/*

 * SSE optimized hash slide

 *

 * Copyright (C) 2017 Intel Corporation

 * Authors:

 *   Arjan van de Ven   <arjan@linux.intel.com>

 *   Jim Kukunas        <james.t.kukunas@linux.intel.com>

 *

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

 */

#ifdef X86_SSE2

#include "zbuild.h"

#include "deflate.h"

#include <immintrin.h>

#include <assert.h>

static inline void slide_hash_chain(Pos *table0, Pos *table1, uint32_t entries0,

                                    uint32_t entries1, const __m128i wsize) {

    uint32_t entries;

    Pos *table;

    __m128i value0, value1, result0, result1;

    int on_chain = 0;

next_chain:

    table = (on_chain) ? table1 : table0;

    entries = (on_chain) ? entries1 : entries0;

    table += entries;

    table -= 16;

    /* ZALLOC allocates this pointer unless the user chose a custom allocator.

     * Our alloc function is aligned to 64 byte boundaries */

    do {

        value0 = _mm_load_si128((__m128i *)table);

        value1 = _mm_load_si128((__m128i *)(table + 8));

        result0 = _mm_subs_epu16(value0, wsize);

        result1 = _mm_subs_epu16(value1, wsize);

        _mm_store_si128((__m128i *)table, result0);

        _mm_store_si128((__m128i *)(table + 8), result1);

        table -= 16;

        entries -= 16;

    } while (entries > 0);

    ++on_chain;

    if (on_chain > 1) {

        return;

    } else {

        goto next_chain;

    }

}

Z_INTERNAL void slide_hash_sse2(deflate_state *s) {

    Assert(s->w_size <= UINT16_MAX, "w_size should fit in uint16_t");

    uint16_t wsize = (uint16_t)s->w_size;

    const __m128i xmm_wsize = _mm_set1_epi16((short)wsize);

    assert(((uintptr_t)s->head & 15) == 0);

    assert(((uintptr_t)s->prev & 15) == 0);

    slide_hash_chain(s->head, s->prev, HASH_SIZE, wsize, xmm_wsize);

}

#endif