OpenCL-1.0.2.2: examples/example04.hs

{- Copyright (c) 2011 Luis Cabellos,

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import System.GPU.OpenCL
import Foreign( castPtr, nullPtr, sizeOf )
import Foreign.C.Types( CFloat )
import Foreign.Marshal.Array( newArray, peekArray )

programSource :: String
programSource = "__kernel void duparray(__global float *in, __global float *out ){\n  int id = get_global_id(0);\n  out[id] = 2*in[id];\n}"

main :: IO ()
main = do
  -- Initialize OpenCL
  (platform:_) <- clGetPlatformIDs
  (dev:_) <- clGetDeviceIDs platform CL_DEVICE_TYPE_ALL
  context <- clCreateContext [dev] print
  q <- clCreateCommandQueue context dev []
  
  -- Compile and get binaries
  program <- clCreateProgramWithSource context programSource
  clBuildProgram program [dev] ""
  bins <- clGetProgramBinaries program
  
  -- Create kernel from binaries
  (program2,_) <- clCreateProgramWithBinary context [dev] bins
  clBuildProgram program2 [dev] ""
  kernel <- clCreateKernel program2 "duparray"
  
  -- Initialize parameters
  let original = [0 .. 20] :: [CFloat]
      elemSize = sizeOf (0 :: CFloat)
      vecSize = elemSize * length original
  putStrLn $ "Original array = " ++ show original
  input  <- newArray original

  mem_in <- clCreateBuffer context [CL_MEM_READ_ONLY, CL_MEM_COPY_HOST_PTR] (vecSize, castPtr input)  
  mem_out <- clCreateBuffer context [CL_MEM_WRITE_ONLY] (vecSize, nullPtr)

  clSetKernelArg kernel 0 mem_in
  clSetKernelArg kernel 1 mem_out
  
  -- Execute Kernel
  eventExec <- clEnqueueNDRangeKernel q kernel [length original] [1] []
  
  -- Get Result
  eventRead <- clEnqueueReadBuffer q mem_out True 0 vecSize (castPtr input) [eventExec]
  
  result <- peekArray (length original) input
  putStrLn $ "Result array = " ++ show result

  return ()