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    //! Rust implementations of various structs used by the OpenCL API.

    use std;
    use std::mem;
    use std::ptr;
    use std::marker::PhantomData;
    use std::collections::HashMap;
    use num_traits::FromPrimitive;
    use error::{Error as OclCoreError, Result as OclCoreResult};
    use ffi::{self,cl_mem, cl_sampler, cl_buffer_region, cl_context_properties, cl_platform_id,
        c_void, size_t};
    use ::{Mem, MemObjectType, ImageChannelOrder, ImageChannelDataType, ContextProperty,
        PlatformId, OclPrm, Sampler};

    // Until everything can be implemented:
    pub type TemporaryPlaceholderType = ();

    /// A reference to a kernel argument value.
    ///
    /// ### Example:
    ///
    /// ```rust, ignore
    /// let kernel = core::create_kernel(&program, "multiply")?;
    /// core::set_kernel_arg(&kernel, 0, ArgVal::scalar(&10.0f32))?;
    /// core::set_kernel_arg(&kernel, 1, ArgVal::mem(&buffer))?;
    /// ```
    ///
    #[derive(Debug, Clone)]
    pub struct ArgVal<'a> {
        size: size_t,
        value: *const c_void,
        _p: PhantomData<&'a c_void>,
    }

    impl<'a> ArgVal<'a> {
        /// Returns a new `ArgVal` referring to a `Mem` object.
        pub fn mem(mem: &'a Mem) -> ArgVal<'a> {
            ArgVal {
                size: mem::size_of::<cl_mem>() as size_t,
                value: mem as *const _ as *const c_void,
                _p: PhantomData,
            }
        }

        /// Returns a new `ArgVal` corresponding to a null `Mem` object.
        pub fn mem_null() -> ArgVal<'a> {
            ArgVal {
                size: mem::size_of::<cl_mem>() as size_t,
                value: ptr::null(),
                _p: PhantomData,
            }
        }

        /// Returns a new `ArgVal` referring to a `Sampler` object.
        pub fn sampler(sampler: &'a Sampler) -> ArgVal<'a> {
            ArgVal {
                size: mem::size_of::<cl_sampler>() as size_t,
                value: sampler as *const _ as *const c_void,
                _p: PhantomData,
            }
        }

        /// Returns a new `ArgVal` referring to a null `Sampler` object.
        pub fn sampler_null() -> ArgVal<'a> {
            ArgVal {
                size: mem::size_of::<cl_sampler>() as size_t,
                value: ptr::null(),
                _p: PhantomData,
            }
        }

        /// Returns a new `ArgVal` referring to a scalar or vector primitive.
        //
        // `::scalar` and `::vector` exist in case, at a future time, scalar and
        // vector types need to be differentiated, at which point this method
        // would be deprecated.
        pub fn primitive<T>(prm: &'a T) -> ArgVal<'a>
                where T: OclPrm {
            ArgVal {
                size: mem::size_of::<T>() as size_t,
                value: prm as *const T as *const c_void,
                _p: PhantomData,
            }
        }

        /// Returns a new `ArgVal` referring to a scalar primitive.
        pub fn scalar<T>(scalar: &'a T) -> ArgVal<'a>
                where T: OclPrm {
            ArgVal::primitive(scalar)
        }

        /// Returns a new `ArgVal` referring to a vector primitive.
        pub fn vector<T>(vector: &'a T) -> ArgVal<'a>
                where T: OclPrm {
            ArgVal::primitive(vector)
        }

        /// Returns a new `ArgVal` corresponding to a `__local` argument.
        ///
        /// To specify a `__local` argument size in bytes, use `::raw` instead
        /// (with `value`: `std::ptr::null()`).
        pub fn local<T>(length: &usize) -> ArgVal<'a>
                where T: OclPrm {
            ArgVal {
                size: (mem::size_of::<T>() * length) as size_t,
                value: ptr::null(),
                _p: PhantomData,
            }
        }

        /// Returns a new `ArgVal` containing the size in bytes and a raw pointer
        /// to the argument value.
        ///
        /// ### Safety
        ///
        /// Caller must ensure that the value pointed to by `value` lives until
        /// the call to `::set_kernel_arg` returns and that `size` accurately
        /// reflects the total number of bytes that should be read.
        pub unsafe fn from_raw(size: size_t, value: *const c_void) -> ArgVal<'a> {
            ArgVal {
                size,
                value,
                _p: PhantomData,
            }
        }

        /// Returns the size (in bytes) and raw pointer to the contained kernel
        /// argument value.
        pub fn as_raw(&self) -> (size_t, *const c_void) {
            (self.size, self.value)
        }

        /// Returns `true` if this `ArgVal` represents a null `Mem` or `Sampler`
        /// object.
        pub fn is_null(&self) -> bool {
            self.value.is_null()
        }
    }

    /// Parsed OpenCL version in the layout `({major}, {minor})`.
    ///
    /// ex.: 'OpenCL 1.2' -> `OpenclVersion(1, 2)`.
    ///
    #[derive(Debug, Clone, Copy, PartialEq, Eq, PartialOrd, Ord)]
    pub struct OpenclVersion {
        ver: [u16; 2],
    }

    impl OpenclVersion {
        pub fn new(major: u16, minor: u16) -> OpenclVersion {
            OpenclVersion { ver: [major, minor] }
        }

        pub fn max(&self) -> OpenclVersion {
            OpenclVersion { ver: [u16::max_value(), u16::max_value()] }
        }

        /// Parse the string `ver` and return a dual-integer result as
        /// `OpenclVersion`.
        ///
        /// Looks for the sequence of chars, "OpenCL" (non-case-sensitive), then
        /// splits the word just after that (at '.') and parses the two results
        /// into integers (major and minor version numbers).
        pub fn from_info_str(ver: &str) -> OclCoreResult<OpenclVersion> {
            let mut version_word_idx: Option<usize> = None;
            let mut version: Option<OpenclVersion> = None;

            for (word_idx, word) in ver.split_whitespace().enumerate() {
                if let Some(wi) = version_word_idx {
                    assert!(wi == word_idx);
                    let nums: Vec<_> = word.split('.').collect();

                    if nums.len() == 2 {
                        let (major, minor) = (nums[0].parse::<u16>(), nums[1].parse::<u16>());

                        if major.is_ok() && minor.is_ok() {
                            version = Some(OpenclVersion::new(major.unwrap(), minor.unwrap()));
                        }
                    }
                    break;
                }

                for (ch_idx, ch) in word.chars().enumerate() {
                    match ch_idx {
                        0 => if ch != 'O' && ch != 'o' { break; },
                        1 => if ch != 'P' && ch != 'p' { break; },
                        2 => if ch != 'E' && ch != 'e' { break; },
                        3 => if ch != 'N' && ch != 'n' { break; },
                        4 => if ch != 'C' && ch != 'c' { break; },
                        5 => if ch == 'L' || ch == 'l' {
                            version_word_idx = Some(word_idx + 1);
                            break;
                        },
                        _ => break,
                    }
                }
            }

            match version {
                Some(cl_ver) => Ok(cl_ver),
                None => Err(format!("DeviceInfoResult::as_opencl_version(): \
                    Error parsing version from the string: '{}'.", ver).into()),
            }
        }
    }

    impl From<[u16; 2]> for OpenclVersion {
        fn from(ver: [u16; 2]) -> OpenclVersion {
            OpenclVersion { ver: ver }
        }
    }

    impl std::fmt::Display for OpenclVersion {
        fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
            write!(f, "{}.{}", self.ver[0], self.ver[1])
        }
    }

    // cl_context_properties enum  Property value  Description
    //
    // CL_CONTEXT_PLATFORM cl_platform_id  Specifies the platform to use.
    //
    // CL_CONTEXT_INTEROP_USER_SYNC    cl_bool Specifies whether the user is
    // responsible for synchronization between OpenCL and other APIs. Please refer
    // to the specific sections in the OpenCL 1.2 extension specification that
    // describe sharing with other APIs for restrictions on using this flag.
    //
    //    - If CL_CONTEXT_INTEROP_USER_ SYNC is not specified, a default of
    //      CL_FALSE is assumed.
    //
    // CL_CONTEXT_D3D10_DEVICE_KHR ID3D10Device*   If the cl_khr_d3d10_sharing
    // extension is enabled, specifies the ID3D10Device* to use for Direct3D 10
    // interoperability. The default value is NULL.
    //
    // CL_GL_CONTEXT_KHR   0, OpenGL context handle    OpenGL context to
    // associated the OpenCL context with (available if the cl_khr_gl_sharing
    // extension is enabled)
    //
    // CL_EGL_DISPLAY_KHR  EGL_NO_DISPLAY, EGLDisplay handle   EGLDisplay an
    // OpenGL context was created with respect to (available if the
    // cl_khr_gl_sharing extension is enabled)
    //
    // CL_GLX_DISPLAY_KHR  None, X handle  X Display an OpenGL context was created
    // with respect to (available if the cl_khr_gl_sharing extension is enabled)
    //
    // CL_CGL_SHAREGROUP_KHR   0, CGL share group handle   CGL share group to
    // associate the OpenCL context with (available if the cl_khr_gl_sharing
    // extension is enabled)
    //
    // CL_WGL_HDC_KHR  0, HDC handle   HDC an OpenGL context was created with
    // respect to (available if the cl_khr_gl_sharing extension is enabled)
    //
    // CL_CONTEXT_ADAPTER_D3D9_KHR IDirect3DDevice9 *  Specifies an
    // IDirect3DDevice9 to use for D3D9 interop (if the cl_khr_dx9_media_sharing
    // extension is supported).
    //
    // CL_CONTEXT_ADAPTER_D3D9EX_KHR   IDirect3DDeviceEx*  Specifies an
    // IDirect3DDevice9Ex to use for D3D9 interop (if the cl_khr_dx9_media_sharing
    // extension is supported).
    //
    // CL_CONTEXT_ADAPTER_DXVA_KHR IDXVAHD_Device *    Specifies an IDXVAHD_Device
    // to use for DXVA interop (if the cl_khr_dx9_media_sharing extension is
    // supported).
    //
    // CL_CONTEXT_D3D11_DEVICE_KHR ID3D11Device *  Specifies the ID3D11Device * to
    // use for Direct3D 11 interoperability. The default value is NULL.
    //
    #[derive(Clone, Debug)]
    pub enum ContextPropertyValue {
        Platform(PlatformId),
        InteropUserSync(bool),
        // Not sure about this type:
        D3d10DeviceKhr(*mut ffi::cl_d3d10_device_source_khr),
        GlContextKhr(*mut c_void),
        EglDisplayKhr(ffi::CLeglDisplayKHR),
        // Not sure about this type:
        GlxDisplayKhr(*mut c_void),
        // Not sure about this type:
        CglSharegroupKhr(*mut c_void),
        // Not sure about this type:
        WglHdcKhr(*mut c_void),
        AdapterD3d9Khr(isize),
        AdapterD3d9exKhr(isize),
        AdapterDxvaKhr(isize),
        D3d11DeviceKhr(isize),
    }

    unsafe impl Send for ContextPropertyValue {}
    unsafe impl Sync for ContextPropertyValue {}

