/*

 * Copyright (c) 2016-present, Yann Collet, Facebook, Inc.

 * All rights reserved.

 *

 * This source code is licensed under both the BSD-style license (found in the

 * LICENSE file in the root directory of this source tree) and the GPLv2 (found

 * in the COPYING file in the root directory of this source tree).

 * You may select, at your option, one of the above-listed licenses.

 */

#include "zstd_compress_internal.h"

#include "zstd_double_fast.h"

void ZSTD_fillDoubleHashTable(ZSTD_matchState_t* ms,

                              void const* end, ZSTD_dictTableLoadMethod_e dtlm)

{

    const ZSTD_compressionParameters* const cParams = &ms->cParams;

    U32* const hashLarge = ms->hashTable;

    U32  const hBitsL = cParams->hashLog;

    U32* const hashSmall = ms->chainTable;

    U32  const hBitsS = cParams->chainLog;

    const BYTE* const base = ms->window.base;

    const BYTE* ip = base + ms->nextToUpdate;

    const BYTE* const iend = ((const BYTE*)end) - HASH_READ_SIZE;

    const U32 fastHashFillStep = 3;

    /* Always insert every fastHashFillStep position into the hash tables.

     * Insert the other positions into the large hash table if their entry

     * is empty.

     */

    for (; ip + fastHashFillStep - 1 <= iend; ip += fastHashFillStep) {

        U32 const current = (U32)(ip - base);

        U32 i;

        for (i = 0; i < fastHashFillStep; ++i) {

            size_t const smHash = ZSTD_hashPtr(ip + i, hBitsS, mls);

            size_t const lgHash = ZSTD_hashPtr(ip + i, hBitsL, 8);

            if (i == 0)

                hashSmall[smHash] = current + i;

            if (i == 0 || hashLarge[lgHash] == 0)

                hashLarge[lgHash] = current + i;

            /* Only load extra positions for ZSTD_dtlm_full */

            if (dtlm == ZSTD_dtlm_fast)

                break;

        }

    }

}

FORCE_INLINE_TEMPLATE

size_t ZSTD_compressBlock_doubleFast_generic(

        ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],

        void const* src, size_t srcSize,

        U32 const mls /* template */, ZSTD_dictMode_e const dictMode)

{

    ZSTD_compressionParameters const* cParams = &ms->cParams;

    U32* const hashLong = ms->hashTable;

    const U32 hBitsL = cParams->hashLog;

    U32* const hashSmall = ms->chainTable;

    const U32 hBitsS = cParams->chainLog;

    const BYTE* const base = ms->window.base;

    const BYTE* const istart = (const BYTE*)src;

    const BYTE* ip = istart;

    const BYTE* anchor = istart;

    const U32 prefixLowestIndex = ms->window.dictLimit;

    const BYTE* const prefixLowest = base + prefixLowestIndex;

    const BYTE* const iend = istart + srcSize;

    const BYTE* const ilimit = iend - HASH_READ_SIZE;

    U32 offset_1=rep[0], offset_2=rep[1];

    U32 offsetSaved = 0;

    const ZSTD_matchState_t* const dms = ms->dictMatchState;

    const ZSTD_compressionParameters* const dictCParams =

                                     dictMode == ZSTD_dictMatchState ?

                                     &dms->cParams : NULL;

    const U32* const dictHashLong  = dictMode == ZSTD_dictMatchState ?

                                     dms->hashTable : NULL;

    const U32* const dictHashSmall = dictMode == ZSTD_dictMatchState ?

                                     dms->chainTable : NULL;

    const U32 dictStartIndex       = dictMode == ZSTD_dictMatchState ?

                                     dms->window.dictLimit : 0;

    const BYTE* const dictBase     = dictMode == ZSTD_dictMatchState ?

                                     dms->window.base : NULL;

    const BYTE* const dictStart    = dictMode == ZSTD_dictMatchState ?

                                     dictBase + dictStartIndex : NULL;

    const BYTE* const dictEnd      = dictMode == ZSTD_dictMatchState ?

                                     dms->window.nextSrc : NULL;

    const U32 dictIndexDelta       = dictMode == ZSTD_dictMatchState ?

