renderscript/1.0/IContext.hal

/*
 * Copyright (C) 2017 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package android.hardware.renderscript@1.0;

import android.hardware.renderscript@1.0::types;

// TODO: is there any way to keep this documentation in sync with the
// corresponding Java doc?
//
// TODO: Some of the documentation was taken from Java docs, whereas others were
// undocumented. Because of this, there's somewhat two different styles of
// comments. Look into having a consistent convention.
//
// TODO: There was some confusion as to why some paramters use vec<> and others
// use Ptr/Size. The convention is that vec<> is used whenever the paramter is
// only an input parameter. HIDL is not supposed to include any output
// parameters, so a more explicit Ptr/Size is used.

interface IContext {

    /**
     * TODO: Do we need to define "selectors"? It may be a property of the
     * "adapted allocation" that's returned.
     *
     * Creates an arbitrary window into the base allocation. The type describes
     * the shape of the window. Any dimensions present in the type must be
     * equal to or smaller than the dimensions in the source allocation. A
     * dimension present in the allocation that is not present in the type must
     * be constrained away with the selectors. If a dimension is present in
     * both the type and allocation, one of two things must happen. If the type
     * is smaller than the allocation, a window must be created, the selected
     * value in the adapter for that dimension must act as the base address,
     * and the type must describe the size of the view starting at that point.
     * If the type and allocation dimension are of the same size, then setting
     * the selector for the dimension must be an error.
     *
     * @param type Type describing data layout
     * @param baseAlloc Allocation
     * @return subAlloc AllocationAdapter
     */
    @callflow(next={"*"})
    allocationAdapterCreate(Type type, Allocation baseAlloc)
                 generates (AllocationAdapter subAlloc);

    /**
     * TODO: Need to relate "offset" back to the terminology in
     * allocationAdapterCreate() -- the latter uses the terms "selector" and
     * "selected value". Can we use consistent terminology? Are "offset" and
     * "selector" actually two different things?
     *
     * TODO: Explain the flattened layout in the offsets vec
     *
     * Sets the offsets for an Allocation Adapter.
     *
     * @param alloc AllocationAdapter
     * @param offsets Collection of offsets
     */
    @callflow(next={"*"})
    allocationAdapterOffset(AllocationAdapter alloc, vec<uint32_t> offsets);

    /**
     * TODO: add more explanation here.
     *
     * Returns the Type of the Allocation.
     *
     * @param allocation Allocation
     * @return type Allocation's Type
     */
    @callflow(next={"*"})
    allocationGetType(Allocation allocation) generates (Type type);

    /**
     * TODO: more clarification needed describing if the pointer can be aliased
     * or if the data can outlive the allocation.
     *
     * Creates an Allocation for use by scripts with a given Type and a backing
     * pointer. For use with ALLOCATION_USAGE_SHARED.
     *
     * @param type Type describing data layout
     * @param mips AllocationMipmapControl specifies desired mipmap behavior for
     *             the allocation
     * @param usage Bit field specifying how the Allocation is utilized
     * @param ptr Pointer to client-side data
     * @return allocation Created Allocation
     */
    @callflow(next={"*"})
    allocationCreateTyped(Type type, AllocationMipmapControl mips,
                          bitfield<AllocationUsageType> usage, Ptr ptr)
               generates (Allocation allocation);

    /**
     * Creates an Allocation from a Bitmap.
     *
     * @param type Type describing data layout
     * @param mips AllocationMipmapControl specifies desired mipmap behavior for
     *             the allocation
     * @param bitmap Bitmap source for the allocation data
     * @param usage Bit field specifying how the Allocation is utilized
     * @return allocation Created Allocation containing bitmap data
     */
    @callflow(next={"*"})
    allocationCreateFromBitmap(Type type, AllocationMipmapControl mips,
                               vec<uint8_t> bitmap,
                               bitfield<AllocationUsageType> usage)
                    generates (Allocation allocation);

