| <!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="Source of the Rust file `/root/.cargo/registry/src/github.com-1ecc6299db9ec823/base64-0.21.2/src/engine/general_purpose/decode.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>decode.rs - source</title><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceSerif4-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../FiraSans-Regular.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../FiraSans-Medium.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceCodePro-Regular.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceSerif4-Bold.ttf.woff2"><link rel="preload" as="font" type="font/woff2" crossorigin href="../../../../SourceCodePro-Semibold.ttf.woff2"><link rel="stylesheet" href="../../../../normalize.css"><link rel="stylesheet" href="../../../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" href="../../../../ayu.css" disabled><link rel="stylesheet" href="../../../../dark.css" disabled><link rel="stylesheet" href="../../../../light.css" id="themeStyle"><script id="default-settings" ></script><script src="../../../../storage.js"></script><script defer src="../../../../source-script.js"></script><script defer src="../../../../source-files.js"></script><script defer src="../../../../main.js"></script><noscript><link rel="stylesheet" href="../../../../noscript.css"></noscript><link rel="alternate icon" type="image/png" href="../../../../favicon-16x16.png"><link rel="alternate icon" type="image/png" href="../../../../favicon-32x32.png"><link rel="icon" type="image/svg+xml" href="../../../../favicon.svg"></head><body class="rustdoc source"><!--[if lte IE 11]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><a class="sidebar-logo" href="../../../../base64/index.html"><div class="logo-container"><img class="rust-logo" src="../../../../rust-logo.svg" alt="logo"></div></a></nav><main><div class="width-limiter"><nav class="sub"><a class="sub-logo-container" href="../../../../base64/index.html"><img class="rust-logo" src="../../../../rust-logo.svg" alt="logo"></a><form class="search-form"><div class="search-container"><span></span><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><div id="help-button" title="help" tabindex="-1"><a href="../../../../help.html">?</a></div><div id="settings-menu" tabindex="-1"><a href="../../../../settings.html" title="settings"><img width="22" height="22" alt="Change settings" src="../../../../wheel.svg"></a></div></div></form></nav><section id="main-content" class="content"><div class="example-wrap"><pre class="src-line-numbers"><span id="1">1</span> |
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| </pre><pre class="rust"><code><span class="kw">use crate</span>::{ |
| engine::{general_purpose::INVALID_VALUE, DecodeEstimate, DecodeMetadata, DecodePaddingMode}, |
| DecodeError, PAD_BYTE, |
| }; |
| |
| <span class="comment">// decode logic operates on chunks of 8 input bytes without padding |
| </span><span class="kw">const </span>INPUT_CHUNK_LEN: usize = <span class="number">8</span>; |
| <span class="kw">const </span>DECODED_CHUNK_LEN: usize = <span class="number">6</span>; |
| |
| <span class="comment">// we read a u64 and write a u64, but a u64 of input only yields 6 bytes of output, so the last |
| // 2 bytes of any output u64 should not be counted as written to (but must be available in a |
| // slice). |
| </span><span class="kw">const </span>DECODED_CHUNK_SUFFIX: usize = <span class="number">2</span>; |
| |
| <span class="comment">// how many u64's of input to handle at a time |
| </span><span class="kw">const </span>CHUNKS_PER_FAST_LOOP_BLOCK: usize = <span class="number">4</span>; |
| |
| <span class="kw">const </span>INPUT_BLOCK_LEN: usize = CHUNKS_PER_FAST_LOOP_BLOCK * INPUT_CHUNK_LEN; |
| |
| <span class="comment">// includes the trailing 2 bytes for the final u64 write |
| </span><span class="kw">const </span>DECODED_BLOCK_LEN: usize = |
| CHUNKS_PER_FAST_LOOP_BLOCK * DECODED_CHUNK_LEN + DECODED_CHUNK_SUFFIX; |
| |
