/*
 * CiderPress
 * Copyright (C) 2007 by faddenSoft, LLC.  All Rights Reserved.
 * See the file LICENSE for distribution terms.
 */
/*
 * DreamGrafix super-hi-res conversions.
 *
 * Based on code provided by Jason Andersen.
 */
#include "StdAfx.h"
#include "SuperHiRes.h"


/*
 * ==========================================================================
 *      ReformatDG256SHR
 * ==========================================================================
 */

/*
 * Decide whether or not we want to handle this file.
 */
void
ReformatDG256SHR::Examine(ReformatHolder* pHolder)
{
    ReformatHolder::ReformatApplies applies = ReformatHolder::kApplicNot;

    if (fDG.ScanDreamGrafix(pHolder) && fDG.fNumColors == 256)
        applies = ReformatHolder::kApplicYes;

    pHolder->SetApplic(ReformatHolder::kReformatSHR_DG256, applies,
        ReformatHolder::kApplicNot, ReformatHolder::kApplicNot);
}

/*
 * Convert a 256-color DreamGrafix Super Hi-Res Image.
 */
int
ReformatDG256SHR::Process(const ReformatHolder* pHolder,
    ReformatHolder::ReformatID id, ReformatHolder::ReformatPart part,
    ReformatOutput* pOutput)
{
    const unsigned char* srcBuf = pHolder->GetSourceBuf(part);
    long srcLen = pHolder->GetSourceLen(part);
    int retval = -1;

    if (fDG.UnpackDG(srcBuf, srcLen, &fScreen, NULL)) {
        MyDIBitmap* pDib = SHRScreenToBitmap8(&fScreen);
        if (pDib != NULL) {
            SetResultBuffer(pOutput, pDib);
            retval = 0;
        }
    }

    return retval;
}


/*
 * ==========================================================================
 *      ReformatDG3200SHR
 * ==========================================================================
 */

/*
 * Decide whether or not we want to handle this file.
 */
void
ReformatDG3200SHR::Examine(ReformatHolder* pHolder)
{
    ReformatHolder::ReformatApplies applies = ReformatHolder::kApplicNot;

    if (fDG.ScanDreamGrafix(pHolder) && fDG.fNumColors == 3200)
        applies = ReformatHolder::kApplicYes;

    pHolder->SetApplic(ReformatHolder::kReformatSHR_DG3200, applies,
        ReformatHolder::kApplicNot, ReformatHolder::kApplicNot);
}

/*
 * Convert a 3200-color DreamGrafix Super Hi-Res Image.
 */
int
ReformatDG3200SHR::Process(const ReformatHolder* pHolder,
    ReformatHolder::ReformatID id, ReformatHolder::ReformatPart part,
    ReformatOutput* pOutput)
{
    const unsigned char* srcBuf = pHolder->GetSourceBuf(part);
    long srcLen = pHolder->GetSourceLen(part);
    int retval = -1;

    if (fDG.UnpackDG(srcBuf, srcLen, &fScreen, fExtColorTable)) {
        MyDIBitmap* pDib = SHR3200ToBitmap24();
        if (pDib != NULL) {
            SetResultBuffer(pOutput, pDib);
            retval = 0;
        }
    }

    return retval;
}




/*
 * ==========================================================================
 *      ReformatDreamGrafix
 * ==========================================================================
 */

/*
 * Examine a DreamGrafix file.  This figures out if its any of the
 * DreamGrafix formats, i.e. 256-color, 3200-color, packed, or unpacked.
 */
bool
DreamGrafix::ScanDreamGrafix(ReformatHolder* pHolder)
{
    long fileType = pHolder->GetFileType();
    long auxType = pHolder->GetAuxType();
    long fileLen = pHolder->GetSourceLen(ReformatHolder::kPartData);
    bool relaxed, couldBe;

    relaxed = pHolder->GetOption(ReformatHolder::kOptRelaxGfxTypeCheck) != 0;
    couldBe = false;

    if (fileType == Reformat::kTypePNT && auxType == 0x8005)
        couldBe = true;     // $c0/8005 DG packed
    else if (fileType == Reformat::kTypePIC && auxType == 0x8003)
        couldBe = false;    // $c1/8003 DG unpacked -- not supported
    else if (relaxed) {
        if (fileType == Reformat::kTypeBIN && auxType == 0x8005)
            couldBe = true;
    }
    if (fileLen < 256)
        couldBe = false;

    if (!couldBe)
        return false;

    const unsigned char* ptr;
    ptr = pHolder->GetSourceBuf(ReformatHolder::kPartData)
            + fileLen - kHeaderOffset;

    if (memcmp(ptr+6, "\x0a""DreamWorld", 11) != 0)
        return false;

    fNumColors = (*ptr == 0) ? 256 : 3200;
    fHeight = Reformat::Get16LE(ptr + 2);
    fWidth = Reformat::Get16LE(ptr + 4);
    if (fWidth != 320 || fHeight != 200) {
        WMSG2("ODD: strange height %dx%x in DG\n", fWidth, fHeight);
        return false;
    }

    return true;
}

/*
 * Unpack a DreamGrafix SHR image compressed with LZW.
 *
 * Returns true on success, false if the uncompress step failed to produce
 * exactly 32768+32*200 bytes.
 */
bool
DreamGrafix::UnpackDG(const unsigned char* srcBuf, long srcLen,
    ReformatSHR::SHRScreen* pScreen, unsigned char* extColorTable)
{
    int expectedLen;
    unsigned char* tmpBuf;
    int actual;

    if (extColorTable == NULL) {
        /*
         * 32000 for pixels (320*200*0.5 bytes)
         * 256 for SCB (200 + 56 unused)
         * 512 for basic palette (16 sets * 16 colors * 2 bytes)\
         * 512 optional/unused?
         */
        expectedLen = 33280;
    } else {
        /*
         * 32000 for pixels (320*200*0.5 bytes)
         * 6400 for palette (200 lines * 16 entries * 2 bytes)
         * 512 optional/unused?
         */
        expectedLen = 38912;
    }

