From e55aa58d419fcadcfd7975b9c9c87bf48ef1bd13 Mon Sep 17 00:00:00 2001
From: SamerKhshiboun <samer.khshiboun@intel.com>
Date: Sun, 17 Mar 2024 21:12:27 +0200
Subject: [PATCH] add byte manipulation functions

---
 .../include/rsutils/byte-manipulation.h       | 13 +++++++
 third-party/rsutils/src/byte-manipulation.cpp | 36 +++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 third-party/rsutils/include/rsutils/byte-manipulation.h
 create mode 100644 third-party/rsutils/src/byte-manipulation.cpp

diff --git a/third-party/rsutils/include/rsutils/byte-manipulation.h b/third-party/rsutils/include/rsutils/byte-manipulation.h
new file mode 100644
index 00000000000..50adf99c6f4
--- /dev/null
+++ b/third-party/rsutils/include/rsutils/byte-manipulation.h
@@ -0,0 +1,13 @@
+// License: Apache 2.0. See LICENSE file in root directory.
+// Copyright(c) 2023 Intel Corporation. All Rights Reserved.
+
+#pragma once
+
+namespace rsutils
+{
+    namespace byte
+    {
+        unsigned char reverse_bits(unsigned char b);
+        void reverse_byte_array_bits(unsigned char* byte_array, int size);
+    }
+}
\ No newline at end of file
diff --git a/third-party/rsutils/src/byte-manipulation.cpp b/third-party/rsutils/src/byte-manipulation.cpp
new file mode 100644
index 00000000000..d442f988da4
--- /dev/null
+++ b/third-party/rsutils/src/byte-manipulation.cpp
@@ -0,0 +1,36 @@
+// License: Apache 2.0. See LICENSE file in root directory.
+// Copyright(c) 2024 Intel Corporation. All Rights Reserved.
+
+#include <rsutils/byte-manipulation.h>
+
+namespace rsutils
+{
+    namespace byte
+    {
+        // A helper function that takes a byte and reverses its bits
+        // e.g. intput: 00110101  output: 10101100
+
+        // First the left four bits are swapped with the right four bits.
+        // Then all adjacent pairs are swapped and then all adjacent single bits.
+        // This results in a reversed order.
+        unsigned char reverse_bits(unsigned char b)
+        {
+            b = (b & 0xF0) >> 4 | (b & 0x0F) << 4;
+            b = (b & 0xCC) >> 2 | (b & 0x33) << 2;
+            b = (b & 0xAA) >> 1 | (b & 0x55) << 1;
+            return b;
+        }
+
+        // A helper function that takes a byte rray of a given size,
+        // and reverses the bits order of for each byte of this array
+        // e.g. intput: byteArray = {byte0=00110101, byte1=11110000}, size = 2
+        // output: byteArray [ byte0=10101100, byte1=00001111]
+        void reverse_byte_array_bits(unsigned char* byte_array, int size) {
+            for (int i = 0; i < size; ++i)
+            {
+                byte_array[i] = reverse_bits(byte_array[i]);
+            }
+        }
+    }
+}
+