31 lines
1.1 KiB
C
31 lines
1.1 KiB
C
#include "amiCrc.h"
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#define CRC32_POLYNOMIAL 0xedb88320
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AM_LIB_C_HEADER(amiCrc, AMI_CRC)
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void amiCrc32RCreateTable(uint32_t *table) {
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for (int i = 0; i < 256; i++) {
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uint32_t value = (~i & 1) - 1 & CRC32_POLYNOMIAL;
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value = ((i >> 1 ^ ~value) & 1) - 1 & CRC32_POLYNOMIAL ^ value >> 1;
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value = ((i >> 2 ^ ~value) & 1) - 1 & CRC32_POLYNOMIAL ^ value >> 1;
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value = ((i >> 3 ^ ~value) & 1) - 1 & CRC32_POLYNOMIAL ^ value >> 1;
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value = ((i >> 4 ^ ~value) & 1) - 1 & CRC32_POLYNOMIAL ^ value >> 1;
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value = ((i >> 5 ^ ~value) & 1) - 1 & CRC32_POLYNOMIAL ^ value >> 1;
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value = ((i >> 6 ^ ~value) & 1) - 1 & CRC32_POLYNOMIAL ^ value >> 1;
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table[0] = ((i >> 7 ^ ~value) & 1) - 1 & CRC32_POLYNOMIAL ^ value >> 1;
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table++;
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}
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}
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uint32_t amiCrc32RGet(uint32_t *table, int length, void *data, uint32_t initial) {
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uint32_t value = ~initial;
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unsigned char* lpcData = (unsigned char*)data;
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while (length > 0) {
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value = value >> 8 ^ table[(lpcData[0] ^ value) & 0xff];
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length += -1;
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lpcData++;
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}
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return ~value;
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}
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