Mercurial > pihelp
diff byteordering.c @ 19:5f9a40d6991b
Import SD handling from http://www.roland-riegel.de/sd-reader/index.html
Use smaller build options
author | Matt Johnston <matt@ucc.asn.au> |
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date | Tue, 25 Jun 2013 13:55:11 +0800 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/byteordering.c Tue Jun 25 13:55:11 2013 +0800 @@ -0,0 +1,110 @@ + +/* + * Copyright (c) 2006-2012 by Roland Riegel <[email protected]> + * + * 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); +} + +/** + * @} + */ +