Greg Steiert / pegasus_dev

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Dependents:   blinky_max32630fthr

features/storage/FEATURE_STORAGE/flash-journal/flash-journal-strategy-sequential/flash_journal_crc.c@3:1198227e6421, 2016-12-16 (annotated)

Committer:
switches
Date:
Fri Dec 16 16:27:57 2016 +0000
Revision:
3:1198227e6421
Parent:
0:5c4d7b2438d3 
Changed ADC scale for MAX32625 platforms to 1.2V full scale to match MAX32630 platforms

Who changed what in which revision?

UserRevisionLine numberNew contents of line
switches 0:5c4d7b2438d3 1 /**********************************************************************
switches 0:5c4d7b2438d3 2 *
switches 0:5c4d7b2438d3 3 * Filename: flash_journal_crc.c
switches 0:5c4d7b2438d3 4 *
switches 0:5c4d7b2438d3 5 * Description: Slow and fast implementations of the CRC standards.
switches 0:5c4d7b2438d3 6 *
switches 0:5c4d7b2438d3 7 * Notes: The parameters for each supported CRC standard are
switches 0:5c4d7b2438d3 8 * defined in the header file crc.h. The implementations
switches 0:5c4d7b2438d3 9 * here should stand up to further additions to that list.
switches 0:5c4d7b2438d3 10 *
switches 0:5c4d7b2438d3 11 *
switches 0:5c4d7b2438d3 12 * Copyright (c) 2000 by Michael Barr. This software is placed into
switches 0:5c4d7b2438d3 13 * the public domain and may be used for any purpose. However, this
switches 0:5c4d7b2438d3 14 * notice must not be changed or removed and no warranty is either
switches 0:5c4d7b2438d3 15 * expressed or implied by its publication or distribution.
switches 0:5c4d7b2438d3 16 **********************************************************************/
switches 0:5c4d7b2438d3 17
switches 0:5c4d7b2438d3 18 #include "flash-journal-strategy-sequential/flash_journal_crc.h"
switches 0:5c4d7b2438d3 19
switches 0:5c4d7b2438d3 20 #define FALSE 0
switches 0:5c4d7b2438d3 21 #define TRUE !FALSE
switches 0:5c4d7b2438d3 22
switches 0:5c4d7b2438d3 23 #define CRC_NAME "CRC-32"
switches 0:5c4d7b2438d3 24 #define POLYNOMIAL 0x04C11DB7
switches 0:5c4d7b2438d3 25 #define INITIAL_REMAINDER 0xFFFFFFFF
switches 0:5c4d7b2438d3 26 #define FINAL_XOR_VALUE 0xFFFFFFFF
switches 0:5c4d7b2438d3 27 #define REFLECT_DATA TRUE
switches 0:5c4d7b2438d3 28 #define REFLECT_REMAINDER TRUE
switches 0:5c4d7b2438d3 29 #define CHECK_VALUE 0xCBF43926
switches 0:5c4d7b2438d3 30
switches 0:5c4d7b2438d3 31
switches 0:5c4d7b2438d3 32 /*
switches 0:5c4d7b2438d3 33 * Derive parameters from the standard-specific parameters in crc.h.
