/*
 * Functions for reading and converting various restricted
 * C64/etc and/or indexed/paletted graphics formats.
 * Programmed and designed by Matti 'ccr' Hamalainen
 * (C) Copyright 2012-2018 Tecnic Software productions (TNSP)
 *
 * Please read file 'COPYING' for information on license and distribution.
 */
#include "lib64gfx.h"

#define BUF_SIZE_INITIAL   (16*1024)
#define BUF_SIZE_GROW      (4*1024)


// Based on Pepto's palette, stolen from VICE
DMColor dmDefaultC64Palette[C64_NCOLORS] =
{
    { 0x00, 0x00, 0x00, 0xff },
    { 0xFF, 0xFF, 0xFF, 0xff },
    { 0x68, 0x37, 0x2B, 0xff },
    { 0x70, 0xA4, 0xB2, 0xff },
    { 0x6F, 0x3D, 0x86, 0xff },
    { 0x58, 0x8D, 0x43, 0xff },
    { 0x35, 0x28, 0x79, 0xff },
    { 0xB8, 0xC7, 0x6F, 0xff },
    { 0x6F, 0x4F, 0x25, 0xff },
    { 0x43, 0x39, 0x00, 0xff },
    { 0x9A, 0x67, 0x59, 0xff },
    { 0x44, 0x44, 0x44, 0xff },
    { 0x6C, 0x6C, 0x6C, 0xff },
    { 0x9A, 0xD2, 0x84, 0xff },
    { 0x6C, 0x5E, 0xB5, 0xff },
    { 0x95, 0x95, 0x95, 0xff },
};


char * dmC64GetImageTypeString(char *buf, const size_t len, const int type, const BOOL lng)
{
    snprintf(buf, len,
        "%s%s%s%s",
        (type & D64_FMT_MC)    ? (lng ? "MultiColor " : "MC ") : "HiRes ",
        (type & D64_FMT_ILACE) ? (lng ? "Interlaced " : "ILace ") : "",
        (type & D64_FMT_FLI)   ? "FLI " : "",
        (type & D64_FMT_CHAR)  ? "CHAR" : ""
        );

    return buf;
}


void dmC64ImageDump(FILE *fh, const DMC64Image *img, const DMC64ImageFormat *fmt, const char *indent)
{
    char typeStr[64], typeStr2[64];

    dmC64GetImageTypeString(typeStr, sizeof(typeStr), fmt->format->type, TRUE);

    if (fmt != NULL)
    {
        fprintf(fh,
            "%sFormat              : %s [%s]\n",
            indent, fmt->name, fmt->fext);
    }

    if (img != NULL)
    {
        dmC64GetImageTypeString(typeStr2, sizeof(typeStr2), img->type, TRUE);

        fprintf(fh,
            "%sType                : %s [%s]\n"
            "%sBanks               : %d\n",
            indent, typeStr, typeStr2,
            indent, img->nbanks);

        if (img->type & D64_FMT_ILACE)
        {
            char *tmps;
            switch (img->laceType)
            {
                case D64_ILACE_COLOR: tmps = "color"; break;
                case D64_ILACE_RES: tmps = "resolution"; break;
                default: tmps = "ERROR"; break;
            }
            fprintf(fh,
                "%sInterlace type      : %s\n",
                indent, tmps);
        }

        fprintf(fh,
            "%sWidth x Height      : %d x %d [%d x %d]\n"
            "%sCHwidth x CHheight  : %d x %d [%d x %d]\n",
            indent, img->width, img->height,
            fmt->format->width, fmt->format->height,
            indent, img->chWidth, img->chHeight,
            fmt->format->chWidth, fmt->format->chHeight);
    }
    else
    {
        fprintf(fh,
            "%sType                : %s\n"
            "%sWidth x Height      : %d x %d\n"
            "%sCHwidth x CHheight  : %d x %d\n",
            indent, typeStr,
            indent, fmt->format->width, fmt->format->height,
            indent, fmt->format->chWidth, fmt->format->chHeight);
    }
}


void dmSetDefaultC64Palette(DMImage *img)
{
    img->constpal = TRUE;
    img->pal      = dmDefaultC64Palette;
    img->ncolors  = C64_NCOLORS;
    img->ctransp  = 255;
}


BOOL dmSetMixedColorC64Palette(DMImage *img)
{
    if (!dmImagePaletteAlloc(img, C64_NCOLORS * C64_NCOLORS, -1))
        return FALSE;

    int n = 0;
    for (int n1 = 0; n1 < C64_NCOLORS; n1++)
    {
        const DMColor *col1 = &dmDefaultC64Palette[n1];
        for (int n2 = 0; n2 < C64_NCOLORS; n2++)
        {
            const DMColor *col2 = &dmDefaultC64Palette[n2];
            img->pal[n].r = (col1->r + col2->r) / 2;
            img->pal[n].g = (col1->g + col2->g) / 2;
            img->pal[n].b = (col1->b + col2->b) / 2;
            n++;
        }
    }

    return TRUE;
}


BOOL dmCompareAddr16(const DMGrowBuf *buf, const size_t offs, const Uint16 addr)
{
    return
        offs + 1 < buf->len &&
        buf->data[offs    ] == (addr & 0xff) &&
        buf->data[offs + 1] == ((addr >> 8) & 0xff);
}


int dmC64ImageGetNumBanks(const DMC64ImageFormat *fmt)
{
    int nbanks = 0;
    for (int i = 0; i < D64_MAX_ENCDEC_OPS; i++)
    {
        const DMC64EncDecOp *op = fmtGetEncDecOp(fmt, i);
        if (op->type == DO_LAST)
            break;

        if (op->bank > nbanks)
            nbanks = op->bank;
    }

    return nbanks + 1;
}


int dmC64MemBlockAlloc(DMC64MemBlock *blk, const size_t size)
{
    if ((blk->data = dmMalloc0(size)) == NULL)
        return DMERR_MALLOC;

    blk->size = size;
    return DMERR_OK;
}


int dmC64MemBlockReAlloc(DMC64MemBlock *blk, const size_t size)
{
    // Reallocate only if new size is larger
    if (size <= blk->size)
        return DMERR_OK;

    if ((blk->data = dmRealloc(blk->data, size)) == NULL)
        return DMERR_MALLOC;

    dmMemset(blk->data + blk->size, 0, size - blk->size);

    blk->size = size;
    return DMERR_OK;
}


int dmC64MemBlockCopy(DMC64MemBlock *dst, const DMC64MemBlock *src)
{
    if (src->data != NULL && src->size > 0)
    {
        dst->size = src->size;
        if ((dst->data = dmMalloc(src->size)) == NULL)
            return DMERR_MALLOC;

        memcpy(dst->data, src->data, src->size);
        return DMERR_OK;
    }
    else
        return DMERR_INVALID_DATA;
}


void dmC64MemBlockFree(DMC64MemBlock *blk)
{
    if (blk != NULL)
    {
        dmFreeR(&blk->data);
        blk->size = 0;
    }
}


