Add FAT16 library

[rmslog.git] / FAT16 / byteordering.h

diff --git a/FAT16/byteordering.h b/FAT16/byteordering.h
new file mode 100644 (file)
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--- /dev/null
+++ b/FAT16/byteordering.h
@@ -0,0 +1,137 @@
+
+/*
+ * Copyright (c) 2006-2009 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.
+ */
+
+#ifndef BYTEORDERING_H
+#define BYTEORDERING_H
+
+#include <stdint.h>
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+/**
+ * \addtogroup byteordering
+ *
+ * @{
+ */
+/**
+ * \file
+ * Byte-order handling header (license: GPLv2 or LGPLv2.1)
+ *
+ * \author Roland Riegel
+ */
+
+/**
+ * \def HTOL16(val)
+ *
+ * Converts a 16-bit integer to little-endian byte order.
+ *
+ * Use this macro for compile time constants only. For variable values
+ * use the function htol16() instead. This saves code size.
+ *
+ * \param[in] val A 16-bit integer in host byte order.
+ * \returns The given 16-bit integer converted to little-endian byte order.
+ */
+/**
+ * \def HTOL32(val)
+ *
+ * Converts a 32-bit integer to little-endian byte order.
+ *
+ * Use this macro for compile time constants only. For variable values
+ * use the function htol32() instead. This saves code size.
+ *
+ * \param[in] val A 32-bit integer in host byte order.
+ * \returns The given 32-bit integer converted to little-endian byte order.
+ */
+
+#if __AVR__
+#define HTOL16(val) (val)
+#define HTOL32(val) (val)
+#elif defined(BIG_ENDIAN)
+#define HTOL16(val) ((((uint16_t) (val)) << 8) | \
+                     (((uint16_t) (val)) >> 8)   \
+                    )
+#define HTOL32(val) (((((uint32_t) (val)) & 0x000000ff) << 24) | \
+                     ((((uint32_t) (val)) & 0x0000ff00) <<  8) | \
+                     ((((uint32_t) (val)) & 0x00ff0000) >>  8) | \
+                     ((((uint32_t) (val)) & 0xff000000) >> 24)   \
+                    )
+#else
+#error "Endianess undefined! Please define LITTLE_ENDIAN=1 or BIG_ENDIAN=1."
+#endif
+
+uint16_t htol16(uint16_t h);
+uint32_t htol32(uint32_t h);
+
+/**
+ * Converts a 16-bit integer to host byte order.
+ *
+ * Use this macro for compile time constants only. For variable values
+ * use the function ltoh16() instead. This saves code size.
+ *
+ * \param[in] val A 16-bit integer in little-endian byte order.
+ * \returns The given 16-bit integer converted to host byte order.
+ */
+#define LTOH16(val) HTOL16(val)
+
+/**
+ * Converts a 32-bit integer to host byte order.
+ *
+ * Use this macro for compile time constants only. For variable values
+ * use the function ltoh32() instead. This saves code size.
+ *
+ * \param[in] val A 32-bit integer in little-endian byte order.
+ * \returns The given 32-bit integer converted to host byte order.
+ */
+#define LTOH32(val) HTOL32(val)
+
+/**
+ * Converts a 16-bit integer to host byte order.
+ *
+ * Use this function on variable values instead of the
+ * macro LTOH16(). This saves code size.
+ *
+ * \param[in] l A 16-bit integer in little-endian byte order.
+ * \returns The given 16-bit integer converted to host byte order.
+ */
+#define ltoh16(l) htol16(l)
+
+/**
+ * Converts a 32-bit integer to host byte order.
+ *
+ * Use this function on variable values instead of the
+ * macro LTOH32(). This saves code size.
+ *
+ * \param[in] l A 32-bit integer in little-endian byte order.
+ * \returns The given 32-bit integer converted to host byte order.
+ */
+#define ltoh32(l) htol32(l)
+
+
+/**
+ * @}
+ */
+
+#if __AVR__
+#define htol16(h) (h)
+#define htol32(h) (h)
+#else
+uint16_t htol16(uint16_t h);
+uint32_t htol32(uint32_t h);
+#endif
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif
+