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/* crc32_p.h -- Private inline functions and macros shared with
* different computation of the CRC-32 checksum
* of a data stream.
* Copyright (C) 2026 Nathan Moinvaziri
* For conditions of distribution and use, see copyright notice in zlib.h
*/
#ifndef CRC32_P_H
#define CRC32_P_H
#define CRC_DO1(c, buf, i) c = crc_table[(c ^ buf[i]) & 0xff] ^ (c >> 8)
#define CRC_DO2(c, buf, i) {CRC_DO1(c, buf, i); CRC_DO1(c, buf, i+1);}
#define CRC_DO4(c, buf, i) {CRC_DO2(c, buf, i); CRC_DO2(c, buf, i+2);}
#define CRC_DO8(c, buf, i) {CRC_DO4(c, buf, i); CRC_DO4(c, buf, i+4);}
Z_FORCEINLINE static uint32_t crc32_copy_small(uint32_t crc, uint8_t *dst, const uint8_t *buf, size_t len,
const int MAX_LEN, const int COPY) {
if (MAX_LEN >= 8) {
while (len >= 8) {
if (COPY) {
memcpy(dst, buf, 8);
dst += 8;
}
CRC_DO8(crc, buf, 0);
buf += 8;
len -= 8;
}
}
if (len & 4) {
if (COPY) {
memcpy(dst, buf, 4);
dst += 4;
}
CRC_DO4(crc, buf, 0);
buf += 4;
}
if (len & 2) {
if (COPY) {
memcpy(dst, buf, 2);
dst += 2;
}
CRC_DO2(crc, buf, 0);
buf += 2;
}
if (len & 1) {
if (COPY)
*dst = *buf;
CRC_DO1(crc, buf, 0);
}
return crc;
}
#endif /* CRC32_P_H */
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