From: lkcl <lkcl@web>
Date: Sat, 14 May 2022 15:19:12 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: opf_rfc_ls005_v1~2241
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=0e0ae69cc1273971048eb774189b00cc7317481f;p=libreriscv.git

---

diff --git a/openpower/sv/biginteger.mdwn b/openpower/sv/biginteger.mdwn
index e92ba87d3..c9ccf5570 100644
--- a/openpower/sv/biginteger.mdwn
+++ b/openpower/sv/biginteger.mdwn
@@ -38,7 +38,9 @@ fashion that is hidden from the user, behind a consistent, stable ISA API.
 
 **DRAFT**
 
-`madded` is VA-Form:
+`madded` is similar to v3.0 `madd`.
+`madded`, like `madd`, is VA-Form despite having 2 outputs: the second
+destination register is implicit.
 
 |0.....5|6..10|11..15|16..20|21..25|26..31|
 |-------|-----|------|------|------|------|
@@ -49,7 +51,7 @@ The pseudocode for `madded RT, RA, RB, RC` is:
     prod[0:127] = (RA) * (RB)
     sum[0:127] = EXTZ(RC) + prod
     RT <- sum[64:127]
-    RS <- sum[0:63] # RS is either RC or RT+VL
+    RS <- sum[0:63] # RS is either RC or RT+MAXVL
 
 RC is zero-extended (not shifted), the 128-bit product added
 to it; the lower half of that result stored in RT and the upper half
@@ -75,7 +77,7 @@ used with the additional bit set for determining RS.
 When `EXTRA2_MODE` is set to zero, the implicit RS register takes
 its Vector/Scalar setting from Rdest_EXTRA2, and takes
 the register number from RT, but all numbering
-is offset by VL. *Note that element-width overrides influence this
+is offset by MAXVL. *Note that element-width overrides influence this
 offset* (see SVP64 [[svp64/appendix]] for full details).
 
 When `EXTRA2_MODE` is set to one, the implicit RS register is identical