LUFA/Common/Common.h

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2011.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6            www.lufa-lib.org
   7 */
   8
   9 /*
  10   Copyright 2011  Dean Camera (dean [at] fourwalledcubicle [dot] com)
  11
  12   Permission to use, copy, modify, distribute, and sell this
  13   software and its documentation for any purpose is hereby granted
  14   without fee, provided that the above copyright notice appear in
  15   all copies and that both that the copyright notice and this
  16   permission notice and warranty disclaimer appear in supporting
  17   documentation, and that the name of the author not be used in
  18   advertising or publicity pertaining to distribution of the
  19   software without specific, written prior permission.
  20
  21   The author disclaim all warranties with regard to this
  22   software, including all implied warranties of merchantability
  23   and fitness.  In no event shall the author be liable for any
  24   special, indirect or consequential damages or any damages
  25   whatsoever resulting from loss of use, data or profits, whether
  26   in an action of contract, negligence or other tortious action,
  27   arising out of or in connection with the use or performance of
  28   this software.
  29 */
  30
  31 /** \file
  32  *  \brief Common library convenience macros and functions.
  33  *
  34  *  This file contains macros which are common to all library elements, and which may be useful in user code. It
  35  *  also includes other common code headers.
  36  */
  37
  38 /** @defgroup Group_Common Common Utility Headers - LUFA/Drivers/Common/Common.h
  39  *
  40  *  Common utility headers containing macros, functions, enums and types which are common to all
  41  *  aspects of the library.
  42  *
  43  *  @{
  44  */
  45
  46 /** @defgroup Group_Debugging Debugging Macros
  47  *
  48  *  Macros for debugging use.
  49  */
  50
  51 /** @defgroup Group_BitManip Endian and Bit Macros
  52  *
  53  *  Functions for swapping endianness and reversing bit orders.
  54  */
  55
  56 #ifndef __COMMON_H__
  57 #define __COMMON_H__
  58
  59         /* Includes: */
  60                 #include <stdint.h>
  61                 #include <stdbool.h>
  62
  63                 #include "Attributes.h"
  64                 #include "BoardTypes.h"
  65
  66         /* Public Interface - May be used in end-application: */
  67                 /* Macros: */
  68                         /** Macro for encasing other multi-statement macros. This should be used along with an opening brace
  69                          *  before the start of any multi-statement macro, so that the macros contents as a whole are treated
  70                          *  as a discrete block and not as a list of separate statements which may cause problems when used as
  71                          *  a block (such as inline \c if statements).
  72                          */
  73                         #define MACROS                  do
  74
  75                         /** Macro for encasing other multi-statement macros. This should be used along with a preceding closing
  76                          *  brace at the end of any multi-statement macro, so that the macros contents as a whole are treated
  77                          *  as a discrete block and not as a list of separate statements which may cause problems when used as
  78                          *  a block (such as inline \c if statements).
  79                          */
  80                         #define MACROE                  while (0)
  81
  82                         /** Defines a volatile \c NOP statement which cannot be optimized out by the compiler, and thus can always
  83                          *  be set as a breakpoint in the resulting code. Useful for debugging purposes, where the optimiser
  84                          *  removes/reorders code to the point where break points cannot reliably be set.
  85                          *
  86                          *  \ingroup Group_Debugging
  87                          */
  88                         #define JTAG_DEBUG_POINT()      __asm__ __volatile__ ("NOP" ::)
  89
  90                         /** Defines an explicit JTAG break point in the resulting binary via the assembly \c BREAK statement. When
  91                          *  a JTAG is used, this causes the program execution to halt when reached until manually resumed.
  92                          *
  93                          *  \ingroup Group_Debugging
  94                          */
  95                         #define JTAG_DEBUG_BREAK()      __asm__ __volatile__ ("BREAK" ::)
  96
  97                         /** Macro for testing condition "x" and breaking via \ref JTAG_DEBUG_BREAK() if the condition is false.
