/*
 * Functions for reading and converting various restricted
 * C64/etc and/or indexed/paletted graphics formats.
 * Programmed and designed by Matti 'ccr' Hamalainen
 * (C) Copyright 2012-2020 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)


int dmC64PaletteFromC64Colors(DMPalette **ppal, const DMColor *colors, const BOOL mixed)
{
    int res;

    if (ppal == NULL || colors == NULL)
        return DMERR_NULLPTR;

    // Allocate and create new
    if (mixed)
    {
        // Mixed 256 color palette
        if ((res = dmPaletteAlloc(ppal, D64_NCOLORS * D64_NCOLORS, -1)) != DMERR_OK)
            return res;

        for (int n1 = 0, n = 0; n1 < D64_NCOLORS; n1++)
        {
            const DMColor *col1 = &colors[n1];
            for (int n2 = 0; n2 < D64_NCOLORS; n2++)
            {
                const DMColor *col2 = &colors[n2];
                (*ppal)->colors[n].r = (col1->r + col2->r) / 2;
                (*ppal)->colors[n].g = (col1->g + col2->g) / 2;
                (*ppal)->colors[n].b = (col1->b + col2->b) / 2;
                n++;
            }
        }
    }
    else
    {
        // Standard palette, just copy it
        if ((res = dmPaletteAlloc(ppal, D64_NCOLORS, 255)) != DMERR_OK)
            return res;

        memcpy((*ppal)->colors, colors, D64_NCOLORS * sizeof(DMColor));
    }

    return DMERR_OK;
}


int dmC64PaletteFromC64Palette(DMPalette **ppal, const DMC64Palette *cpal, const BOOL mixed)
{
    if (ppal == NULL || cpal == NULL)
        return DMERR_NULLPTR;

    return dmC64PaletteFromC64Colors(ppal, cpal->colors, mixed);
}


int dmC64SetImagePalette(DMImage *img, const DMC64ImageConvSpec *spec, const BOOL mixed)
{
    if (img == NULL || spec == NULL)
        return DMERR_NULLPTR;

    // Free previous palette
    if (!img->constpal)
        dmPaletteFree(img->pal);

    img->constpal = FALSE;

    // If specific palette is wanted, use it
    if (spec->pal != NULL)
    {
        if (spec->pal->ncolors > D64_NCOLORS)
            return dmPaletteCopy(&img->pal, spec->pal);
        else
        if (spec->pal->ncolors == D64_NCOLORS)
            return dmC64PaletteFromC64Colors(&img->pal, spec->pal->colors, mixed);
    }

    // Else, use the c64 palette specified
    return dmC64PaletteFromC64Palette(&img->pal, spec->cpal, mixed);
}


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 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;

    memset(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;
    }
}


static void dmC64SetupImageData(DMC64Image *img, const DMC64ImageFormat *fmt)
{
    int nblocks = 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 > nblocks)
            nblocks = op->bank;
    }

    img->fmt      = fmt->format;
    img->nblocks  = nblocks + 1;

    memset(img->extraInfo, 0, sizeof(img->extraInfo));
    img->extraInfo[D64_EI_MODE] = fmt->format->mode;
}


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

    if (img == NULL)
        return NULL;

    // Initialize image information
    dmC64SetupImageData(img, fmt);

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

    return img;

out:
    dmC64ImageFree(img);
    return NULL;
}


void dmC64ImageFree(DMC64Image *img)
{
    if (img != NULL)
    {
        // Free the allocated areas
        for (int i = 0; i < img->nblocks; 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 < D64_MAX_EXTRA_DATA; i++)
            dmC64MemBlockFree(&img->extraData[i]);

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


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

    if (img == NULL)
        return DMERR_NULLPTR;

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

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

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

            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];

                *dp++ = c;
                *dp++ = c;
            }

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

            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];

