Mem: Use range operations in bus in preparation for striping

This patch transitions the bus to use the AddrRange operations instead
of directly accessing the start and end. The change facilitates the
move to a more elaborate AddrRange class that also supports address
striping in the bus by specifying interleaving bits in the ranges.

Two new functions are added to the AddrRange to determine if two
ranges intersect, and if one is a subset of another. The bus
propagation of address ranges is also tweaked such that an update is
only propagated if the bus received information from all the
downstream slave modules. This avoids the iteration and need for the
cycle-breaking scheme that was previously used.

1 files changed, 27 insertions, 0 deletions

diff --git a/src/base/addr_range.hh b/src/base/addr_range.hh
index 21593355b..f7a3b054f 100644
--- a/src/base/addr_range.hh
+++ b/src/base/addr_range.hh
@@ -69,6 +69,33 @@ class AddrRange
 
     Addr size() const { return end - start + 1; }
     bool valid() const { return start < end; }
+
+    /**
+     * Determine if another range intersects this one, i.e. if there
+     * is an address that is both in this range and the other
+     * range. No check is made to ensure either range is valid.
+     *
+     * @param r Range to intersect with
+     * @return true if the intersection of the two ranges is not empty
+     */
+    bool intersects(const AddrRange& r) const
+    {
+        return (start <= r.start && end >= r.start) ||
+            (start <= r.end && end >= r.end);
+    }
+
+    /**
+     * Determine if this range is a subset of another range, i.e. if
+     * every address in this range is also in the other range. No
+     * check is made to ensure either range is valid.
+     *
+     * @param r Range to compare with
+     * @return true if the this range is a subset of the other one
+     */
+    bool isSubset(const AddrRange& r) const
+    {
+        return start >= r.start && end <= r.end;
+    }
 };
 
 /**