  98                          *
  99                          *  \param[in] Condition  Condition that will be evaluated,
 100                          *
 101                          *  \ingroup Group_Debugging
 102                         */
 103                         #define JTAG_DEBUG_ASSERT(Condition)    MACROS{ if (!(Condition)) { JTAG_DEBUG_BREAK(); } }MACROE
 104
 105                         /** Macro for testing condition "x" and writing debug data to the stdout stream if \c false. The stdout stream
 106                          *  must be pre-initialized before this macro is run and linked to an output device, such as the AVR's USART
 107                          *  peripheral.
 108                          *
 109                          *  The output takes the form "{FILENAME}: Function {FUNCTION NAME}, Line {LINE NUMBER}: Assertion {Condition} failed."
 110                          *
 111                          *  \param[in] Condition  Condition that will be evaluated,
 112                          *
 113                          *  \ingroup Group_Debugging
 114                          */
 115                         #define STDOUT_ASSERT(Condition)        MACROS{ if (!(x)) { printf_P(PSTR("%s: Function \"%s\", Line %d: "   \
 116                                                                         "Assertion \"%s\" failed.\r\n"),     \
 117                                                                         __FILE__, __func__, __LINE__, #Condition); } }MACROE
 118
 119                         /** Forces GCC to use pointer indirection (via the AVR's pointer register pairs) when accessing the given
 120                          *  struct pointer. In some cases GCC will emit non-optimal assembly code when accessing a structure through
 121                          *  a pointer, resulting in a larger binary. When this macro is used on a (non \c const) structure pointer before
 122                          *  use, it will force GCC to use pointer indirection on the elements rather than direct store and load
 123                          *  instructions.
 124                          *
 125                          *  \param[in, out] StructPtr  Pointer to a structure which is to be forced into indirect access mode.
 126                          */
 127                         #define GCC_FORCE_POINTER_ACCESS(StructPtr) __asm__ __volatile__("" : "=b" (StructPtr) : "0" (StructPtr))
 128
 129                         #if !defined(pgm_read_ptr) || defined(__DOXYGEN__)
 130                                 /** Reads a pointer out of PROGMEM space. This is currently a wrapper for the avr-libc \c pgm_read_ptr()
 131                                  *  macro with a \c void* cast, so that its value can be assigned directly to a pointer variable or used
 132                                  *  in pointer arithmetic without further casting in C. In a future avr-libc distribution this will be
 133                                  *  part of the standard API and will be implemented in a more formal manner.
 134                                  *
 135                                  *  \param[in] Addr  Address of the pointer to read.
 136                                  *
 137                                  *  \return Pointer retrieved from PROGMEM space.
 138                                  */
 139                                 #define pgm_read_ptr(Addr)    (void*)pgm_read_word(Addr)
 140                         #endif
 141
 142                         /** Swaps the byte ordering of a 16-bit value at compile time. Do not use this macro for swapping byte orderings
 143                          *  of dynamic values computed at runtime, use \ref SwapEndian_16() instead. The result of this macro can be used
 144                          *  inside struct or other variable initializers outside of a function, something that is not possible with the
 145                          *  inline function variant.
 146                          *
 147                          *  \param[in]  x  16-bit value whose byte ordering is to be swapped.
 148                          *
 149                          *  \return Input value with the byte ordering reversed.
 150                          */
 151                         #define SWAPENDIAN_16(x)          ((((x) & 0xFF00) >> 8) | (((x) & 0x00FF) << 8))
 152
 153                         /** Swaps the byte ordering of a 32-bit value at compile time. Do not use this macro for swapping byte orderings
 154                          *  of dynamic values computed at runtime- use \ref SwapEndian_32() instead. The result of this macro can be used
 155                          *  inside struct or other variable initializers outside of a function, something that is not possible with the
 156                          *  inline function variant.
 157                          *
 158                          *  \param[in]  x  32-bit value whose byte ordering is to be swapped.
 159                          *
 160                          *  \return Input value with the byte ordering reversed.
 161                          */
 162                         #define SWAPENDIAN_32(x)          ((((x) & 0xFF000000UL) >> 24UL) | (((x) & 0x00FF0000UL) >> 8UL) | \
 163                                                            (((x) & 0x0000FF00UL) << 8UL)  | (((x) & 0x000000FFUL) << 24UL))
 164
 165                 /* Inline Functions: */
 166                         /** Function to reverse the individual bits in a byte - i.e. bit 7 is moved to bit 0, bit 6 to bit 1,
 167                          *  etc.