                *dp++ = c;
            }

            dpp += img->pitch;
        }
    }

    return DMERR_OK;
}


int dmGenericRLEAnalyze(const DMGrowBuf *buf, DMCompParams *cfg)
{
#define DM_STAT_MAX 256
    Uint8 *stats = NULL;

    // Allocate statistics counts buffer
    if ((stats = dmMalloc0(DM_STAT_MAX * sizeof(Uint8))) == NULL)
        return DMERR_MALLOC;

    // 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);
    return DMERR_OK;
}


//#define RLE_DEBUG

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

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

#ifdef RLE_DEBUG
fprintf(stderr, "dmSetupRLEBuffers:\n");
if (src != NULL)
fprintf(stderr, "  src.len=%" DM_PRIx_SIZE_T ", src.size=%" DM_PRIx_SIZE_T ", src.offs=%" DM_PRIx_SIZE_T "\n", src->len, src->size, src->offs);
if (dst != NULL)
fprintf(stderr, "  dst.len=%" DM_PRIx_SIZE_T ", dst.size=%" DM_PRIx_SIZE_T ", dst.offs=%" DM_PRIx_SIZE_T "\n", dst->len, dst->size, dst->offs);
fprintf(stderr, "------------------\n");
#endif
}


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

#ifdef RLE_DEBUG
fprintf(stderr, "------------------\n");
fprintf(stderr, "dmFinishRLEBuffers:\n");
if (src != NULL)
fprintf(stderr, "  src.len=%" DM_PRIx_SIZE_T ", src.size=%" DM_PRIx_SIZE_T ", src.offs=%" DM_PRIx_SIZE_T "\n", src->len, src->size, src->offs);
if (dst != NULL)
fprintf(stderr, "  dst.len=%" DM_PRIx_SIZE_T ", dst.size=%" DM_PRIx_SIZE_T ", dst.offs=%" DM_PRIx_SIZE_T "\n", dst->len, dst->size, dst->offs);
#endif

    if (dst != NULL)
    {
        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;
        }
    }

#ifdef RLE_DEBUG
fprintf(stderr, "ADJUSTED:\n");
if (src != NULL)
fprintf(stderr, "  src.len=%" DM_PRIx_SIZE_T ", src.size=%" DM_PRIx_SIZE_T ", src.offs=%" DM_PRIx_SIZE_T "\n", src->len, src->size, src->offs);
if (dst != NULL)
fprintf(stderr, "  dst.len=%" DM_PRIx_SIZE_T ", dst.size=%" DM_PRIx_SIZE_T ", dst.offs=%" DM_PRIx_SIZE_T "\n", dst->len, dst->size, dst->offs);
#endif
}


int dmGenericRLEOutputRun(DMGrowBuf *dst, const DMCompParams *cfg, const Uint8 data, const unsigned int count)
{
    for (unsigned int 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))
                {
#ifdef RLE_DEBUG
fprintf(stderr, "  marker=$%02x\n", cfg->rleMarkerB);
fprintf(stderr, "  src.len=%" DM_PRIx_SIZE_T ", src.size=%" DM_PRIx_SIZE_T ", src.offs=%" DM_PRIx_SIZE_T "\n", src.len, src.size, src.offs);
fprintf(stderr, "  dst.len=%" DM_PRIx_SIZE_T ", dst.size=%" DM_PRIx_SIZE_T ", dst.offs=%" DM_PRIx_SIZE_T "\n", dst->len, dst->size, dst->offs);
#endif
                    res = dmError(DMERR_INVALID_DATA,
                        "%s: RLE: Invalid data/out of data for byte length run sequence (1).\n",
                        cfg->func);
                    goto out;
                }
                if (!dmGrowBufGetU8(&src, &tmp2))
                {
#ifdef RLE_DEBUG
fprintf(stderr, "  marker=$%02x, data=$%02x\n", cfg->rleMarkerB, tmp1);
fprintf(stderr, "  src.len=%" DM_PRIx_SIZE_T ", src.size=%" DM_PRIx_SIZE_T ", src.offs=%" DM_PRIx_SIZE_T "\n", src.len, src.size, src.offs);
fprintf(stderr, "  dst.len=%" DM_PRIx_SIZE_T ", dst.size=%" DM_PRIx_SIZE_T ", dst.offs=%" DM_PRIx_SIZE_T "\n", dst->len, dst->size, dst->offs);
#endif
                    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 out;

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

                    case DM_RLE_ORDER_2:
                        if (!dmGrowBufPutU8(dst, data) ||
                            !dmGrowBufPutU16LE(dst, count))
                            goto out;
                        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 out;

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

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

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

    return DMERR_OK;

out:
    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 out;

            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 out;

    dmFinishRLEBuffers(dst, &src, cfg);

out:
    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)
{
    if (op->flags == 0)
    {
        return dmError(DMERR_INTERNAL,
            "Invalid operation flags value %d in generic encode/decode operator %d @ #%d.\n",
            op->flags, op->type, i);
    }

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

                case DS_EXTRA_DATA:
                    if (op->bank < 0 || op->bank >= D64_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 DMC64ImageCommonFormat *fmt)
{
    switch (subject)
    {
        case DS_SCREEN_RAM:
        case DS_COLOR_RAM:
            return fmt->chHeight * fmt->chWidth;

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

        case DS_CHAR_DATA:
            return D64_MAX_CHARS * D64_CHR_SIZE;

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

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


size_t dmC64GetOpSubjectSize(const DMC64EncDecOp *op, const DMC64ImageCommonFormat *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 / border",
        "d021 / background",
        "d022",
        "d023",
        "d024",
    };
    if (subject >= 0 && subject < DS_LAST)
        return subjectNames[subject];
    else
        return NULL;
}


const char *dmC64GetOpType(const int type)
{
    static const char *typeNames[DO_LAST] =
    {
        "COPY",
        "SET_MEM",
        "SET_OP",
        "SET_MEM_HI",
        "SET_MEM_LO",

        "FUNC",
        "CHAR_CFG",
    };
    if (type >= 0 && type < DO_LAST)
        return typeNames[type];
    else
        return "ERROR";
}


const DMC64MemBlock * dmC64GetOpMemBlock(const DMC64Image *img, const int subject, const int bank)
{
    if (bank >= 0 && bank < img->nblocks)
    {
        switch (subject)
        {
            case DS_COLOR_RAM  : return &img->color[bank];
            case DS_SCREEN_RAM : return &img->screen[bank];
            case DS_BITMAP_RAM : return &img->bitmap[bank];
            case DS_CHAR_DATA  : return &img->charData[bank];
            case DS_EXTRA_DATA : return &img->extraData[bank];
        }
    }

    return NULL;
}


typedef struct
{
    int opn;
    const DMC64EncDecOp *op;
    size_t size;
    const DMGrowBuf *buf;
    const char *subjname;
} DMC64EncDecCtx;


static void dmC64EncDecErrorMsg(DMC64EncDecCtx *ctx, const char *msg)
{
    dmErrorMsg(
        "%s in op #%d, subject='%s', "
        "offs=%d ($%04x), bank=%d, "
        "size=%" DM_PRIu_SIZE_T " ($%04" DM_PRIx_SIZE_T ") "
        "@ %" DM_PRIu_SIZE_T " ($%04" DM_PRIx_SIZE_T ")\n",
        msg, ctx->opn, ctx->subjname,
        ctx->op->offs, ctx->op->offs,
        ctx->op->bank,
        ctx->size, ctx->size,
        ctx->buf->len, ctx->buf->len);
}


