From 3390da444643824a34c13668e39981d18601857d Mon Sep 17 00:00:00 2001
From: Peter Rugg <pdr32@cam.ac.uk>
Date: Tue, 28 May 2019 15:23:55 +0100
Subject: [PATCH] Fix reporting of exact in setBounds

---
 CHERICC_Fat.bsv | 5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/CHERICC_Fat.bsv b/CHERICC_Fat.bsv
index 416e6e0..5f83391 100644
--- a/CHERICC_Fat.bsv
+++ b/CHERICC_Fat.bsv
@@ -470,13 +470,16 @@ function Tuple2#(CapFat, Bool) setBoundsFat(CapFat cap, Address lengthFull);
         // The lomask for checking for potential overflow should mask all but the bottom bit of the mantissa.
         lmaskLo = lmask>>fromInteger(shiftAmount+1);
         Bool lengthMax = (len&(~lmaskLo))==(lmask&(~lmaskLo));
+        Bool resultExact = True;
         if(lengthMax && intExp && (lostSignificantLen || lostSignificantBase)) begin
           e = e+1;
           ret.bounds.topBits = (lostSignificantTopHigher) ? (newTopBitsHigher+'b1000):newTopBitsHigher;
           ret.bounds.baseBits = truncateLSB(newBaseBits);
+          if (lostSignificantBaseHigher || lostSignificantTopHigher) resultExact = False;
         end else begin
           ret.bounds.topBits = (lostSignificantTop) ? truncate(newTopBits+'b1000):truncate(newTopBits);
           ret.bounds.baseBits = truncate(newBaseBits);
+          if (lostSignificantBase || lostSignificantTop) resultExact = False;
         end
         
         
@@ -495,7 +498,7 @@ function Tuple2#(CapFat, Bool) setBoundsFat(CapFat cap, Address lengthFull);
         end
         
         // Return derived capability
-        return tuple2(ret, !(lostSignificantBaseHigher || lostSignificantTopHigher));
+        return tuple2(ret, resultExact);
 endfunction
 function CapFat seal(CapFat cap, TempFields tf, CType otype);
         CapFat ret = cap;