                                     prefixLowestIndex - (U32)(dictEnd - dictBase) :

                                     0;

    const U32 dictHBitsL           = dictMode == ZSTD_dictMatchState ?

                                     dictCParams->hashLog : hBitsL;

    const U32 dictHBitsS           = dictMode == ZSTD_dictMatchState ?

                                     dictCParams->chainLog : hBitsS;

    const U32 dictAndPrefixLength  = (U32)(ip - prefixLowest + dictEnd - dictStart);

    assert(dictMode == ZSTD_noDict || dictMode == ZSTD_dictMatchState);

    /* init */

    ip += (dictAndPrefixLength == 0);

    if (dictMode == ZSTD_noDict) {

        U32 const maxRep = (U32)(ip - prefixLowest);

        if (offset_2 > maxRep) offsetSaved = offset_2, offset_2 = 0;

        if (offset_1 > maxRep) offsetSaved = offset_1, offset_1 = 0;

    }

    if (dictMode == ZSTD_dictMatchState) {

        /* dictMatchState repCode checks don't currently handle repCode == 0

         * disabling. */

        assert(offset_1 <= dictAndPrefixLength);

        assert(offset_2 <= dictAndPrefixLength);

    }

    /* Main Search Loop */

    while (ip < ilimit) {   /* < instead of <=, because repcode check at (ip+1) */

        size_t mLength;

        U32 offset;

        size_t const h2 = ZSTD_hashPtr(ip, hBitsL, 8);

        size_t const h = ZSTD_hashPtr(ip, hBitsS, mls);

        size_t const dictHL = ZSTD_hashPtr(ip, dictHBitsL, 8);

        size_t const dictHS = ZSTD_hashPtr(ip, dictHBitsS, mls);

        U32 const current = (U32)(ip-base);

        U32 const matchIndexL = hashLong[h2];

        U32 matchIndexS = hashSmall[h];

        const BYTE* matchLong = base + matchIndexL;

        const BYTE* match = base + matchIndexS;

        const U32 repIndex = current + 1 - offset_1;

        const BYTE* repMatch = (dictMode == ZSTD_dictMatchState

                            && repIndex < prefixLowestIndex) ?

                               dictBase + (repIndex - dictIndexDelta) :

                               base + repIndex;

        hashLong[h2] = hashSmall[h] = current;   /* update hash tables */

        /* check dictMatchState repcode */

        if (dictMode == ZSTD_dictMatchState

            && ((U32)((prefixLowestIndex-1) - repIndex) >= 3 /* intentional underflow */)

            && (MEM_read32(repMatch) == MEM_read32(ip+1)) ) {

            const BYTE* repMatchEnd = repIndex < prefixLowestIndex ? dictEnd : iend;

            mLength = ZSTD_count_2segments(ip+1+4, repMatch+4, iend, repMatchEnd, prefixLowest) + 4;

            ip++;

            ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);

            goto _match_stored;

        }

        /* check noDict repcode */

        if ( dictMode == ZSTD_noDict

          && ((offset_1 > 0) & (MEM_read32(ip+1-offset_1) == MEM_read32(ip+1)))) {

            mLength = ZSTD_count(ip+1+4, ip+1+4-offset_1, iend) + 4;

            ip++;

            ZSTD_storeSeq(seqStore, ip-anchor, anchor, 0, mLength-MINMATCH);

            goto _match_stored;

        }

        if (matchIndexL > prefixLowestIndex) {

            /* check prefix long match */

            if (MEM_read64(matchLong) == MEM_read64(ip)) {

                mLength = ZSTD_count(ip+8, matchLong+8, iend) + 8;

                offset = (U32)(ip-matchLong);

                while (((ip>anchor) & (matchLong>prefixLowest)) && (ip[-1] == matchLong[-1])) { ip--; matchLong--; mLength++; } /* catch up */

                goto _match_found;