    /// Context properties list.
    ///
    /// [MINIMALLY TESTED]
    ///
    /// TODO: Check for duplicate property assignments.
    #[derive(Clone, Debug)]
    pub struct ContextProperties {
        props: HashMap<ContextProperty, ContextPropertyValue>,
        contains_gl_context_or_sharegroup: bool,
    }

    impl ContextProperties {
        /// Returns an empty new list of context properties
        pub fn new() -> ContextProperties {
            ContextProperties {
                props: HashMap::with_capacity(16),
                contains_gl_context_or_sharegroup: false,
            }
        }

        /// Specifies a platform (builder-style).
        pub fn platform<P: Into<PlatformId>>(mut self, platform: P) -> ContextProperties {
            self.set_platform(platform);
            self
        }

        /// Specifies whether the user is responsible for synchronization between
        /// OpenCL and other APIs (builder-style).
        pub fn interop_user_sync(mut self, sync: bool) -> ContextProperties {
            self.set_interop_user_sync(sync);
            self
        }

        /// Specifies an OpenGL context handle (builder-style).
        pub fn gl_context(mut self, gl_ctx: *mut c_void) -> ContextProperties {
            self.set_gl_context(gl_ctx);
            self
        }

        /// Specifies a Display pointer for the GLX context (builder-style).
        pub fn glx_display(mut self, glx_disp: *mut c_void) -> ContextProperties {
            self.set_glx_display(glx_disp);
            self
        }

        /// Specifies a Display pointer for the WGL HDC (builder-style).
        pub fn wgl_hdc(mut self, wgl_hdc: *mut c_void) -> ContextProperties {
            self.set_wgl_hdc(wgl_hdc);
            self
        }

        /// Specifies an OpenGL context CGL share group to associate the OpenCL
        /// context with (builder-style).
        pub fn cgl_sharegroup(mut self, gl_sharegroup: *mut c_void) -> ContextProperties {
            self.set_cgl_sharegroup(gl_sharegroup);
            self
        }

        /// Specifies a pointer for the EGL display (builder-style).
        pub fn egl_display(mut self, egl_disp: *mut c_void) -> ContextProperties {
            self.set_egl_display(egl_disp);
            self
        }

        /// Pushes a `ContextPropertyValue` onto this list of properties
        /// (builder-style).
        pub fn property_value(mut self, prop: ContextPropertyValue) -> ContextProperties {
            self.set_property_value(prop);
            self
        }

        /// Specifies a platform.
        pub fn set_platform<P: Into<PlatformId>>(&mut self, platform: P) {
            self.props.insert(ContextProperty::Platform, ContextPropertyValue::Platform(platform.into()));
        }

        /// Specifies whether the user is responsible for synchronization between
        /// OpenCL and other APIs.
        pub fn set_interop_user_sync(&mut self, sync: bool) {
            self.props.insert(ContextProperty::InteropUserSync, ContextPropertyValue::InteropUserSync(sync));
        }

        /// Specifies an OpenGL context handle.
        pub fn set_gl_context(&mut self, gl_ctx: *mut c_void) {
            self.props.insert(ContextProperty::GlContextKhr, ContextPropertyValue::GlContextKhr(gl_ctx));
            self.contains_gl_context_or_sharegroup = true;
        }

        /// Specifies a Display pointer for the GLX context.
        pub fn set_glx_display(&mut self, glx_disp: *mut c_void) {
            self.props.insert(ContextProperty::GlxDisplayKhr, ContextPropertyValue::GlxDisplayKhr(glx_disp));
            self.contains_gl_context_or_sharegroup = true;
        }

        /// Specifies a Display pointer for the WGL HDC.
        pub fn set_wgl_hdc(&mut self, wgl_hdc: *mut c_void) {
            self.props.insert(ContextProperty::WglHdcKhr, ContextPropertyValue::WglHdcKhr(wgl_hdc));
            self.contains_gl_context_or_sharegroup = true;
        }

        /// Specifies an OpenGL context CGL share group to associate the OpenCL
        /// context with.
        pub fn set_cgl_sharegroup(&mut self, gl_sharegroup: *mut c_void) {
            self.props.insert(ContextProperty::CglSharegroupKhr, ContextPropertyValue::CglSharegroupKhr(gl_sharegroup));
            self.contains_gl_context_or_sharegroup = true;
        }

        /// Specifies a pointer for the EGL display.
        pub fn set_egl_display(&mut self, egl_disp: *mut c_void) {
            self.props.insert(ContextProperty::EglDisplayKhr, ContextPropertyValue::EglDisplayKhr(egl_disp));
            self.contains_gl_context_or_sharegroup = true;
        }

