The BitArray structure

The BitArray structure provides a implementation of monomorphic arrays of booleans implemented one bit per element. The BitArray structure extends the MONO_ARRAY signature with bit-level operations.

Synopsis

signature BIT_ARRAY
structure BitArray :> BIT_ARRAY

Interface

include MONO_ARRAY

val fromString : string -> array option

val bits : (int * int list) -> array

val getBits : array -> int list

val toString : array -> string

val isZero  : array -> bool

val extend0 : (array * int) -> array
val extend1 : (array * int) -> array

val eqBits : (array * array) -> bool
val equal : (array * array) -> bool

val andb : (array * array * int) -> array
val orb  : (array * array * int) -> array
val xorb : (array * array * int) -> array

val notb  : array -> array

val <<  : (array * word) -> array
val >>  : (array * word) -> array

val setBit : (array * int) -> unit
val clrBit : (array * int) -> unit

val union : array -> array -> unit
val intersection : array -> array -> unit

val complement : array -> unit

val lshift  : (array * int) -> array
val rshift  : (array * int) -> array

Description

include MONO_ARRAY

The BIT_ARRAY signature extends the MONO_ARRAY signature from the Standard ML Basis Library. Note that while the MONO_ARRAY signature includes a corresponding monomorphic vector type, there is currently no implementation of a corresponding BitVector structure.

val fromString : string -> array option

fromString s returns SOME ba when the string s is a sequence of hexadecimal digits. The length of ba will be 4*(length s). Returns NONE of a non-hexadecimal character is encountered.

val bits : (int * int list) -> array

bits (n, ixs) returns a new array ba of length n, where ba[ix] is true for each ix in the list of indices ixs. This function raises the Size exception if n < 0 and the Subscript exception if any index is out of bounds.

val getBits : array -> int list

getBits ba returns a list of indices ix for which ba[ix] is true in increasing order.

val toString : array -> string

toString ba returns a string representation of the array as a sequence of hexadecimal digits in little-endian order (i.e., ba[0] is represented as the high-order bit in the first digit).

val isZero : array -> bool

isZero ba returns true if, and only if, no elements are true in ba.

val extend0 : (array * int) -> array

extend0 (ba, n) returns a new array ba' that is max(n, length ba) elements long, where the length ba elements of ba' are copied from ba and the remaining elements are false. This function raises the Size exception if n < 0.

val extend1 : (array * int) -> array

extend1 (ba, n) returns a new array ba' that is max(n, length ba) elements long, where the length ba elements of ba' are copied from ba and the remaining elements are true. This function raises the Size exception if n < 0.

val eqBits : (array * array) -> bool

eqBits (ba1, ba2) returns true if the two arrays have the same true entries. In other words, the following identity holds

eqBits(ba1, ba2) = (getBits ba1 = getBits ba2)

val equal : (array * array) -> bool

equal (ba1, ba2) returns true if the two arrays are the same length and have the same elements.

val andb : (array * array * int) -> array

andb (ba1, ba2, n) returns a new array ba of length n, where the element ba[ix] is the logical AND of ba1[ix] and ba2[ix], where the inputs are extended with false as necessary. This function raises the Size exception if n < 0.

val orb : (array * array * int) -> array

orb (ba1, ba2, n) returns a new array ba of length n, where the element ba[ix] is the logical OR of ba1[ix] and ba2[ix], where the inputs are extended with false as necessary. This function raises the Size exception if n < 0.

val xorb : (array * array * int) -> array

xorb (ba1, ba2, n) returns a new array ba of length n, where the element ba[ix] is the logical XOR of ba1[ix] and ba2[ix], where the inputs are extended with false as necessary. This function raises the Size exception if n < 0.

val notb : array -> array

notb ba returns a new array of the same length as ba with the elements negated.

val << : (array * word) -> array: << (ba, n)`returns a new array by appending `n false elements on the end of ba. The new array will have length equal to n + length ba.

val >> : (array * word) -> array: >> (ba, n)`returns a new array by trimming `n elements from the "right" of ba. The new array will have max(0, length ba - n) elements.
val setBit : (array * int) -> unit: setBit (ba, ix) sets the element of ba at index ix to true. This function raises the Subscript exception if ix is out of bounds.
val clrBit : (array * int) -> unit: setBit (ba, ix) sets the element of ba at index ix to false. This function raises the Subscript exception if ix is out of bounds.
val union : array -> array -> unit: union ba1 ba2 updates ba1 by setting each element ba1[ix] to the logical OR of ba1[ix] and ba2[ix], where ba2[ix] is extended with false elements as necessary to match the length of ba1.
val intersection : array -> array -> unit: intersection ba1 ba2 updates ba1 by setting each element ba1[ix] to the logical AND of ba1[ix] and ba2[ix], where ba2[ix] is extended with false elements as necessary to match the length of ba1.
val complement : array -> unit: complement ba logically negates all of the elements of ba.

Deprecated Functions

val lshift : (array * int) -> array: Use << instead.
val rshift : (array * int) -> array: Use >> instead.

Synopsis

Interface

Description

Deprecated Functions

See Also