            }

        } else if (dictMode == ZSTD_dictMatchState) {

            /* check dictMatchState long match */

            U32 const dictMatchIndexL = dictHashLong[dictHL];

            const BYTE* dictMatchL = dictBase + dictMatchIndexL;

            assert(dictMatchL < dictEnd);

            if (dictMatchL > dictStart && MEM_read64(dictMatchL) == MEM_read64(ip)) {

                mLength = ZSTD_count_2segments(ip+8, dictMatchL+8, iend, dictEnd, prefixLowest) + 8;

                offset = (U32)(current - dictMatchIndexL - dictIndexDelta);

                while (((ip>anchor) & (dictMatchL>dictStart)) && (ip[-1] == dictMatchL[-1])) { ip--; dictMatchL--; mLength++; } /* catch up */

                goto _match_found;

            }

        }

        if (matchIndexS > prefixLowestIndex) {

            /* check prefix short match */

            if (MEM_read32(match) == MEM_read32(ip)) {

                goto _search_next_long;

            }

        } else if (dictMode == ZSTD_dictMatchState) {

            /* check dictMatchState short match */

            U32 const dictMatchIndexS = dictHashSmall[dictHS];

            match = dictBase + dictMatchIndexS;

            matchIndexS = dictMatchIndexS + dictIndexDelta;

            if (match > dictStart && MEM_read32(match) == MEM_read32(ip)) {

                goto _search_next_long;

            }

        }

        ip += ((ip-anchor) >> kSearchStrength) + 1;

        continue;

_search_next_long:

        {

            size_t const hl3 = ZSTD_hashPtr(ip+1, hBitsL, 8);

            size_t const dictHLNext = ZSTD_hashPtr(ip+1, dictHBitsL, 8);

            U32 const matchIndexL3 = hashLong[hl3];

            const BYTE* matchL3 = base + matchIndexL3;

            hashLong[hl3] = current + 1;

            /* check prefix long +1 match */

            if (matchIndexL3 > prefixLowestIndex) {

                if (MEM_read64(matchL3) == MEM_read64(ip+1)) {

                    mLength = ZSTD_count(ip+9, matchL3+8, iend) + 8;

                    ip++;

                    offset = (U32)(ip-matchL3);

                    while (((ip>anchor) & (matchL3>prefixLowest)) && (ip[-1] == matchL3[-1])) { ip--; matchL3--; mLength++; } /* catch up */

                    goto _match_found;

                }

            } else if (dictMode == ZSTD_dictMatchState) {

                /* check dict long +1 match */

                U32 const dictMatchIndexL3 = dictHashLong[dictHLNext];

                const BYTE* dictMatchL3 = dictBase + dictMatchIndexL3;

                assert(dictMatchL3 < dictEnd);

                if (dictMatchL3 > dictStart && MEM_read64(dictMatchL3) == MEM_read64(ip+1)) {

                    mLength = ZSTD_count_2segments(ip+1+8, dictMatchL3+8, iend, dictEnd, prefixLowest) + 8;

                    ip++;

                    offset = (U32)(current + 1 - dictMatchIndexL3 - dictIndexDelta);

                    while (((ip>anchor) & (dictMatchL3>dictStart)) && (ip[-1] == dictMatchL3[-1])) { ip--; dictMatchL3--; mLength++; } /* catch up */

                    goto _match_found;

                }

            }

        }

        /* if no long +1 match, explore the short match we found */

        if (dictMode == ZSTD_dictMatchState && matchIndexS < prefixLowestIndex) {

            mLength = ZSTD_count_2segments(ip+4, match+4, iend, dictEnd, prefixLowest) + 4;

            offset = (U32)(current - matchIndexS);

            while (((ip>anchor) & (match>dictStart)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */

        } else {

            mLength = ZSTD_count(ip+4, match+4, iend) + 4;

            offset = (U32)(ip - match);

            while (((ip>anchor) & (match>prefixLowest)) && (ip[-1] == match[-1])) { ip--; match--; mLength++; } /* catch up */

        }

        /* fall-through */

_match_found:

        offset_2 = offset_1;

        offset_1 = offset;

        ZSTD_storeSeq(seqStore, ip-anchor, anchor, offset + ZSTD_REP_MOVE, mLength-MINMATCH);

_match_stored:

        /* match found */

        ip += mLength;

        anchor = ip;

        if (ip <= ilimit) {

            /* Fill Table */

            hashLong[ZSTD_hashPtr(base+current+2, hBitsL, 8)] =

                hashSmall[ZSTD_hashPtr(base+current+2, hBitsS, mls)] = current+2;  /* here because current+2 could be > iend-8 */

            hashLong[ZSTD_hashPtr(ip-2, hBitsL, 8)] =

                hashSmall[ZSTD_hashPtr(ip-2, hBitsS, mls)] = (U32)(ip-2-base);

            /* check immediate repcode */

            if (dictMode == ZSTD_dictMatchState) {

                while (ip <= ilimit) {

                    U32 const current2 = (U32)(ip-base);

                    U32 const repIndex2 = current2 - offset_2;

                    const BYTE* repMatch2 = dictMode == ZSTD_dictMatchState

                        && repIndex2 < prefixLowestIndex ?

                            dictBase - dictIndexDelta + repIndex2 :

                            base + repIndex2;

                    if ( ((U32)((prefixLowestIndex-1) - (U32)repIndex2) >= 3 /* intentional overflow */)

                       && (MEM_read32(repMatch2) == MEM_read32(ip)) ) {

                        const BYTE* const repEnd2 = repIndex2 < prefixLowestIndex ? dictEnd : iend;

                        size_t const repLength2 = ZSTD_count_2segments(ip+4, repMatch2+4, iend, repEnd2, prefixLowest) + 4;

                        U32 tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset;   /* swap offset_2 <=> offset_1 */

                        ZSTD_storeSeq(seqStore, 0, anchor, 0, repLength2-MINMATCH);

                        hashSmall[ZSTD_hashPtr(ip, hBitsS, mls)] = current2;

                        hashLong[ZSTD_hashPtr(ip, hBitsL, 8)] = current2;

                        ip += repLength2;

                        anchor = ip;

                        continue;

                    }

                    break;

                }

            }

            if (dictMode == ZSTD_noDict) {

                while ( (ip <= ilimit)

                     && ( (offset_2>0)

                        & (MEM_read32(ip) == MEM_read32(ip - offset_2)) )) {

                    /* store sequence */

                    size_t const rLength = ZSTD_count(ip+4, ip+4-offset_2, iend) + 4;

                    U32 const tmpOff = offset_2; offset_2 = offset_1; offset_1 = tmpOff;  /* swap offset_2 <=> offset_1 */

                    hashSmall[ZSTD_hashPtr(ip, hBitsS, mls)] = (U32)(ip-base);

                    hashLong[ZSTD_hashPtr(ip, hBitsL, 8)] = (U32)(ip-base);

                    ZSTD_storeSeq(seqStore, 0, anchor, 0, rLength-MINMATCH);

                    ip += rLength;

                    anchor = ip;

                    continue;   /* faster when present ... (?) */

    }   }   }   }

    /* save reps for next block */

    rep[0] = offset_1 ? offset_1 : offsetSaved;

    rep[1] = offset_2 ? offset_2 : offsetSaved;

    /* Return the last literals size */

    return iend - anchor;

}

size_t ZSTD_compressBlock_doubleFast(

        ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],

        void const* src, size_t srcSize)

{

    switch(mls)

    {

    default: /* includes case 3 */

    case 4 :

        return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, src, srcSize, 4, ZSTD_noDict);

    case 5 :

        return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, src, srcSize, 5, ZSTD_noDict);

    case 6 :

        return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, src, srcSize, 6, ZSTD_noDict);

    case 7 :

        return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, src, srcSize, 7, ZSTD_noDict);

    }

}

size_t ZSTD_compressBlock_doubleFast_dictMatchState(

        ZSTD_matchState_t* ms, seqStore_t* seqStore, U32 rep[ZSTD_REP_NUM],

        void const* src, size_t srcSize)

{

    switch(mls)

    {

    default: /* includes case 3 */

    case 4 :

        return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, src, srcSize, 4, ZSTD_dictMatchState);

    case 5 :

        return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, src, srcSize, 5, ZSTD_dictMatchState);

    case 6 :

        return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, src, srcSize, 6, ZSTD_dictMatchState);

    case 7 :

        return ZSTD_compressBlock_doubleFast_generic(ms, seqStore, rep, src, srcSize, 7, ZSTD_dictMatchState);

    }

}