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                         /** Convenience macro to determine the larger of two values.
  83                          *
  84                          *  \note This macro should only be used with operands that do not have side effects from being evaluated
  85                          *        multiple times.
  86                          *
  87                          *  \param[in] x  First value to compare
  88                          *  \param[in] y  First value to compare
  89                          *
  90                          *  \return The larger of the two input parameters
  91                          */
  92                         #define MAX(x, y)               ((x > y) ? x : y)
  93
  94                         /** Convenience macro to determine the smaller of two values.
  95                          *
  96                          *  \note This macro should only be used with operands that do not have side effects from being evaluated
  97                          *        multiple times.
  98                          *
  99                          *  \param[in] x  First value to compare
 100                          *  \param[in] y  First value to compare
 101                          *
 102                          *  \return The smaller of the two input parameters
 103                          */
 104                         #define MIN(x, y)               ((x < y) ? x : y)
 105
 106                         /** Defines a volatile \c NOP statement which cannot be optimized out by the compiler, and thus can always
 107                          *  be set as a breakpoint in the resulting code. Useful for debugging purposes, where the optimiser
 108                          *  removes/reorders code to the point where break points cannot reliably be set.
 109                          *
 110                          *  \ingroup Group_Debugging
 111                          */
 112                         #define JTAG_DEBUG_POINT()      __asm__ __volatile__ ("NOP" ::)
 113
 114                         /** Defines an explicit JTAG break point in the resulting binary via the assembly \c BREAK statement. When
 115                          *  a JTAG is used, this causes the program execution to halt when reached until manually resumed.
 116                          *
 117                          *  \ingroup Group_Debugging
 118                          */
 119                         #define JTAG_DEBUG_BREAK()      __asm__ __volatile__ ("BREAK" ::)
 120
 121                         /** Macro for testing condition "x" and breaking via \ref JTAG_DEBUG_BREAK() if the condition is false.
 122                          *
 123                          *  \param[in] Condition  Condition that will be evaluated,
 124                          *
 125                          *  \ingroup Group_Debugging
 126                         */
 127                         #define JTAG_DEBUG_ASSERT(Condition)    MACROS{ if (!(Condition)) { JTAG_DEBUG_BREAK(); } }MACROE
 128
 129                         /** Macro for testing condition "x" and writing debug data to the stdout stream if \c false. The stdout stream
 130                          *  must be pre-initialized before this macro is run and linked to an output device, such as the AVR's USART
 131                          *  peripheral.
 132                          *
 133                          *  The output takes the form "{FILENAME}: Function {FUNCTION NAME}, Line {LINE NUMBER}: Assertion {Condition} failed."
 134                          *
 135                          *  \param[in] Condition  Condition that will be evaluated,
 136                          *
 137                          *  \ingroup Group_Debugging
 138                          */
 139                         #define STDOUT_ASSERT(Condition)        MACROS{ if (!(x)) { printf_P(PSTR("%s: Function \"%s\", Line %d: "   \
 140                                                                         "Assertion \"%s\" failed.\r\n"),     \
 141                                                                         __FILE__, __func__, __LINE__, #Condition); } }MACROE
 142
 143                         /** Forces GCC to use pointer indirection (via the AVR's pointer register pairs) when accessing the given
 144                          *  struct pointer. In some cases GCC will emit non-optimal assembly code when accessing a structure through
 145                          *  a pointer, resulting in a larger binary. When this macro is used on a (non \c const) structure pointer before
 146                          *  use, it will force GCC to use pointer indirection on the elements rather than direct store and load
 147                          *  instructions.
 148                          *
 149                          *  \param[in, out] StructPtr  Pointer to a structure which is to be forced into indirect access mode.
 150                          */
 151                         #define GCC_FORCE_POINTER_ACCESS(StructPtr) __asm__ __volatile__("" : "=b" (StructPtr) : "0" (StructPtr))
 152
 153                         #if !defined(pgm_read_ptr) || defined(__DOXYGEN__)
 154                                 /** Reads a pointer out of PROGMEM space. This is currently a wrapper for the avr-libc \c pgm_read_ptr()
 155                                  *  macro with a \c void* cast, so that its value can be assigned directly to a pointer variable or used
 156                                  *  in pointer arithmetic without further casting in C. In a future avr-libc distribution this will be
 157                                  *  part of the standard API and will be implemented in a more formal manner.
 158                                  *
 159                                  *  \param[in] Addr  Address of the pointer to read.
 160                                  *
 161                                  *  \return Pointer retrieved from PROGMEM space.
 162                                  */
 163                                 #define pgm_read_ptr(Addr)    (void*)pgm_read_word(Addr)
 164                         #endif
 165
 166                         /** Swaps the byte ordering of a 16-bit value at compile time. Do not use this macro for swapping byte orderings
 167                          *  of dynamic values computed at runtime, use \ref SwapEndian_16() instead. The result of this macro can be used
 168                          *  inside struct or other variable initializers outside of a function, something that is not possible with the
 169                          *  inline function variant.
 170                          *
 171                          *  \param[in]  x  16-bit value whose byte ordering is to be swapped.
 172                          *
 173                          *  \return Input value with the byte ordering reversed.
