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Convert booleans to bits and back

Convert an array of booleans to an array of bytes with 8 booleans packed in one byte. The reverse operation from a byte array to a boolean array is also provided.

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module BitConverter = 
    let pow2 y = 1 <<< y
    // convert booleans to bytes in a space efficient way
    let FromBooleans (bools:bool []) =
        seq {
            let b = ref 0uy
            for i=0 to bools.Length-1 do
                let rem = (i  % 8)
                if rem = 0 && i<> 0 then 
                    yield !b
                    b := 0uy
                if bools.[i] then
                    b := !b + (byte (pow2 rem))
            yield !b
        } |> Array.ofSeq
    // to booleans only works for bytes created with FromBooleans
    let ToBooleans (bytes:byte []) = 
        bytes
        |> Array.map (fun b -> Array.init 8 (fun i -> ((pow2 i) &&& int b) > 0))
        |> Array.concat
val pow2 : y:int32 -> int

Full name: Script.BitConverter.pow2
val y : int32
val FromBooleans : bools:bool [] -> byte []

Full name: Script.BitConverter.FromBooleans
val bools : bool []
type bool = System.Boolean

Full name: Microsoft.FSharp.Core.bool
Multiple items
val seq : sequence:seq<'T> -> seq<'T>

Full name: Microsoft.FSharp.Core.Operators.seq

--------------------
type seq<'T> = System.Collections.Generic.IEnumerable<'T>

Full name: Microsoft.FSharp.Collections.seq<_>
val b : byte ref
Multiple items
val ref : value:'T -> 'T ref

Full name: Microsoft.FSharp.Core.Operators.ref

--------------------
type 'T ref = Ref<'T>

Full name: Microsoft.FSharp.Core.ref<_>
val i : int
property System.Array.Length: int
val rem : int
Multiple items
val byte : value:'T -> byte (requires member op_Explicit)

Full name: Microsoft.FSharp.Core.Operators.byte

--------------------
type byte = System.Byte

Full name: Microsoft.FSharp.Core.byte
module Array

from Microsoft.FSharp.Collections
val ofSeq : source:seq<'T> -> 'T []

Full name: Microsoft.FSharp.Collections.Array.ofSeq
val ToBooleans : bytes:byte [] -> bool []

Full name: Script.BitConverter.ToBooleans
val bytes : byte []
val map : mapping:('T -> 'U) -> array:'T [] -> 'U []

Full name: Microsoft.FSharp.Collections.Array.map
val b : byte
val init : count:int -> initializer:(int -> 'T) -> 'T []

Full name: Microsoft.FSharp.Collections.Array.init
Multiple items
val int : value:'T -> int (requires member op_Explicit)

Full name: Microsoft.FSharp.Core.Operators.int

--------------------
type int = int32

Full name: Microsoft.FSharp.Core.int

--------------------
type int<'Measure> = int

Full name: Microsoft.FSharp.Core.int<_>
val concat : arrays:seq<'T []> -> 'T []

Full name: Microsoft.FSharp.Collections.Array.concat
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More information

Link:http://fssnip.net/nb
Posted:3 years ago
Author:Samuel Bosch
Tags: bits boolean byte array