    /**
     * Creates a Cubemapped Allocation from a Bitmap.
     *
     * @param type Type describing data layout
     * @param mips AllocationMipmapControl specifies desired mipmap behavior
     *             for the allocation
     * @param bitmap Bitmap with cubemap faces layed out in the following
     *               format: right, left, top, bottom, front, back
     * @param usage Bit field specifying how the Allocation is used
     * @return allocation Created Allocation containing cubemap data
     */
    @callflow(next={"*"})
    allocationCubeCreateFromBitmap(Type type, AllocationMipmapControl mips,
                                   vec<uint8_t> bitmap,
                                   bitfield<AllocationUsageType> usage)
                        generates (Allocation allocation);

    /**
     * Returns the handle to a raw buffer that is being managed by the screen
     * compositor. This operation is only valid for Allocations with
     * USAGE_IO_INPUT.
     *
     * @param allocation Allocation
     * @return nativeWindow NativeWindow object associated with allocation
     */
    @callflow(next={"*"})
    allocationGetNativeWindow(Allocation allocation)
                   generates (NativeWindow nativeWindow);

    /**
     * TODO: more clarification needed
     *
     * Sets the NativeWindow of an Allocation. This operation is only valid
     * for Allocations with USAGE_IO_INPUT.
     *
     * @param allocation Allocation to be modified
     * @pram nativeWindow NativeWindow to associate with allocation
     */
    @callflow(next={"*"})
    allocationSetNativeWindow(Allocation allocation, NativeWindow nativewindow);

    /**
     * Initialize BufferQueue with specified max number of buffers.
     *
     * @param alloc Allocation
     * @param numBuffer Maximum number of buffers
     */
    @callflow(next={"*"})
    allocationSetupBufferQueue(Allocation alloc, uint32_t numBuffer);

    /**
     * TODO: clearly define baseAlloc vs subAlloc
     *
     * Shares the BufferQueue with another Allocation. Both must be
     * USAGE_IO_INPUT Allocations.
     *
     * @param baseAlloc Base Allocation
     * @param subAlloc Allocation to use the same buffer queue as the Base
     *                 Allocation
     */
    @callflow(next={"*"})
    allocationShareBufferQueue(Allocation baseAlloc, Allocation subAlloc);

    /**
     * Copies from the Allocation into a Bitmap. The bitmap must match the
     * dimensions of the Allocation.
     *
     * HIDL is always running in Passthrough mode for RenderScript, so the
     * buffer is modified directly by the driver.
     *
     * @param allocation Allocation
     * @param data Buffer to be copied into
     * @param sizeBytes Size of the buffer pointed to by "data"
     */
    @callflow(next={"*"})
    allocationCopyToBitmap(Allocation allocation, Ptr data, Size sizeBytes);

    /**
     * TODO: should we consolidate all [123]DWrite functions or [123]DRead
     * functions into the same API call? Our current plan is to be very similar
     * to the dispatch table API. How much should we deviate from the original
     * API?
     * TODO: better description on Vec3/Vec4 and padding.
     *
     * Copies data into a 1D region of this Allocation.
     *
     * When this HAL entry is executed, all Vec3 elements have been explicitly
     * padded as Vec4 elements.
     *
     * The size of the region is: count * Element's size.
     *
     * @param allocation Allocation to be modified
     * @param offset The offset of the first element to be copied
     * @param lod Selected mipmap level of detail
     * @param count Number of elements to be copied
     * @param data Source data to be copied to Allocation
     */
    @callflow(next={"*"})
    allocation1DWrite(Allocation allocation, uint32_t offset, uint32_t lod,
                      uint32_t count, vec<uint8_t> data);

    /**
     * Copies a value into a single sub-Element of this Allocation.
     *
     * @param allocation Allocation to be updated
     * @param x X position of the first element in the Allocation to be updated
     * @param y Y position of the first element in the Allocation to be
     *          updated; for a 1D Allocation, this value must be 0
     * @param z Z position of the first element in the Allocation to be
     *          updated; for a 1D or 2D Allocation, this value must be 0
     * @param lod Selected mipmap level of detail
     * @param data Data to be copied from
     * @param compIdx Component number to identify which sub-Element is updated
     */
    @callflow(next={"*"})
    allocationElementWrite(Allocation allocation, uint32_t x, uint32_t y,
                           uint32_t z, uint32_t lod, vec<uint8_t> data,
                           Size compIdx);