        /// Pushes a `ContextPropertyValue` onto this list of properties.
        pub fn set_property_value(&mut self, prop: ContextPropertyValue) {
            match prop {
                ContextPropertyValue::Platform(val) => {
                    self.props.insert(ContextProperty::Platform, ContextPropertyValue::Platform(val));
                },
                ContextPropertyValue::InteropUserSync(val) => {
                    self.props.insert(ContextProperty::InteropUserSync,
                        ContextPropertyValue::InteropUserSync(val));
                },
                ContextPropertyValue::GlContextKhr(val) => {
                    self.props.insert(ContextProperty::GlContextKhr,
                        ContextPropertyValue::GlContextKhr(val));
                    self.contains_gl_context_or_sharegroup = true;
                },
                ContextPropertyValue::GlxDisplayKhr(val) => {
                    self.props.insert(ContextProperty::GlxDisplayKhr,
                        ContextPropertyValue::GlxDisplayKhr(val));
                    self.contains_gl_context_or_sharegroup = true;
                },
                ContextPropertyValue::WglHdcKhr(val) => {
                    self.props.insert(ContextProperty::WglHdcKhr,
                        ContextPropertyValue::WglHdcKhr(val));
                    self.contains_gl_context_or_sharegroup = true;
                },
                ContextPropertyValue::CglSharegroupKhr(val) => {
                    self.props.insert(ContextProperty::CglSharegroupKhr,
                        ContextPropertyValue::CglSharegroupKhr(val));
                    self.contains_gl_context_or_sharegroup = true;
                },
                ContextPropertyValue::EglDisplayKhr(val) => {
                    self.props.insert(ContextProperty::EglDisplayKhr,
                        ContextPropertyValue::EglDisplayKhr(val));
                    self.contains_gl_context_or_sharegroup = true;
                },
                _ => panic!("'{:?}' is not yet a supported variant.", prop),
            }
        }

        /// Returns a platform id or none.
        pub fn get_platform(&self) -> Option<PlatformId> {
            match self.props.get(&ContextProperty::Platform) {
                Some(prop_val) => {
                    if let ContextPropertyValue::Platform(ref plat) = *prop_val {
                        Some(plat.clone())
                    } else {
                        panic!("Internal error returning platform.");
                    }
                },
                None => None
            }
        }

        /// Returns true if this set of context properties specifies any OpenGL
        /// context or sharegroup to associate with.
        pub fn contains_gl_context_or_sharegroup(&self) -> bool {
            self.contains_gl_context_or_sharegroup
        }

        /// Converts this list into a packed-word representation as specified
        /// [here](https://www.khronos.org/registry/cl/sdk/1.2/docs/man/xhtml/clCreateContext.html).
        ///
        // [NOTE]: Meant to replace `::to_bytes`.
        //
        // Return type is `Vec<cl_context_properties>` => `Vec<isize>`
        //
        // [FIXME]: Change return type to `Vec<(cl_context_properties, isize)>`
        pub fn to_raw(&self) -> Vec<isize> {
            let mut props_raw = Vec::with_capacity(32);

            // For each property ...
            for (key, val) in self.props.iter() {
                // convert both the kind of property (a u32 originally) and
                // the value (variable type/size) to an isize:
                match *val {
                    ContextPropertyValue::Platform(ref platform_id_core) => {
                        props_raw.push(key.clone() as isize);
                        props_raw.push(platform_id_core.as_ptr() as isize);
                    },
                    ContextPropertyValue::InteropUserSync(sync) => {
                        props_raw.push(key.clone() as isize);
                        props_raw.push(sync as isize);
                    },
                    ContextPropertyValue::GlContextKhr(sync) => {
                        props_raw.push(key.clone() as isize);
                        props_raw.push(sync as isize);
                    },
                    ContextPropertyValue::GlxDisplayKhr(sync) => {
                        props_raw.push(key.clone() as isize);
                        props_raw.push(sync as isize);
                    },
                    ContextPropertyValue::WglHdcKhr(sync) => {
                        props_raw.push(key.clone() as isize);
                        props_raw.push(sync as isize);
                    },
                    ContextPropertyValue::CglSharegroupKhr(sync) => {
                        props_raw.push(key.clone() as isize);
                        props_raw.push(sync as isize);
                    },
                    ContextPropertyValue::EglDisplayKhr(sync) => {
                        props_raw.push(key.clone() as isize);
                        props_raw.push(sync as isize);
                    },
                    _ => panic!("'{:?}' is not yet a supported variant.", key),
                };
            }

            // Add a terminating 0:
            props_raw.push(0);

            props_raw.shrink_to_fit();
            props_raw
        }

        /// Returns a single context property value.
        pub unsafe fn extract_property_from_raw(property: ContextProperty,
                raw_context_properties: &[isize]) -> Option<ContextPropertyValue>
        {
            // REMEMBER: It's null terminated;

            // The raw properties **should** be `(isize, isize)` pairs + isize (null) terminator.
            assert!(raw_context_properties.len() % 2 == 1);
            assert!(*raw_context_properties.last().unwrap() == 0);

            let pair_count = raw_context_properties.len() / 2;

            match property {
                ContextProperty::Platform => {
                    for pair_idx in 0..pair_count {
                        let idz = pair_idx * 2;
                        let key_raw = *raw_context_properties.get_unchecked(idz);
                        let val_raw = *raw_context_properties.get_unchecked(idz + 1);

                        if key_raw == property as cl_context_properties {
                            return Some(ContextPropertyValue::Platform(
                                PlatformId::from_raw(val_raw as cl_platform_id)));
                        }
                    }
                },
                _ => unimplemented!(),
            }

