From: lkcl <lkcl@web>
Date: Sat, 24 Sep 2022 23:46:25 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: opf_rfc_ls005_v1~303
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=b081942da5c885e4a0a887fc2e2fb25ca519823e;p=libreriscv.git

---

diff --git a/openpower/sv/overview/discussion.mdwn b/openpower/sv/overview/discussion.mdwn
index fc84c0a85..51e0d8c6a 100644
--- a/openpower/sv/overview/discussion.mdwn
+++ b/openpower/sv/overview/discussion.mdwn
@@ -226,19 +226,32 @@ Further we may now also define half-words, words, and double-words,
 confirming the definition of registers (RA as the same example):
 
      H0 = B0||B1, H1 = B2||B3, H2 = B4||B5, H3 = B6||B7
+     RA = H0||H1||H2||H3
      W0 = H0||H1, W1 = H2||H3
      D0 = W0||W1
+     RA = H0||H1||H2||H3
+     RA = W0||W1
      RA = D0
 
-If we then perform the following **arithmetic** operations (assuming
-starting all zeros):
+If we then perform the following **arithmetic** operations:
 
     RA = 1 << 63
     RB = 128
     RT = 3 + 4
 
-The following bits are set (all others zero):
+then the following bits are set (all others zero):
 
     RA.b0 = 1    RA.B0 = 0x80  RA.H0 = 0x8000  RA.W0 = 0x80000000
     RB.b56 = 1   RB.B7 = 0x08  RB.H3 = 0x0008  RB.W1 = 0x00000008
     RT.b61-3 = 1 RT.B7 = 0x07  RT.H3 = 0x0007  RT.W1 = 0x00000007
+
+Now taking the c struct definition `elreg_t` above we may provide
+a link between the two:
+
+    elreg_t x;
+    x.actual_bytes[0] = RA.B7; // byte zero in LE is byte 7 in MSB0
+    x.actual_bytes[1] = RA.B6;
+    ...
+    x.actual_bytes[7] = RA.B0; // byte 7 in LE is byte 0 in MSB0
+    
+