| <span class="attribute">#[doc(hidden)] |
| </span><span class="kw">pub struct </span>GeneralPurposeEstimate { |
| <span class="doccomment">/// Total number of decode chunks, including a possibly partial last chunk |
| </span>num_chunks: usize, |
| decoded_len_estimate: usize, |
| } |
| |
| <span class="kw">impl </span>GeneralPurposeEstimate { |
| <span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>new(encoded_len: usize) -> <span class="self">Self </span>{ |
| <span class="comment">// Formulas that won't overflow |
| </span><span class="self">Self </span>{ |
| num_chunks: encoded_len / INPUT_CHUNK_LEN |
| + (encoded_len % INPUT_CHUNK_LEN > <span class="number">0</span>) <span class="kw">as </span>usize, |
| decoded_len_estimate: (encoded_len / <span class="number">4 </span>+ (encoded_len % <span class="number">4 </span>> <span class="number">0</span>) <span class="kw">as </span>usize) * <span class="number">3</span>, |
| } |
| } |
| } |
| |
| <span class="kw">impl </span>DecodeEstimate <span class="kw">for </span>GeneralPurposeEstimate { |
| <span class="kw">fn </span>decoded_len_estimate(<span class="kw-2">&</span><span class="self">self</span>) -> usize { |
| <span class="self">self</span>.decoded_len_estimate |
| } |
| } |
| |
| <span class="doccomment">/// Helper to avoid duplicating num_chunks calculation, which is costly on short inputs. |
| /// Returns the decode metadata, or an error. |
| </span><span class="comment">// We're on the fragile edge of compiler heuristics here. If this is not inlined, slow. If this is |
| // inlined(always), a different slow. plain ol' inline makes the benchmarks happiest at the moment, |
| // but this is fragile and the best setting changes with only minor code modifications. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">pub</span>(<span class="kw">crate</span>) <span class="kw">fn </span>decode_helper( |
| input: <span class="kw-2">&</span>[u8], |
| estimate: GeneralPurposeEstimate, |
| output: <span class="kw-2">&mut </span>[u8], |
| decode_table: <span class="kw-2">&</span>[u8; <span class="number">256</span>], |
| decode_allow_trailing_bits: bool, |
| padding_mode: DecodePaddingMode, |
| ) -> <span class="prelude-ty">Result</span><DecodeMetadata, DecodeError> { |
| <span class="kw">let </span>remainder_len = input.len() % INPUT_CHUNK_LEN; |
| |
| <span class="comment">// Because the fast decode loop writes in groups of 8 bytes (unrolled to |
| // CHUNKS_PER_FAST_LOOP_BLOCK times 8 bytes, where possible) and outputs 8 bytes at a time (of |
| // which only 6 are valid data), we need to be sure that we stop using the fast decode loop |
| // soon enough that there will always be 2 more bytes of valid data written after that loop. |
| </span><span class="kw">let </span>trailing_bytes_to_skip = <span class="kw">match </span>remainder_len { |
| <span class="comment">// if input is a multiple of the chunk size, ignore the last chunk as it may have padding, |
| // and the fast decode logic cannot handle padding |
| </span><span class="number">0 </span>=> INPUT_CHUNK_LEN, |
| <span class="comment">// 1 and 5 trailing bytes are illegal: can't decode 6 bits of input into a byte |
| </span><span class="number">1 </span>| <span class="number">5 </span>=> { |
| <span class="comment">// trailing whitespace is so common that it's worth it to check the last byte to |
| // possibly return a better error message |
| </span><span class="kw">if let </span><span class="prelude-val">Some</span>(b) = input.last() { |
| <span class="kw">if </span><span class="kw-2">*</span>b != PAD_BYTE && decode_table[<span class="kw-2">*</span>b <span class="kw">as </span>usize] == INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte(input.len() - <span class="number">1</span>, <span class="kw-2">*</span>b)); |
| } |
| } |
| |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidLength); |
| } |
| <span class="comment">// This will decode to one output byte, which isn't enough to overwrite the 2 extra bytes |
