/*
 * LZ4 - Fast LZ compression algorithm
 * Copyright (C) 2011 - 2016, Yann Collet.
 * BSD 2 - Clause License (http://www.opensource.org/licenses/bsd - license.php)
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are
 * met:
 *      * Redistributions of source code must retain the above copyright
 *        notice, this list of conditions and the following disclaimer.
 *      * Redistributions in binary form must reproduce the above
 * copyright notice, this list of conditions and the following disclaimer
 * in the documentation and/or other materials provided with the
 * distribution.
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
 * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
 * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
 * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
 * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * You can contact the author at :
 *      - LZ4 homepage : http://www.lz4.org
 *      - LZ4 source repository : https://github.com/lz4/lz4
 *
 *      Changed for kernel usage by:
 *      Sven Schmidt <4sschmid@informatik.uni-hamburg.de>
 */

/*-************************************
 *      Dependencies
 **************************************/
#include "lz4defs.h"
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/unaligned.h>

static const int LZ4_minLength = (MFLIMIT + 1);
static const int LZ4_64Klimit = ((64 * KB) + (MFLIMIT - 1));

/*-******************************
 *      Compression functions
 ********************************/
static FORCE_INLINE U32 LZ4_hash4(
        U32 sequence,
        tableType_t const tableType)
{
        if (tableType == byU16)
                return ((sequence * 2654435761U)
                        >> ((MINMATCH * 8) - (LZ4_HASHLOG + 1)));
        else
                return ((sequence * 2654435761U)
                        >> ((MINMATCH * 8) - LZ4_HASHLOG));
}

static FORCE_INLINE U32 LZ4_hash5(
        U64 sequence,
        tableType_t const tableType)
{
        const U32 hashLog = (tableType == byU16)
                ? LZ4_HASHLOG + 1
                : LZ4_HASHLOG;

#if LZ4_LITTLE_ENDIAN
        static const U64 prime5bytes = 889523592379ULL;

        return (U32)(((sequence << 24) * prime5bytes) >> (64 - hashLog));
#else
        static const U64 prime8bytes = 11400714785074694791ULL;

        return (U32)(((sequence >> 24) * prime8bytes) >> (64 - hashLog));
#endif
}

static FORCE_INLINE U32 LZ4_hashPosition(
        const void *p,
        tableType_t const tableType)
{
#if LZ4_ARCH64
        if (tableType == byU32)
                return LZ4_hash5(LZ4_read_ARCH(p), tableType);
#endif

        return LZ4_hash4(LZ4_read32(p), tableType);
}

static void LZ4_putPositionOnHash(
        const BYTE *p,
        U32 h,
        void *tableBase,
        tableType_t const tableType,
        const BYTE *srcBase)
{
        switch (tableType) {
        case byPtr:
        {
                const BYTE **hashTable = (const BYTE **)tableBase;

                hashTable[h] = p;
                return;
        }
        case byU32:
        {
                U32 *hashTable = (U32 *) tableBase;

                hashTable[h] = (U32)(p - srcBase);
                return;
        }
        case byU16:
        {
                U16 *hashTable = (U16 *) tableBase;

                hashTable[h] = (U16)(p - srcBase);
                return;
        }
        }
}

static FORCE_INLINE void LZ4_putPosition(
        const BYTE *p,
        void *tableBase,
        tableType_t tableType,
        const BYTE *srcBase)
{
        U32 const h = LZ4_hashPosition(p, tableType);

        LZ4_putPositionOnHash(p, h, tableBase, tableType, srcBase);
}

static const BYTE *LZ4_getPositionOnHash(
        U32 h,
        void *tableBase,
        tableType_t tableType,
        const BYTE *srcBase)
{
        if (tableType == byPtr) {
                const BYTE **hashTable = (const BYTE **) tableBase;

                return hashTable[h];
        }

        if (tableType == byU32) {
                const U32 * const hashTable = (U32 *) tableBase;

                return hashTable[h] + srcBase;
        }

        {
                /* default, to ensure a return */
                const U16 * const hashTable = (U16 *) tableBase;

                return hashTable[h] + srcBase;
        }
}

static FORCE_INLINE const BYTE *LZ4_getPosition(
        const BYTE *p,
        void *tableBase,
        tableType_t tableType,
        const BYTE *srcBase)
{
        U32 const h = LZ4_hashPosition(p, tableType);

