12468275135

Committed 23 Dec 2024 02:21PM UTC coverage: 57.076% (-1.8%) from 58.86%

Build # 12468275135

Build Type

push

github

Committed by

zommiommy

Commit Message

Fixed issue #18 and applied clippy fixes from new version

Run Details

3 of 4 new or added lines in 3 files covered. (75.0%)

77 existing lines in 10 files now uncovered.

1835 of 3215 relevant lines covered (57.08%)

2945514.46 hits per line

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85.71

/src/codes/minimal_binary.rs

/*
 * SPDX-FileCopyrightText: 2023 Tommaso Fontana
 * SPDX-FileCopyrightText: 2023 Inria
 * SPDX-FileCopyrightText: 2023 Sebastiano Vigna
 *
 * SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
 */

//! Minimal binary codes.
//!
//! A minimal binary code with upper bound `u > 0` (AKA [truncated binary
//! encoding](https://en.wikipedia.org/wiki/Truncated_binary_encoding)) is an
//! optimal prefix-free code for the first `u` natural numbers with uniform distribution.
//!
//! There are several such prefix-free codes, and the one implemented here is
//! defined as follows: if `s = ⌊log₂u⌋`, then the first `2^(s+1) - u` codewords are
//! the first binary numbers of length `s – 1`, and the remaining codewords
//! are the last `2u - 2^(s+1)` binary numbers of length `s`.

use crate::traits::*;

/// Returns the length of the minimal binary code for `n` with upper bound `max`.
#[must_use]
#[inline]
pub fn len_minimal_binary(n: u64, max: u64) -> usize {
    if max == 0 {
        return 0;
    }
    let l = max.ilog2();
    let limit = (1 << (l + 1)) - max;
    let mut result = l as usize;
    if n >= limit {
        result += 1;
    }
    result
}

/// Trait for reading minimal binary codes.
pub trait MinimalBinaryRead<E: Endianness>: BitRead<E> {
    #[inline(always)]
    fn read_minimal_binary(&mut self, max: u64) -> Result<u64, Self::Error> {
        let l = max.ilog2();
        let mut prefix = self.read_bits(l as _)?;
        let limit = (1 << (l + 1)) - max;

        Ok(if prefix < limit {
            prefix
        } else {
            prefix <<= 1;
            prefix |= self.read_bits(1)?;
            prefix - limit
        })
    }
}

/// Trait for writing minimal binary codes.
pub trait MinimalBinaryWrite<E: Endianness>: BitWrite<E> {
    #[inline]
    fn write_minimal_binary(&mut self, n: u64, max: u64) -> Result<usize, Self::Error> {
        let l = max.ilog2();
        let limit = (1 << (l + 1)) - max;

        if n < limit {
            self.write_bits(n, l as _)?;
            Ok(l as usize)
        } else {
            let to_write = n + limit;
            self.write_bits(to_write >> 1, l as _)?;
            self.write_bits(to_write & 1, 1)?;
            Ok((l + 1) as usize)
        }
    }
}

impl<E: Endianness, B: BitRead<E>> MinimalBinaryRead<E> for B {}
impl<E: Endianness, B: BitWrite<E>> MinimalBinaryWrite<E> for B {}

1	/*
2	* SPDX-FileCopyrightText: 2023 Tommaso Fontana
3	* SPDX-FileCopyrightText: 2023 Inria
4	* SPDX-FileCopyrightText: 2023 Sebastiano Vigna
5	*
6	* SPDX-License-Identifier: Apache-2.0 OR LGPL-2.1-or-later
7	*/
8
9	//! Minimal binary codes.
10	//!
11	//! A minimal binary code with upper bound `u > 0` (AKA [truncated binary
12	//! encoding](https://en.wikipedia.org/wiki/Truncated_binary_encoding)) is an
13	//! optimal prefix-free code for the first `u` natural numbers with uniform distribution.
14	//!
15	//! There are several such prefix-free codes, and the one implemented here is
16	//! defined as follows: if `s = ⌊log₂u⌋`, then the first `2^(s+1) - u` codewords are
17	//! the first binary numbers of length `s – 1`, and the remaining codewords
18	//! are the last `2u - 2^(s+1)` binary numbers of length `s`.
19
20	use crate::traits::*;
21
22	/// Returns the length of the minimal binary code for `n` with upper bound `max`.
23	#[must_use]
24	#[inline]
25	pub fn len_minimal_binary(n: u64, max: u64) -> usize {	3,554✔
26	if max == 0 {	3,554✔
27	return 0;	×
28	}
29	let l = max.ilog2();	3,554✔
30	let limit = (1 << (l + 1)) - max;	3,554✔
31	let mut result = l as usize;	3,554✔
32	if n >= limit {	7,018✔
33	result += 1;	3,464✔
34	}
UNCOV 35	result	×
36	}
37
38	/// Trait for reading minimal binary codes.
39	pub trait MinimalBinaryRead<E: Endianness>: BitRead<E> {
40	#[inline(always)]
41	fn read_minimal_binary(&mut self, max: u64) -> Result<u64, Self::Error> {	248,943✔
42	let l = max.ilog2();	248,943✔
43	let mut prefix = self.read_bits(l as _)?;	497,886✔
44	let limit = (1 << (l + 1)) - max;	×
45
46	Ok(if prefix < limit {	×
47	prefix	145,515✔
48	} else {
49	prefix <<= 1;	103,428✔
50	prefix \|= self.read_bits(1)?;	103,428✔
51	prefix - limit	103,428✔
52	})
53	}
54	}
55
56	/// Trait for writing minimal binary codes.
57	pub trait MinimalBinaryWrite<E: Endianness>: BitWrite<E> {
58	#[inline]
59	fn write_minimal_binary(&mut self, n: u64, max: u64) -> Result<usize, Self::Error> {	248,061✔
60	let l = max.ilog2();	248,061✔
61	let limit = (1 << (l + 1)) - max;	248,061✔
62
63	if n < limit {	248,061✔
64	self.write_bits(n, l as _)?;	145,501✔
65	Ok(l as usize)	145,501✔
66	} else {
67	let to_write = n + limit;	102,560✔
68	self.write_bits(to_write >> 1, l as _)?;	102,560✔
69	self.write_bits(to_write & 1, 1)?;	102,560✔
70	Ok((l + 1) as usize)	102,560✔
71	}
72	}
73	}
74
75	impl<E: Endianness, B: BitRead<E>> MinimalBinaryRead<E> for B {}
76	impl<E: Endianness, B: BitWrite<E>> MinimalBinaryWrite<E> for B {}

vigna / dsi-bitstream-rs / 12468275135

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