| // written by the fast decode loop. So, we have to ignore both these 2 bytes and the |
| // previous chunk. |
| </span><span class="number">2 </span>=> INPUT_CHUNK_LEN + <span class="number">2</span>, |
| <span class="comment">// If this is 3 un-padded chars, then it would actually decode to 2 bytes. However, if this |
| // is an erroneous 2 chars + 1 pad char that would decode to 1 byte, then it should fail |
| // with an error, not panic from going past the bounds of the output slice, so we let it |
| // use stage 3 + 4. |
| </span><span class="number">3 </span>=> INPUT_CHUNK_LEN + <span class="number">3</span>, |
| <span class="comment">// This can also decode to one output byte because it may be 2 input chars + 2 padding |
| // chars, which would decode to 1 byte. |
| </span><span class="number">4 </span>=> INPUT_CHUNK_LEN + <span class="number">4</span>, |
| <span class="comment">// Everything else is a legal decode len (given that we don't require padding), and will |
| // decode to at least 2 bytes of output. |
| </span><span class="kw">_ </span>=> remainder_len, |
| }; |
| |
| <span class="comment">// rounded up to include partial chunks |
| </span><span class="kw">let </span><span class="kw-2">mut </span>remaining_chunks = estimate.num_chunks; |
| |
| <span class="kw">let </span><span class="kw-2">mut </span>input_index = <span class="number">0</span>; |
| <span class="kw">let </span><span class="kw-2">mut </span>output_index = <span class="number">0</span>; |
| |
| { |
| <span class="kw">let </span>length_of_fast_decode_chunks = input.len().saturating_sub(trailing_bytes_to_skip); |
| |
| <span class="comment">// Fast loop, stage 1 |
| // manual unroll to CHUNKS_PER_FAST_LOOP_BLOCK of u64s to amortize slice bounds checks |
| </span><span class="kw">if let </span><span class="prelude-val">Some</span>(max_start_index) = length_of_fast_decode_chunks.checked_sub(INPUT_BLOCK_LEN) { |
| <span class="kw">while </span>input_index <= max_start_index { |
| <span class="kw">let </span>input_slice = <span class="kw-2">&</span>input[input_index..(input_index + INPUT_BLOCK_LEN)]; |
| <span class="kw">let </span>output_slice = <span class="kw-2">&mut </span>output[output_index..(output_index + DECODED_BLOCK_LEN)]; |
| |
| decode_chunk( |
| <span class="kw-2">&</span>input_slice[<span class="number">0</span>..], |
| input_index, |
| decode_table, |
| <span class="kw-2">&mut </span>output_slice[<span class="number">0</span>..], |
| )<span class="question-mark">?</span>; |
| decode_chunk( |
| <span class="kw-2">&</span>input_slice[<span class="number">8</span>..], |
| input_index + <span class="number">8</span>, |
| decode_table, |
| <span class="kw-2">&mut </span>output_slice[<span class="number">6</span>..], |
| )<span class="question-mark">?</span>; |
| decode_chunk( |
| <span class="kw-2">&</span>input_slice[<span class="number">16</span>..], |
| input_index + <span class="number">16</span>, |
| decode_table, |
| <span class="kw-2">&mut </span>output_slice[<span class="number">12</span>..], |
| )<span class="question-mark">?</span>; |
| decode_chunk( |
| <span class="kw-2">&</span>input_slice[<span class="number">24</span>..], |
| input_index + <span class="number">24</span>, |
| decode_table, |
| <span class="kw-2">&mut </span>output_slice[<span class="number">18</span>..], |
| )<span class="question-mark">?</span>; |
| |
| input_index += INPUT_BLOCK_LEN; |
| output_index += DECODED_BLOCK_LEN - DECODED_CHUNK_SUFFIX; |
| remaining_chunks -= CHUNKS_PER_FAST_LOOP_BLOCK; |
| } |
| } |
| |
| <span class="comment">// Fast loop, stage 2 (aka still pretty fast loop) |
| // 8 bytes at a time for whatever we didn't do in stage 1. |
| </span><span class="kw">if let </span><span class="prelude-val">Some</span>(max_start_index) = length_of_fast_decode_chunks.checked_sub(INPUT_CHUNK_LEN) { |
| <span class="kw">while </span>input_index < max_start_index { |
| decode_chunk( |
| <span class="kw-2">&</span>input[input_index..(input_index + INPUT_CHUNK_LEN)], |
| input_index, |
| decode_table, |