        return LZ4_getPositionOnHash(h, tableBase, tableType, srcBase);
}


/*
 * LZ4_compress_generic() :
 * inlined, to ensure branches are decided at compilation time
 */
static FORCE_INLINE int LZ4_compress_generic(
        LZ4_stream_t_internal * const dictPtr,
        const char * const source,
        char * const dest,
        const int inputSize,
        const int maxOutputSize,
        const limitedOutput_directive outputLimited,
        const tableType_t tableType,
        const dict_directive dict,
        const dictIssue_directive dictIssue,
        const U32 acceleration)
{
        const BYTE *ip = (const BYTE *) source;
        const BYTE *base;
        const BYTE *lowLimit;
        const BYTE * const lowRefLimit = ip - dictPtr->dictSize;
        const BYTE * const dictionary = dictPtr->dictionary;
        const BYTE * const dictEnd = dictionary + dictPtr->dictSize;
        const size_t dictDelta = dictEnd - (const BYTE *)source;
        const BYTE *anchor = (const BYTE *) source;
        const BYTE * const iend = ip + inputSize;
        const BYTE * const mflimit = iend - MFLIMIT;
        const BYTE * const matchlimit = iend - LASTLITERALS;

        BYTE *op = (BYTE *) dest;
        BYTE * const olimit = op + maxOutputSize;

        U32 forwardH;
        size_t refDelta = 0;

        /* Init conditions */
        if ((U32)inputSize > (U32)LZ4_MAX_INPUT_SIZE) {
                /* Unsupported inputSize, too large (or negative) */
                return 0;
        }

        switch (dict) {
        case noDict:
        default:
                base = (const BYTE *)source;
                lowLimit = (const BYTE *)source;
                break;
        case withPrefix64k:
                base = (const BYTE *)source - dictPtr->currentOffset;
                lowLimit = (const BYTE *)source - dictPtr->dictSize;
                break;
        case usingExtDict:
                base = (const BYTE *)source - dictPtr->currentOffset;
                lowLimit = (const BYTE *)source;
                break;
        }

        if ((tableType == byU16)
                && (inputSize >= LZ4_64Klimit)) {
                /* Size too large (not within 64K limit) */
                return 0;
        }

        if (inputSize < LZ4_minLength) {
                /* Input too small, no compression (all literals) */
                goto _last_literals;
        }

        /* First Byte */
        LZ4_putPosition(ip, dictPtr->hashTable, tableType, base);
        ip++;
        forwardH = LZ4_hashPosition(ip, tableType);

        /* Main Loop */
        for ( ; ; ) {
                const BYTE *match;
                BYTE *token;

                /* Find a match */
                {
                        const BYTE *forwardIp = ip;
                        unsigned int step = 1;
                        unsigned int searchMatchNb = acceleration << LZ4_SKIPTRIGGER;

                        do {
                                U32 const h = forwardH;

                                ip = forwardIp;
                                forwardIp += step;
                                step = (searchMatchNb++ >> LZ4_SKIPTRIGGER);

                                if (unlikely(forwardIp > mflimit))
                                        goto _last_literals;

                                match = LZ4_getPositionOnHash(h,
                                        dictPtr->hashTable,
                                        tableType, base);

                                if (dict == usingExtDict) {
                                        if (match < (const BYTE *)source) {
                                                refDelta = dictDelta;
                                                lowLimit = dictionary;
                                        } else {
                                                refDelta = 0;
                                                lowLimit = (const BYTE *)source;
                                }        }

                                forwardH = LZ4_hashPosition(forwardIp,
                                        tableType);

                                LZ4_putPositionOnHash(ip, h, dictPtr->hashTable,
                                        tableType, base);
                        } while (((dictIssue == dictSmall)
                                        ? (match < lowRefLimit)
                                        : 0)
                                || ((tableType == byU16)
                                        ? 0
                                        : (match + MAX_DISTANCE < ip))
                                || (LZ4_read32(match + refDelta)
                                        != LZ4_read32(ip)));
                }

                /* Catch up */
                while (((ip > anchor) & (match + refDelta > lowLimit))
                                && (unlikely(ip[-1] == match[refDelta - 1]))) {
                        ip--;
                        match--;
                }

