diff --git a/src/bot.rs b/src/bot.rs
index c5a5c0c..3c97671 100644
--- a/src/bot.rs
+++ b/src/bot.rs
@@ -1,6 +1,10 @@
+use binrw::{BinReaderExt, binrw};
+
 pub enum Error{
 	InvalidHeader,
-	InvalidSegment,
+	InvalidSegment(binrw::Error),
+	InvalidSegmentId(u64),
+	File(crate::file::Error),
 }
 
 /* block types
@@ -28,40 +32,63 @@ loop{
 
 */
 
-//xdd
+//error hiding mock code
 mod simulation{
+	#[super::binrw]
+	#[brw(little)]
 	pub struct State{}
+	#[super::binrw]
+	#[brw(little)]
 	pub struct Instruction{}
 }
 mod instruction{
-	pub struct TimedInstruction<Instruction>{instruction:Instruction}
+	#[super::binrw]
+	#[brw(little)]
+	pub struct TimedInstruction<Instruction:binrw::BinRead+binrw::BinWrite>{
+		time:u64,
+		instruction:Instruction
+	}
 }
 mod timeline{
-	pub struct Timeline<Instruction>{timeline:Vec<super::instruction::TimedInstruction<Instruction>>}
+	#[super::binrw]
+	#[brw(little)]
+	pub struct Timeline<Instruction:binrw::BinRead+binrw::BinWrite>{
+		#[bw(try_calc(u32::try_from(instructions.len())))]
+		instruction_count:u32,
+		#[br(count=instruction_count)]
+		instructions:Vec<super::instruction::TimedInstruction<Instruction>>
+	}
 }
 
 //serious code
 
+#[binrw]
+#[brw(little)]
 struct SegmentId(u64);
 
+#[binrw]
+#[brw(little)]
 pub struct Segment{
 	state:simulation::State,
+	#[bw(try_calc(u32::try_from(instructions.len())))]
+	instruction_count:u32,
+	#[br(count=instruction_count)]
 	instructions:Vec<instruction::TimedInstruction<simulation::Instruction>>
 }
 
-pub struct StreamableBot{
-	file:crate::file::File,
+pub struct StreamableBot<R:BinReaderExt>{
+	file:crate::file::File<R>,
 	timeline:timeline::Timeline<SegmentId>,
+	segment_id_to_block_id:Vec<crate::file::BlockId>,
 }
-impl StreamableBot{
-	pub fn new(file:crate::file::File)->Result<Self,Error>{
+impl<R:BinReaderExt> StreamableBot<R>{
+	pub(crate) fn new(file:crate::file::File<R>)->Result<Self,Error>{
 		Err(Error::InvalidHeader)
 	}
-	pub fn load_segment(&mut self,segment_id:u64)->Result<Segment,Error>{
-		//load region from disk
-		//parse the models and determine what resources need to be loaded
-		//load resources into self.resources
-		//return Region
-		Err(Error::InvalidSegment)
+	pub fn load_segment(&mut self,segment_id:SegmentId)->Result<Segment,Error>{
+		let block_id=*self.segment_id_to_block_id.get(segment_id.0 as usize).ok_or(Error::InvalidSegmentId(segment_id.0))?;
+		let mut block=self.file.take_block(block_id).map_err(|e|Error::File(e))?;
+		let segment=block.read_le().map_err(|e|Error::InvalidSegment(e))?;
+		Ok(segment)
 	}
 }
\ No newline at end of file
diff --git a/src/demo.rs b/src/demo.rs
index 486f861..302ea5a 100644
--- a/src/demo.rs
+++ b/src/demo.rs
@@ -1,3 +1,5 @@
+use binrw::BinReaderExt;
+
 pub enum Error{
 	InvalidHeader,
 }
@@ -17,12 +19,12 @@ how to do worldstate for deathrun!?
 
