add example on bitwise operations on structure bitfields

modules/structure-bit-fields.md

@@ -41,3 +41,5 @@ foo.a++; // will wrap around to 0 since this is unsigned
 ```
 
 #source bitfield-wraparound.c
+
+#source bitfield-bitwise-ops.c

src/bitfield-bitwise-ops.c

@@ -0,0 +1,18 @@
+#include <stdio.h>
+
+struct foo_s {
+	unsigned int a : 3;
+	unsigned int b : 5;
+} foo;
+
+int
+main(void)
+{
+	foo.a = 5;  /*   101 */
+	foo.b = 16; /* 10000 */
+
+	foo.a = foo.a ^ foo.b;
+	unsigned int xor = foo.a ^ foo.b;
+
+	printf("%u vs %u\n", foo.a, xor);
+}