DM_ATTR_PRINTF_FMT(3, 4)
static int dmC64EncDecError(DMC64EncDecCtx *ctx, const int res, const char *fmt, ...)
{
    char *msg;
    va_list ap;

    va_start(ap, fmt);
    msg = dm_strdup_vprintf(fmt, ap);
    va_end(ap);

    dmC64EncDecErrorMsg(ctx, msg);

    dmFree(msg);
    return res;
}


int dmC64DecodeGenericBMP(DMC64Image *img, const DMGrowBuf *buf, const DMC64ImageFormat *fmt)
{
    DMC64EncDecCtx ctx;
    int res = DMERR_OK;

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

    dmC64SetupImageData(img, fmt);
    ctx.buf = buf;

    // Perform decoding
    for (ctx.opn = 0; ctx.opn < D64_MAX_ENCDEC_OPS; ctx.opn++)
    {
        DMC64MemBlock *blk = NULL;
        const Uint8 *src;
        Uint8 value;

        ctx.op = fmtGetEncDecOp(fmt, ctx.opn);
        ctx.subjname = dmC64GetOpSubjectName(ctx.op->subject);

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

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

        // Check flags
        if ((ctx.op->flags & DF_DECODE) == 0)
            continue;

        // Is the operation inside the bounds?
        ctx.size = dmC64GetOpSubjectSize(ctx.op, fmt->format);
        if (ctx.op->type == DO_COPY && ctx.op->offs + ctx.size > buf->len + 1)
        {
            return dmC64EncDecError(&ctx, DMERR_INVALID_DATA,
                "Decode SRC out of bounds");
        }

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

        // Perform operation
        switch (ctx.op->type)
        {
            case DO_COPY:
            case DO_SET_MEM:
            case DO_SET_MEM_HI:
            case DO_SET_MEM_LO:
            case DO_SET_OP:
                switch (ctx.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
                        blk = (DMC64MemBlock *) dmC64GetOpMemBlock(img, ctx.op->subject, ctx.op->bank);

                        if ((dmC64MemBlockReAlloc(blk, ctx.op->blkoffs + ctx.size)) != DMERR_OK)
                        {
                            return dmC64EncDecError(&ctx, DMERR_MALLOC,
                                "Could not allocate '%s' block",
                                ctx.subjname);
                        }
                        switch (ctx.op->type)
                        {
                            case DO_COPY:
                                memcpy(blk->data + ctx.op->blkoffs, src, ctx.size);
                                break;

                            case DO_SET_MEM:
                                memset(blk->data + ctx.op->blkoffs, *src, ctx.size);
                                break;

                            case DO_SET_MEM_HI:
                                memset(blk->data + ctx.op->blkoffs, (*src >> 4) & 0x0f, ctx.size);
                                break;

                            case DO_SET_MEM_LO:
                                memset(blk->data + ctx.op->blkoffs, *src & 0x0f, ctx.size);
                                break;

                            case DO_SET_OP:
                                memset(blk->data + ctx.op->blkoffs, ctx.op->offs, ctx.size);
                                break;

                            default:
                                return dmC64EncDecError(&ctx, DMERR_INTERNAL,
                                    "Unhandled op type '%s'",
                                    dmC64GetOpType(ctx.op->type));
                        }
                        break;

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

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

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

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

                            default:
                                return dmC64EncDecError(&ctx, DMERR_INTERNAL,
                                    "Unhandled op type '%s'",
                                    dmC64GetOpType(ctx.op->type));
                        }
                        switch (ctx.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;
                            case DS_EXTRA_INFO: img->extraInfo[ctx.op->blkoffs] = value; break;
                        }
                        break;

                    default:
                        return dmC64EncDecError(&ctx, DMERR_INTERNAL,
                            "Unhandled subject '%s'",
                            ctx.subjname);
                }
                break;

            case DO_FUNC:
                if (ctx.op->decFunction != NULL &&
                    (res = ctx.op->decFunction(ctx.op, img, buf, fmt->format)) != DMERR_OK)
                {
                    return dmC64EncDecError(&ctx, res,
                        "Decode op custom function failed");
                }
                break;
        }
    }

