From: lkcl <lkcl@web>
Date: Wed, 11 Sep 2019 13:57:23 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: convert-csv-opcode-to-binary~4107
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=549da67b3234056aeea6abd39c178cc016b5aede;p=libreriscv.git

---

diff --git a/zfpacc_proposal.mdwn b/zfpacc_proposal.mdwn
index 4f2aea2fd..2e21c0740 100644
--- a/zfpacc_proposal.mdwn
+++ b/zfpacc_proposal.mdwn
@@ -7,6 +7,7 @@ TODO: complete writeup
 
 Zfpacc: a proposal to allow implementations to dynamically set the bit-accuracy
 of results, trading speed (reduced latency) for accuracy (higher latency).
+IEE754 format is preserved: only ULP (Unit in Last Place) is permitted to be non-zero.
 
 # Extension of FCSR
 
@@ -86,6 +87,8 @@ The values for the field facc to include the following:
 | 0b100 | Vulkan  | Vulkan compliant    | 
 | 0b110 | Appx    | Machine Learning    |
 
+Note that the format of the operands and result remain the same for all opcodes. The only change is in the *accuracy* of the result, not its format.
+
 maybe a solution would be to add an extra field to the fp control csr
 to allow selecting one of several accurate or fast modes: