experimental filter

filterUltra.fs

let filterUltra f (array : 'T[]) =
    
        let inline computeChunk (x:float32) =
            int((float32)array.Length*x)                 

        
        let chunkProgression = 
            match sizeof<'T> * array.Length with
            | x when x < 4096    -> [|array.Length|]
            | x when x < 65536   -> [|computeChunk 0.25f;computeChunk 0.76f|]
            | x when x < 262144  -> [|computeChunk 0.14f;computeChunk 0.29f;computeChunk 0.58f|]
            | _                  -> [|computeChunk 0.07f;computeChunk 0.13f;computeChunk 0.27f;computeChunk 0.54f|] //4
        
        let chunkCount = chunkProgression.Length
        let chunks = Array.create chunkCount empty        
                
        let mutable chunkIndex = 0
        let mutable totalSize = 0
        let mutable i = 0
        let mutable count = 0
        while i < array.Length && chunkIndex < chunkCount do            
            let chunkSize = chunkProgression.[chunkIndex]                        
            chunks.[chunkIndex]  <- Array.zeroCreateUnchecked (Math.Min(chunkSize,array.Length-i+1))  
            let chunk = chunks.[chunkIndex]
           // printf "allocated new chunk[%A] size %A\n" chunkIndex chunks.[chunkIndex].Length                     
            count <- 0
            while count < chunk.Length && i < array.Length do
                let e = array.[i]                                
                if f e then                    
                    chunk.[count] <- e
                    count <- count + 1                            
                i <- i + 1
            totalSize <- totalSize + count
            chunkIndex <- chunkIndex + 1
        
        let res : 'T[] = Array.zeroCreate totalSize
        let mutable start = 0
        for i = 0 to chunks.Length-1 do
            if chunks.[i] <> empty then                                
                let len = if i = chunks.Length-1 || chunks.[i+1] = empty then count else chunks.[i].Length                
                Array.Copy(chunks.[i],0,res,start,len)
                start <- start + len
        res