            None
        }

        /// Converts raw stuff into other stuff.
        ///
        ///
        #[allow(unused_variables, unused_mut)]
        pub unsafe fn from_raw(raw_context_properties: &[isize]) -> OclCoreResult<ContextProperties> {
            // The raw properties **should** be `(isize, isize)` pairs + isize (null) terminator.
            assert!(mem::size_of::<cl_context_properties>() == mem::size_of::<isize>());
            assert!(raw_context_properties.len() % 2 == 1);
            assert!(*raw_context_properties.last().unwrap() == 0);

            let pair_count = raw_context_properties.len() / 2;
            let mut context_props = ContextProperties {
                props: HashMap::with_capacity(pair_count),
                contains_gl_context_or_sharegroup: false,
            };

            for pair_idx in 0..pair_count {
                let idz = pair_idx * 2;
                let key_raw = *raw_context_properties.get_unchecked(idz);
                let val_raw = *raw_context_properties.get_unchecked(idz + 1);

                let key = ContextProperty::from_isize(key_raw).ok_or(OclCoreError::from(
                    format!("ContextProperties::from_raw: Unable to convert '{}' using \
                        'ContextProperty::from_isize'.", key_raw)))?;

                match key {
                        ContextProperty::Platform => {
                            context_props.props.insert(ContextProperty::Platform,
                                ContextPropertyValue::Platform(PlatformId::from_raw(val_raw as cl_platform_id))
                            );
                        },
                        ContextProperty::InteropUserSync => {
                            context_props.props.insert(ContextProperty::InteropUserSync,
                                ContextPropertyValue::InteropUserSync(val_raw > 0),
                            );
                        },
                        ContextProperty::D3d10DeviceKhr => {
                            context_props.props.insert(ContextProperty::D3d10DeviceKhr,
                                ContextPropertyValue::D3d10DeviceKhr(val_raw as *mut ffi::cl_d3d10_device_source_khr),
                            );
                        },
                        ContextProperty::GlContextKhr => {
                            context_props.props.insert(ContextProperty::GlContextKhr,
                                ContextPropertyValue::GlContextKhr(val_raw as *mut c_void),
                            );
                            context_props.contains_gl_context_or_sharegroup = true;
                        },
                        ContextProperty::EglDisplayKhr => {
                            context_props.props.insert(ContextProperty::EglDisplayKhr,
                                ContextPropertyValue::EglDisplayKhr(val_raw as ffi::CLeglDisplayKHR),
                            );
                            context_props.contains_gl_context_or_sharegroup = true;
                        },
                        ContextProperty::GlxDisplayKhr => {
                            context_props.props.insert(ContextProperty::GlxDisplayKhr,
                                ContextPropertyValue::GlxDisplayKhr(val_raw as *mut c_void),
                            );
                            context_props.contains_gl_context_or_sharegroup = true;
                        },
                        ContextProperty::CglSharegroupKhr => {
                            context_props.props.insert(ContextProperty::CglSharegroupKhr,
                                ContextPropertyValue::CglSharegroupKhr(val_raw as *mut c_void),
                            );
                            context_props.contains_gl_context_or_sharegroup = true;
                        },
                        ContextProperty::WglHdcKhr => {
                            context_props.props.insert(ContextProperty::WglHdcKhr,
                                ContextPropertyValue::WglHdcKhr(val_raw as *mut c_void),
                            );
                            context_props.contains_gl_context_or_sharegroup = true;
                        },
                        ContextProperty::AdapterD3d9Khr => {
                            context_props.props.insert(ContextProperty::AdapterD3d9Khr,
                                ContextPropertyValue::AdapterD3d9Khr(val_raw),
                            );
                        },
                        ContextProperty::AdapterD3d9exKhr => {
                            context_props.props.insert(ContextProperty::AdapterD3d9exKhr,
                                ContextPropertyValue::AdapterD3d9exKhr(val_raw),
                            );
                        },
                        ContextProperty::AdapterDxvaKhr => {
                            context_props.props.insert(ContextProperty::AdapterDxvaKhr,
                                ContextPropertyValue::AdapterDxvaKhr(val_raw),
                            );
                        },
                        ContextProperty::D3d11DeviceKhr => {
                            context_props.props.insert(ContextProperty::D3d11DeviceKhr,
                                ContextPropertyValue::D3d11DeviceKhr(val_raw),
                            );
                        },
                }
            }

            Ok(context_props)
        }
    }

    // impl Into<Vec<isize>> for ContextProperties {
    //     fn into(self) -> Vec<isize> {
    //         self.to_raw()
    //     }
    // }

    impl From<ContextProperties> for Vec<isize> {
        fn from(cp: ContextProperties) -> Vec<isize> {
            cp.to_raw()
        }
    }