 174                          */
 175                         #define SWAPENDIAN_16(x)          ((((x) & 0xFF00) >> 8) | (((x) & 0x00FF) << 8))
 176
 177                         /** Swaps the byte ordering of a 32-bit value at compile time. Do not use this macro for swapping byte orderings
 178                          *  of dynamic values computed at runtime- use \ref SwapEndian_32() instead. The result of this macro can be used
 179                          *  inside struct or other variable initializers outside of a function, something that is not possible with the
 180                          *  inline function variant.
 181                          *
 182                          *  \param[in]  x  32-bit value whose byte ordering is to be swapped.
 183                          *
 184                          *  \return Input value with the byte ordering reversed.
 185                          */
 186                         #define SWAPENDIAN_32(x)          ((((x) & 0xFF000000UL) >> 24UL) | (((x) & 0x00FF0000UL) >> 8UL) | \
 187                                                            (((x) & 0x0000FF00UL) << 8UL)  | (((x) & 0x000000FFUL) << 24UL))
 188
 189                 /* Inline Functions: */
 190                         /** Function to reverse the individual bits in a byte - i.e. bit 7 is moved to bit 0, bit 6 to bit 1,
 191                          *  etc.
 192                          *
 193                          *  \ingroup Group_BitManip
 194                          *
 195                          *  \param[in] Byte  Byte of data whose bits are to be reversed.
 196                          */
 197                         static inline uint8_t BitReverse(uint8_t Byte) ATTR_WARN_UNUSED_RESULT ATTR_CONST;
 198                         static inline uint8_t BitReverse(uint8_t Byte)
 199                         {
 200                                 Byte = (((Byte & 0xF0) >> 4) | ((Byte & 0x0F) << 4));
 201                                 Byte = (((Byte & 0xCC) >> 2) | ((Byte & 0x33) << 2));
 202                                 Byte = (((Byte & 0xAA) >> 1) | ((Byte & 0x55) << 1));
 203
 204                                 return Byte;
 205                         }
 206
 207                         /** Function to reverse the byte ordering of the individual bytes in a 16 bit number.
 208                          *
 209                          *  \ingroup Group_BitManip
 210                          *
 211                          *  \param[in] Word  Word of data whose bytes are to be swapped.
 212                          */
 213                         static inline uint16_t SwapEndian_16(const uint16_t Word) ATTR_WARN_UNUSED_RESULT ATTR_CONST;
 214                         static inline uint16_t SwapEndian_16(const uint16_t Word)
 215                         {
 216                                 uint8_t Temp;
 217
 218                                 union
 219                                 {
 220                                         uint16_t Word;
 221                                         uint8_t  Bytes[2];
 222                                 } Data;
 223
 224                                 Data.Word = Word;
 225
 226                                 Temp = Data.Bytes[0];
 227                                 Data.Bytes[0] = Data.Bytes[1];
 228                                 Data.Bytes[1] = Temp;
 229
 230                                 return Data.Word;
 231                         }
 232
 233                         /** Function to reverse the byte ordering of the individual bytes in a 32 bit number.
 234                          *
 235                          *  \ingroup Group_BitManip
 236                          *
 237                          *  \param[in] DWord  Double word of data whose bytes are to be swapped.
 238                          */
 239                         static inline uint32_t SwapEndian_32(const uint32_t DWord) ATTR_WARN_UNUSED_RESULT ATTR_CONST;
 240                         static inline uint32_t SwapEndian_32(const uint32_t DWord)
 241                         {
 242                                 uint8_t Temp;
 243
 244                                 union
 245                                 {
 246                                         uint32_t DWord;
 247                                         uint8_t  Bytes[4];
 248                                 } Data;
 249
 250                                 Data.DWord = DWord;
 251
 252                                 Temp = Data.Bytes[0];
 253                                 Data.Bytes[0] = Data.Bytes[3];
 254                                 Data.Bytes[3] = Temp;
 255
 256                                 Temp = Data.Bytes[1];
 257                                 Data.Bytes[1] = Data.Bytes[2];
 258                                 Data.Bytes[2] = Temp;
 259
 260                                 return Data.DWord;
 261                         }
 262
 263                         /** Function to reverse the byte ordering of the individual bytes in a n byte number.
 264                          *
 265                          *  \ingroup Group_BitManip
 266                          *
 267                          *  \param[in,out] Data   Pointer to a number containing an even number of bytes to be reversed.
 268                          *  \param[in]     Bytes  Length of the data in bytes.
 269                          */
 270                         static inline void SwapEndian_n(void* Data,
 271                                                         uint8_t Bytes) ATTR_NON_NULL_PTR_ARG(1);
 272                         static inline void SwapEndian_n(void* Data,
 273                                                         uint8_t Bytes)
 274                         {
 275                                 uint8_t* CurrDataPos = (uint8_t*)Data;
 276
 277                                 while (Bytes > 1)
 278                                 {
 279                                         uint8_t Temp = *CurrDataPos;
 280                                         *CurrDataPos = *(CurrDataPos + Bytes - 1);
 281                                         *(CurrDataPos + Bytes - 1) = Temp;
 282
 283                                         CurrDataPos++;
 284                                         Bytes -= 2;
 285                                 }
 286                         }
 287
 288 #endif
 289
 290 /** @} */
 291