/*
 * Compute the CRC32 using a parallelized folding approach with the PCLMULQDQ
 * instruction.
 *
 * A white paper describing this algorithm can be found at:
 * https://www.intel.com/content/dam/www/public/us/en/documents/white-papers/fast-crc-computation-generic-polynomials-pclmulqdq-paper.pdf
 *
 * Copyright (C) 2013 Intel Corporation. All rights reserved.
 * Copyright (C) 2016 Marian Beermann (support for initial value)
 * Authors:
 *     Wajdi Feghali   <wajdi.k.feghali@intel.com>
 *     Jim Guilford    <james.guilford@intel.com>
 *     Vinodh Gopal    <vinodh.gopal@intel.com>
 *     Erdinc Ozturk   <erdinc.ozturk@intel.com>
 *     Jim Kukunas     <james.t.kukunas@linux.intel.com>
 *
 * For conditions of distribution and use, see copyright notice in zlib.h
 */

#ifdef X86_PCLMULQDQ_CRC
#include "../../zbuild.h"

#include <immintrin.h>
#include <wmmintrin.h>
#include <smmintrin.h> // _mm_extract_epi32

#include "x86_features.h"
#include "cpu_features.h"

#include "../../crc32_fold.h"
#include "../../crc32_braid_p.h"
#include <assert.h>

#ifdef X86_VPCLMULQDQ_CRC
extern size_t fold_16_vpclmulqdq(__m128i *xmm_crc0, __m128i *xmm_crc1,
    __m128i *xmm_crc2, __m128i *xmm_crc3, uint8_t *dst, const uint8_t *src, size_t len);
extern size_t fold_16_vpclmulqdq_nocp(__m128i *xmm_crc0, __m128i *xmm_crc1,
    __m128i *xmm_crc2, __m128i *xmm_crc3, const uint8_t *src, size_t len, __m128i init_crc,
    int32_t first);
#endif

static void fold_1(__m128i *xmm_crc0, __m128i *xmm_crc1, __m128i *xmm_crc2, __m128i *xmm_crc3) {
    const __m128i xmm_fold4 = _mm_set_epi32( 0x00000001, 0x54442bd4,
                                             0x00000001, 0xc6e41596);
    __m128i x_tmp3;
    __m128 ps_crc0, ps_crc3, ps_res;

    x_tmp3 = *xmm_crc3;

    *xmm_crc3 = *xmm_crc0;
    *xmm_crc0 = _mm_clmulepi64_si128(*xmm_crc0, xmm_fold4, 0x01);
    *xmm_crc3 = _mm_clmulepi64_si128(*xmm_crc3, xmm_fold4, 0x10);
    ps_crc0 = _mm_castsi128_ps(*xmm_crc0);
    ps_crc3 = _mm_castsi128_ps(*xmm_crc3);
    ps_res = _mm_xor_ps(ps_crc0, ps_crc3);

    *xmm_crc0 = *xmm_crc1;
    *xmm_crc1 = *xmm_crc2;
    *xmm_crc2 = x_tmp3;
    *xmm_crc3 = _mm_castps_si128(ps_res);
}

static void fold_2(__m128i *xmm_crc0, __m128i *xmm_crc1, __m128i *xmm_crc2, __m128i *xmm_crc3) {
    const __m128i xmm_fold4 = _mm_set_epi32( 0x00000001, 0x54442bd4,
                                             0x00000001, 0xc6e41596);
    __m128i x_tmp3, x_tmp2;
    __m128 ps_crc0, ps_crc1, ps_crc2, ps_crc3, ps_res31, ps_res20;

    x_tmp3 = *xmm_crc3;
    x_tmp2 = *xmm_crc2;

