT instructions
There are no cases where UF should be raised because there are no cases where denormalization causes loss of precision. When the result is subnormal, it is only subnormal by either one or two
There are no cases where UF should be raised because there are no cases where denormalization causes loss of precision. When the result is subnormal, it is only subnormal by either one or two

By
Andrew Waterman
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#333
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Re: VFRECIP/VFRSQRT instructions
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?
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?

By
Bill Huffman
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#332
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Re: VFRECIP/VFRSQRT instructions
I've PRed a full definition of these instructions. Please sanitycheck my work:
I've PRed a full definition of these instructions. Please sanitycheck my work:

By
Andrew Waterman
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#331
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Re: Fixed Point (Chapter 13): Clarification Request
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
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

By
Allen Baum
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#330
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Re: Fixed Point (Chapter 13): Clarification Request
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
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

By
CDS <cohen.steed@...>
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#329
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Re: Fixed Point (Chapter 13): Clarification Request
Hi Coheen,
Thanks for the discussion on the fixedpoint vector instructions. Most of Chapter 13 predates my involvement with the Task Group, but I think I am able to address one of your
Hi Coheen,
Thanks for the discussion on the fixedpoint vector instructions. Most of Chapter 13 predates my involvement with the Task Group, but I think I am able to address one of your

By
Nick Knight
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#328
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Re: Fixed Point (Chapter 13): Clarification Request
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
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

By
swallach
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#327
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Re: Integer Overflow/Saturation Operations
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
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

By
CDS <cohen.steed@...>
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#326
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Re: Fixed Point (Chapter 13): Clarification Request
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
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

By
CDS <cohen.steed@...>
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#325
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Edited


Re: Fixed Point (Chapter 13): Clarification Request
 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
 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

By
Krste Asanovic
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#324
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Vector TG minutes for 2020/8/7 meeting
Date: 2020/8/7
Task Group: Vector Extension
Chair: Krste Asanovic
CoChair: Roger Espasa
Number of Attendees: ~22
Current issues on github: https://github.com/riscv/riscvvspec
Issues
Date: 2020/8/7
Task Group: Vector Extension
Chair: Krste Asanovic
CoChair: Roger Espasa
Number of Attendees: ~22
Current issues on github: https://github.com/riscv/riscvvspec
Issues

By
Krste Asanovic
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#323
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Vector TG meeting minutes 2020/7/31 meeting
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
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

By
Krste Asanovic
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#322
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Re: Integer Overflow/Saturation Operations
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
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

By
Andy Glew Si5
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#321
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Re: Fixed Point (Chapter 13): Clarification Request
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
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

By
CDS <cohen.steed@...>
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#320
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Re: Fixed Point (Chapter 13): Clarification Request
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
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

By
Andrew Waterman
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#319
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Re: vrsub.vi, used as negation
Would be mostly redundant with vadd.vi, since the immediate operand is signed. (Same reason the scalar ISA doesn’t provide a subi instruction.)
Would be mostly redundant with vadd.vi, since the immediate operand is signed. (Same reason the scalar ISA doesn’t provide a subi instruction.)

By
Andrew Waterman
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#318
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vrsub.vi, used as negation
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.
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.

By
CDS <cohen.steed@...>
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#317
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Integer Overflow/Saturation Operations
Vectorwidening 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
Vectorwidening 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

By
CDS <cohen.steed@...>
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#316
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Fixed Point (Chapter 13): Clarification Request
The definition of the numeric range (at the beginning of section 13) matches the definition of an integer, not of a fixedpoint number. For example, the range specified is the range of an integer,
The definition of the numeric range (at the beginning of section 13) matches the definition of an integer, not of a fixedpoint number. For example, the range specified is the range of an integer,

By
CDS <cohen.steed@...>
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#315
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