base: Fix signature of SatCounter::saturate()

The variants that use more than 8 bits were broken,
since the size of the difference in those cases
could be larger than 8 bits, and the return value
was only 8-bits long.

Change-Id: I8b75be48f924cc33ebf5e5aeff6d4045fac66bcc
Signed-off-by: Daniel R. Carvalho <odanrc@yahoo.com.br>
Reviewed-on: https://gem5-review.googlesource.com/c/public/gem5/+/66791
Maintainer: Matt Sinclair <mattdsinclair@gmail.com>
Reviewed-by: Matt Sinclair <mattdsinclair@gmail.com>
Tested-by: kokoro <noreply+kokoro@google.com>

src/base/sat_counter.hh

@@ -318,9 +318,9 @@ class GenericSatCounter
      *
      * @ingroup api_sat_counter
      */
-    uint8_t saturate()
+    T saturate()
     {
-        const uint8_t diff = maxVal - counter;
+        const T diff = maxVal - counter;
         counter = maxVal;
         return diff;
     }

src/base/sat_counter.test.cc

@@ -149,6 +149,20 @@ TEST(SatCounterTest, Saturate)
     ASSERT_TRUE(counter.isSaturated());
 }
 
+TEST(SatCounterTest, Saturate16)
+{
+    const unsigned bits = 14;
+    const unsigned max_value = (1 << bits) - 1;
+    SatCounter16 counter(bits);
+    counter++;
+    ASSERT_FALSE(counter.isSaturated());
+
+    // Make sure the value added is what was missing to saturate
+    const unsigned diff = counter.saturate();
+    ASSERT_EQ(diff, max_value - 1);
+    ASSERT_TRUE(counter.isSaturated());
+}
+
 /**
  * Test back and forth against an int.
  */