    *xmm_crc3 = *xmm_crc1;
    *xmm_crc1 = _mm_clmulepi64_si128(*xmm_crc1, xmm_fold4, 0x01);
    *xmm_crc3 = _mm_clmulepi64_si128(*xmm_crc3, xmm_fold4, 0x10);
    ps_crc3 = _mm_castsi128_ps(*xmm_crc3);
    ps_crc1 = _mm_castsi128_ps(*xmm_crc1);
    ps_res31 = _mm_xor_ps(ps_crc3, ps_crc1);

    *xmm_crc2 = *xmm_crc0;
    *xmm_crc0 = _mm_clmulepi64_si128(*xmm_crc0, xmm_fold4, 0x01);
    *xmm_crc2 = _mm_clmulepi64_si128(*xmm_crc2, xmm_fold4, 0x10);
    ps_crc0 = _mm_castsi128_ps(*xmm_crc0);
    ps_crc2 = _mm_castsi128_ps(*xmm_crc2);
    ps_res20 = _mm_xor_ps(ps_crc0, ps_crc2);

    *xmm_crc0 = x_tmp2;
    *xmm_crc1 = x_tmp3;
    *xmm_crc2 = _mm_castps_si128(ps_res20);
    *xmm_crc3 = _mm_castps_si128(ps_res31);
}

static void fold_3(__m128i *xmm_crc0, __m128i *xmm_crc1, __m128i *xmm_crc2, __m128i *xmm_crc3) {
    const __m128i xmm_fold4 = _mm_set_epi32( 0x00000001, 0x54442bd4,
                                             0x00000001, 0xc6e41596);
    __m128i x_tmp3;
    __m128 ps_crc0, ps_crc1, ps_crc2, ps_crc3, ps_res32, ps_res21, ps_res10;

    x_tmp3 = *xmm_crc3;

    *xmm_crc3 = *xmm_crc2;
    *xmm_crc2 = _mm_clmulepi64_si128(*xmm_crc2, xmm_fold4, 0x01);
    *xmm_crc3 = _mm_clmulepi64_si128(*xmm_crc3, xmm_fold4, 0x10);
    ps_crc2 = _mm_castsi128_ps(*xmm_crc2);
    ps_crc3 = _mm_castsi128_ps(*xmm_crc3);
    ps_res32 = _mm_xor_ps(ps_crc2, ps_crc3);

    *xmm_crc2 = *xmm_crc1;
    *xmm_crc1 = _mm_clmulepi64_si128(*xmm_crc1, xmm_fold4, 0x01);
    *xmm_crc2 = _mm_clmulepi64_si128(*xmm_crc2, xmm_fold4, 0x10);
    ps_crc1 = _mm_castsi128_ps(*xmm_crc1);
    ps_crc2 = _mm_castsi128_ps(*xmm_crc2);
    ps_res21 = _mm_xor_ps(ps_crc1, ps_crc2);

    *xmm_crc1 = *xmm_crc0;
    *xmm_crc0 = _mm_clmulepi64_si128(*xmm_crc0, xmm_fold4, 0x01);
    *xmm_crc1 = _mm_clmulepi64_si128(*xmm_crc1, xmm_fold4, 0x10);
    ps_crc0 = _mm_castsi128_ps(*xmm_crc0);
    ps_crc1 = _mm_castsi128_ps(*xmm_crc1);
    ps_res10 = _mm_xor_ps(ps_crc0, ps_crc1);

    *xmm_crc0 = x_tmp3;
    *xmm_crc1 = _mm_castps_si128(ps_res10);
    *xmm_crc2 = _mm_castps_si128(ps_res21);
    *xmm_crc3 = _mm_castps_si128(ps_res32);
}

static void fold_4(__m128i *xmm_crc0, __m128i *xmm_crc1, __m128i *xmm_crc2, __m128i *xmm_crc3) {
    const __m128i xmm_fold4 = _mm_set_epi32( 0x00000001, 0x54442bd4,
                                             0x00000001, 0xc6e41596);
    __m128i x_tmp0, x_tmp1, x_tmp2, x_tmp3;
    __m128 ps_crc0, ps_crc1, ps_crc2, ps_crc3;
    __m128 ps_t0, ps_t1, ps_t2, ps_t3;
    __m128 ps_res0, ps_res1, ps_res2, ps_res3;

    x_tmp0 = *xmm_crc0;
    x_tmp1 = *xmm_crc1;
    x_tmp2 = *xmm_crc2;
    x_tmp3 = *xmm_crc3;

