import sd-reader_source_20120612

[protos/imu.git] / byteordering.c

diff --git a/byteordering.c b/byteordering.c
new file mode 100644 (file)
index 0000000..d1c67cd
--- /dev/null
+++ b/byteordering.c
@@ -0,0 +1,110 @@
+
+/*
+ * Copyright (c) 2006-2012 by Roland Riegel <feedback@roland-riegel.de>
+ *
+ * This file is free software; you can redistribute it and/or modify
+ * it under the terms of either the GNU General Public License version 2
+ * or the GNU Lesser General Public License version 2.1, both as
+ * published by the Free Software Foundation.
+ */
+
+#include "byteordering.h"
+
+/**
+ * \addtogroup byteordering
+ *
+ * Architecture-dependent handling of byte-ordering.
+ *
+ * @{
+ */
+/**
+ * \file
+ * Byte-order handling implementation (license: GPLv2 or LGPLv2.1)
+ *
+ * \author Roland Riegel
+ */
+
+#if DOXYGEN || SWAP_NEEDED
+
+/**
+ * \internal
+ * Swaps the bytes of a 16-bit integer.
+ *
+ * \param[in] i A 16-bit integer which to swap.
+ * \returns The swapped 16-bit integer.
+ */
+uint16_t swap16(uint16_t i)
+{
+    return SWAP16(i);
+}
+
+/**
+ * \internal
+ * Swaps the bytes of a 32-bit integer.
+ *
+ * \param[in] i A 32-bit integer which to swap.
+ * \returns The swapped 32-bit integer.
+ */
+uint32_t swap32(uint32_t i)
+{
+    return SWAP32(i);
+}
+
+#endif
+
+/**
+ * Reads a 16-bit integer from memory in little-endian byte order.
+ *
+ * \param[in] p Pointer from where to read the integer.
+ * \returns The 16-bit integer read from memory.
+ */
+uint16_t read16(const uint8_t* p)
+{
+    return (((uint16_t) p[1]) << 8) |
+           (((uint16_t) p[0]) << 0);
+}
+
+/**
+ * Reads a 32-bit integer from memory in little-endian byte order.
+ *
+ * \param[in] p Pointer from where to read the integer.
+ * \returns The 32-bit integer read from memory.
+ */
+uint32_t read32(const uint8_t* p)
+{
+    return (((uint32_t) p[3]) << 24) |
+           (((uint32_t) p[2]) << 16) |
+           (((uint32_t) p[1]) <<  8) |
+           (((uint32_t) p[0]) <<  0);
+}
+
+/**
+ * Writes a 16-bit integer into memory in little-endian byte order.
+ *
+ * \param[in] p Pointer where to write the integer to.
+ * \param[in] i The 16-bit integer to write.
+ */
+void write16(uint8_t* p, uint16_t i)
+{
+    p[1] = (uint8_t) ((i & 0xff00) >> 8);
+    p[0] = (uint8_t) ((i & 0x00ff) >> 0);
+}
+
+/**
+ * Writes a 32-bit integer into memory in little-endian byte order.
+ *
+ * \param[in] p Pointer where to write the integer to.
+ * \param[in] i The 32-bit integer to write.
+ */
+void write32(uint8_t* p, uint32_t i)
+{
+    p[3] = (uint8_t) ((i & 0xff000000) >> 24);
+    p[2] = (uint8_t) ((i & 0x00ff0000) >> 16);
+    p[1] = (uint8_t) ((i & 0x0000ff00) >>  8);
+    p[0] = (uint8_t) ((i & 0x000000ff) >>  0);
+}
+
+/**
+ * @}
+ */
+