jni-ffi examples in scala

jnrFfiScala.scala

import jnr.ffi._
import jnr.ffi.annotations.{Out, Transient}
import jnr.ffi.types.pid_t

import scala.util.Random


object SimpleFfi {

  val libc = LibraryLoader.create(classOf[SimpleFfi.LibC]).load("c")


  trait LibC {
    @pid_t def getpid: Long

    @pid_t def getppid: Long

    def getlogin: String

    def gettimeofday(@Out @Transient tv: Timeval, unused: Pointer): Int
  }

  final class Timeval(val runtime: Runtime) extends Struct(runtime) {
    val tv_sec = new time_t()
    val tv_usec = new SignedLong()
  }


  def main(args: Array[String]): Unit = {
    println("pid=" + libc.getpid + " parent pid=" + libc.getppid)
    println("login=" + libc.getlogin)

    val runtime = Runtime.getRuntime(libc)
    val tv = new Timeval(runtime)
    libc.gettimeofday(tv, null)
    println("gettimeofday tv.tv_sec=" + tv.tv_sec.get + " tv.tv_usec=" + tv.tv_usec.get)
  }
}


import jnr.ffi.LibraryLoader
import jnr.ffi.Memory
import jnr.ffi.Pointer
import jnr.ffi.annotations.Delegate
import jnr.ffi.types.size_t
import java.nio.Buffer
import java.nio.ByteBuffer
import java.nio.ByteOrder

object Qsort {

  trait Compare {
    @Delegate def compare(p1: Pointer, p2: Pointer): Int
  }

  final class IntCompare extends Qsort.Compare {
    override def compare(p1: Pointer, p2: Pointer): Int = {
      val i1 = p1.getInt(0)
      val i2 = p2.getInt(0)
      if (i1 < i2) -1
      else if (i1 > i2) 1
      else 0
    }
  }

  trait LibC {
    def qsort(data: Array[Int], @size_t count: Int, @size_t width: Int, compare: Compare): Int

    def qsort(data: Pointer, @size_t count: Long, @size_t width: Int, compare: Qsort.Compare): Int

    def qsort(data: Buffer, @size_t count: Long, @size_t width: Int, compare: Qsort.Compare): Int
  }

  def main(args: Array[String]): Unit = {
    val libc = LibraryLoader.create(classOf[Qsort.LibC]).load("c")

    val n = 100
    val numbers = Array.fill(n)(Random.nextInt(n*n*n))

    println("qsort using java int[] array")
    println(s"before: ${numbers.toList}")
    libc.qsort(numbers, numbers.length, 4, new Qsort.IntCompare)
    assert(numbers.sorted sameElements numbers)
    println(s"after: ${numbers.toList}\n")

    println("sort using native memory")
    val memory = Memory.allocate(Runtime.getRuntime(libc), 8)
    memory.putInt(0, 4)
    memory.putInt(4, 3) // offset is in bytes

    println("before, memory[0]=" + memory.getInt(0) + " memory[1]=" + memory.getInt(4))
    libc.qsort(memory, 2, 4, new Qsort.IntCompare)
    println("after, memory[0]=" + memory.getInt(0) + " memory[1]=" + memory.getInt(4) + "\n")


    println("qsort using NIO buffer")
    val intBuffer = ByteBuffer.allocateDirect(8).order(ByteOrder.nativeOrder).asIntBuffer
    intBuffer.put(0, 6)
    intBuffer.put(1, 5) // offset is in units of int elements

    println("before, buffer[0]=" + intBuffer.get(0) + " buffer[1]=" + intBuffer.get(1))
    libc.qsort(intBuffer, 2, 4, new Qsort.IntCompare)
    println("after, buffer[0]=" + intBuffer.get(0) + " buffer[1]=" + intBuffer.get(1))
  }
}