oldloader.h

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/*
 * This file is part of OpenTTD.
 * OpenTTD is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, version 2.
 * OpenTTD is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 * See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with OpenTTD. If not, see <http://www.gnu.org/licenses/>.
 */
 
#ifndef OLDLOADER_H
#define OLDLOADER_H
 
#include "saveload.h"
#include "../tile_type.h"
 
static const uint BUFFER_SIZE = 4096;
static const uint OLD_MAP_SIZE = 256;
 
struct LoadgameState {
  std::optional<FileHandle> file;
 
  uint chunk_size;
 
  bool decoding;
  uint8_t decode_char;
 
  uint buffer_count;
  uint buffer_cur;
  uint8_t buffer[BUFFER_SIZE];
 
  uint total_read;
};
 
/* OldChunk-Type */
enum OldChunkType {
  OC_SIMPLE    = 0,
  OC_NULL      = 1,
  OC_CHUNK     = 2,
  OC_ASSERT    = 3,
  /* 4 bits allocated (16 max) */
 
  OC_TTD       = 1 << 4, 
  OC_TTO       = 1 << 5, 
  /* 4 bits allocated */
 
  OC_VAR_I8    = 1 << 8,
  OC_VAR_U8    = 2 << 8,
  OC_VAR_I16   = 3 << 8,
  OC_VAR_U16   = 4 << 8,
  OC_VAR_I32   = 5 << 8,
  OC_VAR_U32   = 6 << 8,
  OC_VAR_I64   = 7 << 8,
  OC_VAR_U64   = 8 << 8,
  /* 8 bits allocated (256 max) */
 
  OC_FILE_I8   = 1 << 16,
  OC_FILE_U8   = 2 << 16,
  OC_FILE_I16  = 3 << 16,
  OC_FILE_U16  = 4 << 16,
  OC_FILE_I32  = 5 << 16,
  OC_FILE_U32  = 6 << 16,
  /* 8 bits allocated (256 max) */
 
  OC_INT8      = OC_VAR_I8   | OC_FILE_I8,
  OC_UINT8     = OC_VAR_U8   | OC_FILE_U8,
  OC_INT16     = OC_VAR_I16  | OC_FILE_I16,
  OC_UINT16    = OC_VAR_U16  | OC_FILE_U16,
  OC_INT32     = OC_VAR_I32  | OC_FILE_I32,
  OC_UINT32    = OC_VAR_U32  | OC_FILE_U32,
 
  OC_TILE      = OC_VAR_U32  | OC_FILE_U16,
 
  OC_DEREFERENCE_POINTER = 1 << 31,
 
  OC_END       = 0, 
};
 
DECLARE_ENUM_AS_BIT_SET(OldChunkType)
 
typedef bool OldChunkProc(LoadgameState *ls, int num);
typedef void *OffsetProc(void *base);
 
struct OldChunks {
  OldChunkType type;   
  uint32_t amount;       
 
  void *ptr;           
  OffsetProc *offset;  
  OldChunkProc *proc;  
};
 
extern uint _bump_assert_value;
uint8_t ReadByte(LoadgameState *ls);
bool LoadChunk(LoadgameState *ls, void *base, const OldChunks *chunks);
 
bool LoadTTDMain(LoadgameState *ls);
bool LoadTTOMain(LoadgameState *ls);
 
inline uint16_t ReadUint16(LoadgameState *ls)
{
  uint8_t x = ReadByte(ls);
  return x | ReadByte(ls) << 8;
}
 
inline uint32_t ReadUint32(LoadgameState *ls)
{
  uint16_t x = ReadUint16(ls);
  return x | ReadUint16(ls) << 16;
}
 
/* Help:
 *  - OCL_SVAR: load 'type' to offset 'offset' in a struct of type 'base', which must also
 *       be given via base in LoadChunk() as real pointer
 *  - OCL_VAR: load 'type' to a global var
 *  - OCL_END: every struct must end with this
 *  - OCL_NULL: read 'amount' of bytes and send them to /dev/null or something
 *  - OCL_CHUNK: load another proc to load a part of the savegame, 'amount' times
 *  - OCL_ASSERT: to check if we are really at the place we expect to be.. because old savegames are too binary to be sure ;)
 */
#define OCL_SVAR(type, base, offset)         { type,                 1, nullptr, [] (void *b) -> void * { return std::addressof(static_cast<base *>(b)->offset); }, nullptr }
#define OCL_VAR(type, amount, pointer)       { type,            amount, pointer, nullptr, nullptr }
#define OCL_END()                            { OC_END,               0, nullptr, nullptr, nullptr }
#define OCL_CNULL(type, amount)              { OC_NULL | type,  amount, nullptr, nullptr, nullptr }
#define OCL_CCHUNK(type, amount, proc)       { OC_CHUNK | type, amount, nullptr, nullptr, proc }
#define OCL_ASSERT(type, size)               { OC_ASSERT | type,     1, (void *)(size_t)size, nullptr, nullptr }
#define OCL_NULL(amount)        OCL_CNULL((OldChunkType)0, amount)
#define OCL_CHUNK(amount, proc) OCL_CCHUNK((OldChunkType)0, amount, proc)
 
#endif /* OLDLOADER_H */