template inline __attribute__()

in common/checksum/crc.cpp [567:616]

• 48 lines of code
• 8 McCabe index (conditional complexity)

template<typename F> inline __attribute__((always_inline))
uint64_t crc64ecma_hw_portable(const uint8_t *data, size_t nbytes, uint64_t crc, F hw_big) {
    if (unlikely(!nbytes || !data)) return crc;
    using SIMD = SSE;
    using v128 = typename SIMD::v128;
    v128 xmm7 = {(long)~crc};
    auto& ptr = (const v128*&)data;
    if (nbytes >= 256) {
        xmm7 = hw_big(data, nbytes, crc);
    } else if (nbytes >= 16) {
        xmm7 ^= SIMD::loadu(ptr++);
        nbytes -= 16;
    } else /* 0 < nbytes < 16*/ {
        xmm7 ^= SIMD::load_small(data, nbytes);
        if (nbytes >= 8) {
            auto shf = SIMD::loadu(get_shf_table(nbytes));
            xmm7 = SIMD::pshufb(xmm7, shf);
            goto _128_done;
        } else {
            auto shf = SIMD::loadu(get_shf_table(nbytes + 8));
            xmm7 = SIMD::pshufb(xmm7, shf);
            goto _barrett;
        }
    }

    while (nbytes >= 16) {
        xmm7 = SIMD::op(xmm7, RK(1)) ^ SIMD::loadu(ptr++);
        nbytes -= 16;
    }

    if (nbytes) {
        auto p = data + nbytes - 16;
        auto remainder = SIMD::loadu((v128*)p);
        auto xmm0 = SIMD::loadu(get_shf_table(nbytes));
        auto xmm2 = xmm7;
        xmm7 = SIMD::pshufb(xmm7, xmm0);
        xmm0 ^= MASK(3);
        xmm2 = SIMD::pshufb(xmm2, xmm0);
        xmm2 = SIMD::pblendvb(xmm2, remainder, xmm0);
        xmm7 = xmm2 ^ SIMD::op(xmm7, RK(1));
    }
_128_done:
    xmm7  =  SIMD::pclmulqdq<0>(xmm7, RK(5)) ^ SIMD::bsr8(xmm7);
_barrett:
    auto t = SIMD::pclmulqdq<0>(xmm7, RK(7));
    xmm7  ^= SIMD::pclmulqdq<0x10>(t, RK(7)) ^ SIMD::bsl8(t);
    auto p = (uint64_t*)&xmm7;
    crc = ~p[1];
    return crc;
}