Map file

For specifics and code, see https://github.com/sourcehold/sourcehold-maps.

The map file format is currently unknown (at least mostly). Parts of the map file are compressed using the PKWARE algorithm, a good resource to check out how it works is https://github.com/madler/zlib/blob/master/contrib/blast/. Here's some stuff I found out, assuming 160x160 map size and no scenario description is given:

Random stuff (TODO)

• The file is composed of multiple sections, all of them are compressed. They start with a 12-byte header (3 x uint32_t):

struct SectionHeader {
    uint32_t uncompressedLen;
    uint32_t compressedLen;
    uint32_t crc32;
    // PKWARE-compressed chunk starts here
};

• The scenario description is stored right after the preview image. Following this section, there is a structure as follows:

struct ScenarioDesc {
    uint32_t size;  // The size of this struct + the following compressed section 
    uint32_t type;  // 0 if the description is stored as compressed text,
                    // 1 if the index is used to display the description.
    uint32_t index; // An index into a global string table (sh.tex)
    uint32_t u2;    // always 0x3E8
    // The section containing the compressed text starts here. It is always
    // present, even if the index is being used instead.
};

• At the very end of the file, the filename is encoded for campaign missions, every other defaults to "mission9.map"
• The map data is stored in two halves, i.e. top-right edge and bottom-left edge
• After the header and some data (presumably the map preview or description), there's the byte 5D, maybe some marker or ID. 8 bytes after that, there's one byte which seems to be the map type (invasion, etc). 4 bytes after that, there appears to be some kind of locking mechanism (4 bytes), as changing any of them to nonzero will cause the map to be hidden in the loading menu. I presume the structure looks something like this:

struct SomeInfo {
	uint32_t ID; // 0x5D
	uint32_t u1; // 0x02
	uint32_t u2; // 0x03
	uint32_t lock;
	enum MapType : uint8_t {
		SIEGE,
		INVASION,
		ECONOMIC,
		LANDSCAPE
	} type;
}

Since the file changes around in a (so far) seemingly random way, the following offsets are wrong but can be used to calculate the relative offsets.

• 0x43A77: Popularity (1 byte, 0x00 - 0x64)
• 0x439C7: Year (2 bytes)
• 0x439CB: Month (1 byte, January = 0x00)
• 0x439D7: Starting goods (4 bytes each, signed). Order (incomplete):
  • Wood
  • Hops
  • Stone
  • ?
  • ?
  • Iron
  • ?
  • Tar
  • Grain
  • Bread
  • Cheese
  • Meat
  • Apples
  • Beer
  • Gold
  • ?
  • Bows
  • Crossbows
  • Spears
  • Pikes
  • Maces
  • Swords
  • Leather armor
  • Armor