switches 0:5c4d7b2438d3 34 */
switches 0:5c4d7b2438d3 35 #define WIDTH (8 * sizeof(flash_journal_crc32_t))
switches 0:5c4d7b2438d3 36 /* U postfix required to suppress the following warning with TOOLCHAIN_ARM:
switches 0:5c4d7b2438d3 37 * #61-D: integer operation result is out of range
switches 0:5c4d7b2438d3 38 */
switches 0:5c4d7b2438d3 39 #define TOPBIT 0x80000000U
switches 0:5c4d7b2438d3 40
switches 0:5c4d7b2438d3 41 #if (REFLECT_DATA == TRUE)
switches 0:5c4d7b2438d3 42 #undef REFLECT_DATA
switches 0:5c4d7b2438d3 43 #define REFLECT_DATA(X) ((unsigned char) reflect((X), 8))
switches 0:5c4d7b2438d3 44 #else
switches 0:5c4d7b2438d3 45 #undef REFLECT_DATA
switches 0:5c4d7b2438d3 46 #define REFLECT_DATA(X) (X)
switches 0:5c4d7b2438d3 47 #endif
switches 0:5c4d7b2438d3 48
switches 0:5c4d7b2438d3 49 #if (REFLECT_REMAINDER == TRUE)
switches 0:5c4d7b2438d3 50 #undef REFLECT_REMAINDER
switches 0:5c4d7b2438d3 51 #define REFLECT_REMAINDER(X) ((flash_journal_crc32_t) reflect((X), WIDTH))
switches 0:5c4d7b2438d3 52 #else
switches 0:5c4d7b2438d3 53 #undef REFLECT_REMAINDER
switches 0:5c4d7b2438d3 54 #define REFLECT_REMAINDER(X) (X)
switches 0:5c4d7b2438d3 55 #endif
switches 0:5c4d7b2438d3 56
switches 0:5c4d7b2438d3 57
switches 0:5c4d7b2438d3 58 /*********************************************************************
switches 0:5c4d7b2438d3 59 *
switches 0:5c4d7b2438d3 60 * Function: reflect()
switches 0:5c4d7b2438d3 61 *
switches 0:5c4d7b2438d3 62 * Description: Reorder the bits of a binary sequence, by reflecting
switches 0:5c4d7b2438d3 63 * them about the middle position.
switches 0:5c4d7b2438d3 64 *
switches 0:5c4d7b2438d3 65 * Notes: No checking is done that nBits <= 32.
switches 0:5c4d7b2438d3 66 *
switches 0:5c4d7b2438d3 67 * Returns: The reflection of the original data.
switches 0:5c4d7b2438d3 68 *
switches 0:5c4d7b2438d3 69 *********************************************************************/
switches 0:5c4d7b2438d3 70 static uint32_t
switches 0:5c4d7b2438d3 71 reflect(uint32_t data, unsigned char nBits)
switches 0:5c4d7b2438d3 72 {
switches 0:5c4d7b2438d3 73 uint32_t reflection = 0x00000000;
switches 0:5c4d7b2438d3 74 unsigned char bit;
switches 0:5c4d7b2438d3 75
switches 0:5c4d7b2438d3 76 /*
switches 0:5c4d7b2438d3 77 * Reflect the data about the center bit.
switches 0:5c4d7b2438d3 78 */
switches 0:5c4d7b2438d3 79 for (bit = 0; bit < nBits; ++bit)
switches 0:5c4d7b2438d3 80 {
switches 0:5c4d7b2438d3 81 /*
switches 0:5c4d7b2438d3 82 * If the LSB bit is set, set the reflection of it.
switches 0:5c4d7b2438d3 83 */
switches 0:5c4d7b2438d3 84 if (data & 0x01)
switches 0:5c4d7b2438d3 85 {
switches 0:5c4d7b2438d3 86 reflection |= (1 << ((nBits - 1) - bit));
switches 0:5c4d7b2438d3 87 }
switches 0:5c4d7b2438d3 88
switches 0:5c4d7b2438d3 89 data = (data >> 1);
switches 0:5c4d7b2438d3 90 }
switches 0:5c4d7b2438d3 91
switches 0:5c4d7b2438d3 92 return (reflection);
switches 0:5c4d7b2438d3 93
switches 0:5c4d7b2438d3 94 } /* reflect() */
switches 0:5c4d7b2438d3 95
switches 0:5c4d7b2438d3 96
switches 0:5c4d7b2438d3 97 static flash_journal_crc32_t crcTable[256];
switches 0:5c4d7b2438d3 98 static flash_journal_crc32_t crcEngineRemainder = INITIAL_REMAINDER;
switches 0:5c4d7b2438d3 99
switches 0:5c4d7b2438d3 100 /*********************************************************************
switches 0:5c4d7b2438d3 101 *
switches 0:5c4d7b2438d3 102 * Function: flashJournalCrcInit()
switches 0:5c4d7b2438d3 103 *
switches 0:5c4d7b2438d3 104 * Description: Populate the partial CRC lookup table.