 */
 
-pub struct StreamableDemo{
-	map:Box<crate::map::StreamableMap>,
-	bots:Vec<crate::bot::StreamableBot>,
+pub struct StreamableDemo<R:BinReaderExt>{
+	map:Box<crate::map::StreamableMap<R>>,
+	bots:Vec<crate::bot::StreamableBot<R>>,
 }
-impl StreamableDemo{
-	pub fn new(file:crate::file::File)->Result<Self,Error>{
+impl<R:BinReaderExt> StreamableDemo<R>{
+	pub(crate) fn new(file:crate::file::File<R>)->Result<Self,Error>{
 		Err(Error::InvalidHeader)
 	}
 }
\ No newline at end of file
diff --git a/src/file.rs b/src/file.rs
index f3a2473..f1bf2b0 100644
--- a/src/file.rs
+++ b/src/file.rs
@@ -1,10 +1,12 @@
 //file format "sniff"
 
-use binrw::{binrw, BinReaderExt};
+use binrw::{binrw, BinReaderExt, io::TakeSeekExt};
 
 pub enum Error{
 	InvalidHeader(binrw::Error),
 	UnexpectedEOF,
+	InvalidBlockId(usize),
+	Seek(std::io::Error),
 }
 
 /* spec
@@ -56,26 +58,35 @@ struct Header{
 	priming:u64,
 	/// uuid for this file
 	resource:u128,
-	#[bw(try_calc(u64::try_from(block_location.len())))]
+	#[bw(try_calc(u64::try_from(block_location.len()-1)))]
 	block_count:u64,
-	#[br(count=block_count)]
+	#[br(count=block_count+1)]
 	block_location:Vec<u64>,
 }
 
+pub struct BlockId(usize);
 
-pub(crate) struct File{
+pub(crate) struct File<R:BinReaderExt>{
 	header:Header,
 	//reference to the data
+	data:R,
 }
 
-impl File{
-	pub(crate) fn new<R:BinReaderExt>(mut input:R)->Result<Self,Error>{
-		Ok(Self{
+impl<R:BinReaderExt> File<R>{
+	pub(crate) fn new(mut input:R)->Result<File<R>,Error>{
+		Ok(File{
 			header:input.read_le().map_err(|e|Error::InvalidHeader(e))?,
+			data:input,
 		})
 	}
-	pub(crate) fn read_block(&mut self,block_id:u64)->Result<Vec<u8>,Error>{
-		Err(Error::UnexpectedEOF)
+	pub(crate) fn take_block(&mut self,block_id:BlockId)->Result<binrw::io::TakeSeek<&mut R>,Error>{
+		if self.header.block_location.len()<=block_id.0{
+			return Err(Error::InvalidBlockId(block_id.0))
+		}
+		let block_start=self.header.block_location[block_id.0];
+		let block_end=self.header.block_location[block_id.0+1];
+		self.data.seek(std::io::SeekFrom::Start(block_start)).map_err(|e|Error::Seek(e))?;
+		Ok((&mut self.data).take_seek(block_end-block_start))
 	}
 	pub(crate) fn fourcc(&self)->FourCC{
 		self.header.fourcc
diff --git a/src/lib.rs b/src/lib.rs
index 6ea292d..d17883a 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -13,13 +13,13 @@ pub enum Error{
 	Demo(demo::Error),
 }
 
-pub enum SNF{
-	Map(map::StreamableMap),
-	Bot(bot::StreamableBot),
-	Demo(demo::StreamableDemo),
+pub enum SNF<R:BinReaderExt>{
+	Map(map::StreamableMap<R>),
+	Bot(bot::StreamableBot<R>),
+	Demo(demo::StreamableDemo<R>),
 }
 
