Standardise how to interpret a partial byte

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 12 insertions, 0 deletions

diff --git a/libhashsum_reverse_byte__.c b/libhashsum_reverse_byte__.c
new file mode 100644
index 0000000..c608eb0
--- /dev/null
+++ b/libhashsum_reverse_byte__.c
@@ -0,0 +1,12 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+uint8_t
+libhashsum_reverse_byte__(uint8_t x)
+{
+	x = (uint8_t)(((x & 0xAAU) >> 1) | ((x << 1) & 0xAAU));
+	x = (uint8_t)(((x & 0xCCU) >> 2) | ((x << 2) & 0xCCU));
+	x = (uint8_t)(((x & 0xF0U) >> 4) | ((x << 4) & 0xF0U));
+	return x;
+}