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add unpack
This commit is contained in:
parent
59936990c8
commit
c75b7520c3
101
src/lib.rs
101
src/lib.rs
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@ -14,7 +14,7 @@
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//! assert_eq!(buff[1], 0b0000_0001);
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//! ```
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//!
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//! Or using the trait [[PackTwInt]]:
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//! Or using the trait [PackTwInt]:
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//! ```
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//! use std::io::Cursor;
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//! use teeint::PackTwInt;
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@ -28,10 +28,8 @@
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//! assert_eq!(buff[1], 0b0000_0001);
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//! ```
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//!
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//! Thanks to [heinrich5991 libtw2 docs](https://github.com/heinrich5991/libtw2/blob/master/doc/int.md) for help.
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//!
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use std::io::{Result, Write};
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use std::io::{Read, Result, Write};
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/// Pack a i32 into a teeworlds variable integer.
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pub fn pack(dst: &mut impl Write, mut value: i32) -> Result<()> {
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@ -56,24 +54,51 @@ pub fn pack(dst: &mut impl Write, mut value: i32) -> Result<()> {
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while value != 0 {
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// We have more data, set BIT_EXTEND
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current_byte |= 0b1000_0000;
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dst.write(&[current_byte])?;
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dst.write_all(std::slice::from_ref(¤t_byte))?;
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// Write the BITS[7]
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current_byte = value as u8 & 0b0111_1111;
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// Discard them.
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value >>= 7;
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}
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dst.write(&[current_byte])?;
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dst.write_all(std::slice::from_ref(¤t_byte))?;
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Ok(())
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}
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/// Unpack a teeworlds variable int from the provided reader.
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pub fn unpack(src: &mut impl Read) -> Result<i32> {
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// Adapted from https://github.com/ddnet/ddnet/blob/79df5893ff26fa75d67e46f99e58f75b739ac362/src/engine/shared/compression.cpp#L10
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let mut result: i32;
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let mut current_byte: u8 = 0;
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src.read_exact(std::slice::from_mut(&mut current_byte))?;
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let sign = (current_byte >> 6) & 1;
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result = (current_byte & 0x3F) as i32;
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const MASKS: [u8; 4] = [0x7F, 0x7F, 0x7F, 0x0F];
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const SHIFTS: [u8; 4] = [6, 6 + 7, 6 + 7 + 7, 6 + 7 + 7 + 7];
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for (mask, shift) in MASKS.into_iter().zip(SHIFTS.into_iter()) {
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if (current_byte & 0x80) == 0 {
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break;
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}
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src.read_exact(std::slice::from_mut(&mut current_byte))?;
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result |= ((current_byte & mask) << shift) as i32;
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}
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result ^= -(sign as i32);
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Ok(result)
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}
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/// Trait implemented by values that can be packed to a teeworlds variable int.
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///
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/// Note that teeworlds only packs i32 values.
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///
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/// This trait is more of a convenience to allow writing `0i32.pack(&mut buff)`
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pub trait PackTwInt: Copy {
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pub trait PackTwInt {
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/// Pack this value into a teeworlds variable int.
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fn pack(self, dst: &mut impl Write) -> Result<()>;
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}
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@ -90,6 +115,14 @@ mod tests {
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use super::*;
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#[test]
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pub fn unpack_0() {
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let mut buff = Cursor::new([0; 1]);
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assert!(pack(&mut buff, 0).is_ok());
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buff.set_position(0);
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assert_eq!(0, unpack(&mut buff).unwrap());
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}
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#[test]
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pub fn pack_0() {
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let mut buff = Cursor::new([0; 1]);
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@ -106,6 +139,14 @@ mod tests {
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assert_eq!(buff[0], 0b0000_0001);
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}
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#[test]
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pub fn unpack_1() {
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let mut buff = Cursor::new([0; 1]);
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assert!(pack(&mut buff, 1).is_ok());
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buff.set_position(0);
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assert_eq!(1, unpack(&mut buff).unwrap());
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}
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#[test]
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pub fn pack_2() {
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let mut buff = Cursor::new([0; 1]);
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@ -114,6 +155,14 @@ mod tests {
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assert_eq!(buff[0], 0b0000_0010);
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}
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#[test]
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pub fn unpack_2() {
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let mut buff = Cursor::new([0; 1]);
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assert!(pack(&mut buff, 2).is_ok());
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buff.set_position(0);
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assert_eq!(2, unpack(&mut buff).unwrap());
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}
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#[test]
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pub fn pack_minus_2() {
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let mut buff = Cursor::new([0; 1]);
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@ -122,6 +171,14 @@ mod tests {
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assert_eq!(buff[0], 0b0100_0001);
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}
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#[test]
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pub fn unpack_minus_2() {
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let mut buff = Cursor::new([0; 1]);
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assert!(pack(&mut buff, -2).is_ok());
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buff.set_position(0);
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assert_eq!(-2, unpack(&mut buff).unwrap());
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}
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#[test]
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pub fn pack_minus_1() {
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let mut buff = Cursor::new([0; 1]);
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@ -130,13 +187,31 @@ mod tests {
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assert_eq!(buff[0], 0b0100_0000);
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}
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#[test]
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pub fn unpack_minus_1() {
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let mut buff = Cursor::new([0; 1]);
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assert!(pack(&mut buff, -1).is_ok());
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buff.set_position(0);
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assert_eq!(-1, unpack(&mut buff).unwrap());
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}
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#[test]
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pub fn pack_0_to_63() {
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for i in 0..64 {
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let mut buff = Cursor::new([0; 1]);
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assert!(pack(&mut buff, i as i32).is_ok());
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assert!(pack(&mut buff, i).is_ok());
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let buff = buff.into_inner();
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assert_eq!(buff[0], i);
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assert_eq!(buff[0] as i32, i);
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}
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}
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#[test]
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pub fn unpack_0_to_63() {
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for i in 0..64 {
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let mut buff = Cursor::new([0; 1]);
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assert!(pack(&mut buff, i).is_ok());
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buff.set_position(0);
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assert_eq!(i, unpack(&mut buff).unwrap());
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}
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}
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@ -149,6 +224,14 @@ mod tests {
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assert_eq!(buff[1], 0b0000_0001);
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}
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#[test]
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pub fn unpack_64() {
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let mut buff = Cursor::new([0; 2]);
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assert!(pack(&mut buff, 64).is_ok());
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buff.set_position(0);
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assert_eq!(64, unpack(&mut buff).unwrap());
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}
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#[test]
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pub fn pack_64_trait() {
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let mut buff = Cursor::new([0; 2]);
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