From: lkcl <lkcl@web>
Date: Wed, 22 Jun 2022 16:58:52 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: opf_rfc_ls005_v1~1590
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=9ce44bc6dc14113acad60d2fe0009feb7781a7fc;p=libreriscv.git

---

diff --git a/openpower/sv/vector_ops/discussion.mdwn b/openpower/sv/vector_ops/discussion.mdwn
index 3f8765b66..3b6c6fd74 100644
--- a/openpower/sv/vector_ops/discussion.mdwn
+++ b/openpower/sv/vector_ops/discussion.mdwn
@@ -6,6 +6,35 @@ These all it turns out can be done as bitmanip of the form
 x/~x &/|/^ (x / -x / x+1 / x-1) so are being superceded.
 needs some work though
 
+```
+def bmask(mode, RA, RB=None, zero=False):
+    mask = [1] * XLEN
+    mask = RB if RB is not None else 0xffffffffffffffff
+    ra <- RA & mask
+    if mode[0] then a1 <- ra else a1 <-~ra
+    mode2 = (mode >> 1) & 0b11
+    if mode2 = 0 then a2 <- -ra
+    if mode2 = 1 then a2 <- ra-1
+    if mode2 = 2 then a2 <- ra+1
+    if mode2 = 3 then a2 <- ~(ra+1)
+    a1 <- a1 & mask
+    a2 <- a2 & mask
+    mode3 <- mode[3:4]
+    if mode3 = 0 then result <- a1 | a2
+    if mode3 = 1 then result <- a1 & a2
+    if mode3 = 2 result <- a1 ^ a2
+    if mode3 = 3 result <- UNDEFINED
+    result <- result & mask
+    if L = 1 then
+        result <- result | (RA & ~mask)
+    RT <- result
+
+SBF = 0b01010 # set before first
+SOF = 0b01001 # set only first
+SIF = 0b10000 # set including first 10011 also works no idea why yet
+```
+
+
 ## OBSOLETE sbfm
 
    sbfm RT, RA, RB!=0