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annotate byteordering.c @ 31:5d6a841eef82

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/128 prescaler for adc
author Matt Johnston <matt@ucc.asn.au>
date Thu, 27 Jun 2013 00:12:32 +0800
parents 5f9a40d6991b
children
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19
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1
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2 /*
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3 * Copyright (c) 2006-2012 by Roland Riegel <[email protected]>
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4 *
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5 * This file is free software; you can redistribute it and/or modify
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6 * it under the terms of either the GNU General Public License version 2
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7 * or the GNU Lesser General Public License version 2.1, both as
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8 * published by the Free Software Foundation.
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9 */
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10
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11 #include "byteordering.h"
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12
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13 /**
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14 * \addtogroup byteordering
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15 *
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16 * Architecture-dependent handling of byte-ordering.
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17 *
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18 * @{
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19 */
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20 /**
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21 * \file
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22 * Byte-order handling implementation (license: GPLv2 or LGPLv2.1)
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23 *
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24 * \author Roland Riegel
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25 */
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26
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27 #if DOXYGEN || SWAP_NEEDED
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28
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29 /**
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30 * \internal
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31 * Swaps the bytes of a 16-bit integer.
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32 *
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33 * \param[in] i A 16-bit integer which to swap.
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34 * \returns The swapped 16-bit integer.
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35 */
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36 uint16_t swap16(uint16_t i)
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37 {
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38 return SWAP16(i);
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39 }
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40
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41 /**
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42 * \internal
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43 * Swaps the bytes of a 32-bit integer.
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44 *
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45 * \param[in] i A 32-bit integer which to swap.
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46 * \returns The swapped 32-bit integer.
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47 */
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48 uint32_t swap32(uint32_t i)
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49 {
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50 return SWAP32(i);
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51 }
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52
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53 #endif
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54
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55 /**
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56 * Reads a 16-bit integer from memory in little-endian byte order.
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57 *
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58 * \param[in] p Pointer from where to read the integer.
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59 * \returns The 16-bit integer read from memory.
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60 */
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61 uint16_t read16(const uint8_t* p)
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62 {
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63 return (((uint16_t) p[1]) << 8) |
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64 (((uint16_t) p[0]) << 0);
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65 }
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66
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67 /**
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68 * Reads a 32-bit integer from memory in little-endian byte order.
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69 *
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70 * \param[in] p Pointer from where to read the integer.
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71 * \returns The 32-bit integer read from memory.
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72 */
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73 uint32_t read32(const uint8_t* p)
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74 {
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75 return (((uint32_t) p[3]) << 24) |
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76 (((uint32_t) p[2]) << 16) |
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77 (((uint32_t) p[1]) << 8) |
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78 (((uint32_t) p[0]) << 0);
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79 }
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80
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81 /**
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82 * Writes a 16-bit integer into memory in little-endian byte order.
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83 *
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84 * \param[in] p Pointer where to write the integer to.
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85 * \param[in] i The 16-bit integer to write.
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86 */
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87 void write16(uint8_t* p, uint16_t i)
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88 {
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89 p[1] = (uint8_t) ((i & 0xff00) >> 8);
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90 p[0] = (uint8_t) ((i & 0x00ff) >> 0);
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91 }
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92
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93 /**
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94 * Writes a 32-bit integer into memory in little-endian byte order.
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95 *
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96 * \param[in] p Pointer where to write the integer to.
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97 * \param[in] i The 32-bit integer to write.
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98 */
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99 void write32(uint8_t* p, uint32_t i)
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100 {
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101 p[3] = (uint8_t) ((i & 0xff000000) >> 24);
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102 p[2] = (uint8_t) ((i & 0x00ff0000) >> 16);
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103 p[1] = (uint8_t) ((i & 0x0000ff00) >> 8);
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104 p[0] = (uint8_t) ((i & 0x000000ff) >> 0);
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105 }
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106
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107 /**
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108 * @}
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109 */
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110