px_crc8.c

/* =============================================================================
     ____    ___    ____    ___    _   _    ___    __  __   ___  __  __ TM
    |  _ \  |_ _|  / ___|  / _ \  | \ | |  / _ \  |  \/  | |_ _| \ \/ /
    | |_) |  | |  | |     | | | | |  \| | | | | | | |\/| |  | |   \  /
    |  __/   | |  | |___  | |_| | | |\  | | |_| | | |  | |  | |   /  \
    |_|     |___|  \____|  \___/  |_| \_|  \___/  |_|  |_| |___| /_/\_\
 
    Copyright (c) 2020 Pieter Conradie <https://piconomix.com>
 
    License: MIT
    https://github.com/piconomix/px-fwlib/blob/master/LICENSE.md
 
    Title:          px_crc8.h : 8-bit CRC calculator
    Author(s):      Pieter Conradie
    Creation Date:  2020-10-23
 
============================================================================= */
 
/* _____STANDARD INCLUDES____________________________________________________ */
#include <stdio.h>
 
/* _____PROJECT INCLUDES_____________________________________________________ */
#include "px_crc8.h"
 
/* _____LOCAL DEFINITIONS____________________________________________________ */
 
/* _____MACROS_______________________________________________________________ */
 
/* _____GLOBAL VARIABLES_____________________________________________________ */
 
/* _____LOCAL VARIABLES______________________________________________________ */
#if PX_CRC8_RAM_TABLE
static uint8_t px_crc8_table[256];
#endif
 
#if PX_CRC8_ROM_TABLE
static const uint8_t px_crc8_table[256] =
{
    0x00, 0x07, 0x0e, 0x09, 0x1c, 0x1b, 0x12, 0x15,
    0x38, 0x3f, 0x36, 0x31, 0x24, 0x23, 0x2a, 0x2d,
    0x70, 0x77, 0x7e, 0x79, 0x6c, 0x6b, 0x62, 0x65,
    0x48, 0x4f, 0x46, 0x41, 0x54, 0x53, 0x5a, 0x5d,
    0xe0, 0xe7, 0xee, 0xe9, 0xfc, 0xfb, 0xf2, 0xf5,
    0xd8, 0xdf, 0xd6, 0xd1, 0xc4, 0xc3, 0xca, 0xcd,
    0x90, 0x97, 0x9e, 0x99, 0x8c, 0x8b, 0x82, 0x85,
    0xa8, 0xaf, 0xa6, 0xa1, 0xb4, 0xb3, 0xba, 0xbd,
    0xc7, 0xc0, 0xc9, 0xce, 0xdb, 0xdc, 0xd5, 0xd2,
    0xff, 0xf8, 0xf1, 0xf6, 0xe3, 0xe4, 0xed, 0xea,
    0xb7, 0xb0, 0xb9, 0xbe, 0xab, 0xac, 0xa5, 0xa2,
    0x8f, 0x88, 0x81, 0x86, 0x93, 0x94, 0x9d, 0x9a,
    0x27, 0x20, 0x29, 0x2e, 0x3b, 0x3c, 0x35, 0x32,
    0x1f, 0x18, 0x11, 0x16, 0x03, 0x04, 0x0d, 0x0a,
    0x57, 0x50, 0x59, 0x5e, 0x4b, 0x4c, 0x45, 0x42,
    0x6f, 0x68, 0x61, 0x66, 0x73, 0x74, 0x7d, 0x7a,
    0x89, 0x8e, 0x87, 0x80, 0x95, 0x92, 0x9b, 0x9c,
    0xb1, 0xb6, 0xbf, 0xb8, 0xad, 0xaa, 0xa3, 0xa4,
    0xf9, 0xfe, 0xf7, 0xf0, 0xe5, 0xe2, 0xeb, 0xec,
    0xc1, 0xc6, 0xcf, 0xc8, 0xdd, 0xda, 0xd3, 0xd4,
    0x69, 0x6e, 0x67, 0x60, 0x75, 0x72, 0x7b, 0x7c,
    0x51, 0x56, 0x5f, 0x58, 0x4d, 0x4a, 0x43, 0x44,
    0x19, 0x1e, 0x17, 0x10, 0x05, 0x02, 0x0b, 0x0c,
    0x21, 0x26, 0x2f, 0x28, 0x3d, 0x3a, 0x33, 0x34,
    0x4e, 0x49, 0x40, 0x47, 0x52, 0x55, 0x5c, 0x5b,
    0x76, 0x71, 0x78, 0x7f, 0x6a, 0x6d, 0x64, 0x63,
    0x3e, 0x39, 0x30, 0x37, 0x22, 0x25, 0x2c, 0x2b,
    0x06, 0x01, 0x08, 0x0f, 0x1a, 0x1d, 0x14, 0x13,
    0xae, 0xa9, 0xa0, 0xa7, 0xb2, 0xb5, 0xbc, 0xbb,
    0x96, 0x91, 0x98, 0x9f, 0x8a, 0x8d, 0x84, 0x83,
    0xde, 0xd9, 0xd0, 0xd7, 0xc2, 0xc5, 0xcc, 0xcb,
    0xe6, 0xe1, 0xe8, 0xef, 0xfa, 0xfd, 0xf4, 0xf3,
};
#endif
 
/* _____LOCAL FUNCTION DECLARATIONS__________________________________________ */
 
/* _____LOCAL FUNCTIONS______________________________________________________ */
 
/* _____GLOBAL FUNCTIONS_____________________________________________________ */
void px_crc8_init(void)
{
#if PX_CRC8_RAM_TABLE
    uint8_t  i;
    uint16_t j;
    uint8_t  c;
 
    for (j = 0; j < 256; j++)
    {
        c = (uint8_t)j;
        // Repeat for each bit in byte
        for (i = 8; i != 0; i--)
        {
            // Most Significant Bit set?
            if (c & 0x80)
            {
                c = (c << 1) ^ PX_CRC8_POLYNOMIAL;
            }
            else
            {
                c = (c << 1);
            }
        }
        px_crc8_table[j] = c;
    }
#endif
}
 
uint8_t px_crc8_update_u8(uint8_t crc, uint8_t data)
{
#if PX_CRC8_RAM_TABLE || PX_CRC8_ROM_TABLE
    crc = px_crc8_table[crc ^ data];
#else
    uint8_t i;
 
    crc ^= data;
    for(i = 8; i != 0; i--)
    {
        if(crc & 0x80)
        {
            crc = (crc << 1) ^ PX_CRC8_POLYNOMIAL;
        }
        else
        {
            crc = (crc << 1);
        }
    }
 
#endif
    return crc;
}
 
uint8_t px_crc8_update_data(uint8_t crc, const void * data, size_t nr_of_bytes)
{
    const uint8_t * data_u8 = (uint8_t *)data;
 
    while(nr_of_bytes)
    {
        crc = px_crc8_update_u8(crc, *data_u8++);
        nr_of_bytes--;
    }
 
    return crc;
}