    // Sanity check certain things ..
    if ((img->extraInfo[D64_EI_MODE] & D64_FMT_ILACE) &&
        img->extraInfo[D64_EI_ILACE_TYPE] == 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)
{
    DMC64EncDecCtx ctx;
    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)
    {
        return dmError(res,
            "Could not allocate %" DM_PRIu_SIZE_T " bytes of memory for C64 image encoding buffer.\n",
            fmt->size);
    }

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

    ctx.buf = buf;

    // Perform encoding
    for (ctx.opn = 0; ctx.opn < D64_MAX_ENCDEC_OPS; ctx.opn++)
    {
        const DMC64MemBlock *blk = NULL;
        size_t chksize;
        Uint8 value;

        ctx.op = fmtGetEncDecOp(fmt, ctx.opn);
        ctx.subjname = dmC64GetOpSubjectName(ctx.op->subject);

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

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

        // Check flags
        if ((ctx.op->flags & DF_ENCODE) == 0)
            continue;

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

        // Perform operation
        Uint8 *dst = buf->data + buf->offs + ctx.op->offs;
        switch (ctx.op->type)
        {
            case DO_COPY:
            case DO_SET_MEM:
            case DO_SET_MEM_HI:
            case DO_SET_MEM_LO:
            case DO_SET_OP:
                switch (ctx.op->subject)
                {
                    case DS_COLOR_RAM:
                    case DS_SCREEN_RAM:
                    case DS_BITMAP_RAM:
                    case DS_CHAR_DATA:
                    case DS_EXTRA_DATA:
                        blk = dmC64GetOpMemBlock(img, ctx.op->subject, ctx.op->bank);
                        switch (ctx.op->type)
                        {
                            case DO_COPY:
                                if (blk->data == NULL)
                                {
                                    return dmC64EncDecError(&ctx, DMERR_NULLPTR,
                                        "'%s' block is NULL",
                                        ctx.subjname);
                                }
                                if (ctx.op->blkoffs + ctx.size > blk->size)
                                {
                                    return dmC64EncDecError(&ctx, DMERR_INTERNAL,
                                        "'%s' size mismatch %" DM_PRIu_SIZE_T " <> %" DM_PRIu_SIZE_T,
                                        ctx.subjname, ctx.op->blkoffs + ctx.size, blk->size);
                                }
                                memcpy(dst, blk->data + ctx.op->blkoffs, ctx.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 dmC64EncDecError(&ctx, DMERR_INTERNAL,
                                    "Unhandled op type '%s'",
                                    dmC64GetOpType(ctx.op->type));
                        }
                        break;

                    case DS_D020:
                    case DS_BGCOL:
                    case DS_D021:
                    case DS_D022:
                    case DS_D023:
                    case DS_D024:
                    case DS_EXTRA_INFO:
                        switch (ctx.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;
                            case DS_EXTRA_INFO: value = img->extraInfo[ctx.op->blkoffs]; break;
                        }
                        switch (ctx.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
                                // XXX TODO: what about DS_EXTRA_INFO?
                                break;

                            default:
                                return dmC64EncDecError(&ctx, DMERR_INTERNAL,
                                    "Unhandled op type '%s'",
                                    dmC64GetOpType(ctx.op->type));
                        }
                        break;

                    default:
                        return dmC64EncDecError(&ctx, DMERR_INTERNAL,
                            "Unhandled subject '%s'", ctx.subjname);
                }
                break;

            case DO_FUNC:
                if (ctx.op->encFunction != NULL &&
                    (res = ctx.op->encFunction(ctx.op, buf, img, fmt->format)) != DMERR_OK)
                {
                    return dmC64EncDecError(&ctx, res,
                        "Encode op custom function failed");
                }
                break;
        }
    }

