bitwise: add bitfield tests

test/bitwise.cpp

@@ -1,4 +1,5 @@
 #include "bitwise.hpp"
+#include "std.hpp"
 #include "tap.hpp"
 
 
@@ -52,6 +53,30 @@ test_reverse (cruft::TAP::logger &tap)
 }
 
 
+//-----------------------------------------------------------------------------
+void
+test_bitfield (cruft::TAP::logger &tap)
+{
+    union {
+        /// * lo is set to 1 and hi is set to 0 to establish bit ordering
+        /// * mid pattern tests behaviour across byte boundaries
+        u16 raw = 0b0111'0011'0000'0001;
+        //          |  |mid^---^      |
+        //   highest^  |        lowest^
+        //      high^--^
+        cruft::bitfield<u16, 0,1> lowest;
+        cruft::bitfield<u16,15,1> highest;
+        cruft::bitfield<u16,12,4> high;
+        cruft::bitfield<u16, 6,4> mid;
+    };
+
+    tap.expect_eq (lowest,  u16 {   0b1}, "bitfield lowest bit");
+    tap.expect_eq (highest, u16 {   0b0}, "bitfield highest bit");
+    tap.expect_eq (high,    u16 {0b0111}, "bitfield high bits");
+    tap.expect_eq (mid,     u16 {0b1100}, "bitfield byte boundary bits");
+}
+
+
 //-----------------------------------------------------------------------------
 int
 main (int, char**)
@@ -60,6 +85,7 @@ main (int, char**)
 
     test_rotate (tap);
     test_reverse (tap);
+    test_bitfield (tap);
 
     return tap.status ();
 }