[Libre-soc-bugs] [Bug 683] New: possible precedence error in divw XLEN

[bugzilla-daemon at libre-soc.org]

https://bugs.libre-soc.org/show_bug.cgi?id=683

            Bug ID: 683
           Summary: possible precedence error in divw XLEN
           Product: Libre-SOC's first SoC
           Version: unspecified
          Hardware: PC
                OS: Linux
            Status: CONFIRMED
          Severity: enhancement
          Priority: ---
         Component: Source Code
          Assignee: lkcl at lkcl.net
          Reporter: lkcl at lkcl.net
                CC: libre-soc-bugs at lists.libre-soc.org
   NLnet milestone: ---

-    dividend[0:31] <- (RA)[32:63]
-    divisor[0:31] <- (RB) [32:63]
-    if (((dividend = 0x8000_0000) &
-         (divisor = [1]*32)) |
-         (divisor = [0]*32)) then
-        RT[0:63] <- undefined([0]*64)
+    dividend[0:(XLEN/2)-1] <- (RA)[XLEN/2:XLEN-1]
+    divisor[0:(XLEN/2)-1] <- (RB) [XLEN/2:XLEN-1]
+    if (((dividend = (0b1 || ([0b0] * ((XLEN/2)-1)))) &
+         (divisor = [1]*XLEN/2)) |
+         (divisor = [0]*XLEN/2)) then
+        RT[0:XLEN-1] <- undefined([0]*XLEN)

[1]*XLEN/2 *may* be being interpreted as:

   ([1]*XLEN)/2

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