 168                          *
 169                          *  \ingroup Group_BitManip
 170                          *
 171                          *  \param[in] Byte  Byte of data whose bits are to be reversed.
 172                          */
 173                         static inline uint8_t BitReverse(uint8_t Byte) ATTR_WARN_UNUSED_RESULT ATTR_CONST;
 174                         static inline uint8_t BitReverse(uint8_t Byte)
 175                         {
 176                                 Byte = (((Byte & 0xF0) >> 4) | ((Byte & 0x0F) << 4));
 177                                 Byte = (((Byte & 0xCC) >> 2) | ((Byte & 0x33) << 2));
 178                                 Byte = (((Byte & 0xAA) >> 1) | ((Byte & 0x55) << 1));
 179
 180                                 return Byte;
 181                         }
 182
 183                         /** Function to reverse the byte ordering of the individual bytes in a 16 bit number.
 184                          *
 185                          *  \ingroup Group_BitManip
 186                          *
 187                          *  \param[in] Word  Word of data whose bytes are to be swapped.
 188                          */
 189                         static inline uint16_t SwapEndian_16(const uint16_t Word) ATTR_WARN_UNUSED_RESULT ATTR_CONST;
 190                         static inline uint16_t SwapEndian_16(const uint16_t Word)
 191                         {
 192                                 uint8_t Temp;
 193
 194                                 union
 195                                 {
 196                                         uint16_t Word;
 197                                         uint8_t  Bytes[2];
 198                                 } Data;
 199
 200                                 Data.Word = Word;
 201
 202                                 Temp = Data.Bytes[0];
 203                                 Data.Bytes[0] = Data.Bytes[1];
 204                                 Data.Bytes[1] = Temp;
 205
 206                                 return Data.Word;
 207                         }
 208
 209                         /** Function to reverse the byte ordering of the individual bytes in a 32 bit number.
 210                          *
 211                          *  \ingroup Group_BitManip
 212                          *
 213                          *  \param[in] DWord  Double word of data whose bytes are to be swapped.
 214                          */
 215                         static inline uint32_t SwapEndian_32(const uint32_t DWord) ATTR_WARN_UNUSED_RESULT ATTR_CONST;
 216                         static inline uint32_t SwapEndian_32(const uint32_t DWord)
 217                         {
 218                                 uint8_t Temp;
 219
 220                                 union
 221                                 {
 222                                         uint32_t DWord;
 223                                         uint8_t  Bytes[4];
 224                                 } Data;
 225
 226                                 Data.DWord = DWord;
 227
 228                                 Temp = Data.Bytes[0];
 229                                 Data.Bytes[0] = Data.Bytes[3];
 230                                 Data.Bytes[3] = Temp;
 231
 232                                 Temp = Data.Bytes[1];
 233                                 Data.Bytes[1] = Data.Bytes[2];
 234                                 Data.Bytes[2] = Temp;
 235
 236                                 return Data.DWord;
 237                         }
 238
 239                         /** Function to reverse the byte ordering of the individual bytes in a n byte number.
 240                          *
 241                          *  \ingroup Group_BitManip
 242                          *
 243                          *  \param[in,out] Data   Pointer to a number containing an even number of bytes to be reversed.
 244                          *  \param[in]     Bytes  Length of the data in bytes.
 245                          */
 246                         static inline void SwapEndian_n(void* Data,
 247                                                         uint8_t Bytes) ATTR_NON_NULL_PTR_ARG(1);
 248                         static inline void SwapEndian_n(void* Data,
 249                                                         uint8_t Bytes)
 250                         {
 251                                 uint8_t* CurrDataPos = (uint8_t*)Data;
 252
 253                                 while (Bytes > 1)
 254                                 {
 255                                         uint8_t Temp = *CurrDataPos;
 256                                         *CurrDataPos = *(CurrDataPos + Bytes - 1);
 257                                         *(CurrDataPos + Bytes - 1) = Temp;
 258
 259                                         CurrDataPos++;
 260                                         Bytes -= 2;
 261                                 }
 262                         }
 263
 264 #endif
 265
 266 /** @} */
 267