DMC64Image *dmC64ImageAlloc(const DMC64ImageFormat *fmt)
{
    DMC64Image *img = dmMalloc0(sizeof(DMC64Image));

    if (img == NULL)
        return NULL;

    // Initialize image information
    img->type        = fmt->format->type;
    img->width       = fmt->format->width;
    img->height      = fmt->format->height;
    img->chWidth     = fmt->format->chWidth;
    img->chHeight    = fmt->format->chHeight;
    img->nbanks      = dmC64ImageGetNumBanks(fmt);

    // Allocate banks
    if ((img->color = dmCalloc(img->nbanks, sizeof(DMC64MemBlock))) == NULL ||
        (img->bitmap = dmCalloc(img->nbanks, sizeof(DMC64MemBlock))) == NULL ||
        (img->screen = dmCalloc(img->nbanks, sizeof(DMC64MemBlock))) == NULL ||
        (img->charData = dmCalloc(img->nbanks, sizeof(DMC64MemBlock))) == NULL)
        goto err;

    return img;

err:
    dmC64ImageFree(img);
    return NULL;
}


void dmC64ImageFree(DMC64Image *img)
{
    if (img != NULL)
    {
        // Free the allocated areas
        for (int i = 0; i < img->nbanks; i++)
        {
            dmC64MemBlockFree(&img->color[i]);
            dmC64MemBlockFree(&img->bitmap[i]);
            dmC64MemBlockFree(&img->screen[i]);
            dmC64MemBlockFree(&img->charData[i]);
        }

        // Free the pointers to the areas
        dmFree(img->color);
        dmFree(img->bitmap);
        dmFree(img->screen);
        dmFree(img->charData);

        // Extra data ..
        for (int i = 0; i < C64_MAX_EXTRA_DATA; i++)
            dmC64MemBlockFree(&img->extraData[i]);

        dmMemset(img, 0, sizeof(DMC64Image));
        dmFree(img);
    }
}


int dmC64ConvertCSDataToImage(DMImage *img,
    int xoffs, int yoffs, const Uint8 *buf,
    int width, int height, BOOL multicolor,
    int *colors)
{
    int yc, widthpx = width * 8;
    Uint8 *dp;

    if (img == NULL)
        return DMERR_NULLPTR;

    if (xoffs < 0 || yoffs < 0 ||
        xoffs > img->width - widthpx ||
        yoffs > img->height - height)
        return DMERR_INVALID_ARGS;

    dp = img->data + (yoffs * img->pitch) + xoffs;

    if (multicolor)
    {
        for (yc = 0; yc < height; yc++)
        {
            const int offs = yc * width;
            Uint8 *d = dp;

            for (int xc = 0; xc < widthpx / 2; xc++)
            {
                const int b = buf[offs + (xc / 4)];
                const int v = 6 - ((xc * 2) & 6);
                const Uint8 c = colors[(b >> v) & 3];

                *d++ = c;
                *d++ = c;
            }

            dp += img->pitch;
        }
    }
    else
    {
        for (yc = 0; yc < height; yc++)
        {
            const int offs = yc * width;
            Uint8 *d = dp;

            for (int xc = 0; xc < widthpx; xc++)
            {
                const int b = buf[offs + (xc / 8)];
                const int v = 7 - (xc & 7);
                const Uint8 c = colors[(b >> v) & 1];

                *d++ = c;
            }

            dp += img->pitch;
        }
    }

    return DMERR_OK;
}


void dmGenericRLEAnalyze(const DMGrowBuf *buf, DMCompParams *cfg)
{
#define DM_STAT_MAX 256
    size_t *stats;

    // Allocate statistics counts buffer
    if ((stats = dmMalloc0(DM_STAT_MAX * sizeof(size_t))) == NULL)
        return;

    // Get statistics on the data
    for (size_t offs = 0; offs < buf->len; offs++)
        stats[buf->data[offs]]++;

    // According to compression type ..
    switch (cfg->type)
    {
        case DM_COMP_RLE_MARKER:
            {
                size_t selected = 0,
                    smallest = buf->len;

                // Find least used byte value
                for (size_t n = 0; n < DM_STAT_MAX; n++)
                {
                    if (stats[n] < smallest)
                    {
                        switch (cfg->flags & DM_RLE_RUNS_MASK)
                        {
                            case DM_RLE_BYTE_RUNS | DM_RLE_WORD_RUNS:
                                cfg->rleMarkerW = selected;
                                cfg->rleMarkerB = selected = n;
                                break;

                            case DM_RLE_BYTE_RUNS:
                                cfg->rleMarkerB = selected = n;
                                break;

                            case DM_RLE_WORD_RUNS:
                                cfg->rleMarkerW = selected = n;
                                break;
                        }
                        smallest = stats[n];
                    }
                }
            }
            break;

        case DM_COMP_RLE_MASK:
            cfg->rleMarkerMask = 0xC0;
            cfg->rleMarkerBits = 0xC0;
            cfg->rleCountMask  = 0x3f;
            break;
    }

    dmFree(stats);
}


void dmSetupRLEBuffers(DMGrowBuf *dst, DMGrowBuf *src, const DMCompParams *cfg)
{
    if (cfg->flags & DM_RLE_BACKWARDS_INPUT)
    {
        src->offs = src->len;
        src->backwards = TRUE;
    }

    if (cfg->flags & DM_RLE_BACKWARDS_OUTPUT)
    {
        dst->backwards = TRUE;
        dst->offs = dst->size;
    }
}


void dmFinishRLEBuffers(DMGrowBuf *dst, DMGrowBuf *src, const DMCompParams *cfg)
{
    (void) src;