    /**
     * Copies from an array into a rectangular region in this Allocation.
     *
     * When this HAL entry is executed, all Vec3 elements have been explicitly
     * padded as Vec4 elements.
     *
     * The size of the region is: w * h * Element's size.
     *
     * @param allocation Allocation to be modified
     * @param xoff X offset of the region to update in this Allocation
     * @param yoff Y offset of the region to update in this Allocation
     * @param lod Selected mipmap level of detail
     * @param face AllocationCubemapFace
     * @param w Width of the region to update
     * @param h Height of the region to update
     * @param data Data to be placed into the Allocation
     * @param stride For 1D Allocation, the stride must be the number of bytes
     *               of this Allocation. For 2D and 3D Allocations, the stride
     *               must be the stride in X dimension measuring in bytes.
     */
    @callflow(next={"*"})
    allocation2DWrite(Allocation allocation, uint32_t xoff, uint32_t yoff,
                      uint32_t lod, AllocationCubemapFace face, uint32_t w,
                      uint32_t h, vec<uint8_t> data, Size stride);

    /**
     * Copies from an array into a 3D region in this Allocation.
     *
     * When this HAL entry is executed, all Vec3 elements have been explicitly
     * padded as Vec4 elements.
     *
     * The size of the region is: w * h * d * Element's size.
     *
     * @param allocation Allocation to be modified
     * @param xoff X offset of the region to update in this Allocation
     * @param yoff Y offset of the region to update in this Allocation
     * @param zoff Z offset of the region to update in this Allocation
     * @param lod Selected mipmap level of detail
     * @param w Width of the region to update
     * @param h Height of the region to update
     * @param d Depth of the region to update
     * @param data Data to be placed in the Allocation
     * @param stride For 1D Allocation, the stride must be the number of bytes
     *               of this Allocation. For 2D and 3D Allocations, the stride
     *               must be the stride in X dimension measuring in bytes.
     */
    @callflow(next={"*"})
    allocation3DWrite(Allocation allocation, uint32_t xoff, uint32_t yoff,
                      uint32_t zoff, uint32_t lod, uint32_t w, uint32_t h,
                      uint32_t d, vec<uint8_t> data, Size stride);

    /**
     * Generates a mipmap chain. This is only valid if the Type of the
     * Allocation includes mipmaps.
     *
     * This function generates a complete set of mipmaps from the top level
     * LOD.
     *
     * If the Allocation is also using other memory spaces, a call to
     * allocationSyncAll(context, allocation, usage) is required.
     *
     * @param allocation Allocation which has its top LOD read and lower LOD
     *                   written to
     */
    @callflow(next={"*"})
    allocationGenerateMipmaps(Allocation allocation);

    /**
     * Copies all of an Allocation's data into an array.
     *
     * All Vec3 elements of an Allocation are padded to be Vec4, so the data
     * returned by this function automatically includes padding.
     *
     * HIDL is always running in Passthrough mode for RenderScript, so the
     * buffer is modified directly by the driver.
     *
     * @param allocation Allocation to be read
     * @param data Buffer to be copied into
     * @param sizeBytes Size of the buffer pointed to by "data"
     */
    @callflow(next={"*"})
    allocationRead(Allocation allocation, Ptr data, Size sizeBytes);

    /**
     * Copies a 1D region of this Allocation into an array.
     *
     * All Vec3 elements of an Allocation are padded to be Vec4, so the data
     * returned by this function automatically includes padding.
     *
     * The size of the region is: count * Element's size.
     *
     * HIDL is always running in Passthrough mode for RenderScript, so the
     * buffer is modified directly by the driver.
     *
     * @param allocation Allocation to be read
     * @param xoff X offset of the first element to be copied
     * @param lod Mipmap level of detail
     * @param count The number of elements to be copied
     * @param data Buffer to be copied into
     * @param sizeBytes Size of the buffer pointed to by "data"
     */
    @callflow(next={"*"})
    allocation1DRead(Allocation allocation, uint32_t xoff, uint32_t lod,
                     uint32_t count, Ptr data, Size sizeBytes);