| <span class="kw-2">&mut </span>output |
| [output_index..(output_index + DECODED_CHUNK_LEN + DECODED_CHUNK_SUFFIX)], |
| )<span class="question-mark">?</span>; |
| |
| output_index += DECODED_CHUNK_LEN; |
| input_index += INPUT_CHUNK_LEN; |
| remaining_chunks -= <span class="number">1</span>; |
| } |
| } |
| } |
| |
| <span class="comment">// Stage 3 |
| // If input length was such that a chunk had to be deferred until after the fast loop |
| // because decoding it would have produced 2 trailing bytes that wouldn't then be |
| // overwritten, we decode that chunk here. This way is slower but doesn't write the 2 |
| // trailing bytes. |
| // However, we still need to avoid the last chunk (partial or complete) because it could |
| // have padding, so we always do 1 fewer to avoid the last chunk. |
| </span><span class="kw">for _ in </span><span class="number">1</span>..remaining_chunks { |
| decode_chunk_precise( |
| <span class="kw-2">&</span>input[input_index..], |
| input_index, |
| decode_table, |
| <span class="kw-2">&mut </span>output[output_index..(output_index + DECODED_CHUNK_LEN)], |
| )<span class="question-mark">?</span>; |
| |
| input_index += INPUT_CHUNK_LEN; |
| output_index += DECODED_CHUNK_LEN; |
| } |
| |
| <span class="comment">// always have one more (possibly partial) block of 8 input |
| </span><span class="macro">debug_assert!</span>(input.len() - input_index > <span class="number">1 </span>|| input.is_empty()); |
| <span class="macro">debug_assert!</span>(input.len() - input_index <= <span class="number">8</span>); |
| |
| <span class="kw">super</span>::decode_suffix::decode_suffix( |
| input, |
| input_index, |
| output, |
| output_index, |
| decode_table, |
| decode_allow_trailing_bits, |
| padding_mode, |
| ) |
| } |
| |
| <span class="doccomment">/// Decode 8 bytes of input into 6 bytes of output. 8 bytes of output will be written, but only the |
| /// first 6 of those contain meaningful data. |
| /// |
| /// `input` is the bytes to decode, of which the first 8 bytes will be processed. |
| /// `index_at_start_of_input` is the offset in the overall input (used for reporting errors |
| /// accurately) |
| /// `decode_table` is the lookup table for the particular base64 alphabet. |
| /// `output` will have its first 8 bytes overwritten, of which only the first 6 are valid decoded |
| /// data. |
| </span><span class="comment">// yes, really inline (worth 30-50% speedup) |
| </span><span class="attribute">#[inline(always)] |
| </span><span class="kw">fn </span>decode_chunk( |
| input: <span class="kw-2">&</span>[u8], |
| index_at_start_of_input: usize, |
| decode_table: <span class="kw-2">&</span>[u8; <span class="number">256</span>], |
| output: <span class="kw-2">&mut </span>[u8], |
| ) -> <span class="prelude-ty">Result</span><(), DecodeError> { |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">0</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte(index_at_start_of_input, input[<span class="number">0</span>])); |
| } |
| <span class="kw">let </span><span class="kw-2">mut </span>accum = (morsel <span class="kw">as </span>u64) << <span class="number">58</span>; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">1</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| index_at_start_of_input + <span class="number">1</span>, |
| input[<span class="number">1</span>], |
| )); |
| } |
| accum |= (morsel <span class="kw">as </span>u64) << <span class="number">52</span>; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">2</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| index_at_start_of_input + <span class="number">2</span>, |
| input[<span class="number">2</span>], |
| )); |
| } |
| accum |= (morsel <span class="kw">as </span>u64) << <span class="number">46</span>; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">3</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| index_at_start_of_input + <span class="number">3</span>, |
| input[<span class="number">3</span>], |
| )); |
| } |
