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 __LUFA_COMMON_H__
  57 #define __LUFA_COMMON_H__
  58
  59         /* Macros: */
  60                 #if !defined(__DOXYGEN__)
  61                         #define __INCLUDE_FROM_COMMON_H
  62                 #endif
  63
  64         /* Includes: */
  65                 #include <stdint.h>
  66                 #include <stdbool.h>
  67
  68                 #include "Architectures.h"
  69                 #include "Attributes.h"
  70                 #include "BoardTypes.h"
  71
  72         /* Architecture specific utility includes: */
  73                 #if (ARCH == ARCH_AVR8)
  74                         #include <avr/io.h>
  75                         #include <avr/interrupt.h>
  76                         #include <avr/pgmspace.h>
  77                         #include <avr/eeprom.h>
  78                         #include <util/atomic.h>
  79                         #include <util/delay.h>
  80                 #endif
  81
  82         /* Public Interface - May be used in end-application: */
  83                 /* Macros: */
  84                         /** Macro for encasing other multi-statement macros. This should be used along with an opening brace
  85                          *  before the start of any multi-statement macro, so that the macros contents as a whole are treated
  86                          *  as a discrete block and not as a list of separate statements which may cause problems when used as
  87                          *  a block (such as inline \c if statements).
  88                          */
  89                         #define MACROS                  do
  90
  91                         /** Macro for encasing other multi-statement macros. This should be used along with a preceding closing
  92                          *  brace at the end of any multi-statement macro, so that the macros contents as a whole are treated
  93                          *  as a discrete block and not as a list of separate statements which may cause problems when used as
  94                          *  a block (such as inline \c if statements).
  95                          */
  96                         #define MACROE                  while (0)
  97
  98                         /** Convenience macro to determine the larger of two values.
  99                          *
 100                          *  \note This macro should only be used with operands that do not have side effects from being evaluated
 101                          *        multiple times.
 102                          *
 103                          *  \param[in] x  First value to compare
 104                          *  \param[in] y  First value to compare
 105                          *
 106                          *  \return The larger of the two input parameters
 107                          */
 108                         #if !defined(MAX) || defined(__DOXYGEN__)
 109                                 #define MAX(x, y)               ((x > y) ? x : y)
 110                         #endif
 111
 112                         /** Convenience macro to determine the smaller of two values.
 113                          *
 114                          *  \note This macro should only be used with operands that do not have side effects from being evaluated
 115                          *        multiple times.
 116                          *
 117                          *  \param[in] x  First value to compare
 118                          *  \param[in] y  First value to compare
 119                          *
 120                          *  \return The smaller of the two input parameters
 121                          */
 122                         #if !defined(MIN) || defined(__DOXYGEN__)
 123                                 #define MIN(x, y)               ((x < y) ? x : y)
 124                         #endif
 125
 126                         #if (ARCH == ARCH_AVR8)
 127                                 /** Defines a volatile \c NOP statement which cannot be optimized out by the compiler, and thus can always
 128                                  *  be set as a breakpoint in the resulting code. Useful for debugging purposes, where the optimiser
 129                                  *  removes/reorders code to the point where break points cannot reliably be set.
 130                                  *
 131                                  *  \ingroup Group_Debugging
 132                                  */
 133                                 #define JTAG_DEBUG_POINT()      __asm__ __volatile__ ("NOP" ::)
 134
 135                                 /** Defines an explicit JTAG break point in the resulting binary via the assembly \c BREAK statement. When
 136                                  *  a JTAG is used, this causes the program execution to halt when reached until manually resumed.
 137                                  *
 138                                  *  \ingroup Group_Debugging
 139                                  */
 140                                 #define JTAG_DEBUG_BREAK()      __asm__ __volatile__ ("BREAK" ::)
 141
 142                                 #if !defined(pgm_read_ptr) || defined(__DOXYGEN__)
 143                                         /** Reads a pointer out of PROGMEM space. This is currently a wrapper for the avr-libc \c pgm_read_ptr()
 144                                          *  macro with a \c void* cast, so that its value can be assigned directly to a pointer variable or used
 145                                          *  in pointer arithmetic without further casting in C. In a future avr-libc distribution this will be
 146                                          *  part of the standard API and will be implemented in a more formal manner.