    /**
     * Returns the value of a single sub-Element of this Allocation.
     *
     * HIDL is always running in Passthrough mode for RenderScript, so the
     * buffer is modified directly by the driver.
     *
     * @param allocation Allocation to be read
     * @param x X position of the first element in the Allocation to be read
     * @param y Y position of the first element in the Allocation to be read
     * @param z Z position of the first element in the Allocation to be read
     * @param lod Mipmap level of detail
     * @param data Buffer to be copied into
     * @param sizeBytes Size of the buffer pointed to by "data"
     * @param compIdx Component number to identify which sub-Element is updated
     */
    @callflow(next={"*"})
    allocationElementRead(Allocation allocation, uint32_t x, uint32_t y,
                          uint32_t z, uint32_t lod, Ptr data, Size sizeBytes,
                          Size compIdx);

    /**
     * Copies from a rectangular region in this Allocation to an array.
     *
     * All Vec3 elements of an Allocation are padded to be Vec4, so the data
     * returned by this function automatically includes padding.
     *
     * The size of the region is: w * h * Element's size.
     *
     * HIDL is always running in Passthrough mode for RenderScript, so the
     * buffer is modified directly by the driver.
     *
     * @param allocation Allocation to be read
     * @param xoff X offset of the region to copy in this array
     * @param yoff Y offset of the region to copy in this array
     * @param lod Mipmap level of detail
     * @param face AllocationCubemapFace
     * @param w Width of the region to copy
     * @param h Height of the region to copy
     * @param data Buffer to be copied into
     * @param sizeBytes Size of the buffer pointed to by "data"
     * @param stride For 1D Allocation, the stride must be the number of bytes
     *               of this Allocation. For 2D and 3D Allocations, the stride
     *               must be the stride in X dimension measuring in bytes.
     */
    @callflow(next={"*"})
    allocation2DRead(Allocation allocation, uint32_t xoff, uint32_t yoff,
                     uint32_t lod, AllocationCubemapFace face, uint32_t w,
                     uint32_t h, Ptr data, Size sizeBytes, Size stride);

    /**
     * Copies from a rectangular cuboid region in this Allocation to an array.
     *
     * All Vec3 elements of an Allocation are padded to be Vec4, so the data
     * returned by this function automatically includes padding.
     *
     * The size of the region is: w * h * d * Element's size.
     *
     * HIDL is always running in Passthrough mode for RenderScript, so the
     * buffer is modified directly by the driver.
     *
     * @param allocation Allocation to be read
     * @param xoff X offset of the region to copy in this array
     * @param yoff Y offset of the region to copy in this array
     * @param zoff Z offset of the region to copy in this array
     * @param lod Mipmap level of detail
     * @param w Width of the region to copy
     * @param h Height of the region to copy
     * @param d Depth of the region to copy
     * @param data Buffer to be copied into
     * @param sizeBytes Size of the buffer pointed to by "data"
     * @param stride For 1D Allocation, the stride must be the number of bytes
     *               of this Allocation. For 2D and 3D Allocations, the stride
     *               must be the stride in X dimension measuring in bytes.
     */
    @callflow(next={"*"})
    allocation3DRead(Allocation allocation, uint32_t xoff, uint32_t yoff,
                     uint32_t zoff, uint32_t lod, uint32_t w, uint32_t h,
                     uint32_t d, Ptr data, Size sizeBytes, Size stride);

    /**
     * Propagates changes from one usage of the Allocation to the other usages
     * of the Allocation.
     *
     * @param allocation First usage of the Allocation
     * @param usageType Allocation usage type
     */
    @callflow(next={"*"})
    allocationSyncAll(Allocation allocation, AllocationUsageType usageType);

    /**
     * TODO: describe the functionality of resize1D better
     * TODO: original Java Doc description seems to contradict itself ("with
     * null contents and the region is otherwise undefined")
     * TODO: should "new elements" be "new cells"?
     * TODO: what does "objects are created" mean?
     * TODO: what does "new dimension" mean? IS the type of the resized
     * allocation different than the type before resizing?
     *
     * Resizes a 1D allocation. The contents of the allocation are preserved.
     * If new elements are allocated, objects are created with null contents
     * and the new region is otherwise undefined.
     *
     * If the new region is smaller, the references of any object outside the
     * new region must be released.
     *
     * A new type must be created with the new dimension.
     *
     * @param allocation Allocation to be resized
     * @param dimX New size along the x dimension of the Allocation
     */
    @callflow(next={"*"})
    allocationResize1D(Allocation allocation, uint32_t dimX);

