| <!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/itoa-1.0.6/src/udiv128.rs`."><meta name="keywords" content="rust, rustlang, rust-lang"><title>udiv128.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="../../itoa/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="../../itoa/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="attribute">#[cfg(feature = <span class="string">"no-panic"</span>)] |
| </span><span class="kw">use </span>no_panic::no_panic; |
| |
| <span class="doccomment">/// Multiply unsigned 128 bit integers, return upper 128 bits of the result |
| </span><span class="attribute">#[inline] |
| #[cfg_attr(feature = <span class="string">"no-panic"</span>, no_panic)] |
| </span><span class="kw">fn </span>u128_mulhi(x: u128, y: u128) -> u128 { |
| <span class="kw">let </span>x_lo = x <span class="kw">as </span>u64; |
| <span class="kw">let </span>x_hi = (x >> <span class="number">64</span>) <span class="kw">as </span>u64; |
| <span class="kw">let </span>y_lo = y <span class="kw">as </span>u64; |
| <span class="kw">let </span>y_hi = (y >> <span class="number">64</span>) <span class="kw">as </span>u64; |
| |
| <span class="comment">// handle possibility of overflow |
| </span><span class="kw">let </span>carry = (x_lo <span class="kw">as </span>u128 * y_lo <span class="kw">as </span>u128) >> <span class="number">64</span>; |
| <span class="kw">let </span>m = x_lo <span class="kw">as </span>u128 * y_hi <span class="kw">as </span>u128 + carry; |
| <span class="kw">let </span>high1 = m >> <span class="number">64</span>; |
| |
| <span class="kw">let </span>m_lo = m <span class="kw">as </span>u64; |
| <span class="kw">let </span>high2 = (x_hi <span class="kw">as </span>u128 * y_lo <span class="kw">as </span>u128 + m_lo <span class="kw">as </span>u128) >> <span class="number">64</span>; |
| |
| x_hi <span class="kw">as </span>u128 * y_hi <span class="kw">as </span>u128 + high1 + high2 |
| } |
| |
| <span class="doccomment">/// Divide `n` by 1e19 and return quotient and remainder |
| /// |
| /// Integer division algorithm is based on the following paper: |
| /// |
| /// T. Granlund and P. Montgomery, “Division by Invariant Integers Using Multiplication” |
| /// in Proc. of the SIGPLAN94 Conference on Programming Language Design and |
| /// Implementation, 1994, pp. 61–72 |
| /// |
| </span><span class="attribute">#[inline] |
| #[cfg_attr(feature = <span class="string">"no-panic"</span>, no_panic)] |
| </span><span class="kw">pub fn </span>udivmod_1e19(n: u128) -> (u128, u64) { |
| <span class="kw">let </span>d = <span class="number">10_000_000_000_000_000_000_u64</span>; <span class="comment">// 10^19 |
| |
| </span><span class="kw">let </span>quot = <span class="kw">if </span>n < <span class="number">1 </span><< <span class="number">83 </span>{ |
| ((n >> <span class="number">19</span>) <span class="kw">as </span>u64 / (d >> <span class="number">19</span>)) <span class="kw">as </span>u128 |
| } <span class="kw">else </span>{ |
| u128_mulhi(n, <span class="number">156927543384667019095894735580191660403</span>) >> <span class="number">62 |
| </span>}; |
| |
| <span class="kw">let </span>rem = (n - quot * d <span class="kw">as </span>u128) <span class="kw">as </span>u64; |
| <span class="macro">debug_assert_eq!</span>(quot, n / d <span class="kw">as </span>u128); |
| <span class="macro">debug_assert_eq!</span>(rem <span class="kw">as </span>u128, n % d <span class="kw">as </span>u128); |
| |
| (quot, rem) |
| } |
| </code></pre></div> |
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