From: lkcl <lkcl@web>
Date: Wed, 2 Oct 2019 11:16:27 +0000 (+0100)
Subject: (no commit message)
X-Git-Tag: convert-csv-opcode-to-binary~3924
X-Git-Url: https://git.libre-soc.org/?a=commitdiff_plain;h=f0c4b40443f74ffbe8410b1ec5d024b1772c474a;p=libreriscv.git

---

diff --git a/simple_v_extension/specification/bitmanip.mdwn b/simple_v_extension/specification/bitmanip.mdwn
index 1af47e749..fb47df634 100644
--- a/simple_v_extension/specification/bitmanip.mdwn
+++ b/simple_v_extension/specification/bitmanip.mdwn
@@ -95,6 +95,19 @@ This instruction is present in BitManip.
 
 finds the first bit set as an index.
 
+Pseudocode:
+
+
+    uint_xlen_t clz(uint_xlen_t rs1)
+    {
+        for (int count = 0; count < XLEN; count++)
+            if ((rs1 << count) >> (XLEN - 1))
+                return count;
+        return XLEN; // -1
+    }
+
+This is similar but not identical to BitManip "CLZ". CLZ returns XLEN when no bits are set, whereas RVV returns -1.
+
 ## sbf - set before first bit
 
 Sets all LSBs leading up to where an LSB in the src is set.  If the second
@@ -142,6 +155,8 @@ Pseudo-code:
 
 ## sif - set including first bit
 
+Similar to sbf except including the bit which ends a run.
+
      # Example
 
      7 6 5 4 3 2 1 0   Element number