    if (cfg->flags & DM_RLE_BACKWARDS_OUTPUT)
    {
        memmove(dst->data, dst->data + dst->offs, dst->len);
        dst->offs = 0;
    }

    switch (cfg->flags & DM_OUT_CROP_MASK)
    {
        case DM_OUT_CROP_END:
            if (cfg->cropOutLen < dst->len)
            {
                memmove(dst->data, dst->data + dst->len - cfg->cropOutLen, cfg->cropOutLen);
                dst->len = cfg->cropOutLen;
            }
            break;

        case DM_OUT_CROP_START:
            if (cfg->cropOutLen <= dst->len)
                dst->len = cfg->cropOutLen;
            break;
    }
}


int dmGenericRLEOutputRun(DMGrowBuf *dst, const DMCompParams *cfg, const Uint8 data, const unsigned int count)
{
    unsigned int scount;
    for (scount = count; scount; scount--)
    {
        if (!dmGrowBufPutU8(dst, data))
        {
            return dmError(DMERR_MALLOC,
                "%s: RLE: Could not output RLE run %d x 0x%02x @ "
                "offs=0x%" DM_PRIx_SIZE_T ", size=0x%" DM_PRIx_SIZE_T ".\n",
                cfg->func, count, data, dst->offs, dst->size);
        }
    }
    return DMERR_OK;
}


int dmDecodeGenericRLE(DMGrowBuf *dst, const DMGrowBuf *psrc, const DMCompParams *cfg)
{
    int res;
    Uint8 tmp1, tmp2, tmp3, data;
    DMGrowBuf src;

    // As we need to modify the offs, etc. but not the data,
    // we will just make a shallow copy of the DMGrowBuf struct
    dmGrowBufConstCopy(&src, psrc);
    dmSetupRLEBuffers(dst, &src, cfg);

    while (dmGrowBufGetU8(&src, &data))
    {
        unsigned int count = 1;

        if (cfg->type == DM_COMP_RLE_MARKER)
        {
            // A simple marker byte RLE variant: [Marker] [count] [data]
            if ((cfg->flags & DM_RLE_BYTE_RUNS) && data == cfg->rleMarkerB)
            {
                if (!dmGrowBufGetU8(&src, &tmp1))
                {
                    res = dmError(DMERR_INVALID_DATA,
                        "%s: RLE: Invalid data/out of data for byte length run sequence (1).\n",
                        cfg->func);
                    goto out;
                }
                if (!dmGrowBufGetU8(&src, &tmp2))
                {
                    res = dmError(DMERR_INVALID_DATA,
                        "%s: RLE: Invalid data/out of data for byte length run sequence (2).\n",
                        cfg->func);
                    goto out;
                }
                switch (cfg->flags & DM_RLE_ORDER_MASK)
                {
                    case DM_RLE_ORDER_1:
                        count = tmp1;
                        data  = tmp2;
                        break;

                    case DM_RLE_ORDER_2:
                        data  = tmp1;
                        count = tmp2;
                        break;
                }

                if (count == 0 && (cfg->flags & DM_RLE_ZERO_COUNT_MAX))
                    count = 256;
            }
            else
            if ((cfg->flags & DM_RLE_WORD_RUNS) && data == cfg->rleMarkerW)
            {
                if (!dmGrowBufGetU8(&src, &tmp1) ||
                    !dmGrowBufGetU8(&src, &tmp2) ||
                    !dmGrowBufGetU8(&src, &tmp3))
                {
                    res = dmError(DMERR_INVALID_DATA,
                        "%s: RLE: Invalid data/out of data for word length run sequence.\n",
                        cfg->func);
                    goto out;
                }
                switch (cfg->flags & DM_RLE_ORDER_MASK)
                {
                    case DM_RLE_ORDER_1:
                        count = (tmp2 << 8) | tmp1;
                        data = tmp3;
                        break;

                    case DM_RLE_ORDER_2:
                        data = tmp1;
                        count = (tmp3 << 8) | tmp2;
                        break;
                }

                if (count == 0 && (cfg->flags & DM_RLE_ZERO_COUNT_MAX))
                    count = 65536;
            }
        }
        else
        if (cfg->type == DM_COMP_RLE_MASK)
        {
            // Mask marker RLE: usually high bit(s) of byte mark RLE sequence
            // and the lower bits contain the count: [Mask + count] [data]
            if ((data & cfg->rleMarkerMask) == cfg->rleMarkerBits)
            {
                if (!dmGrowBufGetU8(&src, &tmp1))
                {
                    res = dmError(DMERR_INVALID_DATA,
                        "%s: RLE: Invalid data/out of data for byte length mask/run sequence.\n",
                        cfg->func);
                    goto out;
                }

                count = data & cfg->rleCountMask;
                data = tmp1;
            }
        }

        if ((res = dmGenericRLEOutputRun(dst, cfg, data, count)) != DMERR_OK)
            goto out;
    }

    dmFinishRLEBuffers(dst, &src, cfg);
    res = DMERR_OK;

out:
    return res;
}


int dmDecodeGenericRLEAlloc(DMGrowBuf *dst, const DMGrowBuf *src, const DMCompParams *cfg)
{
    int res;
    if ((res = dmGrowBufAlloc(dst, BUF_SIZE_INITIAL, BUF_SIZE_GROW)) != DMERR_OK)
        return res;

    return dmDecodeGenericRLE(dst, src, cfg);
}


int dmEncodeGenericRLESequence(DMGrowBuf *dst, const Uint8 data, unsigned int count, const DMCompParams *cfg)
{
    BOOL copyOnly = FALSE;
    int res;

    switch (cfg->type)
    {
        case DM_COMP_RLE_MARKER:
            if ((cfg->flags & DM_RLE_WORD_RUNS) &&
                (count >= cfg->rleMinCountW || data == cfg->rleMarkerW))
            {
                if (count == 65536 && (cfg->flags & DM_RLE_ZERO_COUNT_MAX))
                    count = 0;

                if (!dmGrowBufPutU8(dst, cfg->rleMarkerW))
                    goto err;

                switch (cfg->flags & DM_RLE_ORDER_MASK)
                {
                    case DM_RLE_ORDER_1:
                        if (!dmGrowBufPutU16LE(dst, count) ||
                            !dmGrowBufPutU8(dst, data))
                            goto err;
                        break;