                /* Encode Literals */
                {
                        unsigned const int litLength = (unsigned int)(ip - anchor);

                        token = op++;

                        if ((outputLimited) &&
                                /* Check output buffer overflow */
                                (unlikely(op + litLength +
                                        (2 + 1 + LASTLITERALS) +
                                        (litLength / 255) > olimit)))
                                return 0;

                        if (litLength >= RUN_MASK) {
                                int len = (int)litLength - RUN_MASK;

                                *token = (RUN_MASK << ML_BITS);

                                for (; len >= 255; len -= 255)
                                        *op++ = 255;
                                *op++ = (BYTE)len;
                        } else
                                *token = (BYTE)(litLength << ML_BITS);

                        /* Copy Literals */
                        LZ4_wildCopy(op, anchor, op + litLength);
                        op += litLength;
                }

_next_match:
                /* Encode Offset */
                LZ4_writeLE16(op, (U16)(ip - match));
                op += 2;

                /* Encode MatchLength */
                {
                        unsigned int matchCode;

                        if ((dict == usingExtDict)
                                && (lowLimit == dictionary)) {
                                const BYTE *limit;

                                match += refDelta;
                                limit = ip + (dictEnd - match);

                                if (limit > matchlimit)
                                        limit = matchlimit;

                                matchCode = LZ4_count(ip + MINMATCH,
                                        match + MINMATCH, limit);

                                ip += MINMATCH + matchCode;

                                if (ip == limit) {
                                        unsigned const int more = LZ4_count(ip,
                                                (const BYTE *)source,
                                                matchlimit);

                                        matchCode += more;
                                        ip += more;
                                }
                        } else {
                                matchCode = LZ4_count(ip + MINMATCH,
                                        match + MINMATCH, matchlimit);
                                ip += MINMATCH + matchCode;
                        }

                        if (outputLimited &&
                                /* Check output buffer overflow */
                                (unlikely(op +
                                        (1 + LASTLITERALS) +
                                        (matchCode >> 8) > olimit)))
                                return 0;

                        if (matchCode >= ML_MASK) {
                                *token += ML_MASK;
                                matchCode -= ML_MASK;
                                LZ4_write32(op, 0xFFFFFFFF);

                                while (matchCode >= 4 * 255) {
                                        op += 4;
                                        LZ4_write32(op, 0xFFFFFFFF);
                                        matchCode -= 4 * 255;
                                }

                                op += matchCode / 255;
                                *op++ = (BYTE)(matchCode % 255);
                        } else
                                *token += (BYTE)(matchCode);
                }

                anchor = ip;

                /* Test end of chunk */
                if (ip > mflimit)
                        break;

                /* Fill table */
                LZ4_putPosition(ip - 2, dictPtr->hashTable, tableType, base);

                /* Test next position */
                match = LZ4_getPosition(ip, dictPtr->hashTable,
                        tableType, base);

                if (dict == usingExtDict) {
                        if (match < (const BYTE *)source) {
                                refDelta = dictDelta;
                                lowLimit = dictionary;
                        } else {
                                refDelta = 0;
                                lowLimit = (const BYTE *)source;
                        }
                }

                LZ4_putPosition(ip, dictPtr->hashTable, tableType, base);

                if (((dictIssue == dictSmall) ? (match >= lowRefLimit) : 1)
                        && (match + MAX_DISTANCE >= ip)
                        && (LZ4_read32(match + refDelta) == LZ4_read32(ip))) {
                        token = op++;
                        *token = 0;
                        goto _next_match;
                }

                /* Prepare next loop */
                forwardH = LZ4_hashPosition(++ip, tableType);
        }

_last_literals:
        /* Encode Last Literals */
        {
                size_t const lastRun = (size_t)(iend - anchor);

                if ((outputLimited) &&
                        /* Check output buffer overflow */
                        ((op - (BYTE *)dest) + lastRun + 1 +
                        ((lastRun + 255 - RUN_MASK) / 255) > (U32)maxOutputSize))
                        return 0;

                if (lastRun >= RUN_MASK) {
                        size_t accumulator = lastRun - RUN_MASK;
                        *op++ = RUN_MASK << ML_BITS;
                        for (; accumulator >= 255; accumulator -= 255)
                                *op++ = 255;
                        *op++ = (BYTE) accumulator;
                } else {
                        *op++ = (BYTE)(lastRun << ML_BITS);
                }