    return DMERR_OK;
}


//
// Helper functions for pixel format decoding
//
int dmC64GetGenericSCPixel(Uint8 *col,
    const DMC64Image *img, const int bmoffs, const int scroffs,
    const int vshift, const int vbank, const int bitmap)
{
    if ((img->bitmap[bitmap].data[bmoffs] >> vshift) & 1)
        *col = img->screen[vbank].data[scroffs] >> 4;
    else
        *col = img->screen[vbank].data[scroffs] & 15;

    return DMERR_OK;
}


int dmC64GetGenericMCPixel(Uint8 *col,
    const DMC64Image *img, const int bmoffs, const int scroffs,
    const int vshift, const int vbank, const int bitmap,
    const int cbank, const int bgcolor)
{
    switch ((img->bitmap[bitmap].data[bmoffs] >> vshift) & 3)
    {
        case  0: *col = bgcolor & 15; break;
        case  1: *col = img->screen[vbank].data[scroffs] >> 4; break;
        case  2: *col = img->screen[vbank].data[scroffs] & 15; break;
        default: *col = img->color[cbank].data[scroffs] & 15; break;
    }

    return DMERR_OK;
}


int dmC64GetGenericCharSCPixel(Uint8 *col,
    const DMC64Image *img, const int scroffs, const int rasterX,
    const int chrbank, const size_t chroffs, const int chr,
    const int cbank, const int bgcolor)
{
    if (chroffs >= img->charData[chrbank].size)
    {
        return dmError(DMERR_INVALID_DATA,
            "Character map index #%d out of bounds for char ROM data.\n",
            chr);
    }

    const int vshift = 7 - (rasterX & 7);
    if ((img->charData[chrbank].data[chroffs] >> vshift) & 1)
        *col = img->color[cbank].data[scroffs] & 15;
    else
        *col = bgcolor & 15;

    return DMERR_OK;
}


int dmC64GetGenericCharMCPixel(Uint8 *col,
    const DMC64Image *img, const int scroffs, const int rasterX,
    const int chrbank, const size_t chroffs, const int chr,
    const int cbank, const int bgcolor,
    const int bgd022, const int bgd023)
{
    if (chroffs >= img->charData[chrbank].size)
    {
        return dmError(DMERR_INVALID_DATA,
            "Character map index #%d out of bounds for char ROM data.\n",
            chr);
    }

    const int ccol = img->color[cbank].data[scroffs];
    if (ccol & 8)
    {
        const int vshift = 6 - (rasterX & 6);
        switch ((img->charData[chrbank].data[chroffs] >> vshift) & 3)
        {
            case 0: *col = bgcolor & 15; break;
            case 1: *col = bgd022 & 15; break;
            case 2: *col = bgd023 & 15; break;
            case 3: *col = ccol & 7;
        }
    }
    else
    {
        const int vshift = 7 - (rasterX & 7);
        if ((img->charData[chrbank].data[chroffs] >> vshift) & 1)
            *col = ccol & 7;
        else
            *col = bgcolor & 15;
    }

    return DMERR_OK;
}


int dmC64GetGenericCharECMPixel(Uint8 *col,
    const DMC64Image *img, const int scroffs, const int rasterX,
    const int chrbank, const size_t chroffs, const int chr,
    const int cbank, const int bgcolor,
    const int bgd022, const int bgd023, const int bgd024)
{
    if (chroffs >= img->charData[0].size)
    {
        return dmError(DMERR_INVALID_DATA,
            "Character map index #%d out of bounds for char ROM data.\n",
            chr);
    }

    const int vshift = 7 - (rasterX & 7);
    if ((img->charData[chrbank].data[chroffs] >> vshift) & 1)
        *col = img->color[cbank].data[scroffs] & 15;
    else
    switch ((chr >> 6) & 3)
    {
        case 0: *col = bgcolor & 15; break;
        case 1: *col = bgd022 & 15; break;
        case 2: *col = bgd023 & 15; break;
        case 3: *col = bgd024 & 15; break;
    }

