crc64_fast.c

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//
//
//  Author:     Lasse Collin
//
//  This file has been put into the public domain.
//  You can do whatever you want with this file.
//
 
#include "check.h"
#include "crc_macros.h"
 
 
#ifdef WORDS_BIGENDIAN
#   define A1(x) ((x) >> 56)
#else
#   define A1 A
#endif
 
 
// See the comments in crc32_fast.c. They aren't duplicated here.
extern LZMA_API(uint64_t)
lzma_crc64(const uint8_t *buf, size_t size, uint64_t crc)
{
    crc = ~crc;
 
#ifdef WORDS_BIGENDIAN
    crc = bswap64(crc);
#endif
 
    if (size > 4) {
        while ((uintptr_t)(buf) & 3) {
            crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
            --size;
        }
 
        const uint8_t *const limit = buf + (size & ~(size_t)(3));
        size &= (size_t)(3);
 
        while (buf < limit) {
#ifdef WORDS_BIGENDIAN
            const uint32_t tmp = (crc >> 32)
                    ^ aligned_read32ne(buf);
#else
            const uint32_t tmp = crc ^ aligned_read32ne(buf);
#endif
            buf += 4;
 
            crc = lzma_crc64_table[3][A(tmp)]
                ^ lzma_crc64_table[2][B(tmp)]
                ^ S32(crc)
                ^ lzma_crc64_table[1][C(tmp)]
                ^ lzma_crc64_table[0][D(tmp)];
        }
    }
 
    while (size-- != 0)
        crc = lzma_crc64_table[0][*buf++ ^ A1(crc)] ^ S8(crc);
 
#ifdef WORDS_BIGENDIAN
    crc = bswap64(crc);
#endif
 
    return ~crc;
}