dd3c6d1303After some discussion with PVH I realise that the repo structure in the last reorg was very rust-centric. In an attempt to put each language on a level footing move the rust code and project files into ./rust
73 lines
2.1 KiB
Rust
73 lines
2.1 KiB
Rust
/// The number of bytes required to encode `val` as a LEB128 integer
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pub(crate) fn lebsize(val: i64) -> u64 {
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let numbits = numbits_i64(val);
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(numbits as f64 / 7.0).floor() as u64 + 1
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}
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/// The number of bytes required to encode `val` as a uLEB128 integer
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pub(crate) fn ulebsize(val: u64) -> u64 {
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if val <= 1 {
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return 1;
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}
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let numbits = numbits_u64(val);
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let mut numblocks = (numbits as f64 / 7.0).floor() as u64;
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if numbits % 7 != 0 {
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numblocks += 1;
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}
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numblocks
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}
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fn numbits_i64(val: i64) -> u64 {
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// Is this right? This feels like it's not right
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(std::mem::size_of::<i64>() as u32 * 8 - val.abs().leading_zeros()) as u64
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}
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fn numbits_u64(val: u64) -> u64 {
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(std::mem::size_of::<u64>() as u32 * 8 - val.leading_zeros()) as u64
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}
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#[cfg(test)]
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mod tests {
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use super::*;
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use proptest::prelude::*;
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proptest! {
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#[test]
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fn test_ulebsize(val in 0..u64::MAX) {
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let mut out = Vec::new();
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leb128::write::unsigned(&mut out, val).unwrap();
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let expected = out.len() as u64;
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assert_eq!(expected, ulebsize(val))
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}
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#[test]
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fn test_lebsize(val in i64::MIN..i64::MAX) {
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let mut out = Vec::new();
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leb128::write::signed(&mut out, val).unwrap();
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let expected = out.len() as u64;
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assert_eq!(expected, lebsize(val))
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}
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}
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#[test]
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fn ulebsize_examples() {
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let scenarios = vec![0, 1, 127, 128, 129, 169];
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for val in scenarios {
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let mut out = Vec::new();
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leb128::write::unsigned(&mut out, val).unwrap();
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let expected = out.len() as u64;
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assert_eq!(ulebsize(val), expected, "value: {}", val)
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}
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}
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#[test]
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fn lebsize_examples() {
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let scenarios = vec![0, 1, -1, 127, 128, -127, -128, -2097152, 169];
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for val in scenarios {
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let mut out = Vec::new();
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leb128::write::signed(&mut out, val).unwrap();
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let expected = out.len() as u64;
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assert_eq!(lebsize(val), expected, "value: {}", val)
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}
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}
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}
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