Add endian.h

1 files changed, 68 insertions, 0 deletions

diff --git a/include/nsutils/endian.h b/include/nsutils/endian.h
new file mode 100644
index 0000000..4fe2420
--- /dev/null
+++ b/include/nsutils/endian.h
@@ -0,0 +1,68 @@
+/*
+ * This file is part of LibNSUtils.
+ * Licensed under the MIT License,
+ *                http://www.opensource.org/licenses/mit-license.php
+ * Copyright 2009 John-Mark Bell <jmb@netsurf-browser.org>
+ */
+
+/**
+ * \file
+ * Endianness helper functions.
+ */
+
+#ifndef NSUTILS_ENDIAN_H_
+#define NSUTILS_ENDIAN_H__
+
+/**
+ * Detect if the host is little endian.
+ *
+ * \return True if the host is little endian; false otherwise.
+ */
+static inline bool endian_host_is_le(void)
+{
+	static uint32_t magic = 0x10000002;
+
+	return (((uint8_t *) &magic)[0] == 0x02);
+}
+
+/**
+ * Swap the endianness of a 32bit value.
+ *
+ * \param val Value to swap endianness of
+ * \return Endian-swapped value
+ */
+static inline uint32_t endian_swap(uint32_t val)
+{
+	return ((val & 0xff000000) >> 24) | ((val & 0x00ff0000) >> 8) |
+		((val & 0x0000ff00) << 8) | ((val & 0x000000ff) << 24);
+}
+
+/**
+ * Convert a host-endian 32bit value to its big-endian equivalent.
+ *
+ * \param host Value to convert
+ * \return Big endian value
+ */
+static inline uint32_t endian_host_to_big(uint32_t host)
+{
+	if (endian_host_is_le())
+		return endian_swap(host);
+
+	return host;
+}
+
+/**
+ * Convert a big-endian 32bit value to its host-endian equivalent.
+ *
+ * \param host Value to convert
+ * \return Host endian value
+ */
+static inline uint32_t endian_big_to_host(uint32_t big)
+{
+	if (endian_host_is_le())
+		return endian_swap(big);
+
+	return big;
+}
+
+#endif