    /**
     * TODO: There are allocationCopy2DRange and 3DRange, but no 1DRange. Should
     * the interface be cleaned up more?
     *
     * Copies a rectangular region from an Allocation into a rectangular region
     * in this Allocation.
     *
     * @param dstAlloc Allocation to be updated
     * @param dstXoff X offset of the region to update
     * @param dstYoff Y offset of the region to update
     * @param dstMip Selected mipmap level of the Allocation to update
     * @param dstFace Destination AllocationCubemapFace
     * @param width Width of the region to update
     * @param height Height of the region to update
     * @param srcAlloc Source Allocation, to be read
     * @param srcXoff X offset of the region in the source Allocation
     * @param srcYoff Y offset of the region in the source Allocation
     * @param srcMip Selected mipmap level of the source Allocation
     * @param srcFace Source AllocationCubemapFace
     */
    @callflow(next={"*"})
    allocationCopy2DRange(Allocation dstAlloc, uint32_t dstXoff,
                          uint32_t dstYoff, uint32_t dstMip,
                          AllocationCubemapFace dstFace, uint32_t width,
                          uint32_t height, Allocation srcAlloc,
                          uint32_t srcXoff, uint32_t srcYoff, uint32_t srcMip,
                          AllocationCubemapFace srcFace);

    /**
     * Copies a rectangular cuboid region into the allocation from another
     * Allocation.
     *
     * @param dstAlloc Allocation to be updated
     * @param dstXoff X offset of the region to update
     * @param dstYoff Y offset of the region to update
     * @param dstZoff Z offset of the region to update
     * @param dstMip Selected mipmap level of the Allocation to update
     * @param width Width of the region to update
     * @param height Height of the region to update
     * @param depth Depth of the region to update
     * @param srcAlloc Source Allocation, to be read
     * @param srcXoff Source X offset of the region in the source Allocation
     * @param srcYoff Source Y offset of the region in the source Allocation
     * @param srcZoff Source Z offset of the region in the souce Allocation
     * @param srcMip Selected mipmap level of the Allocation to read
     */
    @callflow(next={"*"})
    allocationCopy3DRange(Allocation dstAlloc, uint32_t dstXoff,
                          uint32_t dstYoff, uint32_t dstZoff, uint32_t dstMip,
                          uint32_t width, uint32_t height, uint32_t depth,
                          Allocation srcAlloc, uint32_t srcXoff,
                          uint32_t srcYoff, uint32_t srcZoff, uint32_t srcMip);

    /**
     * TODO: define buffer and output stream
     *
     * Sends a buffer to the output stream. The contents of the Allocation may
     * be undefined after this operation. This operation is only valid if
     * USAGE_IO_OUTPUT is set on the Allocation.
     *
     * @param allocation Allocation to be sent
     */
    @callflow(next={"*"})
    allocationIoSend(Allocation allocation);

    /**
     * Receives the latest input into the Allocation. This operation is only
     * valid if USAGE_IO_INPUT is set on the Allocation, otherwise an error
     * must be reported and no operations may be executed.
     *
     * @param allocation Allocation to be updated
     */
    @callflow(next={"*"})
    allocationIoReceive(Allocation allocation);

    /**
     * TODO: describe default values for lod, face, and z better.
     * TODO: what cases can invalidate the pointer? Resize? It should be
     * clarified that this method should always return a valid pointer, but the
     * returned pointer might become invalid later.
     *
     * Retrieves the pointer to the actual data an Allocation contains as well
     * as the data's stride.
     *
     * If Allocation lacks the corresponding dimension for lod, face, or z, an
     * error message must be sent to the message queue and nullptr must be
     * returned for dataPtr and 0 for stride. All missing values must be 0 or
     * NONE in the corresponding enum.
     *
     * @param allocation Allocation
     * @param lod Mipmap level of detail
     * @param face AllocationCubemapFace
     * @param z Z position
     * @return pointer Pointer to the server-side data; if this points to an
     *                 invalid location in memory (because the buffer was
     *                 freed), this may result in undefined behavior
     * @return stride For 1D Allocation, the stride must be the number of bytes
     *                of this Allocation. For 2D and 3D Allocations, the stride
     *                must be the stride in X dimension measuring in bytes.
     */
    @callflow(next={"*"})
    allocationGetPointer(Allocation allocation, uint32_t lod,
                         AllocationCubemapFace face, uint32_t z)
              generates (Ptr dataPtr, Size stride);

