LUFA/Common/Common.h

   1 /*
   2              LUFA Library
   3      Copyright (C) Dean Camera, 2010.
   4
   5   dean [at] fourwalledcubicle [dot] com
   6            www.lufa-lib.org
   7 */
   8
   9 /*
  10   Copyright 2010  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 headers, such as Atomic.h, Attributes.h and BoardTypes.h.
  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 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 IF statements).
  79                          */
  80                         #define MACROE                  while (0)
  81
  82                         /** Defines a volatile 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 ASM 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 JTAG_DEBUG_BREAK() if the condition is false.
  98                          *
  99                          *  \ingroup Group_Debugging
 100                         */
 101                         #define JTAG_DEBUG_ASSERT(x)    MACROS{ if (!(x)) { JTAG_DEBUG_BREAK(); } }MACROE
 102
 103                         /** Macro for testing condition "x" and writing debug data to the stdout stream if false. The stdout stream
 104                          *  must be pre-initialized before this macro is run and linked to an output device, such as the AVR's USART
 105                          *  peripheral.
 106                          *
 107                          *  The output takes the form "{FILENAME}: Function {FUNCTION NAME}, Line {LINE NUMBER}: Assertion {x} failed."
 108                          *
 109                          *  \ingroup Group_Debugging
 110                          */
 111                         #define STDOUT_ASSERT(x)        MACROS{ if (!(x)) { printf_P(PSTR("%s: Function \"%s\", Line %d: "   \
 112                                                                      "Assertion \"%s\" failed.\r\n"),     \
 113                                                                      __FILE__, __func__, __LINE__, #x); } }MACROE
 114
 115                         /** Forces GCC to use pointer indirection (via the AVR's pointer register pairs) when accessing the given
 116                          *  struct pointer. In some cases GCC will emit non-optimal assembly code when accessing a structure through
 117                          *  a pointer, resulting in a larger binary. When this macro is used on a (non-const) structure pointer before
 118                          *  use, it will force GCC to use pointer indirection on the elements rather than direct store and load
 119                          *  instructions.
 120                          *
 121                          *  \param[in, out] StructPtr  Pointer to a structure which is to be forced into indirect access mode.
 122                          */
 123                         #define GCC_FORCE_POINTER_ACCESS(StructPtr) __asm__ __volatile__("" : "=b" (StructPtr) : "0" (StructPtr))
 124
 125                         #if !defined(pgm_read_ptr) || defined(__DOXYGEN__)
 126                                 /** Reads a pointer out of PROGMEM space. This is currently a wrapper for the avr-libc pgm_read_ptr()
 127                                  *  macro with a void* cast, so that its value can be assigned directly to a pointer variable or used
 128                                  *  in pointer arithmetic without further casting in C. In a future avr-libc distribution this will be
 129                                  *  part of the standard API and will be implemented in a more formal manner.
 130                                  *
 131                                  *  \param[in] Addr  Address of the pointer to read.
 132                                  *
 133                                  *  \return Pointer retrieved from PROGMEM space.
 134                                  */
 135                                 #define pgm_read_ptr(Addr)    (void*)pgm_read_word(Addr)
 136                         #endif
 137
 138                         /** Swaps the byte ordering of a 16-bit value at compile time. Do not use this macro for swapping byte orderings
 139                          *  of dynamic values computed at runtime, use \ref SwapEndian_16() instead. The result of this macro can be used
 140                          *  inside struct or other variable initializers outside of a function, something that is not possible with the
 141                          *  inline function variant.
 142                          *
 143                          *  \param[in]  x  16-bit value whose byte ordering is to be swapped.
 144                          *
 145                          *  \return Input value with the byte ordering reversed.
 146                          */
 147                         #define SWAPENDIAN_16(x)          ((((x) & 0xFF00) >> 8) | (((x) & 0x00FF) << 8))
 148
 149                         /** Swaps the byte ordering of a 32-bit value at compile time. Do not use this macro for swapping byte orderings
 150                          *  of dynamic values computed at runtime- use \ref SwapEndian_32() instead. The result of this macro can be used
 151                          *  inside struct or other variable initializers outside of a function, something that is not possible with the
 152                          *  inline function variant.
 153                          *
 154                          *  \param[in]  x  32-bit value whose byte ordering is to be swapped.
 155                          *
 156                          *  \return Input value with the byte ordering reversed.