                    case DM_RLE_ORDER_2:
                        if (!dmGrowBufPutU8(dst, data) ||
                            !dmGrowBufPutU16LE(dst, count))
                            goto err;
                        break;
                }
            }
            else
            if ((cfg->flags & DM_RLE_BYTE_RUNS) &&
                (count >= cfg->rleMinCountB || data == cfg->rleMarkerB))
            {
                if (count == 256 && (cfg->flags & DM_RLE_ZERO_COUNT_MAX))
                    count = 0;

                if (!dmGrowBufPutU8(dst, cfg->rleMarkerB))
                    goto err;

                switch (cfg->flags & DM_RLE_ORDER_MASK)
                {
                    case DM_RLE_ORDER_1:
                        if (!dmGrowBufPutU8(dst, count) ||
                            !dmGrowBufPutU8(dst, data))
                            goto err;
                        break;

                    case DM_RLE_ORDER_2:
                        if (!dmGrowBufPutU8(dst, data) ||
                            !dmGrowBufPutU8(dst, count))
                            goto err;
                        break;
                }
            }
            else
                copyOnly = TRUE;
            break;

        case DM_COMP_RLE_MASK:
            if (count >= cfg->rleMinCountB || (data & cfg->rleMarkerMask) == cfg->rleMarkerBits)
            {
                // Mask marker RLE: usually high bit(s) of byte mark RLE sequence
                // and the lower bits contain the count: [Mask + count] [data]
                if (!dmGrowBufPutU8(dst, cfg->rleMarkerBits | count) ||
                    !dmGrowBufPutU8(dst, data))
                    goto err;
            }
            else
                copyOnly = TRUE;
            break;
    }

    if (copyOnly && (res = dmGenericRLEOutputRun(dst, cfg, data, count)) != DMERR_OK)
        return res;

    return DMERR_OK;

err:
    return dmError(DMERR_MALLOC,
        "%s: RLE: Could not output RLE sequence %d x 0x%02x.\n",
        cfg->func, count, data);
}


int dmEncodeGenericRLE(DMGrowBuf *dst, const DMGrowBuf *psrc, const DMCompParams *cfg)
{
    DMGrowBuf src;
    unsigned int count = 0;
    int prev = -1, res = DMERR_OK;
    Uint8 data;

    // As we need to modify the offs, etc. but not the data,
    // we will just make a shallow copy of the DMGrowBuf struct
    dmGrowBufConstCopy(&src, psrc);
    dmSetupRLEBuffers(dst, &src, cfg);

    while (dmGrowBufGetU8(&src, &data))
    {
        // If new data byte is different, or we exceed the rleMaxCount
        // for the active runs mode(s) .. then encode the run.
        if ((data != prev && prev != -1) ||
            ((cfg->flags & DM_RLE_WORD_RUNS) && count >= cfg->rleMaxCountW) ||
            (((cfg->flags & DM_RLE_RUNS_MASK) == DM_RLE_BYTE_RUNS) && count >= cfg->rleMaxCountB))
        {
            if ((res = dmEncodeGenericRLESequence(dst, prev, count, cfg)) != DMERR_OK)
                goto err;

            count = 1;
        }
        else
            count++;

        prev = data;
    }

    // If there is anything left in the output queue ..
    if ((res = dmEncodeGenericRLESequence(dst, prev, count, cfg)) != DMERR_OK)
        goto err;

    dmFinishRLEBuffers(dst, &src, cfg);

err:
    return res;
}


int dmEncodeGenericRLEAlloc(DMGrowBuf *dst, const DMGrowBuf *src, const DMCompParams *cfg)
{
    int res;
    if ((res = dmGrowBufAlloc(dst, BUF_SIZE_INITIAL, BUF_SIZE_GROW)) != DMERR_OK)
        return res;

    return dmEncodeGenericRLE(dst, src, cfg);
}


int dmC64SanityCheckEncDecOp(const int i, const DMC64EncDecOp *op, const DMC64Image *img)
{
    switch (op->type)
    {
        case DO_COPY:
        case DO_SET_MEM:
        case DO_SET_MEM_HI:
        case DO_SET_MEM_LO:
        case DO_SET_OP:
            switch (op->subject)
            {
                case DS_COLOR_RAM:
                case DS_BITMAP_RAM:
                case DS_SCREEN_RAM:
                case DS_CHAR_DATA:
                    if (op->bank < 0 || op->bank > img->nbanks)
                    {
                        return dmError(DMERR_INTERNAL,
                            "Invalid bank %d / %d definition in generic encode/decode operator %d @ #%d.\n",
                            op->bank, img->nbanks, op->type, i);
                    }
                    break;

                case DS_EXTRA_DATA:
                    if (op->bank < 0 || op->bank >= C64_MAX_EXTRA_DATA)
                    {
                        return dmError(DMERR_INTERNAL,
                            "Invalid bank %d definition in generic encode/decode operator %d @ #%d.\n",
                            op->bank, op->type, i);
                    }
                    break;
            }
            break;

        // Just list the allowed ops here
        case DO_FUNC:
        case DO_CHAR_CFG:
        case DO_LAST:
            break;

        default:
            return dmError(DMERR_INTERNAL,
                "Invalid op type %d in generic encode/decode operator @ #%d.\n",
                op->type, i);
            break;
    }

    return DMERR_OK;
}


size_t dmC64GetSubjectSize(const int subject, const DMC64ImageFormat *fmt)
{
    switch (subject)
    {
        case DS_SCREEN_RAM:
        case DS_COLOR_RAM:
            return fmt->format->chHeight * fmt->format->chWidth;
            break;

        case DS_BITMAP_RAM:
            return fmt->format->chHeight * fmt->format->chWidth * 8;
            break;

        case DS_CHAR_DATA:
            return C64_MAX_CHARS * C64_CHR_SIZE;
            break;

        case DS_D020:
        case DS_BGCOL:
        case DS_D021:
        case DS_D022:
        case DS_D023:
        case DS_D024:
            return 1;
            break;

        default:
            // Default to size of 0
            return 0;
            break;
    }
}


size_t dmC64GetOpSubjectSize(const DMC64EncDecOp *op, const DMC64ImageFormat *fmt)
{
    size_t size = dmC64GetSubjectSize(op->subject, fmt);