    *xmm_crc0 = _mm_clmulepi64_si128(*xmm_crc0, xmm_fold4, 0x01);
    x_tmp0 = _mm_clmulepi64_si128(x_tmp0, xmm_fold4, 0x10);
    ps_crc0 = _mm_castsi128_ps(*xmm_crc0);
    ps_t0 = _mm_castsi128_ps(x_tmp0);
    ps_res0 = _mm_xor_ps(ps_crc0, ps_t0);

    *xmm_crc1 = _mm_clmulepi64_si128(*xmm_crc1, xmm_fold4, 0x01);
    x_tmp1 = _mm_clmulepi64_si128(x_tmp1, xmm_fold4, 0x10);
    ps_crc1 = _mm_castsi128_ps(*xmm_crc1);
    ps_t1 = _mm_castsi128_ps(x_tmp1);
    ps_res1 = _mm_xor_ps(ps_crc1, ps_t1);

    *xmm_crc2 = _mm_clmulepi64_si128(*xmm_crc2, xmm_fold4, 0x01);
    x_tmp2 = _mm_clmulepi64_si128(x_tmp2, xmm_fold4, 0x10);
    ps_crc2 = _mm_castsi128_ps(*xmm_crc2);
    ps_t2 = _mm_castsi128_ps(x_tmp2);
    ps_res2 = _mm_xor_ps(ps_crc2, ps_t2);

    *xmm_crc3 = _mm_clmulepi64_si128(*xmm_crc3, xmm_fold4, 0x01);
    x_tmp3 = _mm_clmulepi64_si128(x_tmp3, xmm_fold4, 0x10);
    ps_crc3 = _mm_castsi128_ps(*xmm_crc3);
    ps_t3 = _mm_castsi128_ps(x_tmp3);
    ps_res3 = _mm_xor_ps(ps_crc3, ps_t3);

    *xmm_crc0 = _mm_castps_si128(ps_res0);
    *xmm_crc1 = _mm_castps_si128(ps_res1);
    *xmm_crc2 = _mm_castps_si128(ps_res2);
    *xmm_crc3 = _mm_castps_si128(ps_res3);
}

static const unsigned ALIGNED_(32) pshufb_shf_table[60] = {
    0x84838281, 0x88878685, 0x8c8b8a89, 0x008f8e8d, /* shl 15 (16 - 1)/shr1 */
    0x85848382, 0x89888786, 0x8d8c8b8a, 0x01008f8e, /* shl 14 (16 - 3)/shr2 */
    0x86858483, 0x8a898887, 0x8e8d8c8b, 0x0201008f, /* shl 13 (16 - 4)/shr3 */
    0x87868584, 0x8b8a8988, 0x8f8e8d8c, 0x03020100, /* shl 12 (16 - 4)/shr4 */
    0x88878685, 0x8c8b8a89, 0x008f8e8d, 0x04030201, /* shl 11 (16 - 5)/shr5 */
    0x89888786, 0x8d8c8b8a, 0x01008f8e, 0x05040302, /* shl 10 (16 - 6)/shr6 */
    0x8a898887, 0x8e8d8c8b, 0x0201008f, 0x06050403, /* shl  9 (16 - 7)/shr7 */
    0x8b8a8988, 0x8f8e8d8c, 0x03020100, 0x07060504, /* shl  8 (16 - 8)/shr8 */
    0x8c8b8a89, 0x008f8e8d, 0x04030201, 0x08070605, /* shl  7 (16 - 9)/shr9 */
    0x8d8c8b8a, 0x01008f8e, 0x05040302, 0x09080706, /* shl  6 (16 -10)/shr10*/
    0x8e8d8c8b, 0x0201008f, 0x06050403, 0x0a090807, /* shl  5 (16 -11)/shr11*/
    0x8f8e8d8c, 0x03020100, 0x07060504, 0x0b0a0908, /* shl  4 (16 -12)/shr12*/
    0x008f8e8d, 0x04030201, 0x08070605, 0x0c0b0a09, /* shl  3 (16 -13)/shr13*/
    0x01008f8e, 0x05040302, 0x09080706, 0x0d0c0b0a, /* shl  2 (16 -14)/shr14*/
    0x0201008f, 0x06050403, 0x0a090807, 0x0e0d0c0b  /* shl  1 (16 -15)/shr15*/
};

