/*

 * 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"  /* ZSTD_hashPtr, ZSTD_count, ZSTD_storeSeq */

#include "zstd_fast.h"

void ZSTD_fillHashTable(ZSTD_matchState_t* ms,

                        const void* const end,

                        ZSTD_dictTableLoadMethod_e dtlm)

{

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

    U32* const hashTable = ms->hashTable;

    U32  const hBits = cParams->hashLog;

    U32  const mls = cParams->minMatch;

    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 table.

     * Insert the other positions if their hash entry is empty.

     */

    for ( ; ip + fastHashFillStep < iend + 2; ip += fastHashFillStep) {

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

        size_t const hash0 = ZSTD_hashPtr(ip, hBits, mls);

        hashTable[hash0] = current;

        if (dtlm == ZSTD_dtlm_fast) continue;

        /* Only load extra positions for ZSTD_dtlm_full */

        {   U32 p;

            for (p = 1; p < fastHashFillStep; ++p) {

                size_t const hash = ZSTD_hashPtr(ip + p, hBits, mls);

                if (hashTable[hash] == 0) {  /* not yet filled */

                    hashTable[hash] = current + p;

    }   }   }   }

}

FORCE_INLINE_TEMPLATE size_t

ZSTD_compressBlock_fast_generic(

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

        void const* src, size_t srcSize,

        U32 const mls)

{

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

    U32* const hashTable = ms->hashTable;

    U32 const hlog = cParams->hashLog;

    /* support stepSize of 0 */

    size_t const stepSize = cParams->targetLength + !(cParams->targetLength) + 1;

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

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

    /* We check ip0 (ip + 0) and ip1 (ip + 1) each loop */

    const BYTE* ip0 = istart;

    const BYTE* ip1;

    const BYTE* anchor = istart;

    const U32   endIndex = (U32)((size_t)(istart - base) + srcSize);

    const U32   maxDistance = 1U << cParams->windowLog;

    const U32   validStartIndex = ms->window.dictLimit;

    const U32   prefixStartIndex = (endIndex - validStartIndex > maxDistance) ? endIndex - maxDistance : validStartIndex;

    const BYTE* const prefixStart = base + prefixStartIndex;

    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;

    /* init */

    DEBUGLOG(5, "ZSTD_compressBlock_fast_generic");

    ip0 += (ip0 == prefixStart);

    ip1 = ip0 + 1;

    {   U32 const maxRep = (U32)(ip0 - prefixStart);

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

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

    }

    /* Main Search Loop */

    while (ip1 < ilimit) {   /* < instead of <=, because check at ip0+2 */

        size_t mLength;

        BYTE const* ip2 = ip0 + 2;

        size_t const h0 = ZSTD_hashPtr(ip0, hlog, mls);

        U32 const val0 = MEM_read32(ip0);

        size_t const h1 = ZSTD_hashPtr(ip1, hlog, mls);

        U32 const val1 = MEM_read32(ip1);

        U32 const current0 = (U32)(ip0-base);

        U32 const current1 = (U32)(ip1-base);

        U32 const matchIndex0 = hashTable[h0];

        U32 const matchIndex1 = hashTable[h1];

        BYTE const* repMatch = ip2-offset_1;

        const BYTE* match0 = base + matchIndex0;

        const BYTE* match1 = base + matchIndex1;

        U32 offcode;

        hashTable[h0] = current0;   /* update hash table */

        hashTable[h1] = current1;   /* update hash table */

        assert(ip0 + 1 == ip1);

        if ((offset_1 > 0) & (MEM_read32(repMatch) == MEM_read32(ip2))) {

            mLength = ip2[-1] == repMatch[-1] ? 1 : 0;

            ip0 = ip2 - mLength;

            match0 = repMatch - mLength;

            offcode = 0;

            goto _match;

        }

        if ((matchIndex0 > prefixStartIndex) && MEM_read32(match0) == val0) {

            /* found a regular match */

            goto _offset;

        }

        if ((matchIndex1 > prefixStartIndex) && MEM_read32(match1) == val1) {

            /* found a regular match after one literal */

            ip0 = ip1;

            match0 = match1;

            goto _offset;

        }

        {   size_t const step = ((size_t)(ip0-anchor) >> (kSearchStrength - 1)) + stepSize;

            assert(step >= 2);

            ip0 += step;

            ip1 += step;

            continue;

