From: lkcl <lkcl@web>
Date: Mon, 5 Sep 2022 18:11:53 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: opf_rfc_ls005_v1~670
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=8a3ccd3e798c7f81dd71a82cc608db39a34009cb;p=libreriscv.git

---

diff --git a/openpower/sv/remap.mdwn b/openpower/sv/remap.mdwn
index 51b1c978a..0d997f9f1 100644
--- a/openpower/sv/remap.mdwn
+++ b/openpower/sv/remap.mdwn
@@ -449,9 +449,18 @@ mode sets different behaviours (straight matrix multiply, FFT, DCT).
 
 ## Parallel Reduction Mode
 
+Creates the Schedules for Parallel Tree Reduction.
+
 * **submode=0b00** selects the left operand index
 * **submode=0b01** selects the right operand index
 
+* When bit 0 of `invxyz` is set, the order of the indices
+  in the inner for-loop are reversed. This has the side-effect
+  of placing the final reduced result in the last element.
+* When bit 1 of `invxyz` is set, the order of the outer loop
+  step is inverted: stepping begins at the nearest power-of two
+  to half of the vector length and reduces by half each time.
+
 ## FFT/DCT mode
 
 submode2=0 is for FFT. For FFT submode the following schedules may be