lib_crc1.rar_E1 SDH_Ethernet_SDH and E1_ethernet e1_sdh

#include "lib_crc.h" /*******************************************************************\ * * * Library : lib_crc * * File : lib_crc.c * * Author : Lammert Bies 1999-2005 * * E-mail : [email protected] * * Language : ANSI C * * * * * * Description * * =========== * * * * The file lib_crc.c contains the private and public func- * * tions used for the calculation of CRC-16, CRC-CCITT and * * CRC-32 cyclic redundancy values. * * * * * * Dependencies * * ============ * * * * lib_crc.h CRC definitions and prototypes * * * * * * Modification history * * ==================== * * * * Date Version Comment * * * * 2005-05-14 1.12 Added CRC-CCITT with start value 0 * * * * 2005-02-05 1.11 Fixed bug in CRC-DNP routine * * * * 2005-02-04 1.10 Added CRC-DNP routines * * * * 1999-02-21 1.01 Added FALSE and TRUE mnemonics * * * * 1999-01-22 1.00 Initial source * * * \*******************************************************************/ /*******************************************************************\ * * * #define P_xxxx * * * * The CRC's are computed using polynomials. The coefficients * * for the algorithms are defined by the following constants. * * * \*******************************************************************/ #define P_16 0xA001 #define P_32 0xEDB88320L #define P_CCITT 0x1021 #define P_DNP 0xA6BC /*******************************************************************\ * * * static int crc_tab...init * * static unsigned ... crc_tab...[] * * * * The algorithms use tables with precalculated values. This * * speeds up the calculation dramaticaly. The first time the * * CRC function is called, the table for that specific calcu- * * lation is set up. The ...init variables are used to deter- * * mine if the initialization has taken place. The calculated * * values are stored in the crc_tab... arrays. * * * * The variables are declared static. This makes them invisi- * * ble for other modules of the program. * * * \*******************************************************************/ static int crc_tab16_init = FALSE; static int crc_tab32_init = FALSE; static int crc_tabccitt_init = FALSE; static int crc_tabdnp_init = FALSE; static unsigned short crc_tab16[256]; static unsigned long crc_tab32[256]; static unsigned short crc_tabccitt[256]; static unsigned short crc_tabdnp[256]; /*******************************************************************\ * * * static void init_crc...tab(); * * * * Three local functions are used to initialize the tables * * with values for the algorithm. * * * \*******************************************************************/ static void init_crc16_tab( void ); static void init_crc32_tab( void ); static void init_crcccitt_tab( void ); static void init_crcdnp_tab( void ); /*******************************************************************\ * * * unsigned short update_crc_ccitt( unsigned long crc, char c ); * * * * The function update_crc_ccitt calculates a new CRC-CCITT * * value based on the previous value of the CRC and the next * * byte of the data to be checked. * * * \*******************************************************************/ unsigned short update_crc_ccitt( unsigned short crc, char c ) { unsigned short tmp, short_c; short_c = 0x00ff & (unsigned short) c; if ( ! crc_tabccitt_init ) init_crcccitt_tab(); tmp = (crc >> 8) ^ short_c; crc = (crc << 8) ^ crc_tabccitt[tmp]; return crc; } /* update_crc_ccitt */ /*******************************************************************\ * * * unsigned short update_crc_16( unsigned long crc, char c ); * * * * The function update_crc_16 calculates a new CRC-16 value * * based on the previous value of the CRC and the next byte * * of the data to be checked. * * * \*******************************************************************/ unsigned short update_crc_16( unsigned short crc, char c ) { unsigned short tmp, short_c; short_c = 0x00ff & (unsigned short) c;