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add recip-sqrt as separate proposal
author
Luke Kenneth Casson Leighton
<lkcl@lkcl.net>
Thu, 8 Aug 2019 05:26:12 +0000
(06:26 +0100)
committer
Luke Kenneth Casson Leighton
<lkcl@lkcl.net>
Thu, 8 Aug 2019 05:26:12 +0000
(06:26 +0100)
ztrans_proposal.mdwn
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diff --git
a/ztrans_proposal.mdwn
b/ztrans_proposal.mdwn
index fd294697a1b840f0eb727d026e631e39784602f9..2c941cdb68102888d0366b06409bccdd6492f2cc 100644
(file)
--- a/
ztrans_proposal.mdwn
+++ b/
ztrans_proposal.mdwn
@@
-19,6
+19,7
@@
Extension subsets:
* **Zfhyp**: hyperbolic/inverse-hyperbolic. sinh, cosh, tanh, asinh,
acosh, atanh (can be synthesised - see below)
* **ZftransAdv**: much more complex to implement in hardware
* **Zfhyp**: hyperbolic/inverse-hyperbolic. sinh, cosh, tanh, asinh,
acosh, atanh (can be synthesised - see below)
* **ZftransAdv**: much more complex to implement in hardware
+* **Zfrsqrt**: Reciprocal square-root.
Minimum recommended requirements for 3D: Zftrans, Ztrigpi, Zarctrigpi,
Zarctrignpi
Minimum recommended requirements for 3D: Zftrans, Ztrigpi, Zarctrigpi,
Zarctrignpi
@@
-32,6
+33,9
@@
Zarctrignpi
* Errors **MUST** be repeatable.
* How about three Platform Specifications? 3D, UNIX and Embedded?
<http://lists.libre-riscv.org/pipermail/libre-riscv-dev/2019-August/002361.html>
* Errors **MUST** be repeatable.
* How about three Platform Specifications? 3D, UNIX and Embedded?
<http://lists.libre-riscv.org/pipermail/libre-riscv-dev/2019-August/002361.html>
+* Reciprocal Square-root is in its own separate extension (Zfrsqrt) as
+ it is desirable on its own by other implementors. This to be evaluated.
+
# List of 2-arg opcodes
# List of 2-arg opcodes
@@
-48,6
+52,7
@@
FHYPOT | hypotenuse | rd = sqrt(rs1^2 + rs2^2) | Zftrans
[[!table data="""
opcode | Description | pseudo-code | Extension |
[[!table data="""
opcode | Description | pseudo-code | Extension |
+FRSQRT | Reciprocal Square-root | rd = sqrt(rs1) | Zfrsqrt |
FCBRT | Cube Root | rd = pow(rs1, 3) | Zftrans |
FEXP2 | power-of-2 | rd = pow(2, rs1) | Zftrans |
FLOG2 | log2 | rd = log2(rs1) | Zftrans |
FCBRT | Cube Root | rd = pow(rs1, 3) | Zftrans |
FEXP2 | power-of-2 | rd = pow(2, rs1) | Zftrans |
FLOG2 | log2 | rd = log2(rs1) | Zftrans |