    /**
     * Retrieves an Element's metadata from native code.
     *
     * @param element Element to be read
     * @return elemData Element data
     */
    @callflow(next={"*"})
    elementGetNativeMetadata(Element element)
                  generates (vec<uint32_t> elemData);

    /**
     * TODO: define Sub-Element handles better.
     *
     * Retrieves an Element's sub Elements, specifically their identifiers,
     * names, and sizes.
     *
     * @param element Element to be read
     * @param numSubElem Number of sub-Elements
     * @return ids Sub-Element handles
     * @return names Sub-Element Names
     * @return arraySizes Sizes of sub-Element arrays
     */
    @callflow(next={"*"})
    elementGetSubElements(Element element, Size numSubElem)
               generates (vec<Element> ids, vec<string> names,
                          vec<Size> arraySizes);

    /**
     * TODO: can normalization flag be removed?
     *
     * Creates an Element.
     *
     * @param dt Data type
     * @param dk Data kind
     * @param norm Flag for normalization
     * @param size Vector length, with scalar = 1
     * @return element Created Element
     */
    @callflow(next={"*"})
    elementCreate(DataType dt, DataKind dk, bool norm, uint32_t size)
       generates (Element element);

    /**
     * Creates a complex Element.
     *
     * @param einsPtr Container of input Elements
     * @param namesPtr Container of input names
     * @param arraySizesPtr Container of array sizes
     * @return element Created Element
     */
    @callflow(next={"*"})
    elementComplexCreate(vec<Element> einsPtr, vec<string> names,
                         vec<Size> arraySizesPtr)
              generates (Element element);

    /**
     * Retrives a Type's metadata from native code.
     *
     * @param type Type describing data layout
     * @return metadata Type's native metadata
     */
    @callflow(next={"*"})
    typeGetNativeMetadata(Type type) generates (vec<OpaqueHandle> metadata);

    /**
     * Creates a new Type.
     *
     * If Type is 1D, Y and Z must be 0. If Type is 2D, Z must be 0.
     *
     * @param element Element of the Type
     * @param dimX X dimension
     * @param dimY Y dimension
     * @param dimZ Z dimension
     * @param mipmaps Flag indicating whether Type has mipmaps
     * @param faces Flag indicating whether Type has faces
     * @param yuv Enumeration specifying which type of YUV format, if any, Type
     *            uses
     * @return type Created Type
     */
    @callflow(next={"*"})
    typeCreate(Element element, uint32_t dimX, uint32_t dimY, uint32_t dimZ,
               bool mipmaps, bool faces, YuvFormat yuv)
    generates (Type type);

    /**
     * Destroys provided RenderScript context, including all objects created in
     * this context.
     */
    @exit
    contextDestroy();

    /**
     * TODO: provide overview of messaging model and figure out if this should
     * be part of HAL or not.
     * TODO: what is the "client" for purposes of this interface?
     * TODO: consider using send/receive to be more similar to other calls
     * TODO: define the purpose of size more
     *
     * Fills the provided buffer with message data. "size" should be at least
     * as large as the message size. Returns the MessageType and size of the
     * message are returned.
     *
     * @param data A pointer to a buffer to be filled with a message
     * @param size Size in bytes of the buffer pointed to by "data"
     * @return messageType Type of message sent to the client
     * @return receiveLen Length of the message in bytes
     */
    @callflow(next={"*"})
    contextGetMessage(Ptr data, Size size)
           generates (MessageToClientType messageType, Size receiveLen);

    /**
     * TODO: define subID better.
     *
     * Gets the metadata of a message to ensure entire message can be properly
     * received. Can be used to determine size of data to allocate when calling
     * contextGetMessage.
     *
     * @return messageType Type of message sent to the client
     * @return receiveLen Length of message
     * @return subID Message sub identifier
     */
    @callflow(next={"*"})
    contextPeekMessage()
            generates (MessageToClientType messageType, Size receiveLen,
                       uint32_t subID);