                LZ4_memcpy(op, anchor, lastRun);

                op += lastRun;
        }

        /* End */
        return (int) (((char *)op) - dest);
}

static int LZ4_compress_fast_extState(
        void *state,
        const char *source,
        char *dest,
        int inputSize,
        int maxOutputSize,
        int acceleration)
{
        LZ4_stream_t_internal *ctx = &((LZ4_stream_t *)state)->internal_donotuse;
#if LZ4_ARCH64
        const tableType_t tableType = byU32;
#else
        const tableType_t tableType = byPtr;
#endif

        LZ4_resetStream((LZ4_stream_t *)state);

        if (acceleration < 1)
                acceleration = LZ4_ACCELERATION_DEFAULT;

        if (maxOutputSize >= LZ4_COMPRESSBOUND(inputSize)) {
                if (inputSize < LZ4_64Klimit)
                        return LZ4_compress_generic(ctx, source,
                                dest, inputSize, 0,
                                noLimit, byU16, noDict,
                                noDictIssue, acceleration);
                else
                        return LZ4_compress_generic(ctx, source,
                                dest, inputSize, 0,
                                noLimit, tableType, noDict,
                                noDictIssue, acceleration);
        } else {
                if (inputSize < LZ4_64Klimit)
                        return LZ4_compress_generic(ctx, source,
                                dest, inputSize,
                                maxOutputSize, limitedOutput, byU16, noDict,
                                noDictIssue, acceleration);
                else
                        return LZ4_compress_generic(ctx, source,
                                dest, inputSize,
                                maxOutputSize, limitedOutput, tableType, noDict,
                                noDictIssue, acceleration);
        }
}

int LZ4_compress_fast(const char *source, char *dest, int inputSize,
        int maxOutputSize, int acceleration, void *wrkmem)
{
        return LZ4_compress_fast_extState(wrkmem, source, dest, inputSize,
                maxOutputSize, acceleration);
}
EXPORT_SYMBOL(LZ4_compress_fast);

int LZ4_compress_default(const char *source, char *dest, int inputSize,
        int maxOutputSize, void *wrkmem)
{
        return LZ4_compress_fast(source, dest, inputSize,
                maxOutputSize, LZ4_ACCELERATION_DEFAULT, wrkmem);
}
EXPORT_SYMBOL(LZ4_compress_default);

/*-******************************
 *      *_destSize() variant
 ********************************/
static int LZ4_compress_destSize_generic(
        LZ4_stream_t_internal * const ctx,
        const char * const src,
        char * const dst,
        int * const srcSizePtr,
        const int targetDstSize,
        const tableType_t tableType)
{
        const BYTE *ip = (const BYTE *) src;
        const BYTE *base = (const BYTE *) src;
        const BYTE *lowLimit = (const BYTE *) src;
        const BYTE *anchor = ip;
        const BYTE * const iend = ip + *srcSizePtr;
        const BYTE * const mflimit = iend - MFLIMIT;
        const BYTE * const matchlimit = iend - LASTLITERALS;

        BYTE *op = (BYTE *) dst;
        BYTE * const oend = op + targetDstSize;
        BYTE * const oMaxLit = op + targetDstSize - 2 /* offset */
                - 8 /* because 8 + MINMATCH == MFLIMIT */ - 1 /* token */;
        BYTE * const oMaxMatch = op + targetDstSize
                - (LASTLITERALS + 1 /* token */);
        BYTE * const oMaxSeq = oMaxLit - 1 /* token */;

        U32 forwardH;

        /* Init conditions */
        /* Impossible to store anything */
        if (targetDstSize < 1)
                return 0;
        /* Unsupported input size, too large (or negative) */
        if ((U32)*srcSizePtr > (U32)LZ4_MAX_INPUT_SIZE)
                return 0;
        /* Size too large (not within 64K limit) */
        if ((tableType == byU16) && (*srcSizePtr >= LZ4_64Klimit))
                return 0;
        /* Input too small, no compression (all literals) */
        if (*srcSizePtr < LZ4_minLength)
                goto _last_literals;