    // If the operator specified size is larger, use it.
    if (op->size > size)
        size = op->size;

    return size;
}


const char *dmC64GetOpSubjectName(const int subject)
{
    static const char *subjectNames[DS_LAST] =
    {
        "Color RAM",
        "Bitmap RAM",
        "Screen RAM",
        "Extra data",
        "Character data",

        "d020",
        "d021/bgcol",
        "d022",
        "d023",
        "d024",
    };
    if (subject >= 0 && subject < DS_LAST)
        return subjectNames[subject];
    else
        return NULL;
}


void dmC64GetOpMemBlock(const DMC64Image *img, const int subject, const int bank, const DMC64MemBlock **blk)
{
    *blk = NULL;

    if (bank >= 0 && bank < img->nbanks)
    {
        switch (subject)
        {
            case DS_COLOR_RAM  : *blk = &img->color[bank]; break;
            case DS_SCREEN_RAM : *blk = &img->screen[bank]; break;
            case DS_BITMAP_RAM : *blk = &img->bitmap[bank]; break;
            case DS_CHAR_DATA  : *blk = &img->charData[bank]; break;
            case DS_EXTRA_DATA : *blk = &img->extraData[bank]; break;
        }
    }
}


int dmC64DecodeGenericBMP(DMC64Image *img, const DMGrowBuf *buf, const DMC64ImageFormat *fmt)
{
    int res = DMERR_OK;

    if (buf == NULL || buf->data == NULL || img == NULL || fmt == NULL)
        return DMERR_NULLPTR;

    // Clear the image structure, set basics
    img->type      = fmt->format->type;
    img->width     = fmt->format->width;
    img->height    = fmt->format->height;
    img->chWidth   = fmt->format->chWidth;
    img->chHeight  = fmt->format->chHeight;
    img->nbanks    = dmC64ImageGetNumBanks(fmt);

    // Perform decoding
    for (int i = 0; i < D64_MAX_ENCDEC_OPS; i++)
    {
        const DMC64EncDecOp *op = fmtGetEncDecOp(fmt, i);
        const Uint8 *src;
        DMC64MemBlock *blk = NULL;
        const char *subjname = dmC64GetOpSubjectName(op->subject);
        size_t size;
        Uint8 value;

        // Check for last operator
        if (op->type == DO_LAST)
            break;

        // Check operation validity
        if ((res = dmC64SanityCheckEncDecOp(i, op, img)) != DMERR_OK)
            return res;

        // Is the operation inside the bounds?
        size = dmC64GetOpSubjectSize(op, fmt);
        if (op->type == DO_COPY && op->offs + size > buf->len + 1)
        {
            return dmError(DMERR_INVALID_DATA,
                "Decode SRC out of bounds, op #%d type=%d, subj=%s, offs=%d ($%04x), "
                "bank=%d, size=%d ($%04x) @ %d ($%04x)\n",
                i, op->type, subjname, op->offs, op->offs, op->bank,
                size, size, buf->len, buf->len);
        }

        src = buf->data + op->offs;

        // Perform operation
        switch (op->type)
        {
            case DO_COPY:
            case DO_SET_MEM:
            case DO_SET_MEM_HI:
            case DO_SET_MEM_LO:
            case DO_SET_OP:
                switch (op->subject)
                {
                    case DS_COLOR_RAM:
                    case DS_SCREEN_RAM:
                    case DS_BITMAP_RAM:
                    case DS_CHAR_DATA:
                    case DS_EXTRA_DATA:
                        // XXX BZZZT .. a nasty cast here --v
                        dmC64GetOpMemBlock(img, op->subject, op->bank, (const DMC64MemBlock **) &blk);

                        if ((dmC64MemBlockReAlloc(blk, op->offs2 + size)) != DMERR_OK)
                        {
                            return dmError(DMERR_MALLOC,
                                "Could not allocate '%s' block! "
                                "op #%d, offs=%d ($%04x), bank=%d, size=%d ($%04x) @ %d ($%04x)\n",
                                subjname, i, op->offs, op->offs, op->bank, op->offs2 + size, op->offs2 + size, buf->len, buf->len);
                        }
                        switch (op->type)
                        {
                            case DO_COPY:
                                memcpy(blk->data + op->offs2, src, size);
                                break;

                            case DO_SET_MEM:
                                dmMemset(blk->data + op->offs2, *src, size);
                                break;

                            case DO_SET_MEM_HI:
                                dmMemset(blk->data + op->offs2, (*src >> 4) & 0x0f, size);
                                break;

                            case DO_SET_MEM_LO:
                                dmMemset(blk->data + op->offs2, *src & 0x0f, size);
                                break;

                            case DO_SET_OP:
                                dmMemset(blk->data + op->offs2, op->offs, size);
                                break;

                            default:
                                return dmError(DMERR_INTERNAL,
                                    "Unhandled op type %d in "
                                    "op #%d, offs=%d ($%04x), bank=%d, size=%d ($%04x) @ %d ($%04x)\n",
                                    op->type, i, op->offs, op->offs, op->bank, size, size, buf->len, buf->len);
                        }
                        break;

                    case DS_D020:
                    case DS_BGCOL:
                    case DS_D021:
                    case DS_D022:
                    case DS_D023:
                    case DS_D024:
                        switch (op->type)
                        {
                            case DO_COPY:
                            case DO_SET_MEM:
                                value = *src;
                                break;

                            case DO_SET_OP:
                                value = op->offs;
                                break;

                            case DO_SET_MEM_HI:
                                value = (*src >> 4) & 0x0f;
                                break;

                            case DO_SET_MEM_LO:
                                value = *src & 0x0f;
                                break;

