/*
   LZ4 - Fast LZ compression algorithm
   Copyright (C) 2011-2017, 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
*/

/* modified for reduce code size by Franklin Wei */
/* currently compiles to 324 bytes when thumb is used */

#ifndef ROCKBOX
#include <string.h>
#include <stdint.h>
#else
#include "rbcompat.h"
#include "lz4tiny.h"
#endif

typedef uint8_t BYTE;
typedef uint16_t U16;
typedef uint32_t U32;
typedef int32_t S32;
typedef uint64_t U64;
typedef uintptr_t uptrval;

#if (defined(__GNUC__) && (__GNUC__ >= 3)) || (defined(__INTEL_COMPILER) && (__INTEL_COMPILER >= 800)) || defined(__clang__)
#  define expect(expr,value)    (__builtin_expect ((expr),(value)) )
#else
#  define expect(expr,value)    (expr)
#endif

#define likely(expr)     expect((expr) != 0, 1)
#define unlikely(expr) expect((expr) != 0, 0)

/*-************************************
*  Local Structures and types
**************************************/
typedef enum { notLimited = 0, limitedOutput = 1 } limitedOutput_directive;
typedef enum { byPtr, byU32, byU16 } tableType_t;

typedef enum { noDict = 0, withPrefix64k, usingExtDict } dict_directive;
typedef enum { noDictIssue = 0, dictSmall } dictIssue_directive;

typedef enum { endOnOutputSize = 0, endOnInputSize = 1 } endCondition_directive;
typedef enum { full = 0, partial = 1 } earlyEnd_directive;

/*-************************************
*  Common Constants
**************************************/
#define MINMATCH 4

#define WILDCOPYLENGTH 8
#define LASTLITERALS 5
#define MFLIMIT (WILDCOPYLENGTH+MINMATCH)

#define KB *(1 <<10)
#define MB *(1 <<20)
#define GB *(1U<<30)

#define MAXD_LOG 16
#define MAX_DISTANCE ((1 << MAXD_LOG) - 1)

#define ML_BITS  4
#define ML_MASK  ((1U<<ML_BITS)-1)
#define RUN_BITS (8-ML_BITS)
#define RUN_MASK ((1U<<RUN_BITS)-1)

static void LZ4_write32(void* memPtr, U32 value)
{
    memcpy(memPtr, &value, sizeof(value));
}

static U16 LZ4_readLE16(const void* memPtr)
{
    const BYTE* p = (const BYTE*)memPtr;
    return (U16)((U16)p[0] + (p[1]<<8));
}

/* a weird memcpy */
static void LZ4_wildCopy(void* dstPtr, const void* srcPtr, void* dstEnd)
{
    memcpy(dstPtr, srcPtr, dstEnd - dstPtr);
}

void LZ4_decompress_tiny(const char* const source, char* const dest, int outputSize)
{
    /* Local Variables */
    const BYTE* ip = (const BYTE*) source;

    BYTE* op = (BYTE*) dest;
    BYTE* const oend = op + outputSize;
    BYTE* cpy;

    /* save a few bytes */
    const unsigned char dec32table[] = {0, 1, 2, 1, 4, 4, 4, 4};
    const char dec64table[] = {0, 0, 0, -1, 0, 1, 2, 3};

    /* Main Loop : decode sequences */
    while (1) {
        size_t length;
        const BYTE* match;
        size_t offset;

        /* get literal length */
        unsigned const token = *ip++;
        if ((length=(token>>ML_BITS)) == RUN_MASK) {
            unsigned s;
            do {
                s = *ip++;
                length += s;
            } while ( 1 & (s==255) );
        }

        /* copy literals */
        cpy = op+length;
        memcpy(op, ip, length);
        if (op + length > oend - WILDCOPYLENGTH)
            break;     /* Necessarily EOF, due to parsing restrictions */
        ip += length; op = cpy;

        /* get offset */
        offset = LZ4_readLE16(ip); ip+=2;
        match = op - offset;
        LZ4_write32(op, (U32)offset); /* costs ~1%; silence an msan warning when offset==0 */

        /* get matchlength */
        length = token & ML_MASK;
        if (length == ML_MASK) {
            unsigned s;
            do {
                s = *ip++;
                length += s;
            } while (s==255);
        }
        length += MINMATCH;

        /* copy match within block */
        cpy = op + length;
        if (unlikely(offset<8)) {
            const int dec64 = dec64table[offset];
            op[0] = match[0];
            op[1] = match[1];
            op[2] = match[2];
            op[3] = match[3];
            match += dec32table[offset];
            memcpy(op+4, match, 4);
            match -= dec64;
        } else { memcpy(op, match, 8); match+=8; }
        op += 8;

        if (unlikely(cpy>oend-12)) {
            BYTE* const oCopyLimit = oend-(WILDCOPYLENGTH-1);
            if (op < oCopyLimit) {
                LZ4_wildCopy(op, match, oCopyLimit);
                match += oCopyLimit - op;
                op = oCopyLimit;
            }
            while (op<cpy) *op++ = *match++;
        } else {
            memcpy(op, match, 8);
            if (length>16) LZ4_wildCopy(op+8, match+8, cpy);
        }
        op=cpy;   /* correction */
    }
}

/* testing code */
#ifndef ROCKBOX
#include "help.h"
#include <stdlib.h>
#include <stdio.h>
int main()
{
    char *buf = malloc(help_text_len);
    LZ4_decompress_tiny(help_text, buf, help_text_len);
    puts(buf);
    free(buf);
}
#endif