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Annotation of hatari/src/utils.c, revision 1.1.1.3

1.1       root        1: /*
                      2:  * Hatari - utils.c
                      3:  *
                      4:  * This file is distributed under the GNU Public License, version 2 or at
                      5:  * your option any later version. Read the file gpl.txt for details.
                      6:  *
                      7:  * Utils functions :
                      8:  *     - CRC32
                      9:  *
                     10:  * This file contains various utility functions used by different parts of Hatari.
                     11:  */
1.1.1.3 ! root       12: const char Utils_fileid[] = "Hatari utils.c : " __DATE__ " " __TIME__;
1.1       root       13: 
                     14: #include "utils.h"
                     15: 
                     16: 
                     17: /************************************************************************/
                     18: /* Functions used to compute the CRC32 of a stream of bytes.           */
                     19: /* These functions require a pointer to an unsigned int (Uint32) to    */
                     20: /* store the resulting CRC.                                            */
                     21: /*     crc32_reset : call this once to reset the CRC, before adding    */
                     22: /*             some bytes.                                             */
                     23: /*     crc32_add_byte : update the current CRC with a new byte.        */
                     24: /************************************************************************/
                     25: 
                     26: /*--------------------------------------------------------------*/
                     27: /* Reset the crc32 value. This should be done before calling   */
                     28: /* crc32_add_byte().                                           */
                     29: /*--------------------------------------------------------------*/
                     30: 
                     31: void   crc32_reset ( Uint32 *crc )
                     32: {
                     33:        *crc = 0xffffffff;
                     34: }
                     35: 
                     36: 
                     37: /*--------------------------------------------------------------*/
                     38: /* Update the current value of crc with a new byte.            */
                     39: /* Call crc32_reset() first to init the crc value.             */
                     40: /*--------------------------------------------------------------*/
                     41: 
                     42: void   crc32_add_byte ( Uint32 *crc , Uint8 c )
                     43: {
                     44:        int     bit;
                     45:     
                     46:        for ( bit=0 ; bit<8; bit++ )
                     47:        {
                     48:                if ( ( c & 0x80 ) ^ ( *crc & 0x80000000 ) )
                     49:                        *crc = ( *crc << 1 ) ^ CRC32_POLY;
                     50: 
                     51:                else
                     52:                        *crc = *crc << 1;
                     53: 
                     54:             c <<= 1;
                     55:         }
                     56: }
                     57: 
                     58: 
                     59: /************************************************************************/
                     60: 
                     61: 

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