From abe4edc419c49ba7bbe8c2d1db574761aa94c898 Mon Sep 17 00:00:00 2001
From: Ahmet Inan <inan@aicodix.de>
Date: Sat, 22 Sep 2018 19:13:37 +0200
Subject: [PATCH] added bit manipulation helpers

---
 README.md |  4 ++++
 bitman.hh | 45 +++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 bitman.hh

diff --git a/README.md b/README.md
index c07b5f3..ff3e97a 100644
--- a/README.md
+++ b/README.md
@@ -31,6 +31,10 @@ Here a [Pseudorandom number generator](https://en.wikipedia.org/wiki/Pseudorando
 
 When dealing with unaligned and arbitrary-bit-sized elements in a data stream, the bitwise stream container might help avoiding some headaches.
 
+### [bitman.hh](bitman.hh)
+
+Simple bit manipulation on byte arrays.
+
 ### [galois_field.hh](galois_field.hh)
 
 We have to thank [Évariste Galois](https://en.wikipedia.org/wiki/%C3%89variste_Galois) for his contribution of the [Finite field](https://en.wikipedia.org/wiki/Finite_field) to mathematics, which laid the cornerstone for a variety of applications that we take for granted today.
diff --git a/bitman.hh b/bitman.hh
new file mode 100644
index 0000000..074841b
--- /dev/null
+++ b/bitman.hh
@@ -0,0 +1,45 @@
+/*
+Bit manipulation of byte arrays
+
+Copyright 2018 Ahmet Inan <inan@aicodix.de>
+*/
+
+#ifndef BITMAN_HH
+#define BITMAN_HH
+
+namespace CODE {
+
+void xor_be_bit(uint8_t *buf, int pos, bool val)
+{
+	buf[pos/8] ^= val<<(7-pos%8);
+}
+
+void xor_le_bit(uint8_t *buf, int pos, bool val)
+{
+	buf[pos/8] ^= val<<(pos%8);
+}
+
+void set_be_bit(uint8_t *buf, int pos, bool val)
+{
+	buf[pos/8] = (~(1<<(7-pos%8))&buf[pos/8])|(val<<(7-pos%8));
+}
+
+void set_le_bit(uint8_t *buf, int pos, bool val)
+{
+	buf[pos/8] = (~(1<<(pos%8))&buf[pos/8])|(val<<(pos%8));
+}
+
+bool get_be_bit(uint8_t *buf, int pos)
+{
+	return (buf[pos/8]>>(7-pos%8))&1;
+}
+
+bool get_le_bit(uint8_t *buf, int pos)
+{
+	return (buf[pos/8]>>(pos%8))&1;
+}
+
+}
+
+#endif
+