| accum |= (morsel <span class="kw">as </span>u64) << <span class="number">40</span>; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">4</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| index_at_start_of_input + <span class="number">4</span>, |
| input[<span class="number">4</span>], |
| )); |
| } |
| accum |= (morsel <span class="kw">as </span>u64) << <span class="number">34</span>; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">5</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| index_at_start_of_input + <span class="number">5</span>, |
| input[<span class="number">5</span>], |
| )); |
| } |
| accum |= (morsel <span class="kw">as </span>u64) << <span class="number">28</span>; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">6</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| index_at_start_of_input + <span class="number">6</span>, |
| input[<span class="number">6</span>], |
| )); |
| } |
| accum |= (morsel <span class="kw">as </span>u64) << <span class="number">22</span>; |
| |
| <span class="kw">let </span>morsel = decode_table[input[<span class="number">7</span>] <span class="kw">as </span>usize]; |
| <span class="kw">if </span>morsel == INVALID_VALUE { |
| <span class="kw">return </span><span class="prelude-val">Err</span>(DecodeError::InvalidByte( |
| index_at_start_of_input + <span class="number">7</span>, |
| input[<span class="number">7</span>], |
| )); |
| } |
| accum |= (morsel <span class="kw">as </span>u64) << <span class="number">16</span>; |
| |
| write_u64(output, accum); |
| |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="doccomment">/// Decode an 8-byte chunk, but only write the 6 bytes actually decoded instead of including 2 |
| /// trailing garbage bytes. |
| </span><span class="attribute">#[inline] |
| </span><span class="kw">fn </span>decode_chunk_precise( |
| input: <span class="kw-2">&</span>[u8], |
| index_at_start_of_input: usize, |
| decode_table: <span class="kw-2">&</span>[u8; <span class="number">256</span>], |
| output: <span class="kw-2">&mut </span>[u8], |
| ) -> <span class="prelude-ty">Result</span><(), DecodeError> { |
| <span class="kw">let </span><span class="kw-2">mut </span>tmp_buf = [<span class="number">0_u8</span>; <span class="number">8</span>]; |
| |
| decode_chunk( |
| input, |
| index_at_start_of_input, |
| decode_table, |
| <span class="kw-2">&mut </span>tmp_buf[..], |
| )<span class="question-mark">?</span>; |
| |
| output[<span class="number">0</span>..<span class="number">6</span>].copy_from_slice(<span class="kw-2">&</span>tmp_buf[<span class="number">0</span>..<span class="number">6</span>]); |
| |
| <span class="prelude-val">Ok</span>(()) |
| } |
| |
| <span class="attribute">#[inline] |
| </span><span class="kw">fn </span>write_u64(output: <span class="kw-2">&mut </span>[u8], value: u64) { |
| output[..<span class="number">8</span>].copy_from_slice(<span class="kw-2">&</span>value.to_be_bytes()); |
| } |
| |
| <span class="attribute">#[cfg(test)] |
| </span><span class="kw">mod </span>tests { |
| <span class="kw">use super</span>::<span class="kw-2">*</span>; |
| |
| <span class="kw">use </span><span class="kw">crate</span>::engine::general_purpose::STANDARD; |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>decode_chunk_precise_writes_only_6_bytes() { |
| <span class="kw">let </span>input = <span class="string">b"Zm9vYmFy"</span>; <span class="comment">// "foobar" |
| </span><span class="kw">let </span><span class="kw-2">mut </span>output = [<span class="number">0_u8</span>, <span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>]; |
| |
| decode_chunk_precise(<span class="kw-2">&</span>input[..], <span class="number">0</span>, <span class="kw-2">&</span>STANDARD.decode_table, <span class="kw-2">&mut </span>output).unwrap(); |