                            default:
                                return dmError(DMERR_INTERNAL,
                                    "Unhandled op type %d in "
                                    "op #%d, offs=%d ($%04x), bank=%d, size=%d ($%04x) @ %d ($%04x)\n",
                                    op->type, i, op->offs, op->offs, op->bank, size, size, buf->len, buf->len);
                        }
                        switch (op->subject)
                        {
                            case DS_D020: img->d020 = value; break;
                            case DS_BGCOL:
                            case DS_D021: img->bgcolor = value; break;
                            case DS_D022: img->d022 = value; break;
                            case DS_D023: img->d023 = value; break;
                            case DS_D024: img->d024 = value; break;
                        }
                        break;

                    default:
                        return dmError(DMERR_INTERNAL,
                            "Unhandled subject %d in "
                            "op #%d, offs=%d ($%04x), bank=%d, size=%d ($%04x) @ %d ($%04x)\n",
                            op->subject, i, op->offs, op->offs, op->bank, size, size, buf->len, buf->len);
                }
                break;

            case DO_CHAR_CFG:
                switch (op->subject)
                {
                    case D64_CHCFG_SCREEN:
                        break;

                    case D64_CHCFG_LINEAR:
                        for (int bank = 0; bank < img->nbanks; bank++)
                        {
                            for (int offs = 0; offs < fmt->format->chHeight * fmt->format->chWidth; offs++)
                                img->screen[bank].data[offs] = offs & 0xff;
                        }
                        break;

                    default:
                        return dmError(DMERR_INTERNAL,
                            "Unhandled DO_CHAR_CFG mode %d in ",
                            "op #%d, bank=%d, size=%d ($%04x) @ %d ($%04x)\n",
                            op->subject, i, op->bank, size, size, buf->len, buf->len);
                }
                break;

            case DO_FUNC:
                if (op->decFunction != NULL &&
                    !op->decFunction(img, op, buf, fmt))
                {
                    return dmError(DMERR_INTERNAL,
                        "Decode op custom function failed: op #%d, "
                        "offs=%d ($%04x), bank=%d, size=%d ($%04x) @ %d ($%04x)\n",
                        i, op->offs, op->offs, op->bank, size, size, buf->len, buf->len);
                }
                break;
        }
    }

    // Sanity check certain things ..
    if ((fmt->format->type & D64_FMT_ILACE) && img->laceType == D64_ILACE_NONE)
    {
        return dmError(DMERR_INTERNAL,
            "Format '%s' (%s) has interlace flag set, but interlace type is not set.\n",
            fmt->name, fmt->fext);
    }

    return DMERR_OK;
}


int dmC64EncodeGenericBMP(const BOOL allocate, DMGrowBuf *buf, const DMC64Image *img, const DMC64ImageFormat *fmt)
{
    int res = DMERR_OK;

    if (img == NULL || fmt == NULL)
        return DMERR_NULLPTR;

    // Allocate the output buffer if requested
    if (allocate && (res = dmGrowBufAlloc(buf, BUF_SIZE_INITIAL, BUF_SIZE_GROW)) != DMERR_OK)
    {
        dmError(res,
            "Could not allocate %d bytes of memory for C64 image encoding buffer.\n",
            fmt->size);
        goto err;
    }

    if (buf->backwards)
    {
        dmError(DMERR_INVALID_DATA,
            "Buffer specified for dmC64EncodeGenericBMP() is in backwards mode, which is not supported.\n");
        goto err;
    }

    // Perform encoding
    for (int i = 0; i < D64_MAX_ENCDEC_OPS; i++)
    {
        const DMC64EncDecOp *op = fmtGetEncDecOp(fmt, i);
        size_t size, chksize;
        const DMC64MemBlock *blk = NULL;
        const char *subjname = dmC64GetOpSubjectName(op->subject);
        Uint8 value;

        // Check for last operator
        if (op->type == DO_LAST)
            break;

        // Check operation validity
        if ((res = dmC64SanityCheckEncDecOp(i, op, img)) != DMERR_OK)
            goto err;

        // Do we need to reallocate some more space?
        size = dmC64GetOpSubjectSize(op, fmt);
        chksize = buf->offs + op->offs + size;
        if (!dmGrowBufCheckGrow(buf, chksize))
        {
            res = dmError(DMERR_MALLOC,
                "Could not re-allocate %d bytes of memory for C64 image encoding buffer.\n",
                chksize);
            goto err;
        }

        // Perform operation
        Uint8 *dst = buf->data + buf->offs + op->offs;
        switch (op->type)
        {
            case DO_COPY:
            case DO_SET_MEM:
            case DO_SET_MEM_HI:
            case DO_SET_MEM_LO:
            case DO_SET_OP:
                switch (op->subject)
                {
                    case DS_COLOR_RAM:
                    case DS_SCREEN_RAM:
                    case DS_BITMAP_RAM:
                    case DS_CHAR_DATA:
                    case DS_EXTRA_DATA:
                        dmC64GetOpMemBlock(img, op->subject, op->bank, &blk);
                        switch (op->type)
                        {
                            case DO_COPY:
                                if (blk->data == NULL)
                                {
                                    res = dmError(DMERR_NULLPTR,
                                        "'%s' block is NULL in "
                                        "op #%d, offs=%d ($%04x), bank=%d, size=%d ($%04x) @ %d ($%04x)\n",
                                        subjname, i, op->offs, op->offs, op->bank, size, size, buf->len, buf->len);
                                    goto err;
                                }
                                if (op->offs2 + size > blk->size)
                                {
                                    res = dmError(DMERR_INTERNAL,
                                        "'%s' size mismatch %d <> %d in "
                                        "op #%d, offs=%d ($%04x), bank=%d, offs2=%d ($%02x), size=%d ($%04x)\n",
                                        subjname, op->offs2 + size, blk->size, i, op->offs, op->offs, op->bank, op->offs2, op->offs2, size, size);
                                    goto err;
                                }
                                memcpy(dst, blk->data + op->offs2, size);
                                break;

                            case DO_SET_MEM:
                            case DO_SET_MEM_HI:
                            case DO_SET_MEM_LO:
                            case DO_SET_OP:
                                // This operation makes no sense in encoding, so do nothing
                                break;

                            default:
                                return dmError(DMERR_INTERNAL,
                                    "Unhandled op type %d in "
                                    "op #%d, offs=%d ($%04x), bank=%d, size=%d ($%04x) @ %d ($%04x)\n",
                                    op->type, i, op->offs, op->offs, op->bank, size, size, buf->len, buf->len);
                        }
                        break;

                    case DS_D020:
                    case DS_BGCOL:
                    case DS_D021:
                    case DS_D022:
                    case DS_D023:
                    case DS_D024:
                        switch (op->subject)
                        {
                            case DS_D020: value = img->d020; break;
                            case DS_BGCOL:
                            case DS_D021: value = img->bgcolor; break;
                            case DS_D022: value = img->d022; break;
                            case DS_D023: value = img->d023; break;
                            case DS_D024: value = img->d024; break;
                        }
                        switch (op->type)
                        {
                            case DO_COPY:
                            case DO_SET_MEM:
                                *dst = value;
                                break;