    return DMERR_OK;
}


static int fmtGetGenericSCPixel(DMC64ScanLine *scan,
    const DMC64Image *img, const int rasterX, const int rasterY)
{
    DM_C64_GENERIC_SC_PIXEL_DEFS(img)

    return dmC64GetGenericSCPixel(
        scan->col, img,
        bmoffs, scroffs,
        vshift, 0, 0);
}


static int fmtGetGenericMCPixel(DMC64ScanLine *scan,
    const DMC64Image *img, const int rasterX, const int rasterY)
{
    DM_C64_GENERIC_MC_PIXEL_DEFS(img)

    return dmC64GetGenericMCPixel(
        scan->col, img,
        bmoffs, scroffs,
        vshift, 0,
        0, 0, img->bgcolor);
}


static int fmtGetGenericCharPixel(DMC64ScanLine *scan,
    const DMC64Image *img, const int rasterX, const int rasterY)
{
    DM_C64_GENERIC_CHAR_PIXEL(img)
    int chr = img->screen[0].data[scroffs];

    if (!img->extraInfo[D64_EI_CHAR_CUSTOM] &&
        img->extraInfo[D64_EI_CHAR_CASE])
        chr += 256; // lower case, so add 256 to char ROM offset

    switch (img->extraInfo[D64_EI_MODE] & D64_FMT_MODE_MASK)
    {
        case D64_FMT_HIRES:
            return dmC64GetGenericCharSCPixel(
                scan->col, img,
                scroffs, rasterX,
                0, (chr * D64_CHR_SIZE) + (rasterY & 7), chr,
                0, img->bgcolor);

        case D64_FMT_MC:
            return dmC64GetGenericCharMCPixel(
                scan->col, img,
                scroffs, rasterX,
                0, (chr * D64_CHR_SIZE) + (rasterY & 7), chr,
                0, img->bgcolor, img->d022, img->d023);

        case D64_FMT_ECM:
            return dmC64GetGenericCharECMPixel(
                scan->col, img,
                scroffs, rasterX,
                0, ((chr & 0x3f) * D64_CHR_SIZE) + (rasterY & 7), chr,
                0, img->bgcolor, img->d022, img->d023, img->d024);

        default:
            return dmError(DMERR_INVALID_DATA,
                "Invalid character map image mode=0x%x.\n",
                img->extraInfo[D64_EI_MODE]);
    }
}


// Convert a C64 format bitmap in DMC64Image struct to
// a indexed/paletted bitmap image.
static int dmC64ConvertGenericBMP2Image(DMImage *dst, const DMC64Image *src, const DMC64ImageConvSpec *spec)
{
    DMC64GetPixelFunc getPixel;
    DMC64ScanLine scan;

    (void) spec;

    // Check pixel getter function
    if (src->fmt->getPixel != NULL)
        getPixel = src->fmt->getPixel;
    else
    if (src->extraInfo[D64_EI_MODE] & D64_FMT_CHAR)
        getPixel = fmtGetGenericCharPixel;
    else
    switch (src->extraInfo[D64_EI_MODE] & D64_FMT_MODE_MASK)
    {
        case D64_FMT_MC    : getPixel = fmtGetGenericMCPixel; break;
        case D64_FMT_HIRES : getPixel = fmtGetGenericSCPixel; break;
        default:
            return dmError(DMERR_INVALID_DATA,
                "Invalid bitmap image type/fmt=0x%x.\n",
                src->extraInfo[D64_EI_MODE]);
    }

    memset(dst->data, 0, dst->size);
    memset(&scan, 0, sizeof(scan));

    // Perform conversion
    for (int yc = 0; yc < dst->height; yc++)
    {
        scan.col = dst->data + (yc * dst->pitch);
        for (int xc = 0; xc < dst->width; xc++, scan.col++)
        {
            int res;
            if ((res = getPixel(&scan, src, xc, yc)) != DMERR_OK)
                return res;
        }
    }

    return DMERR_OK;
}


int dmC64ConvertBMP2Image(DMImage **pdst, const DMC64Image *src, const DMC64ImageConvSpec *pspec)
{
    DMC64ImageConvSpec spec;
    BOOL mixed;
    int res;

