//int blockWidth = width / blockSizeX;          // width of image in blocks
    //int blockHeight = height / blockSizeY;            // height of image in blocks

    int blockWidth = (width + (blockSizeX - 1)) / blockSizeX;           // width of image in blocks
    int blockHeight = (height + (blockSizeY - 1)) / (blockSizeY - 1);   // height of image in blocks

    // Term "GOB" means "group of bytes". bytes_per_gob_y affects only gobOffset value.
    int gobs_per_block_x = (blockWidth * bytesPerBlock + 63) / 64;
    int bytes_per_gob_x = 64;

    int multi = height / width;
    int bytes_per_gob_y = 8 * multi;

    /*if (blockSizeX == 1 && blockSizeY == 1)
    {
        // Uncompressed tiled texture
        bytes_per_gob_y = 16;
        if (blockHeight < 128) bytes_per_gob_y = 8;
        //?? didn't find when to switch to value 8 (but it seems code works well anyway)
    }*/

    int gob_bytes = bytes_per_gob_x * bytes_per_gob_y; // usually has value 512

    // Smaller textures has different memory layout
    /*if (blockHeight < 64) bytes_per_gob_y = 4;
    if (blockHeight < 32) bytes_per_gob_y = 2;
    if (blockHeight < 16) bytes_per_gob_y = 1;*/

    // Smaller textures has different memory layout
    if (blockHeight < 48) bytes_per_gob_y = 4;
    if (blockHeight < 24) bytes_per_gob_y = 2;
    if (blockHeight < 16) bytes_per_gob_y = 1;

    ////////......////////
    if (swzAddr >= dataSize)
        return true;