physics versioning plan

lib/snf/src/bot.rs

@@ -28,12 +28,16 @@ pub enum Error{
 /* block types
 
 BLOCK_BOT_HEADER:
-// Tegments are laid out in chronological order,
+// Segments are laid out in chronological order,
 // but block_id is not necessarily in ascending order.
 //
 // This is to place the final segment close to the start of the file,
 // which allows the duration of the bot to be conveniently calculated
 // from the first and last instruction timestamps.
+//
+// Use exact physics version for replay playback
+// Use highest compatible physics version for verification
+u32 physics_version
 u32 num_segments
 for _ in 0..num_segments{
 	i64 time
@@ -61,6 +65,7 @@ struct SegmentHeader{
 #[binrw]
 #[brw(little)]
 struct Header{
+	physics_version:u32,
 	num_segments:u32,
 	#[br(count=num_segments)]
 	segments:Vec<SegmentHeader>,
@@ -151,7 +156,7 @@ impl<R:BinReaderExt> StreamableBot<R>{
 }
 
 const MAX_BLOCK_SIZE:usize=64*1024;//64 kB
-pub fn write_bot<W:BinWriterExt>(mut writer:W,instructions:impl IntoIterator<Item=TimedPhysicsInstruction>)->Result<(),Error>{
+pub fn write_bot<W:BinWriterExt>(mut writer:W,physics_version:u32,instructions:impl IntoIterator<Item=TimedPhysicsInstruction>)->Result<(),Error>{
 	// decide which instructions to put in which segment
 	// write segment 1 to block 1
 	// write segment N to block 2
@@ -251,6 +256,7 @@ pub fn write_bot<W:BinWriterExt>(mut writer:W,instructions:impl IntoIterator<Ite
 	};
 
 	let header=Header{
+		physics_version,
 		num_segments:num_segments as u32,
 		segments,
 	};