    /* over-alloc -- our LZW decoder doesn't check often */
    tmpBuf = new unsigned char[expectedLen + 1024];
    if (tmpBuf == NULL)
        return false;

    actual = UnpackLZW(srcBuf, srcLen, tmpBuf, expectedLen);
    if (actual != expectedLen && actual != (expectedLen-512)) {
        WMSG2("UnpackLZW expected %d, got %d\n", expectedLen, actual);
        free(tmpBuf);
        return false;
    }

    memcpy(pScreen->pixels, tmpBuf, 32000);
    if (extColorTable == NULL) {
        memcpy(pScreen->scb, tmpBuf + 32000, 256);
        memcpy(pScreen->colorTable, tmpBuf + 32256, 512);
    } else {
        const unsigned short* pSrcTable;
        unsigned short* pDstTable;
        
        pSrcTable = (const unsigned short*) (tmpBuf + 32000);
        pDstTable = (unsigned short*) extColorTable;
        int table;
        for (table = 0; table < ReformatSHR::kNumLines; table++) {
            int entry;
            for (entry = 0; entry < ReformatSHR::kNumEntriesPerColorTable; entry++) {
                pDstTable[(ReformatSHR::kNumEntriesPerColorTable-1) - entry] =
                    *pSrcTable++;
            }
            pDstTable += ReformatSHR::kNumEntriesPerColorTable;
        }
    }

    free(tmpBuf);
    return true;
}

/*
 * Constants for LZW.
 */
static const int kClearCode = 256;
static const int kEofCode = 257;
static const int kFirstFreeCode = 258;

static const unsigned int bitMasks[] = {
    0, 0, 0, 0, 0, 0, 0, 0, 0, 0x1ff, 0x3ff, 0x7ff, 0xfff
};

/* initialize the table */
#define INIT_TABLE() {                          \
        nBitMod1 = 9;                           \
        nBitMask = bitMasks[nBitMod1];          \
        maxCode = 1 << nBitMod1;                \
        freeCode = kFirstFreeCode;              \
    };

/* add a new code to our data structure */
#define ADD_CODE() {                            \
        hashChar[freeCode] = k;                 \
        hashNext[freeCode] = oldCode;           \
        freeCode++;                             \
    };

/* read the next code and put the value into iCode */
#define READ_CODE() {                           \
        int bit_idx  = bitOffset & 0x7;         \
        int byte_idx = bitOffset >> 3;          \
                                                \
        iCode = srcBuf[ byte_idx ];             \
        iCode &= 0xFF;                          \
        iCode |= (srcBuf[ byte_idx+1 ]<<8);     \
        iCode &= 0xFFFF;                        \
        iCode |= (srcBuf[ byte_idx+2 ]<<16);    \
        iCode >>= bit_idx;                      \
        iCode &= nBitMask;                      \
        bitOffset += nBitMod1;                  \
    };

/*static*/ int
DreamGrafix::UnpackLZW(const unsigned char* srcBuf, long srcLen,
    unsigned char* dstBuf, long dstLen)
{
    unsigned short finChar, oldCode, inCode, freeCode, maxCode, k;
    unsigned short nBitMod1, nBitMask;
    int bitOffset;
    unsigned short hashNext[4096];
    unsigned short hashChar[4096];

    unsigned char* pOrigDst = dstBuf;
    int iCode;
    short stack[32768];
    int stackIdx = 0;

    /* initialize table and code reader */
    INIT_TABLE();
    bitOffset = 0;

    while (true) {
        if (dstBuf - pOrigDst > dstLen) {
            WMSG0("LZW overrun\n");
            return -1;
        }

        int A;
        int Y;
        READ_CODE();
        if (iCode == kEofCode) {
            break;
        }

        if (iCode == kClearCode) {
            // Got Clear
            INIT_TABLE();
            READ_CODE();
            oldCode = iCode;
            k = iCode;
            finChar = iCode;
            *dstBuf++ = (unsigned char)iCode;
            continue;
        }

        A = inCode = iCode;

        if (iCode < freeCode) {
            goto inTable;
        }

        stack[stackIdx] = finChar;
        stackIdx++;
        A = oldCode;
inTable:
        if (A < 256) {
            goto gotChar;
        }
        while (A >= 256) {
            Y = A;
            A = hashChar[Y];
    
            stack[stackIdx] = A;
            stackIdx++;
    
            A = hashNext[Y];
        }
gotChar:
        A &= 0xFF;
        finChar = A;
        k = A;
        Y = 0;

        dstBuf[Y++] = A;

        while (stackIdx) {
            stackIdx--;
            A = stack[stackIdx];
            dstBuf[Y++] = A;
        }

        dstBuf += Y;

        ADD_CODE();

        oldCode = inCode;

        if (freeCode < maxCode) {
            continue; // goto nextCode;
        }

        if (12 == nBitMod1) {
            continue; // goto nextCode;
        }

        nBitMod1++;
        nBitMask = bitMasks[nBitMod1];
        //printf("nBitMod1 = %d, nBitMask = %04x\n",
        //          nBitMod1, nBitMask);
        maxCode <<= 1;
    }

    return dstBuf - pOrigDst;
}