                            case DO_SET_MEM_HI:
                                *dst |= (value & 0x0f) << 4;
                                break;

                            case DO_SET_MEM_LO:
                                *dst |= value & 0x0f;
                                break;

                            case DO_SET_OP:
                                // Do nothing in this case
                                break;

                            default:
                                return dmError(DMERR_INTERNAL,
                                    "Unhandled op type %d in "
                                    "op #%d, offs=%d ($%04x), bank=%d, size=%d ($%04x) @ %d ($%04x)\n",
                                    op->type, i, op->offs, op->offs, op->bank, size, size, buf->len, buf->len);
                        }
                        break;

                    default:
                        return dmError(DMERR_INTERNAL,
                            "Unhandled subject '%s' in "
                            "op #%d, offs=%d ($%04x), bank=%d, size=%d ($%04x) @ %d ($%04x)\n",
                            subjname, i, op->offs, op->offs, op->bank, size, size, buf->len, buf->len);
                }
                break;

            case DO_FUNC:
                if (op->encFunction != NULL &&
                    !op->encFunction(op, buf, img, fmt))
                {
                    res = dmError(DMERR_INTERNAL,
                        "Encode op custom function failed: op #%d, "
                        "offs=%d ($%04x), bank=%d, size=%d ($%04x) @ %d ($%04x)\n",
                        i, op->offs, op->offs, op->bank, size, size, buf->len, buf->len);
                    goto err;
                }
                break;
        }
    }

    res = DMERR_OK;

err:
    return res;
}


// Convert a generic "C64" format bitmap in DMC64Image struct to
// a indexed/paletted bitmap image.
int dmC64ConvertGenericBMP2Image(DMImage *dst, const DMC64Image *src,
    const DMC64ImageFormat *fmt, const DMC64ImageConvSpec *spec)
{
    DMC64GetPixelFunc getPixel;

    // Sanity check arguments
    if (dst == NULL || src == NULL || fmt == NULL || spec == NULL)
        return DMERR_NULLPTR;

    if (dst->width < src->width || dst->height < src->height)
    {
        return dmError(DMERR_INVALID_DATA,
            "Invalid src vs. dst width/height %d x %d <-> %d x %d\n",
            src->width, src->height, dst->width, dst->height);
    }

    dmMemset(dst->data, 0, dst->size);

    // Check pixel getter function
    if (fmt->format->getPixel != NULL)
        getPixel = fmt->format->getPixel;
    else
        getPixel = (fmt->format->type & D64_FMT_MC) ? fmtGetGenericMCPixel : fmtGetGenericSCPixel;

    // Resolution interlaced pics need to halve the source width
    int rwidth = src->width;
    if ((src->type & D64_FMT_ILACE) && src->laceType == D64_ILACE_RES)
        rwidth /= 2;

    // Perform conversion
    for (int yc = 0; yc < src->height; yc++)
    {
        Uint8 *dp = dst->data + (yc * dst->pitch);
        const int y = yc / 8, yb = yc & 7;
        const int scroffsy = y * src->chWidth;
        const int bmoffsy = y * src->chWidth * 8 + yb;

        for (int xc = 0; xc < rwidth; xc++)
        if (src->type & D64_FMT_CHAR)
        {
            // Charmode conversion
            if ((src->type & D64_FMT_MC) == D64_FMT_HIRES)
            {
                // Hi-res charmap
                const int x = xc / 8;
                const int scroffs = scroffsy + x;
                const int chr = src->screen[0].data[scroffs];
                const int vshift = 7 - (xc & 7);

                if ((src->charData[0].data[chr * C64_CHR_SIZE + yb] >> vshift) & 1)
                    *dp++ = src->color[0].data[scroffs];
                else
                    *dp++ = src->bgcolor;
            }
            else
            {
                // Multicolor variants
                const int x = xc / 4;
                const int scroffs = scroffsy + x;
                const int chr = src->screen[0].data[scroffs];
                const int col = src->color[0].data[scroffs] & 15;

                if (col & 8)
                {
                    const int vshift = 6 - ((xc * 2) & 6);
                    switch ((src->charData[0].data[chr * C64_CHR_SIZE + yb] >> vshift) & 3)
                    {
                        case 0: *dp++ = src->bgcolor; break;
                        case 1: *dp++ = src->d022; break;
                        case 2: *dp++ = src->d023; break;
                        case 3: *dp++ = col;
                    }
                }
                else
                {
                    const int vshift = 7 - (xc & 7);
                    if ((src->charData[0].data[chr * C64_CHR_SIZE + yb] >> vshift) & 1)
                        *dp++ = src->color[0].data[scroffs];
                    else
                        *dp++ = src->bgcolor;
                }
            }
        }
        else
        {
            // Perform generic BITMAP conversion
            if ((src->type & D64_FMT_MC) == D64_FMT_HIRES)
            {
                // Hi-res bitmap
                const int x = xc / 8;
                const int scroffs = scroffsy + x;
                const int bmoffs = bmoffsy + (x * 8);
                const int vshift = 7 - (xc & 7);

                *dp++ = getPixel(src, bmoffs, scroffs, vshift, 0, xc, yc);
            }
            else
            {
                // Multicolor bitmap and variants
                const int x = xc / 4;
                const int scroffs = scroffsy + x;
                const int bmoffs = bmoffsy + (x * 8);
                const int vshift = 6 - ((xc * 2) & 6);

                if (src->type & D64_FMT_ILACE)
                {
                    switch (src->laceType)
                    {
                        case D64_ILACE_RES:
                            *dp++ = getPixel(src, bmoffs, scroffs, vshift, 0, xc, yc);
                            *dp++ = getPixel(src, bmoffs, scroffs, vshift, 1, xc, yc);
                            break;

                        default:
                            return DMERR_NOT_SUPPORTED;
                    }
                }
                else
                {
                    *dp++ = getPixel(src, bmoffs, scroffs, vshift, 0, xc, yc);
                }
            }
        }
    }

    return DMERR_OK;
}


int dmC64ConvertBMP2Image(DMImage **pdst, const DMC64Image *src,
    const DMC64ImageFormat *fmt, const DMC64ImageConvSpec *spec)
{
    int res;
    DMImage *dst;

    if (pdst == NULL || src == NULL || fmt == NULL || spec == NULL)
        return DMERR_NULLPTR;