        /* First Byte */
        *srcSizePtr = 0;
        LZ4_putPosition(ip, ctx->hashTable, tableType, base);
        ip++; forwardH = LZ4_hashPosition(ip, tableType);

        /* Main Loop */
        for ( ; ; ) {
                const BYTE *match;
                BYTE *token;

                /* Find a match */
                {
                        const BYTE *forwardIp = ip;
                        unsigned int step = 1;
                        unsigned int searchMatchNb = 1 << LZ4_SKIPTRIGGER;

                        do {
                                U32 h = forwardH;

                                ip = forwardIp;
                                forwardIp += step;
                                step = (searchMatchNb++ >> LZ4_SKIPTRIGGER);

                                if (unlikely(forwardIp > mflimit))
                                        goto _last_literals;

                                match = LZ4_getPositionOnHash(h, ctx->hashTable,
                                        tableType, base);
                                forwardH = LZ4_hashPosition(forwardIp,
                                        tableType);
                                LZ4_putPositionOnHash(ip, h,
                                        ctx->hashTable, tableType,
                                        base);

                        } while (((tableType == byU16)
                                ? 0
                                : (match + MAX_DISTANCE < ip))
                                || (LZ4_read32(match) != LZ4_read32(ip)));
                }

                /* Catch up */
                while ((ip > anchor)
                        && (match > lowLimit)
                        && (unlikely(ip[-1] == match[-1]))) {
                        ip--;
                        match--;
                }

                /* Encode Literal length */
                {
                        unsigned int litLength = (unsigned int)(ip - anchor);

                        token = op++;
                        if (op + ((litLength + 240) / 255)
                                + litLength > oMaxLit) {
                                /* Not enough space for a last match */
                                op--;
                                goto _last_literals;
                        }
                        if (litLength >= RUN_MASK) {
                                unsigned int len = litLength - RUN_MASK;
                                *token = (RUN_MASK<<ML_BITS);
                                for (; len >= 255; len -= 255)
                                        *op++ = 255;
                                *op++ = (BYTE)len;
                        } else
                                *token = (BYTE)(litLength << ML_BITS);

                        /* Copy Literals */
                        LZ4_wildCopy(op, anchor, op + litLength);
                        op += litLength;
                }

_next_match:
                /* Encode Offset */
                LZ4_writeLE16(op, (U16)(ip - match)); op += 2;

                /* Encode MatchLength */
                {
                        size_t matchLength = LZ4_count(ip + MINMATCH,
                        match + MINMATCH, matchlimit);

                        if (op + ((matchLength + 240)/255) > oMaxMatch) {
                                /* Match description too long : reduce it */
                                matchLength = (15 - 1) + (oMaxMatch - op) * 255;
                        }
                        ip += MINMATCH + matchLength;

                        if (matchLength >= ML_MASK) {
                                *token += ML_MASK;
                                matchLength -= ML_MASK;
                                while (matchLength >= 255) {
                                        matchLength -= 255;
                                        *op++ = 255;
                                }
                                *op++ = (BYTE)matchLength;
                        } else
                                *token += (BYTE)(matchLength);
                }

                anchor = ip;

                /* Test end of block */
                if (ip > mflimit)
                        break;
                if (op > oMaxSeq)
                        break;

                /* Fill table */
                LZ4_putPosition(ip - 2, ctx->hashTable, tableType, base);

                /* Test next position */
                match = LZ4_getPosition(ip, ctx->hashTable, tableType, base);
                LZ4_putPosition(ip, ctx->hashTable, tableType, base);

                if ((match + MAX_DISTANCE >= ip)
                        && (LZ4_read32(match) == LZ4_read32(ip))) {
                        token = op++; *token = 0;
                        goto _next_match;
                }

                /* Prepare next loop */
                forwardH = LZ4_hashPosition(++ip, tableType);
        }

_last_literals:
        /* Encode Last Literals */
        {
                size_t lastRunSize = (size_t)(iend - anchor);

                if (op + 1 /* token */
                        + ((lastRunSize + 240) / 255) /* litLength */
                        + lastRunSize /* literals */ > oend) {
                        /* adapt lastRunSize to fill 'dst' */
                        lastRunSize     = (oend - op) - 1;
                        lastRunSize -= (lastRunSize + 240) / 255;
                }
                ip = anchor + lastRunSize;

                if (lastRunSize >= RUN_MASK) {
                        size_t accumulator = lastRunSize - RUN_MASK;