| <span class="macro">assert_eq!</span>(<span class="kw-2">&</span><span class="macro">vec!</span>[<span class="string">b'f'</span>, <span class="string">b'o'</span>, <span class="string">b'o'</span>, <span class="string">b'b'</span>, <span class="string">b'a'</span>, <span class="string">b'r'</span>, <span class="number">6</span>, <span class="number">7</span>], <span class="kw-2">&</span>output); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>decode_chunk_writes_8_bytes() { |
| <span class="kw">let </span>input = <span class="string">b"Zm9vYmFy"</span>; <span class="comment">// "foobar" |
| </span><span class="kw">let </span><span class="kw-2">mut </span>output = [<span class="number">0_u8</span>, <span class="number">1</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">4</span>, <span class="number">5</span>, <span class="number">6</span>, <span class="number">7</span>]; |
| |
| decode_chunk(<span class="kw-2">&</span>input[..], <span class="number">0</span>, <span class="kw-2">&</span>STANDARD.decode_table, <span class="kw-2">&mut </span>output).unwrap(); |
| <span class="macro">assert_eq!</span>(<span class="kw-2">&</span><span class="macro">vec!</span>[<span class="string">b'f'</span>, <span class="string">b'o'</span>, <span class="string">b'o'</span>, <span class="string">b'b'</span>, <span class="string">b'a'</span>, <span class="string">b'r'</span>, <span class="number">0</span>, <span class="number">0</span>], <span class="kw-2">&</span>output); |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>estimate_short_lengths() { |
| <span class="kw">for </span>(range, (num_chunks, decoded_len_estimate)) <span class="kw">in </span>[ |
| (<span class="number">0</span>..=<span class="number">0</span>, (<span class="number">0</span>, <span class="number">0</span>)), |
| (<span class="number">1</span>..=<span class="number">4</span>, (<span class="number">1</span>, <span class="number">3</span>)), |
| (<span class="number">5</span>..=<span class="number">8</span>, (<span class="number">1</span>, <span class="number">6</span>)), |
| (<span class="number">9</span>..=<span class="number">12</span>, (<span class="number">2</span>, <span class="number">9</span>)), |
| (<span class="number">13</span>..=<span class="number">16</span>, (<span class="number">2</span>, <span class="number">12</span>)), |
| (<span class="number">17</span>..=<span class="number">20</span>, (<span class="number">3</span>, <span class="number">15</span>)), |
| ] { |
| <span class="kw">for </span>encoded_len <span class="kw">in </span>range { |
| <span class="kw">let </span>estimate = GeneralPurposeEstimate::new(encoded_len); |
| <span class="macro">assert_eq!</span>(num_chunks, estimate.num_chunks); |
| <span class="macro">assert_eq!</span>(decoded_len_estimate, estimate.decoded_len_estimate); |
| } |
| } |
| } |
| |
| <span class="attribute">#[test] |
| </span><span class="kw">fn </span>estimate_via_u128_inflation() { |
| <span class="comment">// cover both ends of usize |
| </span>(<span class="number">0</span>..<span class="number">1000</span>) |
| .chain(usize::MAX - <span class="number">1000</span>..=usize::MAX) |
| .for_each(|encoded_len| { |
| <span class="comment">// inflate to 128 bit type to be able to safely use the easy formulas |
| </span><span class="kw">let </span>len_128 = encoded_len <span class="kw">as </span>u128; |
| |
| <span class="kw">let </span>estimate = GeneralPurposeEstimate::new(encoded_len); |
| <span class="macro">assert_eq!</span>( |
| ((len_128 + (INPUT_CHUNK_LEN - <span class="number">1</span>) <span class="kw">as </span>u128) / (INPUT_CHUNK_LEN <span class="kw">as </span>u128)) |
| <span class="kw">as </span>usize, |
| estimate.num_chunks |
| ); |
| <span class="macro">assert_eq!</span>( |
| ((len_128 + <span class="number">3</span>) / <span class="number">4 </span>* <span class="number">3</span>) <span class="kw">as </span>usize, |
| estimate.decoded_len_estimate |
| ); |
| }) |
| } |
| } |
| </code></pre></div> |
| </section></div></main><div id="rustdoc-vars" data-root-path="../../../../" data-current-crate="base64" data-themes="ayu,dark,light" data-resource-suffix="" data-rustdoc-version="1.66.0-nightly (5c8bff74b 2022-10-21)" ></div></body></html> |