    /// Defines a buffer region for creating a sub-buffer.
    ///
    /// ### Info (from [SDK](https://www.khronos.org/registry/cl/sdk/1.2/docs/man/xhtml/clCreateSubBuffer.html))
    ///
    /// (origin, size) defines the offset and size in bytes in buffer.
    ///
    /// If buffer is created with CL_MEM_USE_HOST_PTR, the host_ptr associated with
    /// the buffer object returned is host_ptr + origin.
    ///
    /// The buffer object returned references the data store allocated for buffer and
    /// points to a specific region given by (origin, size) in this data store.
    ///
    /// CL_INVALID_VALUE is returned in errcode_ret if the region specified by
    /// (origin, size) is out of bounds in buffer.
    ///
    /// CL_INVALID_BUFFER_SIZE if size is 0.
    ///
    /// CL_MISALIGNED_SUB_BUFFER_OFFSET is returned in errcode_ret if there are no
    /// devices in context associated with buffer for which the origin value is
    /// aligned to the CL_DEVICE_MEM_BASE_ADDR_ALIGN value.
    ///
    pub struct BufferRegion<T> {
        origin: usize,
        len: usize,
        _data: PhantomData<T>,
    }

    impl<T: OclPrm> BufferRegion<T> {
        pub fn new(origin: usize, len: usize) -> BufferRegion<T> {
            BufferRegion {
                origin: origin,
                len: len,
                _data: PhantomData,
            }
        }

        pub fn to_bytes(&self) -> cl_buffer_region {
            cl_buffer_region {
                origin: self.origin * mem::size_of::<T>(),
                size: self.len * mem::size_of::<T>(),
            }
        }

        pub fn from_bytes(ffi_struct: cl_buffer_region) -> BufferRegion<T> {
            assert!(ffi_struct.origin % mem::size_of::<T>() == 0);
            assert!(ffi_struct.size % mem::size_of::<T>() == 0);

            BufferRegion::new(ffi_struct.origin / mem::size_of::<T>(),
                ffi_struct.size / mem::size_of::<T>())
        }
    }

    pub enum ImageFormatParseError {
        UnknownImageChannelOrder(ffi::cl_channel_order),
        UnknownImageChannelDataType(ffi::cl_channel_type),
    }

    impl ::std::fmt::Debug for ImageFormatParseError {
        fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
            match *self {
                ImageFormatParseError::UnknownImageChannelOrder(ord) => {
                    write!(f, "unknown image channel ordering: '{}'", ord)
                },
                ImageFormatParseError::UnknownImageChannelDataType(dt) => {
                    write!(f, "unknown image channel data type: '{}'", dt)
                },
            }
        }
    }

    impl ::std::fmt::Display for ImageFormatParseError {
        fn fmt(&self, f: &mut ::std::fmt::Formatter) -> ::std::fmt::Result {
            write!(f, "{:?}", self)
        }
    }

    impl ::std::error::Error for ImageFormatParseError {
        fn description(&self) -> &str {
            match *self {
                ImageFormatParseError::UnknownImageChannelOrder(_) => "unknown image channel ordering",
                ImageFormatParseError::UnknownImageChannelDataType(_) => "unknown image channel data type",
            }
        }
    }

    pub type ImageFormatParseResult = Result<ImageFormat, ImageFormatParseError>;

    /// Image format properties used by `Image`.
    ///
    /// A structure that describes format properties of the image to be allocated. (from SDK)
    ///
    /// # Examples (from SDK)
    ///
    /// To specify a normalized unsigned 8-bit / channel RGBA image:
    ///    image_channel_order = CL_RGBA
    ///    image_channel_data_type = CL_UNORM_INT8
    ///
    /// image_channel_data_type values of CL_UNORM_SHORT_565, CL_UNORM_SHORT_555
    /// and CL_UNORM_INT_101010 are special cases of packed image formats where
    /// the channels of each element are packed into a single unsigned short or
    /// unsigned int. For these special packed image formats, the channels are
    /// normally packed with the first channel in the most significant bits of the
    /// bitfield, and successive channels occupying progressively less significant
    /// locations. For CL_UNORM_SHORT_565, R is in bits 15:11, G is in bits 10:5
    /// and B is in bits 4:0. For CL_UNORM_SHORT_555, bit 15 is undefined, R is in
    /// bits 14:10, G in bits 9:5 and B in bits 4:0. For CL_UNORM_INT_101010, bits
    /// 31:30 are undefined, R is in bits 29:20, G in bits 19:10 and B in bits
    /// 9:0. OpenCL implementations must maintain the minimum precision specified
    /// by the number of bits in image_channel_data_type. If the image format
    /// specified by image_channel_order, and image_channel_data_type cannot be
    /// supported by the OpenCL implementation, then the call to clCreateImage
    /// will return a NULL memory object.
    ///
    #[derive(Debug, Clone)]
    pub struct ImageFormat {
        pub channel_order: ImageChannelOrder,
        pub channel_data_type: ImageChannelDataType,
    }

    impl ImageFormat {
        pub fn new(order: ImageChannelOrder, data_type: ImageChannelDataType) -> ImageFormat {
            ImageFormat {
                channel_order: order,
                channel_data_type: data_type,
            }
        }

        pub fn new_rgba() -> ImageFormat {
            ImageFormat {
                channel_order: ImageChannelOrder::Rgba,
                channel_data_type: ImageChannelDataType::SnormInt8,
            }
        }

        pub fn from_raw(fmt_raw: ffi::cl_image_format) -> ImageFormatParseResult {
            let channel_order = match ImageChannelOrder::from_u32(fmt_raw.image_channel_order) {
                Some(ord) => ord,
                None => return Err(ImageFormatParseError::UnknownImageChannelOrder(
                    fmt_raw.image_channel_order)),
            };

            let channel_data_type = match ImageChannelDataType::from_u32(fmt_raw.image_channel_data_type) {
                Some(dt) => dt,
                None => return Err(ImageFormatParseError::UnknownImageChannelDataType(
                    fmt_raw.image_channel_data_type)),
            };

