208 lines
6.5 KiB
Rust
208 lines
6.5 KiB
Rust
// Copyright 2012 The Rust Project Developers. See the COPYRIGHT
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// file at the top-level directory of this distribution and at
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// http://rust-lang.org/COPYRIGHT.
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//
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// Licensed under the Apache License, Version 2.0 <LICENSE-APACHE or
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// http://www.apache.org/licenses/LICENSE-2.0> or the MIT license
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// <LICENSE-MIT or http://opensource.org/licenses/MIT>, at your
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// option. This file may not be copied, modified, or distributed
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// except according to those terms.
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//! Operations and constants for `uint`
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pub use self::inst::{
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div_ceil, div_round, div_floor, iterate,
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next_power_of_two
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};
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pub mod inst {
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use sys;
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use uint;
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use iter;
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pub type T = uint;
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#[allow(non_camel_case_types)]
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pub type T_SIGNED = int;
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#[cfg(target_arch = "x86")]
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#[cfg(target_arch = "arm")]
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pub const bits: uint = 32;
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#[cfg(target_arch = "x86_64")]
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pub const bits: uint = 64;
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/**
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* Divide two numbers, return the result, rounded up.
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*
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* # Arguments
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*
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* * x - an integer
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* * y - an integer distinct from 0u
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*
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* # Return value
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*
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* The smallest integer `q` such that `x/y <= q`.
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*/
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pub pure fn div_ceil(x: uint, y: uint) -> uint {
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let div = x / y;
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if x % y == 0u { div }
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else { div + 1u }
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}
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/**
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* Divide two numbers, return the result, rounded to the closest integer.
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*
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* # Arguments
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*
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* * x - an integer
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* * y - an integer distinct from 0u
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*
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* # Return value
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*
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* The integer `q` closest to `x/y`.
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*/
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pub pure fn div_round(x: uint, y: uint) -> uint {
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let div = x / y;
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if x % y * 2u < y { div }
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else { div + 1u }
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}
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/**
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* Divide two numbers, return the result, rounded down.
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*
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* Note: This is the same function as `div`.
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*
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* # Arguments
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*
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* * x - an integer
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* * y - an integer distinct from 0u
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*
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* # Return value
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*
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* The smallest integer `q` such that `x/y <= q`. This
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* is either `x/y` or `x/y + 1`.
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*/
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pub pure fn div_floor(x: uint, y: uint) -> uint { return x / y; }
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/**
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* Iterate over the range [`lo`..`hi`), or stop when requested
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*
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* # Arguments
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*
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* * lo - The integer at which to start the loop (included)
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* * hi - The integer at which to stop the loop (excluded)
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* * it - A block to execute with each consecutive integer of the range.
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* Return `true` to continue, `false` to stop.
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*
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* # Return value
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*
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* `true` If execution proceeded correctly, `false` if it was interrupted,
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* that is if `it` returned `false` at any point.
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*/
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pub pure fn iterate(lo: uint, hi: uint, it: fn(uint) -> bool) -> bool {
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let mut i = lo;
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while i < hi {
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if (!it(i)) { return false; }
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i += 1u;
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}
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return true;
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}
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pub impl uint: iter::Times {
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#[inline(always)]
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/**
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* A convenience form for basic iteration. Given a uint `x`,
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* `for x.times { ... }` executes the given block x times.
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*
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* Equivalent to `for uint::range(0, x) |_| { ... }`.
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*
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* Not defined on all integer types to permit unambiguous
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* use with integer literals of inferred integer-type as
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* the self-value (eg. `for 100.times { ... }`).
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*/
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pure fn times(&self, it: fn() -> bool) {
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let mut i = *self;
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while i > 0 {
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if !it() { break }
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i -= 1;
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}
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}
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}
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/// Returns the smallest power of 2 greater than or equal to `n`
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#[inline(always)]
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pub pure fn next_power_of_two(n: uint) -> uint {
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let halfbits: uint = sys::size_of::<uint>() * 4u;
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let mut tmp: uint = n - 1u;
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let mut shift: uint = 1u;
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while shift <= halfbits { tmp |= tmp >> shift; shift <<= 1u; }
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return tmp + 1u;
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}
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#[test]
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fn test_next_power_of_two() {
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assert (uint::next_power_of_two(0u) == 0u);
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assert (uint::next_power_of_two(1u) == 1u);
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assert (uint::next_power_of_two(2u) == 2u);
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assert (uint::next_power_of_two(3u) == 4u);
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assert (uint::next_power_of_two(4u) == 4u);
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assert (uint::next_power_of_two(5u) == 8u);
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assert (uint::next_power_of_two(6u) == 8u);
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assert (uint::next_power_of_two(7u) == 8u);
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assert (uint::next_power_of_two(8u) == 8u);
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assert (uint::next_power_of_two(9u) == 16u);
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assert (uint::next_power_of_two(10u) == 16u);
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assert (uint::next_power_of_two(11u) == 16u);
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assert (uint::next_power_of_two(12u) == 16u);
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assert (uint::next_power_of_two(13u) == 16u);
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assert (uint::next_power_of_two(14u) == 16u);
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assert (uint::next_power_of_two(15u) == 16u);
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assert (uint::next_power_of_two(16u) == 16u);
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assert (uint::next_power_of_two(17u) == 32u);
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assert (uint::next_power_of_two(18u) == 32u);
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assert (uint::next_power_of_two(19u) == 32u);
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assert (uint::next_power_of_two(20u) == 32u);
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assert (uint::next_power_of_two(21u) == 32u);
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assert (uint::next_power_of_two(22u) == 32u);
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assert (uint::next_power_of_two(23u) == 32u);
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assert (uint::next_power_of_two(24u) == 32u);
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assert (uint::next_power_of_two(25u) == 32u);
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assert (uint::next_power_of_two(26u) == 32u);
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assert (uint::next_power_of_two(27u) == 32u);
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assert (uint::next_power_of_two(28u) == 32u);
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assert (uint::next_power_of_two(29u) == 32u);
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assert (uint::next_power_of_two(30u) == 32u);
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assert (uint::next_power_of_two(31u) == 32u);
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assert (uint::next_power_of_two(32u) == 32u);
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assert (uint::next_power_of_two(33u) == 64u);
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assert (uint::next_power_of_two(34u) == 64u);
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assert (uint::next_power_of_two(35u) == 64u);
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assert (uint::next_power_of_two(36u) == 64u);
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assert (uint::next_power_of_two(37u) == 64u);
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assert (uint::next_power_of_two(38u) == 64u);
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assert (uint::next_power_of_two(39u) == 64u);
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}
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#[test]
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fn test_overflows() {
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assert (uint::max_value > 0u);
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assert (uint::min_value <= 0u);
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assert (uint::min_value + uint::max_value + 1u == 0u);
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}
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#[test]
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fn test_div() {
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assert(uint::div_floor(3u, 4u) == 0u);
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assert(uint::div_ceil(3u, 4u) == 1u);
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assert(uint::div_round(3u, 4u) == 1u);
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}
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#[test]
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pub fn test_times() {
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use iter::Times;
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let ten = 10 as uint;
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let mut accum = 0;
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for ten.times { accum += 1; }
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assert (accum == 10);
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}
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}
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