Load.cs

/* Load */

namespace SharpDune;

static class Load
{
    /*
     * In case the current house is Mercenary, another palette is loaded.
     */
    internal static void Load_Palette_Mercenaries()
    {
        if (g_playerHouseID == HouseType.HOUSE_MERCENARY)
        {
            File_ReadBlockFile("IBM.PAL", g_palette1, 256 * 3);
        }
    }

    internal static bool SaveGame_LoadFile(string filename)
    {
        FileStream fp;
        bool res;

        Sound_Output_Feedback(0xFFFE);

        Game_Init();

        fp = FOpenDataDir(SearchDirectory.SEARCHDIR_PERSONAL_DATA_DIR, filename, "rb");
        if (fp == null)
        {
            Trace.WriteLine($"ERROR: Failed to open file '{filename}' for reading.");
            return false;
        }

        Sprites_LoadTiles();

        g_validateStrictIfZero++;
        res = Load_Main(fp);
        g_validateStrictIfZero--;

        fp.Close();

        if (!res)
        {
            Trace.WriteLine($"ERROR: Error while loading savegame '{filename}'.");
            return false;
        }

        if (g_gameMode != GameMode.GM_RESTART) Game_Prepare();

        return true;
    }

    static bool Load_Main(FileStream fp)
    {
        uint position;
        uint length;
        uint header;
        ushort version;

        try
        {
            using var br = new BinaryReader(fp);
            /* All SharpDUNE / Dune2 savegames should start with 'FORM' */
            header = br.ReadUInt32(); //if (fread(&header, sizeof(uint32), 1, fp) != 1) return false;
            if (BEToH32(header) != (uint)SharpDune.MultiChar[FourCC.FORM])
            {
                Trace.WriteLine("ERROR: Invalid magic header in savegame. Not a SharpDUNE / Dune2 savegame.");
                return false;
            }

            /* The total length field, which is ignored */
            length = br.ReadUInt32(); //if (fread(&length, sizeof(uint32), 1, fp) != 1) return false;

            /* The next 'chunk' is fake, and has no length field */
            header = br.ReadUInt32(); //if (fread(&header, sizeof(uint32), 1, fp) != 1) return false;
            if (BEToH32(header) != (uint)SharpDune.MultiChar[FourCC.SCEN]) return false;

            position = (uint)fp.Position; //ftell(fp);

            /* Find the 'INFO' chunk, as it contains the savegame version */
            version = 0;
            length = Load_FindChunk(br, (uint)SharpDune.MultiChar[FourCC.INFO]);
            if (length == 0) return false;

            /* Read the savegame version */
            if (!FRead_LE_UInt16(ref version, fp)) return false;
            length -= 2;
            if (version == 0) return false;

            if (version != 0x0290)
            {
                /* Get the scenarioID / campaignID */
                if (!Info_LoadOld(br)) return false;

                g_gameMode = GameMode.GM_RESTART;

                /* Find the 'PLYR' chunk */
                fp.Seek(position, SeekOrigin.Begin); //fseek(fp, position, SEEK_SET);
                length = Load_FindChunk(br, (uint)SharpDune.MultiChar[FourCC.PLYR]);
                if (length == 0) return false;

                /* Find the human player */
                if (!House_LoadOld(br, length)) return false;

                GUI_DisplayModalMessage(String_Get_ByIndex(Text.STR_WARNING_ORIGINAL_SAVED_GAMES_ARE_INCOMPATABLE_WITH_THE_NEW_VERSION_THE_BATTLE_WILL_BE_RESTARTED), 0xFFFF);

                return true;
            }

            /* Load the 'INFO' chunk'. It has to be the first chunk loaded */
            if (!Info_Load(br, length)) return false;

            /* Rewind, and read other chunks */
            fp.Seek(position, SeekOrigin.Begin); //fseek(fp, position, SEEK_SET);

            while (true) //(fread(&header, sizeof(uint32), 1, fp) == 1)
            {
                header = br.ReadUInt32();
                length = br.ReadUInt32(); //(fread(&length, sizeof(uint32), 1, fp) != 1)
                length = BEToH32(length);

                var headerValue = BEToH32(header);
                if (headerValue == SharpDune.MultiChar[FourCC.NAME])
                {
                    /* 'NAME' chunk is of no interest to us */
                }
                else if (headerValue == SharpDune.MultiChar[FourCC.INFO])
                {
                    /* 'INFO' chunk is already read */
                }
                else if (headerValue == SharpDune.MultiChar[FourCC.MAP])
                {
                    if (!Map_Load(fp, length)) return false;
                }
                else if (headerValue == SharpDune.MultiChar[FourCC.PLYR])
                {
                    if (!House_Load(br, length)) return false;
                }
                else if (headerValue == SharpDune.MultiChar[FourCC.UNIT])
                {
                    if (!Unit_Load(br, length)) return false;
                }
                else if (headerValue == SharpDune.MultiChar[FourCC.BLDG])
                {
                    if (!Structure_Load(br, length)) return false;
                }
                else if (headerValue == SharpDune.MultiChar[FourCC.TEAM])
                {
                    if (!Team_Load(br, length)) return false;
                }
                else if (headerValue == SharpDune.MultiChar[FourCC.ODUN])
                {
                    if (!UnitNew_Load(br, length)) return false;
                }
                else
                {
                    Trace.WriteLine($"ERROR: Unknown chunk in savegame: {header}{header >> 8}{header >> 16}{header >> 24} (length: {length}). Skipped.");
                }

                /* Savegames are word aligned */
                position += length + 8 + (length & 1);
                fp.Seek(position, SeekOrigin.Begin); //fseek(fp, position, SEEK_SET);
            }
        }
        catch (EndOfStreamException)
        {
            return true;
        }
        catch (IOException e)
        {
            Trace.WriteLine($"ERROR: {e.Message}");
            return false;
        }
    }

    static uint Load_FindChunk(BinaryReader br, uint chunk)
    {
        uint header;
        uint length;

        try
        {
            while (true) //(fread(&header, sizeof(uint32), 1, fp) == 1)
            {
                header = br.ReadUInt32();
                length = br.ReadUInt32(); //(fread(&length, sizeof(uint32), 1, fp) != 1)
                length = BEToH32(length);
                if (BEToH32(header) != chunk)
                {
                    br.BaseStream.Seek(length + (length & 1), SeekOrigin.Current); //fseek(fp, length + (length & 1), SEEK_CUR);
                    continue;
                }
                return length;
            }
        }
        catch (IOException)
        {
            return 0;
        }
    }
}