 147                                          *
 148                                          *  \param[in] Addr  Address of the pointer to read.
 149                                          *
 150                                          *  \return Pointer retrieved from PROGMEM space.
 151                                          */
 152                                         #define pgm_read_ptr(Addr)    (void*)pgm_read_word(Addr)
 153                                 #endif
 154
 155                                 /** Macro for testing condition "x" and breaking via \ref JTAG_DEBUG_BREAK() if the condition is false.
 156                                  *
 157                                  *  \param[in] Condition  Condition that will be evaluated,
 158                                  *
 159                                  *  \ingroup Group_Debugging
 160                                 */
 161                                 #define JTAG_DEBUG_ASSERT(Condition)    MACROS{ if (!(Condition)) { JTAG_DEBUG_BREAK(); } }MACROE
 162
 163                                 /** Macro for testing condition "x" and writing debug data to the stdout stream if \c false. The stdout stream
 164                                  *  must be pre-initialized before this macro is run and linked to an output device, such as the AVR's USART
 165                                  *  peripheral.
 166                                  *
 167                                  *  The output takes the form "{FILENAME}: Function {FUNCTION NAME}, Line {LINE NUMBER}: Assertion {Condition} failed."
 168                                  *
 169                                  *  \param[in] Condition  Condition that will be evaluated,
 170                                  *
 171                                  *  \ingroup Group_Debugging
 172                                  */
 173                                 #define STDOUT_ASSERT(Condition)        MACROS{ if (!(x)) { printf_P(PSTR("%s: Function \"%s\", Line %d: "   \
 174                                                                                 "Assertion \"%s\" failed.\r\n"),     \
 175                                                                                 __FILE__, __func__, __LINE__, #Condition); } }MACROE
 176                         #endif
 177
 178                         /** Forces GCC to use pointer indirection (via the AVR's pointer register pairs) when accessing the given
 179                          *  struct pointer. In some cases GCC will emit non-optimal assembly code when accessing a structure through
 180                          *  a pointer, resulting in a larger binary. When this macro is used on a (non \c const) structure pointer before
 181                          *  use, it will force GCC to use pointer indirection on the elements rather than direct store and load
 182                          *  instructions.
 183                          *
 184                          *  \param[in, out] StructPtr  Pointer to a structure which is to be forced into indirect access mode.
 185                          */
 186                         #define GCC_FORCE_POINTER_ACCESS(StructPtr) __asm__ __volatile__("" : "=b" (StructPtr) : "0" (StructPtr))
 187
 188                         /** Swaps the byte ordering of a 16-bit value at compile time. Do not use this macro for swapping byte orderings
 189                          *  of dynamic values computed at runtime, use \ref SwapEndian_16() instead. The result of this macro can be used
 190                          *  inside struct or other variable initializers outside of a function, something that is not possible with the
 191                          *  inline function variant.
 192                          *
 193                          *  \param[in]  x  16-bit value whose byte ordering is to be swapped.
 194                          *
 195                          *  \return Input value with the byte ordering reversed.
 196                          */
 197                         #define SWAPENDIAN_16(x)          ((((x) & 0xFF00) >> 8) | (((x) & 0x00FF) << 8))
 198
 199                         /** Swaps the byte ordering of a 32-bit value at compile time. Do not use this macro for swapping byte orderings
 200                          *  of dynamic values computed at runtime- use \ref SwapEndian_32() instead. The result of this macro can be used
 201                          *  inside struct or other variable initializers outside of a function, something that is not possible with the
 202                          *  inline function variant.
 203                          *
 204                          *  \param[in]  x  32-bit value whose byte ordering is to be swapped.
 205                          *
 206                          *  \return Input value with the byte ordering reversed.
 207                          */
 208                         #define SWAPENDIAN_32(x)          ((((x) & 0xFF000000UL) >> 24UL) | (((x) & 0x00FF0000UL) >> 8UL) | \
 209                                                            (((x) & 0x0000FF00UL) << 8UL)  | (((x) & 0x000000FFUL) << 24UL))
 210
 211                 /* Inline Functions: */
 212                         /** Function to reverse the individual bits in a byte - i.e. bit 7 is moved to bit 0, bit 6 to bit 1,
 213                          *  etc.
