/* adler32_sse42.c -- compute the Adler-32 checksum of a data stream

 * Copyright (C) 1995-2011 Mark Adler

 * Authors:

 *   Adam Stylinski <kungfujesus06@gmail.com>

 *   Brian Bockelman <bockelman@gmail.com>

 * For conditions of distribution and use, see copyright notice in zlib.h

 */

#ifdef X86_SSE42

#include "zbuild.h"

#include "adler32_p.h"

#include "adler32_ssse3_p.h"

#include <immintrin.h>

Z_INTERNAL uint32_t adler32_copy_sse42(uint32_t adler, uint8_t *dst, const uint8_t *src, size_t len) {

    uint32_t adler0, adler1;

    adler1 = (adler >> 16) & 0xffff;

    adler0 = adler & 0xffff;

rem_peel:

    if (UNLIKELY(len < 16))

       return adler32_copy_len_16(adler0, dst, src, len, adler1, 1);

    __m128i vbuf, vbuf_0;

    __m128i vs1_0, vs3, vs1, vs2, vs2_0, v_sad_sum1, v_short_sum2, v_short_sum2_0,

            v_sad_sum2, vsum2, vsum2_0;

    __m128i zero = _mm_setzero_si128();

    const __m128i dot2v = _mm_setr_epi8(32, 31, 30, 29, 28, 27, 26, 25, 24, 23, 22, 21, 20, 19, 18, 17);

    const __m128i dot2v_0 = _mm_setr_epi8(16, 15, 14, 13, 12, 11, 10, 9, 8, 7, 6, 5, 4, 3, 2, 1);

    const __m128i dot3v = _mm_set1_epi16(1);

    while (len >= 16) {

        size_t k = ALIGN_DOWN(MIN(len, NMAX), 16);

        len -= k;

        vs1 = _mm_cvtsi32_si128(adler0);

        vs2 = _mm_cvtsi32_si128(adler1);

        vs3 = _mm_setzero_si128();

        vs2_0 = _mm_setzero_si128();

        vs1_0 = vs1;

        while (k >= 32) {

            /*

               vs1 = adler + sum(c[i])

               vs2 = sum2 + 16 vs1 + sum( (16-i+1) c[i] )

            */

            vbuf = _mm_loadu_si128((__m128i*)src);

            vbuf_0 = _mm_loadu_si128((__m128i*)(src + 16));

            src += 32;

            k -= 32;

            v_sad_sum1 = _mm_sad_epu8(vbuf, zero);

            v_sad_sum2 = _mm_sad_epu8(vbuf_0, zero);

            _mm_storeu_si128((__m128i*)dst, vbuf);

            _mm_storeu_si128((__m128i*)(dst + 16), vbuf_0);

            dst += 32;

            v_short_sum2 = _mm_maddubs_epi16(vbuf, dot2v);

            v_short_sum2_0 = _mm_maddubs_epi16(vbuf_0, dot2v_0);

            vs1 = _mm_add_epi32(v_sad_sum1, vs1);

            vs3 = _mm_add_epi32(vs1_0, vs3);

            vsum2 = _mm_madd_epi16(v_short_sum2, dot3v);

            vsum2_0 = _mm_madd_epi16(v_short_sum2_0, dot3v);

            vs1 = _mm_add_epi32(v_sad_sum2, vs1);

            vs2 = _mm_add_epi32(vsum2, vs2);

            vs2_0 = _mm_add_epi32(vsum2_0, vs2_0);

            vs1_0 = vs1;

        }

        vs2 = _mm_add_epi32(vs2_0, vs2);

        vs3 = _mm_slli_epi32(vs3, 5);

        vs2 = _mm_add_epi32(vs3, vs2);

        vs3 = _mm_setzero_si128();

        while (k >= 16) {

            /*

               vs1 = adler + sum(c[i])

               vs2 = sum2 + 16 vs1 + sum( (16-i+1) c[i] )

            */

            vbuf = _mm_loadu_si128((__m128i*)src);

            src += 16;

            k -= 16;

            v_sad_sum1 = _mm_sad_epu8(vbuf, zero);

            v_short_sum2 = _mm_maddubs_epi16(vbuf, dot2v_0);

            vs1 = _mm_add_epi32(v_sad_sum1, vs1);

            vs3 = _mm_add_epi32(vs1_0, vs3);

            vsum2 = _mm_madd_epi16(v_short_sum2, dot3v);

            vs2 = _mm_add_epi32(vsum2, vs2);

            vs1_0 = vs1;

            _mm_storeu_si128((__m128i*)dst, vbuf);

            dst += 16;

        }

        vs3 = _mm_slli_epi32(vs3, 4);

        vs2 = _mm_add_epi32(vs2, vs3);

        adler0 = partial_hsum(vs1) % BASE;

        adler1 = hsum(vs2) % BASE;

    }

    /* If this is true, there's fewer than 16 elements remaining */

    if (len) {

        goto rem_peel;

    }

    return adler0 | (adler1 << 16);

}

#endif