Add bitfield helper functions from libdevdev-util.h and some tests

Signed-off-by: Stephen Chandler Paul <thatslyude@gmail.com>
Reviewed-by: Peter Hutterer <peter.hutterer@who-t.net>
Reviewed-by: Hans de Goede <hdegoede@redhat.com>

src/libinput-util.h

@@ -84,4 +84,26 @@ zalloc(size_t size)
 	return calloc(1, size);
 }
 
+/* This bitfield helper implementation is taken from from libevdev-util.h,
+ * except that it has been modified to work with arrays of unsigned chars
+ */
+
+static inline int
+bit_is_set(const unsigned char *array, int bit)
+{
+    return !!(array[bit / 8] & (1 << (bit % 8)));
+}
+
+static inline void
+set_bit(unsigned char *array, int bit)
+{
+    array[bit / 8] |= (1 << (bit % 8));
+}
+
+static inline void
+clear_bit(unsigned char *array, int bit)
+{
+    array[bit / 8] &= ~(1 << (bit % 8));
+}
+
 #endif /* LIBINPUT_UTIL_H */

test/misc.c

@@ -29,6 +29,7 @@
 #include <unistd.h>
 
 #include "litest.h"
+#include "libinput-util.h"
 
 static int open_restricted(const char *path, int flags, void *data)
 {
@@ -371,12 +372,50 @@ START_TEST(event_conversion_touch)
 }
 END_TEST
 
+START_TEST(bitfield_helpers)
+{
+	/* This value has a bit set on all of the word boundaries we want to
+	 * test: 0, 1, 7, 8, 31, 32, and 33
+	 */
+	unsigned char read_bitfield[] = { 0x83, 0x1, 0x0, 0x80, 0x3 };
+	unsigned char write_bitfield[ARRAY_LENGTH(read_bitfield)];
+	size_t i;
+
+	/* Now check that the bitfield we wrote to came out to be the same as
+	 * the bitfield we were writing from */
+	for (i = 0; i < ARRAY_LENGTH(read_bitfield) * 8; i++) {
+		switch (i) {
+		case 0:
+		case 1:
+		case 7:
+		case 8:
+		case 31:
+		case 32:
+		case 33:
+			ck_assert(bit_is_set(read_bitfield, i));
+			set_bit(write_bitfield, i);
+			break;
+		default:
+			ck_assert(!bit_is_set(read_bitfield, i));
+			clear_bit(write_bitfield, i);
+			break;
+		}
+	}
+
+	ck_assert_int_eq(memcmp(read_bitfield,
+				write_bitfield,
+				sizeof(read_bitfield)),
+			 0);
+}
+END_TEST
+
 int main (int argc, char **argv) {
 	litest_add_no_device("events:conversion", event_conversion_device_notify);
 	litest_add_no_device("events:conversion", event_conversion_pointer);
 	litest_add_no_device("events:conversion", event_conversion_pointer_abs);
 	litest_add_no_device("events:conversion", event_conversion_key);
 	litest_add_no_device("events:conversion", event_conversion_touch);
+	litest_add_no_device("bitfield_helpers", bitfield_helpers);
 
 	return litest_run(argc, argv);
 }