                        *op++ = RUN_MASK << ML_BITS;
                        for (; accumulator >= 255; accumulator -= 255)
                                *op++ = 255;
                        *op++ = (BYTE) accumulator;
                } else {
                        *op++ = (BYTE)(lastRunSize<<ML_BITS);
                }
                LZ4_memcpy(op, anchor, lastRunSize);
                op += lastRunSize;
        }

        /* End */
        *srcSizePtr = (int) (((const char *)ip) - src);
        return (int) (((char *)op) - dst);
}

static int LZ4_compress_destSize_extState(
        LZ4_stream_t *state,
        const char *src,
        char *dst,
        int *srcSizePtr,
        int targetDstSize)
{
#if LZ4_ARCH64
        const tableType_t tableType = byU32;
#else
        const tableType_t tableType = byPtr;
#endif

        LZ4_resetStream(state);

        if (targetDstSize >= LZ4_COMPRESSBOUND(*srcSizePtr)) {
                /* compression success is guaranteed */
                return LZ4_compress_fast_extState(
                        state, src, dst, *srcSizePtr,
                        targetDstSize, 1);
        } else {
                if (*srcSizePtr < LZ4_64Klimit)
                        return LZ4_compress_destSize_generic(
                                &state->internal_donotuse,
                                src, dst, srcSizePtr,
                                targetDstSize, byU16);
                else
                        return LZ4_compress_destSize_generic(
                                &state->internal_donotuse,
                                src, dst, srcSizePtr,
                                targetDstSize, tableType);
        }
}


int LZ4_compress_destSize(
        const char *src,
        char *dst,
        int *srcSizePtr,
        int targetDstSize,
        void *wrkmem)
{
        return LZ4_compress_destSize_extState(wrkmem, src, dst, srcSizePtr,
                targetDstSize);
}
EXPORT_SYMBOL(LZ4_compress_destSize);

/*-******************************
 *      Streaming functions
 ********************************/
void LZ4_resetStream(LZ4_stream_t *LZ4_stream)
{
        memset(LZ4_stream, 0, sizeof(LZ4_stream_t));
}

int LZ4_loadDict(LZ4_stream_t *LZ4_dict,
        const char *dictionary, int dictSize)
{
        LZ4_stream_t_internal *dict = &LZ4_dict->internal_donotuse;
        const BYTE *p = (const BYTE *)dictionary;
        const BYTE * const dictEnd = p + dictSize;
        const BYTE *base;

        if ((dict->initCheck)
                || (dict->currentOffset > 1 * GB)) {
                /* Uninitialized structure, or reuse overflow */
                LZ4_resetStream(LZ4_dict);
        }

        if (dictSize < (int)HASH_UNIT) {
                dict->dictionary = NULL;
                dict->dictSize = 0;
                return 0;
        }

        if ((dictEnd - p) > 64 * KB)
                p = dictEnd - 64 * KB;
        dict->currentOffset += 64 * KB;
        base = p - dict->currentOffset;
        dict->dictionary = p;
        dict->dictSize = (U32)(dictEnd - p);
        dict->currentOffset += dict->dictSize;

        while (p <= dictEnd - HASH_UNIT) {
                LZ4_putPosition(p, dict->hashTable, byU32, base);
                p += 3;
        }

        return dict->dictSize;
}
EXPORT_SYMBOL(LZ4_loadDict);

static void LZ4_renormDictT(LZ4_stream_t_internal *LZ4_dict,
        const BYTE *src)
{
        if ((LZ4_dict->currentOffset > 0x80000000) ||
                ((uptrval)LZ4_dict->currentOffset > (uptrval)src)) {
                /* address space overflow */
                /* rescale hash table */
                U32 const delta = LZ4_dict->currentOffset - 64 * KB;
                const BYTE *dictEnd = LZ4_dict->dictionary + LZ4_dict->dictSize;
                int i;

                for (i = 0; i < LZ4_HASH_SIZE_U32; i++) {
                        if (LZ4_dict->hashTable[i] < delta)
                                LZ4_dict->hashTable[i] = 0;
                        else
                                LZ4_dict->hashTable[i] -= delta;
                }
                LZ4_dict->currentOffset = 64 * KB;
                if (LZ4_dict->dictSize > 64 * KB)
                        LZ4_dict->dictSize = 64 * KB;
                LZ4_dict->dictionary = dictEnd - LZ4_dict->dictSize;
        }
}