-pub fn read_snf<R:BinReaderExt>(input:R)->Result<SNF,Error>{
+pub fn read_snf<R:BinReaderExt>(input:R)->Result<SNF<R>,Error>{
 	let file=file::File::new(input).map_err(|e|Error::Header(e))?;
 	Ok(match file.fourcc(){
 		file::FourCC::Map=>SNF::Map(map::StreamableMap::new(file).map_err(|e|Error::Map(e))?),
@@ -27,21 +27,21 @@ pub fn read_snf<R:BinReaderExt>(input:R)->Result<SNF,Error>{
 		file::FourCC::Demo=>SNF::Demo(demo::StreamableDemo::new(file).map_err(|e|Error::Demo(e))?),
 	})
 }
-pub fn read_map<R:BinReaderExt>(input:R)->Result<map::StreamableMap,Error>{
+pub fn read_map<R:BinReaderExt>(input:R)->Result<map::StreamableMap<R>,Error>{
 	let file=file::File::new(input).map_err(|e|Error::Header(e))?;
 	match file.fourcc(){
 		file::FourCC::Map=>Ok(map::StreamableMap::new(file).map_err(|e|Error::Map(e))?),
 		_=>Err(Error::UnexpectedFourCC)
 	}
 }
-pub fn read_bot<R:BinReaderExt>(input:R)->Result<bot::StreamableBot,Error>{
+pub fn read_bot<R:BinReaderExt>(input:R)->Result<bot::StreamableBot<R>,Error>{
 	let file=file::File::new(input).map_err(|e|Error::Header(e))?;
 	match file.fourcc(){
 		file::FourCC::Bot=>Ok(bot::StreamableBot::new(file).map_err(|e|Error::Bot(e))?),
 		_=>Err(Error::UnexpectedFourCC)
 	}
 }
-pub fn read_demo<R:BinReaderExt>(input:R)->Result<demo::StreamableDemo,Error>{
+pub fn read_demo<R:BinReaderExt>(input:R)->Result<demo::StreamableDemo<R>,Error>{
 	let file=file::File::new(input).map_err(|e|Error::Header(e))?;
 	match file.fourcc(){
 		file::FourCC::Demo=>Ok(demo::StreamableDemo::new(file).map_err(|e|Error::Demo(e))?),
diff --git a/src/map.rs b/src/map.rs
index 53e6501..4ed7885 100644
--- a/src/map.rs
+++ b/src/map.rs
@@ -1,6 +1,10 @@
+use binrw::{BinReaderExt, binrw};
+
 pub enum Error{
 	InvalidHeader,
-	InvalidNode,
+	InvalidNodeId(u64),
+	InvalidRegion(binrw::Error),
+	File(crate::file::Error),
 }
 
 /* block types
@@ -53,12 +57,14 @@ for model_id in 0..num_models{
 */
 
 
-//xdd
+//error hiding mock code
 mod physics{
 	pub struct StyleModifiers{}
 }
 mod model{
 	pub struct IndexedModel{}
+	#[super::binrw]
+	#[brw(little)]
 	pub struct ModelInstance{}
 }
 mod image{
@@ -73,17 +79,26 @@ pub struct BvhNodeId(u64);
 struct BvhNode{
 	//
 }
+#[binrw]
+#[brw(little)]
+struct Region{
+	#[bw(try_calc(u32::try_from(models.len())))]
+	model_count:u32,
+	#[br(count=model_count)]
+	models:Vec<model::ModelInstance>,
+}
 
-pub struct StreamableMap{
-	file:crate::file::File,
+pub struct StreamableMap<R:BinReaderExt>{
+	file:crate::file::File<R>,
 	style:physics::StyleModifiers,//probably should move this out of physics
 	bvh:BvhNode,
+	node_id_to_block_id:Vec<crate::file::BlockId>,
 	//do not need this?  return only new data with load_node
 	resource_model:std::collections::HashMap<ModelUuid,model::IndexedModel>,
 	resource_image:std::collections::HashMap<ImageUuid,image::Image>,
 }
-impl StreamableMap{
-	pub fn new(file:crate::file::File)->Result<Self,Error>{
+impl<R:BinReaderExt> StreamableMap<R>{
+	pub(crate) fn new(file:crate::file::File<R>)->Result<Self,Error>{
 		Err(Error::InvalidHeader)
 	}
 	pub fn load_node(&mut self,node_id:BvhNodeId)->Result<Vec<model::ModelInstance>,Error>{
@@ -91,6 +106,9 @@ impl StreamableMap{
 		//parse the models and determine what resources need to be loaded
 		//load resources into self.resources
 		//return Region
-		Err(Error::InvalidNode)
+		let block_id=*self.node_id_to_block_id.get(node_id.0 as usize).ok_or(Error::InvalidNodeId(node_id.0))?;
+		let mut block=self.file.take_block(block_id).map_err(|e|Error::File(e))?;
+		let region:Region=block.read_le().map_err(|e|Error::InvalidRegion(e))?;
+		Ok(region.models)
 	}
 }
\ No newline at end of file