static void partial_fold(const size_t len, __m128i *xmm_crc0, __m128i *xmm_crc1, __m128i *xmm_crc2,
                         __m128i *xmm_crc3, __m128i *xmm_crc_part) {

    const __m128i xmm_fold4 = _mm_set_epi32( 0x00000001, 0x54442bd4,
                                             0x00000001, 0xc6e41596);
    const __m128i xmm_mask3 = _mm_set1_epi32((int32_t)0x80808080);

    __m128i xmm_shl, xmm_shr, xmm_tmp1, xmm_tmp2, xmm_tmp3;
    __m128i xmm_a0_0, xmm_a0_1;
    __m128 ps_crc3, psa0_0, psa0_1, ps_res;

    xmm_shl = _mm_load_si128((__m128i *)pshufb_shf_table + (len - 1));
    xmm_shr = xmm_shl;
    xmm_shr = _mm_xor_si128(xmm_shr, xmm_mask3);

    xmm_a0_0 = _mm_shuffle_epi8(*xmm_crc0, xmm_shl);

    *xmm_crc0 = _mm_shuffle_epi8(*xmm_crc0, xmm_shr);
    xmm_tmp1 = _mm_shuffle_epi8(*xmm_crc1, xmm_shl);
    *xmm_crc0 = _mm_or_si128(*xmm_crc0, xmm_tmp1);

    *xmm_crc1 = _mm_shuffle_epi8(*xmm_crc1, xmm_shr);
    xmm_tmp2 = _mm_shuffle_epi8(*xmm_crc2, xmm_shl);
    *xmm_crc1 = _mm_or_si128(*xmm_crc1, xmm_tmp2);

    *xmm_crc2 = _mm_shuffle_epi8(*xmm_crc2, xmm_shr);
    xmm_tmp3 = _mm_shuffle_epi8(*xmm_crc3, xmm_shl);
    *xmm_crc2 = _mm_or_si128(*xmm_crc2, xmm_tmp3);

    *xmm_crc3 = _mm_shuffle_epi8(*xmm_crc3, xmm_shr);
    *xmm_crc_part = _mm_shuffle_epi8(*xmm_crc_part, xmm_shl);
    *xmm_crc3 = _mm_or_si128(*xmm_crc3, *xmm_crc_part);

    xmm_a0_1 = _mm_clmulepi64_si128(xmm_a0_0, xmm_fold4, 0x10);
    xmm_a0_0 = _mm_clmulepi64_si128(xmm_a0_0, xmm_fold4, 0x01);

    ps_crc3 = _mm_castsi128_ps(*xmm_crc3);
    psa0_0 = _mm_castsi128_ps(xmm_a0_0);
    psa0_1 = _mm_castsi128_ps(xmm_a0_1);

    ps_res = _mm_xor_ps(ps_crc3, psa0_0);
    ps_res = _mm_xor_ps(ps_res, psa0_1);

