/* Ppmd7Enc.c -- PPMdH Encoder
2015-09-28 : Igor Pavlov : Public domain
This code is based on PPMd var.H (2001): Dmitry Shkarin : Public domain */

#include "Precomp.h"

#include "Ppmd7.h"

#define kTopValue (1 << 24)

void Ppmd7z_RangeEnc_Init(CPpmd7z_RangeEnc* p)
{
    p->Low = 0;
    p->Range = 0xFFFFFFFF;
    p->Cache = 0;
    p->CacheSize = 1;
}

static void RangeEnc_ShiftLow(CPpmd7z_RangeEnc* p)
{
    if ((UInt32)p->Low < (UInt32)0xFF000000 || (unsigned)(p->Low >> 32) != 0)
    {
        Byte temp = p->Cache;
        do
        {
            p->Stream->Write(p->Stream, (Byte)(temp + (Byte)(p->Low >> 32)));
            temp = 0xFF;
        } while (--p->CacheSize != 0);
        p->Cache = (Byte)((UInt32)p->Low >> 24);
    }
    p->CacheSize++;
    p->Low = (UInt32)p->Low << 8;
}

static void RangeEnc_Encode(CPpmd7z_RangeEnc* p, UInt32 start, UInt32 size, UInt32 total)
{
    p->Low += start * (p->Range /= total);
    p->Range *= size;
    while (p->Range < kTopValue)
    {
        p->Range <<= 8;
        RangeEnc_ShiftLow(p);
    }
}

static void RangeEnc_EncodeBit_0(CPpmd7z_RangeEnc* p, UInt32 size0)
{
    p->Range = (p->Range >> 14) * size0;
    while (p->Range < kTopValue)
    {
        p->Range <<= 8;
        RangeEnc_ShiftLow(p);
    }
}

static void RangeEnc_EncodeBit_1(CPpmd7z_RangeEnc* p, UInt32 size0)
{
    UInt32 newBound = (p->Range >> 14) * size0;
    p->Low += newBound;
    p->Range -= newBound;
    while (p->Range < kTopValue)
    {
        p->Range <<= 8;
        RangeEnc_ShiftLow(p);
    }
}

void Ppmd7z_RangeEnc_FlushData(CPpmd7z_RangeEnc* p)
{
    unsigned i;
    for (i = 0; i < 5; i++)
        RangeEnc_ShiftLow(p);
}


#define MASK(sym) ((signed char *)charMask)[sym]

void Ppmd7_EncodeSymbol(CPpmd7* p, CPpmd7z_RangeEnc* rc, int symbol)
{
    size_t charMask[256 / sizeof(size_t)];
    if (p->MinContext->NumStats != 1)
    {
        CPpmd_State* s = Ppmd7_GetStats(p, p->MinContext);
        UInt32 sum;
        unsigned i;
        if (s->Symbol == symbol)
        {
            RangeEnc_Encode(rc, 0, s->Freq, p->MinContext->SummFreq);
            p->FoundState = s;
            Ppmd7_Update1_0(p);
            return;
        }
        p->PrevSuccess = 0;
        sum = s->Freq;
        i = p->MinContext->NumStats - 1;
        do
        {
            if ((++s)->Symbol == symbol)
            {
                RangeEnc_Encode(rc, sum, s->Freq, p->MinContext->SummFreq);
                p->FoundState = s;
                Ppmd7_Update1(p);
                return;
            }
            sum += s->Freq;
        } while (--i);

        p->HiBitsFlag = p->HB2Flag[p->FoundState->Symbol];
        PPMD_SetAllBitsIn256Bytes(charMask);
        MASK(s->Symbol) = 0;
        i = p->MinContext->NumStats - 1;
        do { MASK((--s)->Symbol) = 0; } while (--i);
        RangeEnc_Encode(rc, sum, p->MinContext->SummFreq - sum, p->MinContext->SummFreq);
    }
    else
    {
        UInt16* prob = Ppmd7_GetBinSumm(p);
        CPpmd_State* s = Ppmd7Context_OneState(p->MinContext);
        if (s->Symbol == symbol)
        {
            RangeEnc_EncodeBit_0(rc, *prob);
            *prob = (UInt16)PPMD_UPDATE_PROB_0(*prob);
            p->FoundState = s;
            Ppmd7_UpdateBin(p);
            return;
        }
        else
        {
            RangeEnc_EncodeBit_1(rc, *prob);
            *prob = (UInt16)PPMD_UPDATE_PROB_1(*prob);
            p->InitEsc = PPMD7_kExpEscape[*prob >> 10];
            PPMD_SetAllBitsIn256Bytes(charMask);
            MASK(s->Symbol) = 0;
            p->PrevSuccess = 0;
        }
    }
    for (;;)
    {
        UInt32 escFreq;
        CPpmd_See* see;
        CPpmd_State* s;
        UInt32 sum;
        unsigned i, numMasked = p->MinContext->NumStats;
        do
        {
            p->OrderFall++;
            if (!p->MinContext->Suffix)
                return; /* EndMarker (symbol = -1) */
            p->MinContext = Ppmd7_GetContext(p, p->MinContext->Suffix);
        } while (p->MinContext->NumStats == numMasked);

        see = Ppmd7_MakeEscFreq(p, numMasked, &escFreq);
        s = Ppmd7_GetStats(p, p->MinContext);
        sum = 0;
        i = p->MinContext->NumStats;
        do
        {
            int cur = s->Symbol;
            if (cur == symbol)
            {
                UInt32 low = sum;
                CPpmd_State* s1 = s;
                do
                {
                    sum += (s->Freq & (int)(MASK(s->Symbol)));
                    s++;
                } while (--i);
                RangeEnc_Encode(rc, low, s1->Freq, sum + escFreq);
                Ppmd_See_Update(see);
                p->FoundState = s1;
                Ppmd7_Update2(p);
                return;
            }
            sum += (s->Freq & (int)(MASK(cur)));
            MASK(cur) = 0;
            s++;
        } while (--i);

        RangeEnc_Encode(rc, sum, escFreq, sum + escFreq);
        see->Summ = (UInt16)(see->Summ + sum + escFreq);
    }
}