 214                          *
 215                          *  \ingroup Group_BitManip
 216                          *
 217                          *  \param[in] Byte  Byte of data whose bits are to be reversed.
 218                          */
 219                         static inline uint8_t BitReverse(uint8_t Byte) ATTR_WARN_UNUSED_RESULT ATTR_CONST;
 220                         static inline uint8_t BitReverse(uint8_t Byte)
 221                         {
 222                                 Byte = (((Byte & 0xF0) >> 4) | ((Byte & 0x0F) << 4));
 223                                 Byte = (((Byte & 0xCC) >> 2) | ((Byte & 0x33) << 2));
 224                                 Byte = (((Byte & 0xAA) >> 1) | ((Byte & 0x55) << 1));
 225
 226                                 return Byte;
 227                         }
 228
 229                         /** Function to reverse the byte ordering of the individual bytes in a 16 bit number.
 230                          *
 231                          *  \ingroup Group_BitManip
 232                          *
 233                          *  \param[in] Word  Word of data whose bytes are to be swapped.
 234                          */
 235                         static inline uint16_t SwapEndian_16(const uint16_t Word) ATTR_WARN_UNUSED_RESULT ATTR_CONST;
 236                         static inline uint16_t SwapEndian_16(const uint16_t Word)
 237                         {
 238                                 uint8_t Temp;
 239
 240                                 union
 241                                 {
 242                                         uint16_t Word;
 243                                         uint8_t  Bytes[2];
 244                                 } Data;
 245
 246                                 Data.Word = Word;
 247
 248                                 Temp = Data.Bytes[0];
 249                                 Data.Bytes[0] = Data.Bytes[1];
 250                                 Data.Bytes[1] = Temp;
 251
 252                                 return Data.Word;
 253                         }
 254
 255                         /** Function to reverse the byte ordering of the individual bytes in a 32 bit number.
 256                          *
 257                          *  \ingroup Group_BitManip
 258                          *
 259                          *  \param[in] DWord  Double word of data whose bytes are to be swapped.
 260                          */
 261                         static inline uint32_t SwapEndian_32(const uint32_t DWord) ATTR_WARN_UNUSED_RESULT ATTR_CONST;
 262                         static inline uint32_t SwapEndian_32(const uint32_t DWord)
 263                         {
 264                                 uint8_t Temp;
 265
 266                                 union
 267                                 {
 268                                         uint32_t DWord;
 269                                         uint8_t  Bytes[4];
 270                                 } Data;
 271
 272                                 Data.DWord = DWord;
 273
 274                                 Temp = Data.Bytes[0];
 275                                 Data.Bytes[0] = Data.Bytes[3];
 276                                 Data.Bytes[3] = Temp;
 277
 278                                 Temp = Data.Bytes[1];
 279                                 Data.Bytes[1] = Data.Bytes[2];
 280                                 Data.Bytes[2] = Temp;
 281
 282                                 return Data.DWord;
 283                         }
 284
 285                         /** Function to reverse the byte ordering of the individual bytes in a n byte number.
 286                          *
 287                          *  \ingroup Group_BitManip
 288                          *
 289                          *  \param[in,out] Data   Pointer to a number containing an even number of bytes to be reversed.
 290                          *  \param[in]     Bytes  Length of the data in bytes.
 291                          */
 292                         static inline void SwapEndian_n(void* Data,
 293                                                         uint8_t Bytes) ATTR_NON_NULL_PTR_ARG(1);
 294                         static inline void SwapEndian_n(void* Data,
 295                                                         uint8_t Bytes)
 296                         {
 297                                 uint8_t* CurrDataPos = (uint8_t*)Data;
 298
 299                                 while (Bytes > 1)
 300                                 {
 301                                         uint8_t Temp = *CurrDataPos;
 302                                         *CurrDataPos = *(CurrDataPos + Bytes - 1);
 303                                         *(CurrDataPos + Bytes - 1) = Temp;
 304
 305                                         CurrDataPos++;
 306                                         Bytes -= 2;
 307                                 }
 308                         }
 309
 310 #endif
 311
 312 /** @} */
 313