    *xmm_crc3 = _mm_castps_si128(ps_res);
}

static inline void crc32_fold_load(__m128i *fold, __m128i *fold0, __m128i *fold1, __m128i *fold2, __m128i *fold3) {
    *fold0 = _mm_load_si128(fold + 0);
    *fold1 = _mm_load_si128(fold + 1);
    *fold2 = _mm_load_si128(fold + 2);
    *fold3 = _mm_load_si128(fold + 3);
}

static inline void crc32_fold_save(__m128i *fold, __m128i fold0, __m128i fold1, __m128i fold2, __m128i fold3) {
    _mm_storeu_si128(fold + 0, fold0);
    _mm_storeu_si128(fold + 1, fold1);
    _mm_storeu_si128(fold + 2, fold2);
    _mm_storeu_si128(fold + 3, fold3);
}

static inline void crc32_fold_save_partial(__m128i *fold, __m128i foldp) {
    _mm_store_si128(fold + 4, foldp);
}

Z_INTERNAL uint32_t crc32_fold_reset_pclmulqdq(crc32_fold *crc) {
    __m128i xmm_crc0 = _mm_cvtsi32_si128(0x9db42487);
    __m128i xmm_zero = _mm_setzero_si128();
    crc32_fold_save((__m128i *)crc->fold, xmm_crc0, xmm_zero, xmm_zero, xmm_zero);
    return 0;
}

Z_INTERNAL void crc32_fold_copy_pclmulqdq(crc32_fold *crc, uint8_t *dst, const uint8_t *src, size_t len) {
    unsigned long algn_diff;
    __m128i xmm_t0, xmm_t1, xmm_t2, xmm_t3;
    __m128i xmm_crc0, xmm_crc1, xmm_crc2, xmm_crc3, xmm_crc_part;
    char ALIGNED_(16) partial_buf[16] = { 0 };

    crc32_fold_load((__m128i *)crc->fold, &xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3);

    if (len < 16) {
        if (len == 0)
            return;

        memcpy(partial_buf, src, len);
        xmm_crc_part = _mm_load_si128((const __m128i *)partial_buf);
        memcpy(dst, partial_buf, len);
        goto partial;
    }

    algn_diff = ((uintptr_t)16 - ((uintptr_t)src & 0xF)) & 0xF;
    if (algn_diff) {
        xmm_crc_part = _mm_loadu_si128((__m128i *)src);
        _mm_storeu_si128((__m128i *)dst, xmm_crc_part);

        dst += algn_diff;
        src += algn_diff;
        len -= algn_diff;

        partial_fold(algn_diff, &xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3, &xmm_crc_part);
    } else {
        xmm_crc_part = _mm_setzero_si128();
    }

#ifdef X86_VPCLMULQDQ_CRC
    if (x86_cpu_has_vpclmulqdq && x86_cpu_has_avx512 && (len >= 256)) {
        size_t n = fold_16_vpclmulqdq(&xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3, dst, src, len);

        len -= n;
        src += n;
        dst += n;
    }
#endif

    while (len >= 64) {
        crc32_fold_load((__m128i *)src, &xmm_t0, &xmm_t1, &xmm_t2, &xmm_t3);

        fold_4(&xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3);

        crc32_fold_save((__m128i *)dst, xmm_t0, xmm_t1, xmm_t2, xmm_t3);

        xmm_crc0 = _mm_xor_si128(xmm_crc0, xmm_t0);
        xmm_crc1 = _mm_xor_si128(xmm_crc1, xmm_t1);
        xmm_crc2 = _mm_xor_si128(xmm_crc2, xmm_t2);
        xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_t3);

        src += 64;
        dst += 64;
        len -= 64;
    }

    /*
     * len = num bytes left - 64
     */
    if (len >= 48) {
        xmm_t0 = _mm_load_si128((__m128i *)src);
        xmm_t1 = _mm_load_si128((__m128i *)src + 1);
        xmm_t2 = _mm_load_si128((__m128i *)src + 2);

        fold_3(&xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3);