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

    memcpy(&spec, pspec, sizeof(spec));

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

    // Set palette information
    mixed = (src->extraInfo[D64_EI_MODE] & D64_FMT_ILACE) &&
        src->extraInfo[D64_EI_ILACE_TYPE] == D64_ILACE_COLOR;

    if ((res = dmC64SetImagePalette(*pdst, &spec, mixed)) != DMERR_OK)
        return res;

    // Perform the conversion
    if (src->fmt->convertFrom != NULL)
        res = src->fmt->convertFrom(*pdst, src, &spec);
    else
        res = dmC64ConvertGenericBMP2Image(*pdst, src, &spec);

    return res;
}


int dmC64DecodeBMP(DMC64Image **img, const DMGrowBuf *buf,
    ssize_t probeOffs, ssize_t dataOffs,
    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 < 0)
            probeOffs = 0;

        if ((size_t) 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 (*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;

    // If the format has a loading address, adjust buffer
    if (dataOffs < 0)
        dataOffs = 2;

    if ((*fmt)->addr >= 0)
        dmGrowBufConstCopyOffs(&tmp, buf, dataOffs);
    else
        dmGrowBufConstCopy(&tmp, buf);

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


int dmC64MemBlockAllocSubj(DMC64Image *img, const int subject, const int bank)
{
    const char *subjname = dmC64GetOpSubjectName(subject);
    size_t size = dmC64GetSubjectSize(subject, img->fmt);
    DMC64MemBlock *blk = (DMC64MemBlock *) dmC64GetOpMemBlock(img, subject, bank);
    int res;

    if ((res = dmC64MemBlockAlloc(blk, size)) != DMERR_OK)
    {
        return dmError(res,
            "Could not allocate '%s' block with size %" DM_PRIu_SIZE_T " bytes.\n",
            subjname, size);
    }

    return DMERR_OK;
}


// Convert a generic bitmap image to DMC64Image
static 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_NOT_SUPPORTED;
}


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 out;

    // Add the loading address, if needed
    if (fmt->addr >= 0 &&
        !dmGrowBufPutU16LE(buf, fmt->addr))
    {
        res = DMERR_MALLOC;
        goto out;
    }

    // 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 out;

    // 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 out;
    }

    return DMERR_OK;

out:
    // 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;
}


BOOL             dmLib64GFXInitialized = FALSE;
DMC64ImageFormat **dmC64ImageFormatsSorted = NULL;


int dmC64ImageFormatCompare(const void *va, const void *vb)
{
    const DMC64ImageFormat
        *fmta = *(DMC64ImageFormat **) va,
        *fmtb = *(DMC64ImageFormat **) vb;

    int res = fmta->format->mode - fmtb->format->mode;
    if (res == 0)
        return strcmp(fmta->name, fmtb->name);
    else
        return res;
}


int dmLib64GFXInit(void)
{
    // Safety check
    if (dmLib64GFXInitialized)
        dmLib64GFXClose();

    dmLib64GFXInitialized = TRUE;

    if ((dmC64ImageFormatsSorted = dmCalloc(ndmC64ImageFormats, sizeof(dmC64ImageFormatsSorted[0]))) == NULL)
        return DMERR_MALLOC;

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

        dmC64ImageFormatsSorted[i] = fmt;
    }

    qsort(dmC64ImageFormatsSorted, ndmC64ImageFormats,
        sizeof(DMC64ImageFormat *), dmC64ImageFormatCompare);

    return DMERR_OK;
}


void dmLib64GFXClose(void)
{
    dmFreeR(&dmC64ImageFormatsSorted);
    dmLib64GFXInitialized = FALSE;
}