switches 0:5c4d7b2438d3 105 *
switches 0:5c4d7b2438d3 106 * Notes: This function must be rerun any time the CRC standard
switches 0:5c4d7b2438d3 107 * is changed. If desired, it can be run "offline" and
switches 0:5c4d7b2438d3 108 * the table results stored in an embedded system's ROM.
switches 0:5c4d7b2438d3 109 *
switches 0:5c4d7b2438d3 110 * Returns: None defined.
switches 0:5c4d7b2438d3 111 *
switches 0:5c4d7b2438d3 112 *********************************************************************/
switches 0:5c4d7b2438d3 113 void
switches 0:5c4d7b2438d3 114 flashJournalCrcInit(void)
switches 0:5c4d7b2438d3 115 {
switches 0:5c4d7b2438d3 116 flash_journal_crc32_t remainder;
switches 0:5c4d7b2438d3 117 int dividend;
switches 0:5c4d7b2438d3 118 unsigned char bit;
switches 0:5c4d7b2438d3 119
switches 0:5c4d7b2438d3 120
switches 0:5c4d7b2438d3 121 /*
switches 0:5c4d7b2438d3 122 * Compute the remainder of each possible dividend.
switches 0:5c4d7b2438d3 123 */
switches 0:5c4d7b2438d3 124 for (dividend = 0; dividend < 256; ++dividend)
switches 0:5c4d7b2438d3 125 {
switches 0:5c4d7b2438d3 126 /*
switches 0:5c4d7b2438d3 127 * Start with the dividend followed by zeros.
switches 0:5c4d7b2438d3 128 */
switches 0:5c4d7b2438d3 129 remainder = dividend << (WIDTH - 8);
switches 0:5c4d7b2438d3 130
switches 0:5c4d7b2438d3 131 /*
switches 0:5c4d7b2438d3 132 * Perform modulo-2 division, a bit at a time.
switches 0:5c4d7b2438d3 133 */
switches 0:5c4d7b2438d3 134 for (bit = 8; bit > 0; --bit)
switches 0:5c4d7b2438d3 135 {
switches 0:5c4d7b2438d3 136 /*
switches 0:5c4d7b2438d3 137 * Try to divide the current data bit.
switches 0:5c4d7b2438d3 138 */
switches 0:5c4d7b2438d3 139 if (remainder & TOPBIT)
switches 0:5c4d7b2438d3 140 {
switches 0:5c4d7b2438d3 141 remainder = (remainder << 1) ^ POLYNOMIAL;
switches 0:5c4d7b2438d3 142 }
switches 0:5c4d7b2438d3 143 else
switches 0:5c4d7b2438d3 144 {
switches 0:5c4d7b2438d3 145 remainder = (remainder << 1);
switches 0:5c4d7b2438d3 146 }
switches 0:5c4d7b2438d3 147 }
switches 0:5c4d7b2438d3 148
switches 0:5c4d7b2438d3 149 /*
switches 0:5c4d7b2438d3 150 * Store the result into the table.
switches 0:5c4d7b2438d3 151 */
switches 0:5c4d7b2438d3 152 crcTable[dividend] = remainder;
switches 0:5c4d7b2438d3 153 }
switches 0:5c4d7b2438d3 154
switches 0:5c4d7b2438d3 155 } /* flashJournalCrcInit() */
switches 0:5c4d7b2438d3 156
switches 0:5c4d7b2438d3 157 /*********************************************************************
switches 0:5c4d7b2438d3 158 *
switches 0:5c4d7b2438d3 159 * Function: flashJournalCrcReset()
switches 0:5c4d7b2438d3 160 *
switches 0:5c4d7b2438d3 161 * Description: Resets internal state before calling crcCummulative().
switches 0:5c4d7b2438d3 162 *
switches 0:5c4d7b2438d3 163 * Notes: See the notes to crcCummulative().