        _mm_storeu_si128((__m128i *)dst, xmm_t0);
        _mm_storeu_si128((__m128i *)dst + 1, xmm_t1);
        _mm_storeu_si128((__m128i *)dst + 2, xmm_t2);

        xmm_crc1 = _mm_xor_si128(xmm_crc1, xmm_t0);
        xmm_crc2 = _mm_xor_si128(xmm_crc2, xmm_t1);
        xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_t2);
        len -= 48;
        if (len == 0)
            goto done;

        dst += 48;
        memcpy(&xmm_crc_part, (__m128i *)src + 3, len);
    } else if (len >= 32) {
        xmm_t0 = _mm_load_si128((__m128i *)src);
        xmm_t1 = _mm_load_si128((__m128i *)src + 1);

        fold_2(&xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3);

        _mm_storeu_si128((__m128i *)dst, xmm_t0);
        _mm_storeu_si128((__m128i *)dst + 1, xmm_t1);

        xmm_crc2 = _mm_xor_si128(xmm_crc2, xmm_t0);
        xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_t1);

        len -= 32;
        if (len == 0)
            goto done;

        dst += 32;
        memcpy(&xmm_crc_part, (__m128i *)src + 2, len);
    } else if (len >= 16) {
        xmm_t0 = _mm_load_si128((__m128i *)src);

        fold_1(&xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3);

        _mm_storeu_si128((__m128i *)dst, xmm_t0);

        xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_t0);

        len -= 16;
        if (len == 0)
            goto done;

        dst += 16;
        memcpy(&xmm_crc_part, (__m128i *)src + 1, len);
    } else {
        if (len == 0)
            goto done;
        memcpy(&xmm_crc_part, src, len);
    }

    _mm_storeu_si128((__m128i *)partial_buf, xmm_crc_part);
    memcpy(dst, partial_buf, len);

partial:
    partial_fold((size_t)len, &xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3, &xmm_crc_part);
done:
    crc32_fold_save((__m128i *)crc->fold, xmm_crc0, xmm_crc1, xmm_crc2, xmm_crc3);
    crc32_fold_save_partial((__m128i *)crc->fold, xmm_crc_part);
}

#define ONCE(op) if (first) { \
    first = 0; \
    (op); \
}
#define XOR_INITIAL(where) ONCE(where = _mm_xor_si128(where, xmm_initial))

Z_INTERNAL void crc32_fold_pclmulqdq(crc32_fold *crc, const uint8_t *src, size_t len, uint32_t init_crc) {
    unsigned long algn_diff;
    __m128i xmm_t0, xmm_t1, xmm_t2, xmm_t3;
    __m128i xmm_crc0, xmm_crc1, xmm_crc2, xmm_crc3, xmm_crc_part;
    __m128i xmm_initial = _mm_cvtsi32_si128(init_crc);
    xmm_crc_part = _mm_setzero_si128();
    int32_t first = init_crc != 0;

    /* Technically the CRC functions don't even call this for input < 64, but a bare minimum of 31
     * bytes of input is needed for the aligning load that occurs.  If there's an initial CRC, to
     * carry it forward through the folded CRC there must be 16 - src % 16 + 16 bytes available, which
     * by definition can be up to 15 bytes + one full vector load. */
    assert(len >= 31 || first == 0);
    crc32_fold_load((__m128i *)crc->fold, &xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3);

    if (len < 16) {
        goto partial_nocpy;
    }

    algn_diff = ((uintptr_t)16 - ((uintptr_t)src & 0xF)) & 0xF;
    if (algn_diff) {
        if (algn_diff >= 4 || init_crc == 0) {
            xmm_crc_part = _mm_loadu_si128((__m128i *)src);

            src += algn_diff;
            len -= algn_diff;