        }

_offset: /* Requires: ip0, match0 */

        /* Compute the offset code */

        offset_2 = offset_1;

        offset_1 = (U32)(ip0-match0);

        offcode = offset_1 + ZSTD_REP_MOVE;

        mLength = 0;

        /* Count the backwards match length */

        while (((ip0>anchor) & (match0>prefixStart))

             && (ip0[-1] == match0[-1])) { ip0--; match0--; mLength++; } /* catch up */

_match: /* Requires: ip0, match0, offcode */

        /* Count the forward length */

        mLength += ZSTD_count(ip0+mLength+4, match0+mLength+4, iend) + 4;

        ZSTD_storeSeq(seqStore, (size_t)(ip0-anchor), anchor, iend, offcode, mLength-MINMATCH);

        /* match found */

        ip0 += mLength;

        anchor = ip0;

        ip1 = ip0 + 1;

        if (ip0 <= ilimit) {

            /* Fill Table */

            assert(base+current0+2 > istart);  /* check base overflow */

            hashTable[ZSTD_hashPtr(base+current0+2, hlog, mls)] = current0+2;  /* here because current+2 could be > iend-8 */

            hashTable[ZSTD_hashPtr(ip0-2, hlog, mls)] = (U32)(ip0-2-base);

            while ( ((ip0 <= ilimit) & (offset_2>0))  /* offset_2==0 means offset_2 is invalidated */

                 && (MEM_read32(ip0) == MEM_read32(ip0 - offset_2)) ) {

                /* store sequence */

                size_t const rLength = ZSTD_count(ip0+4, ip0+4-offset_2, iend) + 4;

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

                hashTable[ZSTD_hashPtr(ip0, hlog, mls)] = (U32)(ip0-base);

                ip0 += rLength;

                ip1 = ip0 + 1;

                ZSTD_storeSeq(seqStore, 0 /*litLen*/, anchor, iend, 0 /*offCode*/, rLength-MINMATCH);

                anchor = ip0;

                continue;   /* faster when present (confirmed on gcc-8) ... (?) */

            }

        }

    }

    /* 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 (size_t)(iend - anchor);

}

size_t ZSTD_compressBlock_fast(

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

        void const* src, size_t srcSize)

{

    U32 const mls = ms->cParams.minMatch;

    assert(ms->dictMatchState == NULL);

    switch(mls)

    {

    default: /* includes case 3 */

    case 4 :

        return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, 4);

    case 5 :

        return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, 5);

    case 6 :

        return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, 6);

    case 7 :

        return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, 7);

    }

}

FORCE_INLINE_TEMPLATE

size_t ZSTD_compressBlock_fast_dictMatchState_generic(

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

        void const* src, size_t srcSize, U32 const mls)

{

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

    U32* const hashTable = ms->hashTable;

    U32 const hlog = cParams->hashLog;

    /* support stepSize of 0 */

    U32 const stepSize = cParams->targetLength + !(cParams->targetLength);

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

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

    const BYTE* ip = istart;

    const BYTE* anchor = istart;

    const U32   prefixStartIndex = ms->window.dictLimit;

    const BYTE* const prefixStart = base + prefixStartIndex;

    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 = &dms->cParams ;

    const U32* const dictHashTable = dms->hashTable;

    const U32 dictStartIndex       = dms->window.dictLimit;

    const BYTE* const dictBase     = dms->window.base;

    const BYTE* const dictStart    = dictBase + dictStartIndex;

    const BYTE* const dictEnd      = dms->window.nextSrc;

    const U32 dictIndexDelta       = prefixStartIndex - (U32)(dictEnd - dictBase);

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

    const U32 dictHLog             = dictCParams->hashLog;

    /* if a dictionary is still attached, it necessarily means that

     * it is within window size. So we just check it. */

    const U32 maxDistance = 1U << cParams->windowLog;

    const U32 endIndex = (U32)((size_t)(ip - base) + srcSize);

    assert(endIndex - prefixStartIndex <= maxDistance);

    (void)maxDistance; (void)endIndex;   /* these variables are not used when assert() is disabled */

    /* ensure there will be no no underflow

     * when translating a dict index into a local index */

    assert(prefixStartIndex >= (U32)(dictEnd - dictBase));

    /* init */

    DEBUGLOG(5, "ZSTD_compressBlock_fast_dictMatchState_generic");

    ip += (dictAndPrefixLength == 0);

    /* 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;

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

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

        U32 const matchIndex = hashTable[h];

        const BYTE* match = base + matchIndex;

        const U32 repIndex = current + 1 - offset_1;

        const BYTE* repMatch = (repIndex < prefixStartIndex) ?