            Ok(ImageFormat { channel_order, channel_data_type })
        }

        pub fn list_from_raw(list_raw: Vec<ffi::cl_image_format>)
                -> Vec<ImageFormatParseResult>
        {
            list_raw.into_iter().map(|fmt_raw| ImageFormat::from_raw(fmt_raw)).collect()
        }

        pub fn to_raw(&self) -> ffi::cl_image_format {
            ffi::cl_image_format {
                image_channel_order: self.channel_order as ffi::cl_channel_order,
                image_channel_data_type: self.channel_data_type as ffi::cl_channel_type,
            }
        }

        pub fn new_raw() -> ffi::cl_image_format {
            ffi::cl_image_format {
                image_channel_order: 0 as ffi::cl_channel_order,
                image_channel_data_type: 0 as ffi::cl_channel_type,
            }
        }

        /// Returns the size in bytes of a pixel using the format specified by this
        /// `ImageFormat`.
        ///
        /// TODO: Add a special case for Depth & DepthStencil
        /// (https://www.khronos.org/registry/cl/sdk/2.0/docs/man/xhtml/cl_khr_gl_depth_images.html).
        ///
        /// TODO: Validate combinations.
        /// TODO: Use `core::get_image_info` to check these with a test.
        ///
        pub fn pixel_bytes(&self) -> usize {
            let channel_count = match self.channel_order {
                ImageChannelOrder::R => 1,
                ImageChannelOrder::A => 1,
                ImageChannelOrder::Rg => 2,
                ImageChannelOrder::Ra => 2,
                // This format can only be used if channel data type = CL_UNORM_SHORT_565, CL_UNORM_SHORT_555 or CL_UNORM_INT101010:
                ImageChannelOrder::Rgb => 1,
                ImageChannelOrder::Rgba => 4,
                // This format can only be used if channel data type = CL_UNORM_INT8, CL_SNORM_INT8, CL_SIGNED_INT8 or CL_UNSIGNED_INT8:
                ImageChannelOrder::Bgra => 4,
                // This format can only be used if channel data type = CL_UNORM_INT8, CL_SNORM_INT8, CL_SIGNED_INT8 or CL_UNSIGNED_INT8:
                ImageChannelOrder::Argb => 4,
                // This format can only be used if channel data type = CL_UNORM_INT8, CL_UNORM_INT16, CL_SNORM_INT8, CL_SNORM_INT16, CL_HALF_FLOAT, or CL_FLOAT:
                ImageChannelOrder::Intensity => 4,
                // This format can only be used if channel data type = CL_UNORM_INT8, CL_UNORM_INT16, CL_SNORM_INT8, CL_SNORM_INT16, CL_HALF_FLOAT, or CL_FLOAT:
                ImageChannelOrder::Luminance => 4,
                ImageChannelOrder::Rx => 2,
                ImageChannelOrder::Rgx => 4,
                // This format can only be used if channel data type = CL_UNORM_SHORT_565, CL_UNORM_SHORT_555 or CL_UNORM_INT101010:
                ImageChannelOrder::Rgbx => 4,
                // Depth => 1,
                // DepthStencil => 1,
                _ => 0,
            };

            let channel_size = match self.channel_data_type {
                // Each channel component is a normalized signed 8-bit integer value:
                ImageChannelDataType::SnormInt8 => 1,
                // Each channel component is a normalized signed 16-bit integer value:
                ImageChannelDataType::SnormInt16 => 2,
                // Each channel component is a normalized unsigned 8-bit integer value:
                ImageChannelDataType::UnormInt8 => 1,
                // Each channel component is a normalized unsigned 16-bit integer value:
                ImageChannelDataType::UnormInt16 => 2,
                // Represents a normalized 5-6-5 3-channel RGB image. The channel order must be CL_RGB or CL_RGBx:
                ImageChannelDataType::UnormShort565 => 2,
                // Represents a normalized x-5-5-5 4-channel xRGB image. The channel order must be CL_RGB or CL_RGBx:
                ImageChannelDataType::UnormShort555 => 2,
                // Represents a normalized x-10-10-10 4-channel xRGB image. The channel order must be CL_RGB or CL_RGBx:
                ImageChannelDataType::UnormInt101010 => 4,
                // Each channel component is an unnormalized signed 8-bit integer value:
                ImageChannelDataType::SignedInt8 => 1,
                // Each channel component is an unnormalized signed 16-bit integer value:
                ImageChannelDataType::SignedInt16 => 2,
                // Each channel component is an unnormalized signed 32-bit integer value:
                ImageChannelDataType::SignedInt32 => 4,
                // Each channel component is an unnormalized unsigned 8-bit integer value:
                ImageChannelDataType::UnsignedInt8 => 1,
                // Each channel component is an unnormalized unsigned 16-bit integer value:
                ImageChannelDataType::UnsignedInt16 => 2,
                // Each channel component is an unnormalized unsigned 32-bit integer value:
                ImageChannelDataType::UnsignedInt32 => 4,
                // Each channel component is a 16-bit half-float value:
                ImageChannelDataType::HalfFloat => 2,
                // Each channel component is a single precision floating-point value:
                ImageChannelDataType::Float => 4,
                // Each channel component is a normalized unsigned 24-bit integer value:
                // UnormInt24 => 3,
                _ => 0
            };

