From: lkcl <lkcl@web>
Date: Thu, 23 Jun 2022 18:23:24 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: opf_rfc_ls005_v1~1562
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=eee568d5224ca9e4d2b285ebcd5e2c68631b01db;p=libreriscv.git

---

diff --git a/openpower/sv/svstep.mdwn b/openpower/sv/svstep.mdwn
index cee53a613..163c91150 100644
--- a/openpower/sv/svstep.mdwn
+++ b/openpower/sv/svstep.mdwn
@@ -27,12 +27,23 @@ Instruction format:
     svstep RT,SVi,vf  (Rc=0)
     svstep. RT,SVi,vf (Rc=1)
 
-When `vf=1` then the REMAP Schedule for a given SVSHAPE, specified
-in `SVi` (values 0-3 are legal) may be
-returned in `RT`. To obtain the full set of possible computed element
+When `vf=1` then stepping occurs. When `vf=0` svstep may be used
+to enquire about the REMAP Schedule state, without altering internal
+state.  If `SVi=0, Rc=0, vf=0` this instruction is a `nop`.
+
+When `SVi` is 1-4 the REMAP Schedule for a given SVSHAPE  may be
+returned in `RT`.  SVi=1 selects SVSHAPE0 current state,
+through to SVi=4 selects SVSHAPE3.
+
+To obtain the full set of possible computed element
 indices use `svstep RT.v,SVI,1` which will store all computed element
 indices, starting from RT.  If Rc=1 then a co-result Vector of CR Fields
 will also be returned, comprising the "end-points" of each of the inner
 loops when either Matrix Mode or DCT/FFT is set.  In other words,
 for example, when the `xdim` inner loop reaches the end and on the next
 iteration it will begin again at zero, the CR Field `EQ` will be set.
+
+*Programmer's note: VL in some situations, particularly larger Matrices,
+may exceed 64,
+meaning that `sv.svshape` returning a considerable number of values. Under
+such circumstances `sv.svshape/ew=8` is recommended.*