    /**
     * TODO: Define "previous commands" better
     * TODO: Is the message identifier the same as subID?
     *
     * Places a message into the message queue to be sent back to the message
     * handler once all previous commands have been executed. The message data
     * is copied into the queue and can be discarded by the client after this
     * call.
     *
     * @param id Message identifier
     * @param data Message data
     */
    @callflow(next={"*"})
    contextSendMessage(uint32_t id, vec<uint8_t> data);

    /**
     * TODO: Can this be done automatically as part of context creation? What
     * happens if we perform message operations before doing this?
     *
     * Initializes the messaging thread, so that the front-end API can receive
     * messages from the driver. This call also waits for the messaging FIFO to
     * start up.
     */
    @callflow(next={"*"})
    contextInitToClient();

    /**
     * TODO: Why doesn't this happen automatically as part of context
     * destruction? What happens if the FIFO is not empty?
     *
     * Deinitializes a the messaging thread. Shuts down the FIFO.
     */
    @callflow(next={"*"})
    contextDeinitToClient();

    /**
     * TODO: do we need to mark asynchronous operations in this interface
     * definition?
     *
     * Waits for any pending asynchronous operations (such as copies to a RS
     * allocation or RS script executions) to complete.
     */
    @callflow(next={"*"})
    contextFinish();

    /**
     * Prints the currently available debugging information about the state of
     * the RS context to the logcat.
     */
    @callflow(next={"*"})
    contextLog();

    /**
     * TODO: full path? relative path? Investigate further.
     *
     * Sets the cache directory of the context.
     *
     * @param cacheDir Name of the application's cache directory
     */
    @callflow(next={"*"})
    contextSetCacheDir(string cacheDir);

    /**
     * TODO: does this apply to the GPU as well?
     *
     * Changes the priority of the cpu worker threads for this context.
     *
     * @param priority Priority of the thread
     */
    @callflow(next={"*"})
    contextSetPriority(ThreadPriorities priority);

    /**
     * TODO: does this need to be part of the HAL? What if the object already
     * has a name?
     *
     * Assigns a name to a base object.
     *
     * @param obj Object to be named
     * @param name Assigned name
     */
    @callflow(next={"*"})
    assignName(ObjectBase obj, string name);

    /**
     * TODO: what if the object has no name?
     *
     * Returns the name of an object.
     *
     * @param obj Object to be read
     * @return name Name of the object
     */
    @callflow(next={"*"})
    getName(ObjectBase obj) generates (string name);

    /**
     * TODO: starting here we have a set of interfaces for use with
     * ScriptGroups. At the very least we should indicate for each one that's
     * what it's for. Should we include ScriptGroup in the interface names?
     * TODO: sweep whole file and remove prefix "v" from all parameter names
     * TODO: there are some places where we use Size for size, and others where
     * we use int32_t. Is there a reason it's int32_t? In some cases, it
     * requires a negative value.
     *
     * Creates a Closure which represents a function call to a ForEach Kernel
     * combined with arguments and values for global variables.
     *
     * @param kernelID Kernel identifier
     * @param returnValue Allocation used in output of Closure
     * @param fieldIDS Collection of Script's Field identifiers
     * @param values Collection of Script's data values
     * @param sizes Collection of Script's data sizes
     * @param depClosures Collection of Closures
     * @param depFieldIDS Collection of Script's dependent Field identifiers
     * @return closure Created Closure
     */
    @callflow(next={"*"})
    closureCreate(ScriptKernelID kernelID, Allocation returnValue,
                  vec<ScriptFieldID> fieldIDS, vec<int64_t> values,
                  vec<int32_t> sizes, vec<Closure> depClosures,
                  vec<ScriptFieldID> depFieldIDS)
       generates (Closure closure);

    /**
     * Creates a Closure which represents a function call to a invocable
     * function, combined with arguments and values for global variables.
     *
     * @param invokeID Invokable function identifier
     * @param params Collection of Invoke script parameters
     * @param fieldIDS Collection of Script Field identifiers
     * @param values Collection of values
     * @param sizes Collection of sizes
     * @return closure Created Closure
     */
    @callflow(next={"*"})
    invokeClosureCreate(ScriptInvokeID invokeID, vec<uint8_t> params,
                        vec<ScriptFieldID> fieldIDS, vec<int64_t> values,
                        vec<int32_t> sizes)
             generates (Closure closure);