            XOR_INITIAL(xmm_crc_part);
            partial_fold(algn_diff, &xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3, &xmm_crc_part);
        } else {
            xmm_t0 = _mm_loadu_si128((__m128i*)src);
            xmm_crc_part = _mm_loadu_si128((__m128i*)src + 1);
            XOR_INITIAL(xmm_t0);
            fold_1(&xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3);
            xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_t0);
            partial_fold(algn_diff, &xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3, &xmm_crc_part);

            src += (algn_diff + 16);
            len -= (algn_diff + 16);
        }

        xmm_crc_part = _mm_setzero_si128();
    }

#ifdef X86_VPCLMULQDQ_CRC
    if (x86_cpu_has_vpclmulqdq && x86_cpu_has_avx512 && (len >= 256)) {
        size_t n = fold_16_vpclmulqdq_nocp(&xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3, src, len,
                xmm_initial, first);
        first = 0;

        len -= n;
        src += n;
    }
#endif

    while (len >= 64) {
        crc32_fold_load((__m128i *)src, &xmm_t0, &xmm_t1, &xmm_t2, &xmm_t3);
        XOR_INITIAL(xmm_t0);
        fold_4(&xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3);

        xmm_crc0 = _mm_xor_si128(xmm_crc0, xmm_t0);
        xmm_crc1 = _mm_xor_si128(xmm_crc1, xmm_t1);
        xmm_crc2 = _mm_xor_si128(xmm_crc2, xmm_t2);
        xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_t3);

        src += 64;
        len -= 64;
    }

    /*
     * len = num bytes left - 64
     */
    if (len >= 48) {
        xmm_t0 = _mm_load_si128((__m128i *)src);
        xmm_t1 = _mm_load_si128((__m128i *)src + 1);
        xmm_t2 = _mm_load_si128((__m128i *)src + 2);
        XOR_INITIAL(xmm_t0);

        fold_3(&xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3);

        xmm_crc1 = _mm_xor_si128(xmm_crc1, xmm_t0);
        xmm_crc2 = _mm_xor_si128(xmm_crc2, xmm_t1);
        xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_t2);
        len -= 48;
        src += 48;
    } else if (len >= 32) {
        xmm_t0 = _mm_load_si128((__m128i *)src);
        xmm_t1 = _mm_load_si128((__m128i *)src + 1);
        XOR_INITIAL(xmm_t0);

        fold_2(&xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3);

        xmm_crc2 = _mm_xor_si128(xmm_crc2, xmm_t0);
        xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_t1);

        len -= 32;
        src += 32;
    } else if (len >= 16) {
        xmm_t0 = _mm_load_si128((__m128i *)src);
        XOR_INITIAL(xmm_t0);

        fold_1(&xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3);

        xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_t0);

        len -= 16;
        src += 16;
    }

partial_nocpy:
    if (len) {
        memcpy(&xmm_crc_part, src, len);
        partial_fold((size_t)len, &xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3, &xmm_crc_part);
    }

    crc32_fold_save((__m128i *)crc->fold, xmm_crc0, xmm_crc1, xmm_crc2, xmm_crc3);
}

static const unsigned ALIGNED_(16) crc_k[] = {
    0xccaa009e, 0x00000000, /* rk1 */
    0x751997d0, 0x00000001, /* rk2 */
    0xccaa009e, 0x00000000, /* rk5 */
    0x63cd6124, 0x00000001, /* rk6 */
    0xf7011640, 0x00000001, /* rk7 */
    0xdb710640, 0x00000001  /* rk8 */
};

static const unsigned ALIGNED_(16) crc_mask[4] = {
    0xFFFFFFFF, 0xFFFFFFFF, 0x00000000, 0x00000000
};

static const unsigned ALIGNED_(16) crc_mask2[4] = {
    0x00000000, 0xFFFFFFFF, 0xFFFFFFFF, 0xFFFFFFFF
};

