diff options
| -rw-r--r-- | gifed/Cargo.toml | 3 | ||||
| -rw-r--r-- | gifed/src/lzw.rs | 42 |
2 files changed, 37 insertions, 8 deletions
diff --git a/gifed/Cargo.toml b/gifed/Cargo.toml index 79f86ce..48b4bf5 100644 --- a/gifed/Cargo.toml +++ b/gifed/Cargo.toml @@ -9,3 +9,6 @@ repository = "https://github.com/genuinebyte/gifed" [dependencies] weezl = "0.1.5" + +[dev-dependencies] +rand = "0.8.5" diff --git a/gifed/src/lzw.rs b/gifed/src/lzw.rs index c5ad5b3..cd3fcd5 100644 --- a/gifed/src/lzw.rs +++ b/gifed/src/lzw.rs @@ -5,7 +5,7 @@ impl LZW { pub fn encode(minimum_size: u8, indicies: &[u8]) -> Vec<u8> { let mut dictionary: HashMap<Vec<u8>, u16> = HashMap::new(); - let cc = 2u16.pow(minimum_size as u32); + let cc = 1 << minimum_size; let eoi = cc + 1; println!("mcs {} | cc {}", minimum_size, cc); @@ -39,7 +39,7 @@ impl LZW { next_code += 1; // If the next_code can't fit in the code_size, we have to increase it - if next_code - 1 == 2u16.pow(code_size as u32) { + if next_code - 1 == 1 << code_size { code_size += 1; } @@ -58,7 +58,9 @@ impl LZW { match dictionary.get(&buffer) { Some(&code) => out.push_bits(code_size, code), None => { - panic!("Codes left in the buffer but the buffer is not a valid dictionary key!") + unreachable!( + "Codes left in the buffer but the buffer is not a valid dictionary key!" + ) } } } @@ -72,23 +74,47 @@ impl LZW { mod lzw_test { use super::*; + fn rand_against_weezl(length: usize) { + let range = rand::distributions::Uniform::from(0..=1); + let indices = rand::Rng::sample_iter(rand::thread_rng(), &range) + .take(length) + .collect::<Vec<_>>(); + let weezl = weezl::encode::Encoder::new(weezl::BitOrder::Lsb, 2) + .encode(&indices) + .unwrap(); + let us = LZW::encode(2, &indices); + + assert_eq!(us.len(), weezl.len()); + } + + #[test] + fn fortyk_against_weezl() { + rand_against_weezl(40_000); + } + + #[test] + #[ignore] + fn thirtyeightk_against_weezl() { + rand_against_weezl(38_000); + } + #[test] fn encode() { - let indicies = vec![0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0]; + let indices = vec![0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0]; let output = vec![0x84, 0x1D, 0x81, 0x7A, 0x50]; - let lzout = LZW::encode(2, &indicies); + let lzout = LZW::encode(2, &indices); assert_eq!(lzout, output); } #[test] fn against_weezl() { - let indicies = vec![0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0]; + let indices = vec![0, 0, 0, 0, 0, 1, 1, 0, 0, 1, 1, 0, 0, 0, 0, 0]; let weezl = weezl::encode::Encoder::new(weezl::BitOrder::Lsb, 2) - .encode(&indicies) + .encode(&indices) .unwrap(); - let us = LZW::encode(2, &indicies); + let us = LZW::encode(2, &indices); assert_eq!(weezl, us); } |