149 lines
4.3 KiB
Rust
149 lines
4.3 KiB
Rust
type T = uint;
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#[doc = "
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Divide two numbers, return the result, rounded up.
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# Arguments
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* x - an integer
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* y - an integer distinct from 0u
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# Return value
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The smallest integer `q` such that `x/y <= q`.
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"]
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pure fn div_ceil(x: uint, y: uint) -> uint {
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let div = div(x, y);
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if x % y == 0u { ret div;}
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else { ret div + 1u; }
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}
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#[doc = "
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Divide two numbers, return the result, rounded to the closest integer.
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# Arguments
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* x - an integer
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* y - an integer distinct from 0u
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# Return value
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The integer `q` closest to `x/y`.
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"]
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pure fn div_round(x: uint, y: uint) -> uint {
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let div = div(x, y);
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if x % y * 2u < y { ret div;}
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else { ret div + 1u; }
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}
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#[doc = "
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Divide two numbers, return the result, rounded down.
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Note: This is the same function as `div`.
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# Arguments
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* x - an integer
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* y - an integer distinct from 0u
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# Return value
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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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pure fn div_floor(x: uint, y: uint) -> uint { ret x / y; }
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#[doc = "Produce a uint suitable for use in a hash table"]
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pure fn hash(x: uint) -> uint { ret x; }
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#[doc = "
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Iterate over the range [`lo`..`hi`), or stop when requested
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# Arguments
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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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# Return value
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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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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)) { ret false; }
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i += 1u;
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}
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ret true;
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}
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#[doc = "Returns the smallest power of 2 greater than or equal to `n`"]
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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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ret 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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