                               dictBase + (repIndex - dictIndexDelta) :

                               base + repIndex;

        hashTable[h] = current;   /* update hash table */

        if ( ((U32)((prefixStartIndex-1) - repIndex) >= 3) /* intentional underflow : ensure repIndex isn't overlapping dict + prefix */

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

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

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

            ip++;

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

        } else if ( (matchIndex <= prefixStartIndex) ) {

            size_t const dictHash = ZSTD_hashPtr(ip, dictHLog, mls);

            U32 const dictMatchIndex = dictHashTable[dictHash];

            const BYTE* dictMatch = dictBase + dictMatchIndex;

            if (dictMatchIndex <= dictStartIndex ||

                MEM_read32(dictMatch) != MEM_read32(ip)) {

                assert(stepSize >= 1);

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

                continue;

            } else {

                /* found a dict match */

                U32 const offset = (U32)(current-dictMatchIndex-dictIndexDelta);

                mLength = ZSTD_count_2segments(ip+4, dictMatch+4, iend, dictEnd, prefixStart) + 4;

                while (((ip>anchor) & (dictMatch>dictStart))

                     && (ip[-1] == dictMatch[-1])) {

                    ip--; dictMatch--; mLength++;

                } /* catch up */

                offset_2 = offset_1;

                offset_1 = offset;

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

            }

        } else if (MEM_read32(match) != MEM_read32(ip)) {

            /* it's not a match, and we're not going to check the dictionary */

            assert(stepSize >= 1);

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

            continue;

        } else {

            /* found a regular match */

            U32 const offset = (U32)(ip-match);

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

            while (((ip>anchor) & (match>prefixStart))

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

            offset_2 = offset_1;

            offset_1 = offset;

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

        }

        /* match found */

        ip += mLength;

        anchor = ip;

        if (ip <= ilimit) {

            /* Fill Table */

            assert(base+current+2 > istart);  /* check base overflow */

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

            hashTable[ZSTD_hashPtr(ip-2, hlog, mls)] = (U32)(ip-2-base);

            /* check immediate repcode */

            while (ip <= ilimit) {

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

                U32 const repIndex2 = current2 - offset_2;

                const BYTE* repMatch2 = repIndex2 < prefixStartIndex ?

                        dictBase - dictIndexDelta + repIndex2 :

                        base + repIndex2;

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

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

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

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

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

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

                    hashTable[ZSTD_hashPtr(ip, hlog, mls)] = current2;

                    ip += repLength2;

                    anchor = ip;

                    continue;

                }

                break;

            }

        }

    }

    /* 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 (size_t)(iend - anchor);

}

size_t ZSTD_compressBlock_fast_dictMatchState(

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

        void const* src, size_t srcSize)

{

    U32 const mls = ms->cParams.minMatch;

    assert(ms->dictMatchState != NULL);

    switch(mls)

    {

    default: /* includes case 3 */

    case 4 :

        return ZSTD_compressBlock_fast_dictMatchState_generic(ms, seqStore, rep, src, srcSize, 4);

    case 5 :

        return ZSTD_compressBlock_fast_dictMatchState_generic(ms, seqStore, rep, src, srcSize, 5);

    case 6 :

        return ZSTD_compressBlock_fast_dictMatchState_generic(ms, seqStore, rep, src, srcSize, 6);

    case 7 :

        return ZSTD_compressBlock_fast_dictMatchState_generic(ms, seqStore, rep, src, srcSize, 7);

    }

}

static size_t ZSTD_compressBlock_fast_extDict_generic(

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

        void const* src, size_t srcSize, U32 const mls)

{

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

    U32* const hashTable = ms->hashTable;

    U32 const hlog = cParams->hashLog;

    /* support stepSize of 0 */

    U32 const stepSize = cParams->targetLength + !(cParams->targetLength);

