From: lkcl <lkcl@web>
Date: Sun, 16 Apr 2023 09:41:13 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: opf_rfc_ls009_v1~41
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=3a72b38b23564e2036eb537c120e2fe0c41d49ba;p=libreriscv.git

---

diff --git a/openpower/sv/remap.mdwn b/openpower/sv/remap.mdwn
index df8837db5..7e66568a7 100644
--- a/openpower/sv/remap.mdwn
+++ b/openpower/sv/remap.mdwn
@@ -107,6 +107,8 @@ hold the partial results).
 
 ## Basic principle
 
+The following illustrates why REMAP was added.
+
 * normal vector element read/write of operands would be sequential
   (0 1 2 3 ....)
 * this is not appropriate for (e.g.) Matrix multiply which requires
@@ -120,6 +122,9 @@ hold the partial results).
 * Matrix Schedules are not at all restricted to power-of-two boundaries
   making it unnecessary to have for example specialised 3x4 transpose
   instructions of other Vector ISAs.
+* DCT and FFT REMAP are RADIX-2 limited but this is the case in existing Packed/Predicated
+  SIMD ISAs anyway (and Bluestein Convolution is typically deployed to
+  solve that).
 
 Only the most commonly-used algorithms in computer science have REMAP
 support, due to the high cost in both the ISA and in hardware.  For