switches 0:5c4d7b2438d3 164 *
switches 0:5c4d7b2438d3 165 * Returns: None defined.
switches 0:5c4d7b2438d3 166 *
switches 0:5c4d7b2438d3 167 *********************************************************************/
switches 0:5c4d7b2438d3 168 void
switches 0:5c4d7b2438d3 169 flashJournalCrcReset(void)
switches 0:5c4d7b2438d3 170 {
switches 0:5c4d7b2438d3 171 static unsigned initCalled = 0;
switches 0:5c4d7b2438d3 172 if (!initCalled) {
switches 0:5c4d7b2438d3 173 flashJournalCrcInit();
switches 0:5c4d7b2438d3 174 initCalled = 1;
switches 0:5c4d7b2438d3 175 }
switches 0:5c4d7b2438d3 176
switches 0:5c4d7b2438d3 177 crcEngineRemainder = INITIAL_REMAINDER;
switches 0:5c4d7b2438d3 178
switches 0:5c4d7b2438d3 179 } /* flashJournalCrcReset() */
switches 0:5c4d7b2438d3 180
switches 0:5c4d7b2438d3 181 /*********************************************************************
switches 0:5c4d7b2438d3 182 *
switches 0:5c4d7b2438d3 183 * Function: crcCummulative()
switches 0:5c4d7b2438d3 184 *
switches 0:5c4d7b2438d3 185 * Description: Compute the CRC of a group of messages.
switches 0:5c4d7b2438d3 186 *
switches 0:5c4d7b2438d3 187 * Notes:
switches 0:5c4d7b2438d3 188 * This function is intended to be used in the following way:
switches 0:5c4d7b2438d3 189 * - crcReset() is called first to reset internal state before the first
switches 0:5c4d7b2438d3 190 * fragment of a new message is processed with crcCummulative().
switches 0:5c4d7b2438d3 191 * - crcCummulative() called successfully appending additional message
switches 0:5c4d7b2438d3 192 * fragments to those previously supplied (in order), and returning
switches 0:5c4d7b2438d3 193 * the current crc for the message payload so far.
switches 0:5c4d7b2438d3 194 *
switches 0:5c4d7b2438d3 195 * Returns: The CRC of the message.
switches 0:5c4d7b2438d3 196 *
switches 0:5c4d7b2438d3 197 *********************************************************************/
switches 0:5c4d7b2438d3 198 flash_journal_crc32_t
switches 0:5c4d7b2438d3 199 flashJournalCrcCummulative(unsigned char const message[], int nBytes)
switches 0:5c4d7b2438d3 200 {
switches 0:5c4d7b2438d3 201 unsigned char data;
switches 0:5c4d7b2438d3 202 int byte;
switches 0:5c4d7b2438d3 203
switches 0:5c4d7b2438d3 204
switches 0:5c4d7b2438d3 205 /*
switches 0:5c4d7b2438d3 206 * Divide the message by the polynomial, a byte at a time.
switches 0:5c4d7b2438d3 207 */
switches 0:5c4d7b2438d3 208 for (byte = 0; byte < nBytes; ++byte)
switches 0:5c4d7b2438d3 209 {
switches 0:5c4d7b2438d3 210 data = REFLECT_DATA(message[byte]) ^ (crcEngineRemainder >> (WIDTH - 8));
switches 0:5c4d7b2438d3 211 crcEngineRemainder = crcTable[data] ^ (crcEngineRemainder << 8);
switches 0:5c4d7b2438d3 212 }
switches 0:5c4d7b2438d3 213
switches 0:5c4d7b2438d3 214 /*
switches 0:5c4d7b2438d3 215 * The final remainder is the CRC.
switches 0:5c4d7b2438d3 216 */
switches 0:5c4d7b2438d3 217 return (REFLECT_REMAINDER(crcEngineRemainder) ^ FINAL_XOR_VALUE);
switches 0:5c4d7b2438d3 218
switches 0:5c4d7b2438d3 219 } /* crcCummulative() */
switches 0:5c4d7b2438d3 220