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

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

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

    const BYTE* ip = istart;

    const BYTE* anchor = istart;

    const U32   endIndex = (U32)((size_t)(istart - base) + srcSize);

    const U32   lowLimit = ZSTD_getLowestMatchIndex(ms, endIndex, cParams->windowLog);

    const U32   dictStartIndex = lowLimit;

    const BYTE* const dictStart = dictBase + dictStartIndex;

    const U32   dictLimit = ms->window.dictLimit;

    const U32   prefixStartIndex = dictLimit < lowLimit ? lowLimit : dictLimit;

    const BYTE* const prefixStart = base + prefixStartIndex;

    const BYTE* const dictEnd = dictBase + prefixStartIndex;

    const BYTE* const iend = istart + srcSize;

    const BYTE* const ilimit = iend - 8;

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

    DEBUGLOG(5, "ZSTD_compressBlock_fast_extDict_generic");

    /* switch to "regular" variant if extDict is invalidated due to maxDistance */

    if (prefixStartIndex == dictStartIndex)

        return ZSTD_compressBlock_fast_generic(ms, seqStore, rep, src, srcSize, mls);

    /* Search Loop */

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

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

        const U32    matchIndex = hashTable[h];

        const BYTE* const matchBase = matchIndex < prefixStartIndex ? dictBase : base;

        const BYTE*  match = matchBase + matchIndex;

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

        const U32    repIndex = current + 1 - offset_1;

        const BYTE* const repBase = repIndex < prefixStartIndex ? dictBase : base;

        const BYTE* const repMatch = repBase + repIndex;

        hashTable[h] = current;   /* update hash table */

        assert(offset_1 <= current +1);   /* check repIndex */

        if ( (((U32)((prefixStartIndex-1) - repIndex) >= 3) /* intentional underflow */ & (repIndex > dictStartIndex))

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

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

            size_t const rLength = ZSTD_count_2segments(ip+1 +4, repMatch +4, iend, repMatchEnd, prefixStart) + 4;

            ip++;

            ZSTD_storeSeq(seqStore, (size_t)(ip-anchor), anchor, iend, 0, rLength-MINMATCH);

            ip += rLength;

            anchor = ip;

        } else {

            if ( (matchIndex < dictStartIndex) ||

                 (MEM_read32(match) != MEM_read32(ip)) ) {

                assert(stepSize >= 1);

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

                continue;

            }

            {   const BYTE* const matchEnd = matchIndex < prefixStartIndex ? dictEnd : iend;

                const BYTE* const lowMatchPtr = matchIndex < prefixStartIndex ? dictStart : prefixStart;

                U32 const offset = current - matchIndex;

                size_t mLength = ZSTD_count_2segments(ip+4, match+4, iend, matchEnd, prefixStart) + 4;

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

                offset_2 = offset_1; offset_1 = offset;  /* update offset history */

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

                ip += mLength;

                anchor = ip;

        }   }

        if (ip <= ilimit) {

            /* Fill Table */

            hashTable[ZSTD_hashPtr(base+current+2, hlog, mls)] = current+2;

            hashTable[ZSTD_hashPtr(ip-2, hlog, mls)] = (U32)(ip-2-base);

            /* check immediate repcode */

            while (ip <= ilimit) {

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

                U32 const repIndex2 = current2 - offset_2;

                const BYTE* const repMatch2 = repIndex2 < prefixStartIndex ? dictBase + repIndex2 : base + repIndex2;

                if ( (((U32)((prefixStartIndex-1) - repIndex2) >= 3) & (repIndex2 > dictStartIndex))  /* intentional overflow */

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

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

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

                    { U32 const tmpOffset = offset_2; offset_2 = offset_1; offset_1 = tmpOffset; }  /* swap offset_2 <=> offset_1 */

                    ZSTD_storeSeq(seqStore, 0 /*litlen*/, anchor, iend, 0 /*offcode*/, repLength2-MINMATCH);

                    hashTable[ZSTD_hashPtr(ip, hlog, mls)] = current2;

                    ip += repLength2;

                    anchor = ip;

                    continue;

                }

                break;

    }   }   }

    /* save reps for next block */

    rep[0] = offset_1;

    rep[1] = offset_2;

    /* Return the last literals size */

    return (size_t)(iend - anchor);

}

size_t ZSTD_compressBlock_fast_extDict(

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

        void const* src, size_t srcSize)

{

    U32 const mls = ms->cParams.minMatch;

    switch(mls)

    {

    default: /* includes case 3 */

    case 4 :

        return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, 4);

    case 5 :

        return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, 5);

    case 6 :

        return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, 6);

    case 7 :

        return ZSTD_compressBlock_fast_extDict_generic(ms, seqStore, rep, src, srcSize, 7);

    }

}