Z_INTERNAL uint32_t crc32_fold_final_pclmulqdq(crc32_fold *crc) {
    const __m128i xmm_mask  = _mm_load_si128((__m128i *)crc_mask);
    const __m128i xmm_mask2 = _mm_load_si128((__m128i *)crc_mask2);
    __m128i xmm_crc0, xmm_crc1, xmm_crc2, xmm_crc3;
    __m128i x_tmp0, x_tmp1, x_tmp2, crc_fold;

    crc32_fold_load((__m128i *)crc->fold, &xmm_crc0, &xmm_crc1, &xmm_crc2, &xmm_crc3);

    /*
     * k1
     */
    crc_fold = _mm_load_si128((__m128i *)crc_k);

    x_tmp0 = _mm_clmulepi64_si128(xmm_crc0, crc_fold, 0x10);
    xmm_crc0 = _mm_clmulepi64_si128(xmm_crc0, crc_fold, 0x01);
    xmm_crc1 = _mm_xor_si128(xmm_crc1, x_tmp0);
    xmm_crc1 = _mm_xor_si128(xmm_crc1, xmm_crc0);

    x_tmp1 = _mm_clmulepi64_si128(xmm_crc1, crc_fold, 0x10);
    xmm_crc1 = _mm_clmulepi64_si128(xmm_crc1, crc_fold, 0x01);
    xmm_crc2 = _mm_xor_si128(xmm_crc2, x_tmp1);
    xmm_crc2 = _mm_xor_si128(xmm_crc2, xmm_crc1);

    x_tmp2 = _mm_clmulepi64_si128(xmm_crc2, crc_fold, 0x10);
    xmm_crc2 = _mm_clmulepi64_si128(xmm_crc2, crc_fold, 0x01);
    xmm_crc3 = _mm_xor_si128(xmm_crc3, x_tmp2);
    xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_crc2);

    /*
     * k5
     */
    crc_fold = _mm_load_si128((__m128i *)crc_k + 1);

    xmm_crc0 = xmm_crc3;
    xmm_crc3 = _mm_clmulepi64_si128(xmm_crc3, crc_fold, 0);
    xmm_crc0 = _mm_srli_si128(xmm_crc0, 8);
    xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_crc0);

    xmm_crc0 = xmm_crc3;
    xmm_crc3 = _mm_slli_si128(xmm_crc3, 4);
    xmm_crc3 = _mm_clmulepi64_si128(xmm_crc3, crc_fold, 0x10);
    xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_crc0);
    xmm_crc3 = _mm_and_si128(xmm_crc3, xmm_mask2);

    /*
     * k7
     */
    xmm_crc1 = xmm_crc3;
    xmm_crc2 = xmm_crc3;
    crc_fold = _mm_load_si128((__m128i *)crc_k + 2);

    xmm_crc3 = _mm_clmulepi64_si128(xmm_crc3, crc_fold, 0);
    xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_crc2);
    xmm_crc3 = _mm_and_si128(xmm_crc3, xmm_mask);

    xmm_crc2 = xmm_crc3;
    xmm_crc3 = _mm_clmulepi64_si128(xmm_crc3, crc_fold, 0x10);
    xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_crc2);
    xmm_crc3 = _mm_xor_si128(xmm_crc3, xmm_crc1);

    crc->value = ~((uint32_t)_mm_extract_epi32(xmm_crc3, 2));

    return crc->value;
}

uint32_t crc32_pclmulqdq(uint32_t crc32, const unsigned char* buf, uint64_t len) {
    /* For lens < 64, crc32_braid method is faster. The CRC32 instruction for
     * these short lengths might also prove to be effective */
    if (len < 64)
        return crc32_braid(crc32, buf, len);

    crc32_fold ALIGNED_(16) crc_state;
    crc32_fold_reset_pclmulqdq(&crc_state);
    crc32_fold_pclmulqdq(&crc_state, buf, len, crc32);
    return crc32_fold_final_pclmulqdq(&crc_state);
}

#endif