int LZ4_saveDict(LZ4_stream_t *LZ4_dict, char *safeBuffer, int dictSize)
{
        LZ4_stream_t_internal * const dict = &LZ4_dict->internal_donotuse;
        const BYTE * const previousDictEnd = dict->dictionary + dict->dictSize;

        if ((U32)dictSize > 64 * KB) {
                /* useless to define a dictionary > 64 * KB */
                dictSize = 64 * KB;
        }
        if ((U32)dictSize > dict->dictSize)
                dictSize = dict->dictSize;

        memmove(safeBuffer, previousDictEnd - dictSize, dictSize);

        dict->dictionary = (const BYTE *)safeBuffer;
        dict->dictSize = (U32)dictSize;

        return dictSize;
}
EXPORT_SYMBOL(LZ4_saveDict);

int LZ4_compress_fast_continue(LZ4_stream_t *LZ4_stream, const char *source,
        char *dest, int inputSize, int maxOutputSize, int acceleration)
{
        LZ4_stream_t_internal *streamPtr = &LZ4_stream->internal_donotuse;
        const BYTE * const dictEnd = streamPtr->dictionary
                + streamPtr->dictSize;

        const BYTE *smallest = (const BYTE *) source;

        if (streamPtr->initCheck) {
                /* Uninitialized structure detected */
                return 0;
        }

        if ((streamPtr->dictSize > 0) && (smallest > dictEnd))
                smallest = dictEnd;

        LZ4_renormDictT(streamPtr, smallest);

        if (acceleration < 1)
                acceleration = LZ4_ACCELERATION_DEFAULT;

        /* Check overlapping input/dictionary space */
        {
                const BYTE *sourceEnd = (const BYTE *) source + inputSize;

                if ((sourceEnd > streamPtr->dictionary)
                        && (sourceEnd < dictEnd)) {
                        streamPtr->dictSize = (U32)(dictEnd - sourceEnd);
                        if (streamPtr->dictSize > 64 * KB)
                                streamPtr->dictSize = 64 * KB;
                        if (streamPtr->dictSize < 4)
                                streamPtr->dictSize = 0;
                        streamPtr->dictionary = dictEnd - streamPtr->dictSize;
                }
        }

        /* prefix mode : source data follows dictionary */
        if (dictEnd == (const BYTE *)source) {
                int result;

                if ((streamPtr->dictSize < 64 * KB) &&
                        (streamPtr->dictSize < streamPtr->currentOffset)) {
                        result = LZ4_compress_generic(
                                streamPtr, source, dest, inputSize,
                                maxOutputSize, limitedOutput, byU32,
                                withPrefix64k, dictSmall, acceleration);
                } else {
                        result = LZ4_compress_generic(
                                streamPtr, source, dest, inputSize,
                                maxOutputSize, limitedOutput, byU32,
                                withPrefix64k, noDictIssue, acceleration);
                }
                streamPtr->dictSize += (U32)inputSize;
                streamPtr->currentOffset += (U32)inputSize;
                return result;
        }

        /* external dictionary mode */
        {
                int result;

                if ((streamPtr->dictSize < 64 * KB) &&
                        (streamPtr->dictSize < streamPtr->currentOffset)) {
                        result = LZ4_compress_generic(
                                streamPtr, source, dest, inputSize,
                                maxOutputSize, limitedOutput, byU32,
                                usingExtDict, dictSmall, acceleration);
                } else {
                        result = LZ4_compress_generic(
                                streamPtr, source, dest, inputSize,
                                maxOutputSize, limitedOutput, byU32,
                                usingExtDict, noDictIssue, acceleration);
                }
                streamPtr->dictionary = (const BYTE *)source;
                streamPtr->dictSize = (U32)inputSize;
                streamPtr->currentOffset += (U32)inputSize;
                return result;
        }
}
EXPORT_SYMBOL(LZ4_compress_fast_continue);

MODULE_LICENSE("Dual BSD/GPL");
MODULE_DESCRIPTION("LZ4 compressor");