Trait bv::BlockType[−][src]

pub trait BlockType: Copy + PartialEq + Ord + BitAnd<Output = Self> + BitOr<Output = Self> + BitXor<Output = Self> + Not<Output = Self> + Shl<usize, Output = Self> + Shr<usize, Output = Self> + Sub<Output = Self> {
    fn leading_zeros(self) -> usize;
    fn to_usize(self) -> Option<usize>;
    fn zero() -> Self;
    fn one() -> Self;

    fn nbits() -> usize { ... }
    fn div_nbits(index: u64) -> usize { ... }
    fn checked_div_nbits(index: u64) -> Option<usize> { ... }
    fn ceil_div_nbits(index: u64) -> usize { ... }
    fn checked_ceil_div_nbits(index: u64) -> Option<usize> { ... }
    fn mod_nbits(index: u64) -> usize { ... }
    fn mul_nbits(index: usize) -> u64 { ... }
    fn block_bits(len: u64, position: usize) -> usize { ... }
    fn last_block_bits(len: u64) -> usize { ... }
    fn lg_nbits() -> usize { ... }
    fn lg_nbits_mask<Result: BlockType>() -> Result { ... }
    fn low_mask(element_bits: usize) -> Self { ... }
    fn nth_mask(bit_index: usize) -> Self { ... }
    fn get_bit(self, bit_index: usize) -> bool { ... }
    fn with_bit(self, bit_index: usize, bit_value: bool) -> Self { ... }
    fn get_bits(self, start: usize, len: usize) -> Self { ... }
    fn with_bits(self, start: usize, len: usize, value: Self) -> Self { ... }
    fn ceil_lg(self) -> usize { ... }
    fn floor_lg(self) -> usize { ... }
}

Interface to primitive bit storage.

Types implementing this trait can be used as the blocks of a bit-vector.

Required Methods

`fn leading_zeros(self) -> usize`

Returns the number of leading zero bits in the given number.

`fn to_usize(self) -> Option<usize>`

Converts the number to a usize, if it fits.

`fn zero() -> Self`

Returns 0.

`fn one() -> Self`

Returns 1.

Provided Methods

`fn nbits() -> usize`

The number of bits in a block.

`fn div_nbits(index: u64) -> usize`

Returns index / Self::nbits(), computed by shifting.

This is intended for converting a bit address into a block address, which is why it takes u64 and returns usize. There is no check that the result actually fits in a usize, so this should only be used when index is already known to be small enough.

`fn checked_div_nbits(index: u64) -> Option<usize>`

Returns index / Self::nbits(), computed by shifting.

This is intended for converting a bit address into a block address, which is why it takes u64 and returns usize. It can only fail (returning None) if usize is 32 bits.

`fn ceil_div_nbits(index: u64) -> usize`

Returns index / Self::nbits() rounded up, computed by shifting.

This is intended for converting a bit size into a block size, which is why it takes u64 and returns usize.

`fn checked_ceil_div_nbits(index: u64) -> Option<usize>`

Returns index / Self::nbits() rounded up, computed by shifting.

This is intended for converting a bit size into a block size, which is why it takes u64 and returns usize. There is no check that the result actually fits in a usize, so this should only be used when index is already known to be small enough.

`fn mod_nbits(index: u64) -> usize`

Returns index % Self::nbits(), computed by masking.

This is intended for converting a bit address into a bit offset within a block, which is why it takes u64 and returns usize.

`fn mul_nbits(index: usize) -> u64`

Returns index * Self::nbits(), computed by shifting.

This is intended for converting a block address into a bit address, which is why it takes a usize and returns a u64.

`fn block_bits(len: u64, position: usize) -> usize`

The number of bits in the block at position, given a total bit length of len.

This will be Self::nbits() for all but the last block, for which it will be Self::last_block_bits(len).

Precondition

position * Self::nbits() <= len, or the block doesn't exist and the result is undefined.

`fn last_block_bits(len: u64) -> usize`

Computes how many bits are in the last block of an array of len bits.

This is like Self::mod_nbits, but it returns Self::nbits() in lieu of 0. Note that this means that if you have 0 bits then the last block is full.