From: lkcl <lkcl@web>
Date: Wed, 18 Nov 2020 11:24:28 +0000 (+0000)
Subject: (no commit message)
X-Git-Tag: convert-csv-opcode-to-binary~1730
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=afecd85d0b4e03bf60024366ef66d67a6a30bef9;p=libreriscv.git

---

diff --git a/openpower/sv/16_bit_compressed.mdwn b/openpower/sv/16_bit_compressed.mdwn
index bad8b996d..44ca28823 100644
--- a/openpower/sv/16_bit_compressed.mdwn
+++ b/openpower/sv/16_bit_compressed.mdwn
@@ -225,10 +225,12 @@ is "nop"
 
 Notes:
 
+* All-zeros being an illegal instruction is normal for ISAs.  Ensuring that 
+  this remains true at all times i.e. for both 10 bit and 16 bit mode is
+  common sense.
 * The 10-bit nop (bit 15, M=1) is intended for circumstances
-  where alignment to 32-bit before rwturning to v3.0B is required.
-  M=1 being an indication
-  "return to Standard v3.0B Encoding Mode"
+  where alignment to 32-bit before returning to v3.0B is required.
+  M=1 being an indication "return to Standard v3.0B Encoding Mode". 
 * The 16-bit nop (bit 0, N=1) is intended for circumstances where a
   return to Standard v3.0B Encoding is required for one cycle
   but one cycle where alignment to a 32-bit boundary is needed
@@ -236,6 +238,8 @@ Notes:
   the 10-bit variant can be used, because each one returns to
   Standard v3.0B Encoding Mode, each time.
 
+In essence the 2 nops are needed due to there being 2 different C forms: 10 and 16 bit.  
+
 ### Branch
 
     | 16-bit mode | | 10-bit mode                 |