changed everything

memoribbon.rs

@@ -4,8 +4,67 @@ use std::io::prelude::*;
 use std::fs::File;
 use std::io;
 
-static FILTER_STRENGTH:u8 = 10;
-static RESET_THRESH:usize = 100; // this many samples with no bits = reset byte position
+static FILTER_STRENGTH:u8 = 10; // how severely to low-pass the incoming data
+static RESET_THRESH:usize = 20; // this many samples with no bits = reset byte position
+static OVERSAMPLE_FACTOR:usize = 10; // how many samples long are each bit in the decoder input?
+static INVERT:bool = false; // whether or not the source inverts the samples
+
+struct StreamCoder {
+	encoder:[u16;256],
+	decoder:[u8;4096],
+}
+
+fn streamcoder_gen() -> StreamCoder {
+	let mut output_a:[u16;256] = [0x0000;256];
+	let mut output_b:[u8;4096] = [0x20;4096];
+	let mut a:usize = 0;
+	let mut b:usize = 0;
+	while a < 256 {
+		if b.count_ones() == b.count_zeros() {
+			output_a[a] = b as u16;
+			output_b[b] = a as u8;
+			a += 1;
+		}
+		b += 1;
+	}
+	return StreamCoder {
+		encoder:output_a,
+		decoder:output_b,
+	};
+}
+
+fn code_bits(n:u16) -> [bool;12] {
+	let mut output:[bool;12] = [false;12];
+	for i in 0..12 {
+		output[i] = (n >> i) & 0x01 == 0x01;
+	}
+	return output;
+}
+
+fn bits_code(b:&[bool]) -> u16 {
+	let mut output:u16 = 0;
+	if b.len() < 12 {
+		return 0;
+	}
+	for i in 0..12 {
+		if b[i] {
+			output += (0x01 << i) as u16;
+		}
+	}
+	return output;
+}
+
+impl StreamCoder {
+
+	fn encode(&self,byte:u8) -> [bool;12] {
+		return code_bits(self.encoder[byte as usize]);
+	}
+
+	fn decode(&self,states:&[bool]) -> u8 {
+		return self.decoder[bits_code(states) as usize];
+	}
+
+}
 
 fn main() {
 	let argv = args().collect::<Vec<String>>();
@@ -34,6 +93,7 @@ fn main() {
 			Ok(f) => Box::new(f),
 		},
 	};
+	let coder = streamcoder_gen();
 	if mode == "e" {
 		match iooutput.write_all(&[0x80;1000]) {
 			Err(why) => {
@@ -54,26 +114,29 @@ fn main() {
 				},
 				Ok(_) => (),
 			};
-			for i in 0..8 {
-				let payload:[u8;8] = match ibuffer[0] & (0x80 >> i) != 0x00 {
-					true  => [0x80,0x80,0x80,0xFF,0x80,0x00,0x80,0x80],
-					false => [0x80,0x80,0xFF,0x80,0x00,0x80,0x80,0x80],
-				};
-				match iooutput.write_all(&payload) {
-					Err(why) => {
-						eprintln!("write failed: {}",why);
-						exit(1);
-					},
-					Ok(_) => (),
+			let mut payload:[u8;16] = [0x80;16];
+			let bits = coder.encode(ibuffer[0]);
+			for i in 0..12 {
+				payload[i] = match bits[i] {
+					true  => 0xFF,
+					false => 0x00,
 				};
 			}
+			match iooutput.write_all(&payload) {
+				Err(why) => {
+					eprintln!("write failed: {}",why);
+					exit(1);
+				},
+				Ok(_) => (),
+			};
 		}
 	} else if mode == "d" {
-		let mut ibuffer:[u8;2] = [0x00,0x00];
-		let mut filterstates:[u16;2] = [0x0000,0x0000];
-		let mut logicstates:[bool;2] = [false,false];
-		let mut outbits:Vec<bool> = Vec::with_capacity(8);
-		let mut idlecycles:usize = 0;
+		let mut ibuffer:[u8;1] = [0x00];
+		let mut filterstate:u16 = 0x0000;
+		let mut logicstate:i8 = 0;
+		let mut statecount:Option<(i8,usize)> = None;
+		let mut count:usize = 1;
+		let mut outbits:Vec<bool> = Vec::with_capacity(12);
 		loop {
 			match ioinput.read_exact(&mut ibuffer) {
 				Err(why) => match why.kind() {
@@ -85,29 +148,45 @@ fn main() {
 				},
 				Ok(_) => (),
 			};
-			filterstates[0] = filterstates[0]*(FILTER_STRENGTH as u16)/0x00FF + ((0x00FF-FILTER_STRENGTH as u16)*ibuffer[0] as u16)/0x00FF;
-			filterstates[1] = filterstates[1]*(FILTER_STRENGTH as u16)/0x00FF + ((0x00FF-FILTER_STRENGTH as u16)*ibuffer[1] as u16)/0x00FF;
-			if filterstates[0] > 180 && !logicstates[0] {
-				logicstates[0] = true;
-				outbits.push(false);
-				idlecycles = 0;
-			} else if filterstates[0] < 170 && logicstates[0] {
-				logicstates[0] = false
+			filterstate = filterstate*(FILTER_STRENGTH as u16)/0x00FF + ((0x00FF-FILTER_STRENGTH as u16)*ibuffer[0] as u16)/0x00FF;
+			if filterstate > 170 {
+				if logicstate == 1 {
+					count += 1;
+				} else {
+					statecount = Some((logicstate,count));
+					count = 1;
+					logicstate = 1;
+				}
+			} else if filterstate < 85 {
+				if logicstate == -1 {
+					count += 1;
+				} else {
+					statecount = Some((logicstate,count));
+					count = 1;
+					logicstate = -1;
+				}
+			} else {
+				if logicstate != 0 {
+					count = 1;
+					logicstate = 0;
+				}
+				statecount = Some((logicstate,count));
 			}
-			if filterstates[1] > 180 && !logicstates[1] {
-				logicstates[1] = true;
-				outbits.push(true);
-				idlecycles = 0;
-			} else if filterstates[1] < 170 && logicstates[1] {
-				logicstates[1] = false
-			}
-			if outbits.len() >= 8 {
-				let mut outbyte:u8 = 0x00;
-				for i in 0..8 {
-					if outbits[i] {
-						outbyte |= 0x80 >> i;
+			if let Some((state,n)) = statecount {
+				if state == 0 {
+					if n >= RESET_THRESH {
+						outbits.clear();
+					}
+				} else {
+					for _ in 0..(n+OVERSAMPLE_FACTOR/2)/OVERSAMPLE_FACTOR {
+						outbits.push((state > 0) ^ INVERT);
 					}
 				}
+				statecount = None;
+			}
+			if outbits.len() >= 12 {
+				let outbyte:u8 = coder.decode(&outbits);
+				outbits.clear();
 				match iooutput.write_all(&[outbyte]) {
 					Err(why) => {
 						eprintln!("write failed: {}",why);
@@ -115,12 +194,6 @@ fn main() {
 					},
 					Ok(_) => (),
 				};
-				outbits.clear();
-			}
-			if idlecycles < RESET_THRESH {
-				idlecycles += 1;
-			} else {
-				outbits.clear();
 			}
 		}
 	} else {