    // Allocate image structure
    if ((*pdst = dst = dmImageAlloc(src->width, src->height, DM_COLFMT_PALETTE, -1)) == NULL)
        return DMERR_MALLOC;

    // Set partial palette information
    dst->ncolors  = C64_NCOLORS;
    dst->constpal = TRUE;
    dst->pal      = dmDefaultC64Palette;

    // Convert
    if (fmt->format->convertFrom != NULL)
        res = fmt->format->convertFrom(dst, src, fmt, spec);
    else
        res = dmC64ConvertGenericBMP2Image(dst, src, fmt, spec);

    return res;
}


int dmC64DecodeBMP(DMC64Image **img, const DMGrowBuf *buf,
    const size_t probeOffs, const size_t loadOffs,
    const DMC64ImageFormat **fmt, const DMC64ImageFormat *forced)
{
    DMGrowBuf tmp;

    if (img == NULL || buf == NULL)
        return DMERR_NULLPTR;

    // Check for forced format
    if (forced != NULL)
        *fmt = forced;
    else
    {
        // Nope, perform a generic probe
        if (probeOffs >= buf->len)
            return DMERR_OUT_OF_DATA;

        dmGrowBufConstCopyOffs(&tmp, buf, probeOffs);
        if (dmC64ProbeBMP(&tmp, fmt) == DM_PROBE_SCORE_FALSE)
            return DMERR_NOT_SUPPORTED;
    }

    if (loadOffs >= buf->len)
        return DMERR_INVALID_ARGS;

    if (*fmt == NULL)
        return DMERR_NOT_SUPPORTED;

    // Format supports only reading?
    if (((*fmt)->flags & DM_FMT_RD) == 0)
        return DMERR_NOT_SUPPORTED;

    // Allocate memory
    if ((*img = dmC64ImageAlloc(*fmt)) == NULL)
        return DMERR_MALLOC;

    dmGrowBufConstCopyOffs(&tmp, buf, loadOffs);

    // Decode the bitmap to memory layout
    if ((*fmt)->decode != NULL)
        return (*fmt)->decode(*img, &tmp, *fmt);
    else
        return dmC64DecodeGenericBMP(*img, &tmp, *fmt);
}


// Convert a generic bitmap image to DMC64Image
int dmC64ConvertGenericImage2BMP(DMC64Image *dst, const DMImage *src,
    const DMC64ImageFormat *fmt, const DMC64ImageConvSpec *spec)
{
    if (dst == NULL || src == NULL || fmt == NULL || spec == NULL)
        return DMERR_NULLPTR;

    return DMERR_OK;
}


int dmC64ConvertImage2BMP(DMC64Image **pdst, const DMImage *src,
    const DMC64ImageFormat *fmt, const DMC64ImageConvSpec *spec)
{
    int res;
    DMC64Image *dst;

    if (pdst == NULL || src == NULL)
        return DMERR_NULLPTR;

    // Allocate the basic C64 bitmap image structure
    if ((*pdst = dst = dmC64ImageAlloc(fmt)) == NULL)
        return DMERR_MALLOC;

    // Convert
    if (fmt->format->convertTo != NULL)
        res = fmt->format->convertTo(dst, src, fmt, spec);
    else
        res = dmC64ConvertGenericImage2BMP(dst, src, fmt, spec);

    return res;
}


int dmC64EncodeBMP(DMGrowBuf *buf, const DMC64Image *img, const DMC64ImageFormat *fmt)
{
    int res;

    if (buf == NULL || img == NULL || fmt == NULL)
        return DMERR_NULLPTR;

    if ((fmt->flags & DM_FMT_WR) == 0)
        return DMERR_NOT_SUPPORTED;

    // Allocate a buffer
    if ((res = dmGrowBufAlloc(buf, BUF_SIZE_INITIAL, BUF_SIZE_GROW)) != DMERR_OK)
        goto err;

    // Add the loading address
    if (!dmGrowBufPutU16LE(buf, fmt->addr))
        goto err;

    // Attempt to encode the image to a buffer
    if (fmt->encode != NULL)
        res = fmt->encode(buf, img, fmt);
    else
        res = dmC64EncodeGenericBMP(FALSE, buf, img, fmt);

    if (res != DMERR_OK)
        goto err;

    // Finally, if the format has a set size and our buffer is smaller
    // than that size, we grow the buffer to match (with zeroed data).
    // This accounts for format variants that are otherwise identical.
    if (fmt->size > 0 && buf->len < fmt->size &&
        !dmGrowBufCheckGrow(buf, fmt->size))
    {
        res = DMERR_MALLOC;
        goto err;
    }

    return DMERR_OK;

err:
    // In error case, free the buffer
    dmGrowBufFree(buf);
    return res;
}


// Perform probing of the given data buffer, trying to determine
// if it contains a supported "C64" image format. Returns the
// "probe score", see libgfx.h for list of values. If a match
// is found, pointer to format description is set to *pfmt.
int dmC64ProbeBMP(const DMGrowBuf *buf, const DMC64ImageFormat **pfmt)
{
    int scoreMax = DM_PROBE_SCORE_FALSE, scoreIndex = -1;

    for (int i = 0; i < ndmC64ImageFormats; i++)
    {
        const DMC64ImageFormat *fmt = &dmC64ImageFormats[i];
        int score = DM_PROBE_SCORE_FALSE;
        if (fmt->probe == NULL && fmt->size > 0 && fmt->addr > 0)
        {
            // Generic probe just checks matching size and load address
            if (buf->len == fmt->size && dmCompareAddr16(buf, 0, fmt->addr))
                score = DM_PROBE_SCORE_GOOD;
        }
        else
        if (fmt->probe != NULL)
            score = fmt->probe(buf, fmt);

        if (score > scoreMax)
        {
            scoreMax = score;
            scoreIndex = i;
        }
    }

    if (scoreIndex >= 0)
    {
        *pfmt = &dmC64ImageFormats[scoreIndex];
        return scoreMax;
    }
    else
        return DM_PROBE_SCORE_FALSE;
}


void dmC64InitializeFormats(void)
{
    for (int i = 0; i < ndmC64ImageFormats; i++)
    {
        DMC64ImageFormat *fmt = &dmC64ImageFormats[i];
        if (fmt->format == NULL)
            fmt->format = &fmt->formatDef;
    }
}