From: Luke Kenneth Casson Leighton <lkcl@lkcl.net>
Date: Sat, 24 Jul 2021 11:57:21 +0000 (+0100)
Subject: update submodes for DCT
X-Git-Tag: DRAFT_SVP64_0_1~596
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=6b1d421c08a9ab72b330b1c2d5c0558f35f5cf42;p=libreriscv.git

update submodes for DCT
---

diff --git a/openpower/sv/shape_table_format.mdwn b/openpower/sv/shape_table_format.mdwn
index 316e26814..241e03e6c 100644
--- a/openpower/sv/shape_table_format.mdwn
+++ b/openpower/sv/shape_table_format.mdwn
@@ -27,10 +27,10 @@ is also performed.
     in-place
 * **submode=0b010** selects the ``j+halfsize`` offset of the innermost for-loop,
   in reverse-order, in-place
-* **submode=0b10** selects the ``j`` offset of the innermost for-loop,
-    in non-in-place mode
-* **submode=0b11** selects the ``j+halfsize`` offset of the innermost for-loop,
-  in reverse-order, in non-in-place mode.
+* **submode=0b10** selects the ``ci`` count of the innermost for-loop,
+  useful for calculating the cosine coefficient
+* **submode=0b11** selects the ``size`` offset of the outermost for-loop,
+  useful for the cosine coefficient ``cos(ci + 0.5) * pi / size``
 
 When submode2 is 3 or 4, for DCT outer butterfly submode the following
 schedules may be selected.  When submode is 3, additional bit-reversing