126 lines
2.2 KiB
C
126 lines
2.2 KiB
C
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#include "utl_crc32.h"
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int utl_crc32Init(CRC32_CTX *crcContext)
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{
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int i,j;
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CrcUint32 c;
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/* Sanity check context pointer */
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if (crcContext==NULL) {
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return(-1);
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}
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/*
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* Build auxiliary table for parallel byte-at-a-time CRC-32
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*/
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#ifdef ORIGINAL_METHOD
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for (i = 0; i < 256; ++i) {
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for (c = i << 24, j = 8; j > 0; --j) {
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c = c & 0x80000000 ? (c << 1) ^ CRC32_POLY : (c << 1);
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}
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crcContext->crc32_table[i] = c;
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}
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#else
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for (i=0; i<256; i++) {
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c = i;
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for (j=8; j>0; j--) {
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if (c & 1) {
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c = (c >> 1) ^ CRC32_POLY;
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} else {
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c >>= 1;
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}
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}
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crcContext->crc32_table[i] = c;
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}
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#endif
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return(0);
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}
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/* Complete CRC32 calculation on a memory block */
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int utl_crc32Calc(CRC32_CTX * crcContext, CrcUint8 *inBuf, CrcUint32 inLen, CrcUint32 *crc32)
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{
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if (utl_crc32CalcStart(crcContext,crc32)) {
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return(-1);
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}
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if (utl_crc32CalcBuffer(crcContext, inBuf, inLen, crc32)) {
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return(-1);
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}
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if (utl_crc32CalcEnd(crcContext, crc32)) {
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return(-1);
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}
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return(0);
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}
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/* Start crc calculation */
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int utl_crc32CalcStart(CRC32_CTX * crcContext, CrcUint32 *crc32)
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{
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/* Sanity check pointers */
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if (crcContext==NULL) {
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*crc32=0;
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return(-1);
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}
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/*
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* Preload shift register, per CRC-32 spec
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*/
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*crc32 = 0xffffffff;
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return(0);
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}
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/* Finish crc calculation */
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int utl_crc32CalcEnd(CRC32_CTX * crcContext, CrcUint32 *crc32)
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{
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/*
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* Return complement, per CRC-32 spec
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*/
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*crc32 = (~(*crc32));
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return(0);
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}
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/* Include memory block in crc */
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int utl_crc32CalcBuffer(CRC32_CTX * crcContext, CrcUint8 *inBuf, CrcUint32 inLen, CrcUint32 *crc32)
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{
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CrcUint8 *p;
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register CrcUint32 crc;
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/* Sanity check pointers */
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if (crcContext==NULL) {
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*crc32=0;
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return(-1);
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}
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/*
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* Calculate CRC from data
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*/
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crc = *crc32;
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for (p = inBuf; inLen > 0; ++p, --inLen) {
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#ifdef ORIGINAL_METHOD
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crc = (crc << 8) ^ crcContext->crc32_table[(crc >> 24) ^ *p];
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#else
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crc = ((crc >> 8) & 0x00FFFFFF) ^ crcContext->crc32_table[ (crc ^ *p) & 0xFF ];
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#endif
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}
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*crc32 = crc;
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return(0);
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}
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int utl_crc32Done(CRC32_CTX * crcContext)
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{
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/* Sanity check context pointer */
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if (crcContext==NULL) {
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return(-1);
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}
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return(0);
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}
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