 157                          */
 158                         #define SWAPENDIAN_32(x)          ((((x) & 0xFF000000UL) >> 24UL) | (((x) & 0x00FF0000UL) >> 8UL) | \
 159                                                            (((x) & 0x0000FF00UL) << 8UL)  | (((x) & 0x000000FFUL) << 24UL))
 160
 161                 /* Inline Functions: */
 162                         /** Function to reverse the individual bits in a byte - i.e. bit 7 is moved to bit 0, bit 6 to bit 1,
 163                          *  etc.
 164                          *
 165                          *  \ingroup Group_BitManip
 166                          *
 167                          *  \param[in] Byte  Byte of data whose bits are to be reversed.
 168                          */
 169                         static inline uint8_t BitReverse(uint8_t Byte) ATTR_WARN_UNUSED_RESULT ATTR_CONST;
 170                         static inline uint8_t BitReverse(uint8_t Byte)
 171                         {
 172                                 Byte = (((Byte & 0xF0) >> 4) | ((Byte & 0x0F) << 4));
 173                                 Byte = (((Byte & 0xCC) >> 2) | ((Byte & 0x33) << 2));
 174                                 Byte = (((Byte & 0xAA) >> 1) | ((Byte & 0x55) << 1));
 175
 176                                 return Byte;
 177                         }
 178
 179                         /** Function to reverse the byte ordering of the individual bytes in a 16 bit number.
 180                          *
 181                          *  \ingroup Group_BitManip
 182                          *
 183                          *  \param[in] Word  Word of data whose bytes are to be swapped.
 184                          */
 185                         static inline uint16_t SwapEndian_16(const uint16_t Word) ATTR_WARN_UNUSED_RESULT ATTR_CONST;
 186                         static inline uint16_t SwapEndian_16(const uint16_t Word)
 187                         {
 188                                 uint8_t Temp;
 189
 190                                 union
 191                                 {
 192                                         uint16_t Word;
 193                                         uint8_t  Bytes[2];
 194                                 } Data;
 195
 196                                 Data.Word = Word;
 197
 198                                 Temp = Data.Bytes[0];
 199                                 Data.Bytes[0] = Data.Bytes[1];
 200                                 Data.Bytes[1] = Temp;
 201
 202                                 return Data.Word;
 203                         }
 204
 205                         /** Function to reverse the byte ordering of the individual bytes in a 32 bit number.
 206                          *
 207                          *  \ingroup Group_BitManip
 208                          *
 209                          *  \param[in] DWord  Double word of data whose bytes are to be swapped.
 210                          */
 211                         static inline uint32_t SwapEndian_32(const uint32_t DWord) ATTR_WARN_UNUSED_RESULT ATTR_CONST;
 212                         static inline uint32_t SwapEndian_32(const uint32_t DWord)
 213                         {
 214                                 uint8_t Temp;
 215
 216                                 union
 217                                 {
 218                                         uint32_t DWord;
 219                                         uint8_t  Bytes[4];
 220                                 } Data;
 221
 222                                 Data.DWord = DWord;
 223
 224                                 Temp = Data.Bytes[0];
 225                                 Data.Bytes[0] = Data.Bytes[3];
 226                                 Data.Bytes[3] = Temp;
 227
 228                                 Temp = Data.Bytes[1];
 229                                 Data.Bytes[1] = Data.Bytes[2];
 230                                 Data.Bytes[2] = Temp;
 231
 232                                 return Data.DWord;
 233                         }
 234
 235                         /** Function to reverse the byte ordering of the individual bytes in a n byte number.
 236                          *
 237                          *  \ingroup Group_BitManip
 238                          *
 239                          *  \param[in,out] Data   Pointer to a number containing an even number of bytes to be reversed.
 240                          *  \param[in]     Bytes  Length of the data in bytes.
 241                          */
 242                         static inline void SwapEndian_n(void* Data,
 243                                                         uint8_t Bytes) ATTR_NON_NULL_PTR_ARG(1);
 244                         static inline void SwapEndian_n(void* Data,
 245                                                         uint8_t Bytes)
 246                         {
 247                                 uint8_t* CurrDataPos = (uint8_t*)Data;
 248
 249                                 while (Bytes > 1)
 250                                 {
 251                                         uint8_t Temp = *CurrDataPos;
 252                                         *CurrDataPos = *(CurrDataPos + Bytes - 1);
 253                                         *(CurrDataPos + Bytes - 1) = Temp;
 254
 255                                         CurrDataPos++;
 256                                         Bytes -= 2;
 257                                 }
 258                         }
 259
 260 #endif
 261
 262 /** @} */
 263