intbits 0.2.0

Easy access to individual bits of integers
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171

use super::{Bits, BitsIndex};
use core::ops::Bound::{Excluded, Included, Unbounded};
use core::ops::{Bound, RangeBounds};

trait BitRange<T>: Bits {
	fn mask(end: Bound<&T>) -> Self::Bits;
	fn shift(end: Bound<&T>) -> Option<T>;
}

macro_rules! bits {
	($t:tt, $ut:tt, $n:tt, $i:tt) => {
		#[allow(unused_comparisons)]
		impl BitRange<$i> for $t {
			#[inline]
			fn mask(end: Bound<&$i>) -> $ut {
				match end {
					Unbounded => !0,
					Excluded(&i) if i > $n && i - 1 == $n => !0,
					Excluded(&i) if i <= $n && i >= 0 => !0 >> 1 >> ($n - i),
					Included(&i) if i < 0 && i + 1 == 0 => 0,
					Included(&i) if i <= $n && i >= 0 => !0 >> ($n - i),
					_ => panic!("invalid bit range"),
				}
			}

			#[inline]
			fn shift(start: Bound<&$i>) -> Option<$i> {
				match start {
					Unbounded => Some(0),
					Included(&i) if i > $n && i - 1 == $n => None,
					Included(&i) if i <= $n && i >= 0 => Some(i),
					Excluded(&i) if i == $n => None,
					Excluded(&i) if i < $n && i + 1 >= 0 => Some(i + 1),
					_ => panic!("invalid bit range"),
				}
			}
		}

		#[allow(unused_comparisons)]
		impl BitsIndex<$t> for $i {
			#[inline]
			fn bit(v: $t, i: Self) -> bool {
				assert!(i >= 0 && i <= $n, "invalid bit index");
				v >> i & 1 != 0
			}

			#[inline]
			fn bits<R>(v: $t, range: R) -> $ut
			where
				R: RangeBounds<Self>,
			{
				let mask = $t::mask(range.end_bound());
				if let Some(shift) = $t::shift(range.start_bound()) {
					(v as $ut & mask) >> shift
				} else {
					0
				}
			}

			#[inline]
			fn set_bit(v: &mut $t, i: Self, bit: bool) {
				assert!(i >= 0 && i <= $n, "invalid bit index");
				*v = *v & !(1 << i) | (bit as $t) << i;
			}

			#[inline]
			fn set_bits<R>(v: &mut $t, range: R, bits: $ut)
			where
				R: RangeBounds<Self>,
			{
				let mask = $t::mask(range.end_bound());
				if let Some(shift) = $t::shift(range.start_bound()) {
					let and_mask = !(mask & !0 << shift);
					let or_mask = bits << shift;
					if or_mask & and_mask != 0 {
						panic!("bits outside range");
					}
					*v = *v & and_mask as $t | or_mask as $t;
				}
			}
		}
	};
	($t:tt, $ut:tt, $n:tt) => {
		impl Bits for $t {
			type Bits = $ut;
			const N_BITS: u32 = $n + 1;
			#[inline]
			fn bit<I>(self, i: I) -> bool
			where
				I: BitsIndex<Self>,
			{
				I::bit(self, i)
			}
			#[inline]
			fn bits<I, R>(self, range: R) -> $ut
			where
				I: BitsIndex<Self>,
				R: RangeBounds<I>,
			{
				I::bits(self, range)
			}
			#[inline]
			fn set_bit<I>(&mut self, i: I, bit: bool)
			where
				I: BitsIndex<Self>,
			{
				I::set_bit(self, i, bit)
			}
			#[inline]
			fn set_bits<I, R>(&mut self, range: R, bits: $ut)
			where
				I: BitsIndex<Self>,
				R: RangeBounds<I>,
			{
				I::set_bits(self, range, bits)
			}
			#[inline]
			fn with_bit<I>(mut self, i: I, bit: bool) -> Self
			where
				I: BitsIndex<Self>,
			{
				I::set_bit(&mut self, i, bit);
				self
			}
			#[inline]
			fn with_bits<I, R>(mut self, range: R, bits: $ut) -> Self
			where
				I: BitsIndex<Self>,
				R: RangeBounds<I>,
			{
				I::set_bits(&mut self, range, bits);
				self
			}
		}
		bits!($t, $ut, $n, i8);
		bits!($t, $ut, $n, u8);
		bits!($t, $ut, $n, i16);
		bits!($t, $ut, $n, u16);
		bits!($t, $ut, $n, i32);
		bits!($t, $ut, $n, u32);
		bits!($t, $ut, $n, i64);
		bits!($t, $ut, $n, u64);
		bits!($t, $ut, $n, i128);
		bits!($t, $ut, $n, u128);
		bits!($t, $ut, $n, isize);
		bits!($t, $ut, $n, usize);
	};
}

bits!(i8, u8, 7);
bits!(u8, u8, 7);
bits!(i16, u16, 15);
bits!(u16, u16, 15);
bits!(i32, u32, 31);
bits!(u32, u32, 31);
bits!(i64, u64, 63);
bits!(u64, u64, 63);
bits!(i128, u128, 127);
bits!(u128, u128, 127);

#[cfg(target_pointer_width = "32")]
bits!(isize, usize, 31);

#[cfg(target_pointer_width = "32")]
bits!(usize, usize, 31);

#[cfg(target_pointer_width = "64")]
bits!(isize, usize, 63);

#[cfg(target_pointer_width = "64")]
bits!(usize, usize, 63);