            channel_count * channel_size
        }
    }

    /// An image descriptor use in the creation of `Image`.
    ///
    /// image_type
    /// Describes the image type and must be either CL_MEM_OBJECT_IMAGE1D, CL_MEM_OBJECT_IMAGE1D_BUFFER, CL_MEM_OBJECT_IMAGE1D_ARRAY, CL_MEM_OBJECT_IMAGE2D, CL_MEM_OBJECT_IMAGE2D_ARRAY, or CL_MEM_OBJECT_IMAGE3D.
    ///
    /// image_width
    /// The width of the image in pixels. For a 2D image and image array, the image width must be ≤ CL_DEVICE_IMAGE2D_MAX_WIDTH. For a 3D image, the image width must be ≤ CL_DEVICE_IMAGE3D_MAX_WIDTH. For a 1D image buffer, the image width must be ≤ CL_DEVICE_IMAGE_MAX_BUFFER_SIZE. For a 1D image and 1D image array, the image width must be ≤ CL_DEVICE_IMAGE2D_MAX_WIDTH.
    ///
    /// image_height
    /// The height of the image in pixels. This is only used if the image is a 2D, 3D or 2D image array. For a 2D image or image array, the image height must be ≤ CL_DEVICE_IMAGE2D_MAX_HEIGHT. For a 3D image, the image height must be ≤ CL_DEVICE_IMAGE3D_MAX_HEIGHT.
    ///
    /// image_depth
    /// The depth of the image in pixels. This is only used if the image is a 3D image and must be a value ≥ 1 and ≤ CL_DEVICE_IMAGE3D_MAX_DEPTH.
    ///
    /// image_array_size
    /// The number of images in the image array. This is only used if the image is a 1D or 2D image array. The values for image_array_size, if specified, must be a value ≥ 1 and ≤ CL_DEVICE_IMAGE_MAX_ARRAY_SIZE.
    ///
    /// Note that reading and writing 2D image arrays from a kernel with image_array_size = 1 may be lower performance than 2D images.
    ///
    /// image_row_pitch
    /// The scan-line pitch in bytes. This must be 0 if host_ptr is NULL and can be either 0 or ≥ image_width * size of element in bytes if host_ptr is not NULL. If host_ptr is not NULL and image_row_pitch = 0, image_row_pitch is calculated as image_width * size of element in bytes. If image_row_pitch is not 0, it must be a multiple of the image element size in bytes.
    ///
    /// image_slice_pitch
    /// The size in bytes of each 2D slice in the 3D image or the size in bytes of each image in a 1D or 2D image array. This must be 0 if host_ptr is NULL. If host_ptr is not NULL, image_slice_pitch can be either 0 or ≥ image_row_pitch * image_height for a 2D image array or 3D image and can be either 0 or ≥ image_row_pitch for a 1D image array. If host_ptr is not NULL and image_slice_pitch = 0, image_slice_pitch is calculated as image_row_pitch * image_height for a 2D image array or 3D image and image_row_pitch for a 1D image array. If image_slice_pitch is not 0, it must be a multiple of the image_row_pitch.
    ///
    /// num_mip_level, num_samples
    /// Must be 0.
    ///
    /// buffer
    /// Refers to a valid buffer memory object if image_type is CL_MEM_OBJECT_IMAGE1D_BUFFER. Otherwise it must be NULL. For a 1D image buffer object, the image pixels are taken from the buffer object's data store. When the contents of a buffer object's data store are modified, those changes are reflected in the contents of the 1D image buffer object and vice-versa at corresponding sychronization points. The image_width * size of element in bytes must be ≤ size of buffer object data store.
    ///
    /// Note
    /// Concurrent reading from, writing to and copying between both a buffer object and 1D image buffer object associated with the buffer object is undefined. Only reading from both a buffer object and 1D image buffer object associated with the buffer object is defined.
    #[allow(dead_code)]
    #[derive(Debug, Clone)]
    pub struct ImageDescriptor {
        pub image_type: MemObjectType,
        pub image_width: usize,
        pub image_height: usize,
        pub image_depth: usize,
        pub image_array_size: usize,
        pub image_row_pitch: usize,
        pub image_slice_pitch: usize,
        num_mip_levels: u32,
        num_samples: u32,
        pub buffer: Option<Mem>,
    }

    impl ImageDescriptor {
        pub fn new(image_type: MemObjectType, width: usize, height: usize, depth: usize,
                    array_size: usize, row_pitch: usize, slc_pitch: usize, buffer: Option<Mem>,
                    ) -> ImageDescriptor {
            ImageDescriptor {
                image_type: image_type,
                image_width: width,
                image_height: height,
                image_depth: depth,
                image_array_size: array_size,
                image_row_pitch: row_pitch,
                image_slice_pitch: slc_pitch,
                num_mip_levels: 0,
                num_samples: 0,
                buffer: buffer,
            }
        }

        pub fn to_raw(&self) -> ffi::cl_image_desc {
            ffi::cl_image_desc {
                image_type: self.image_type as u32,
                image_width: self.image_width,
                image_height: self.image_height,
                image_depth: self.image_depth,
                image_array_size: self.image_array_size,
                image_row_pitch: self.image_row_pitch,
                image_slice_pitch: self.image_slice_pitch,
                num_mip_levels: self.num_mip_levels,
                num_samples: self.num_mip_levels,
                buffer: match self.buffer {
                            Some(ref b) => b.as_ptr(),
                            None => 0 as cl_mem,
                        },
            }
        }
    }

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