    /**
     * Sets the argument of a Closure at specified index and size to provided
     * value.
     *
     * @param closure Closure to be modified
     * @param index Index
     * @param value Value
     * @param size Size
     */
    @callflow(next={"*"})
    closureSetArg(Closure closure, uint32_t index, Ptr value, int32_t size);

    /**
     * Sets a global variable in a Closure.
     *
     * @param closure Closure
     * @param fieldID Global's Field identifier
     * @param value Value
     * @param size Size
     */
    @callflow(next={"*"})
    closureSetGlobal(Closure closure, ScriptFieldID fieldID, int64_t value,
                     int32_t size);

    /**
     * TODO: should slot be unsigned? (applies to other two ID interfaces, too)
     *
     * Creates a Script Kernel ID.
     *
     * @param script Script
     * @param slot Slot
     * @param sig Bitfield describing Kernel signature and operation
     * @return scriptKernelID Script's Kernel identifier
     */
    @callflow(next={"*"})
    scriptKernelIDCreate(Script script, int32_t slot,
                         bitfield<MetadataSignatureBitval> sig)
              generates (ScriptKernelID scriptKernelID);

    /**
     * Creates a Script Invoke ID.
     *
     * @param script Script
     * @param slot Slot
     * @return scriptInvokeID Invoke Script's identifier
     */
    @callflow(next={"*"})
    scriptInvokeIDCreate(Script script, int32_t slot)
              generates (ScriptInvokeID scriptInvokeID);

    /**
     * TODO: describe the return value better. What is it?
     *
     * Creates a Script Field ID.
     *
     * @param script Script
     * @param slot Slot
     * @return scriptFieldID Script's Field identifier
     */
    @callflow(next={"*"})
    scriptFieldIDCreate(Script script, int32_t slot)
             generates (ScriptFieldID scriptFieldID);

    /**
     * TODO: add more description
     *
     * Creates a Script Group.
     *
     * @param kernels Collection of Scripts' Kernel identifiers
     * @param srcK Source Kernel identifiers
     * @param dstK Destination Kernel identifiers
     * @param dstF Destination Script Field identifiers
     * @param types Collection of Types describing data layout
     * @return scriptGroup Created Script Group
     */
    @callflow(next={"*"})
    scriptGroupCreate(vec<ScriptKernelID> kernels, vec<ScriptKernelID> srcK,
                      vec<ScriptKernelID> dstK, vec<ScriptFieldID> dstF,
                      vec<Type> types)
           generates (ScriptGroup scriptGroup);

    /**
     * Creates a Script Group.
     *
     * @param name Name
     * @param cacheDir Cache directory
     * @param closures Collection of Closures
     * @return scriptGroup2 Created Script Group
     */
    @callflow(next={"*"})
    scriptGroup2Create(string name, string cacheDir, vec<Closure> closures)
            generates (ScriptGroup2 scriptGroup2);

    /**
     * TODO: if SetInput/Output corresponds to the Java API setInput() and
     * setOutput(), which are documented as deprecated in API 23, do we need to
     * support them? Or can we fallback to the CPU when they're used? Or can't
     * we tell whether they're used early enough to do fallback?
     *
     * Sets an output of the ScriptGroup. This specifies an Allocation to be
     * used for the kernels that require an output Allocation visible after the
     * ScriptGroup is executed.
     *
     * @param sg Script Group
     * @param kid Script's Kernel identifier to be changed
     * @param alloc Allocation to be filled by output
     */
    @callflow(next={"*"})
    scriptGroupSetOutput(ScriptGroup sg, ScriptKernelID kid, Allocation alloc);

    /**
     * Sets an input of the Script Group. This specifies an Allocation to be
     * used for kernels that require an input Allocation provided from outside
     * of the Script Group.
     *
     * @param sg Script Group
     * @param kid Script's Kernel identifier to be changed
     * @param alloc Allocation to be read as input
     */
    @callflow(next={"*"})
    scriptGroupSetInput(ScriptGroup sg, ScriptKernelID kid, Allocation alloc);

    /**
     * Executes a Script Group.
     *
     * @param sg Script Group to be executed.
     */
    @callflow(next={"*"})
    scriptGroupExecute( ScriptGroup sg);

    /**
     * Frees any native resources associated with this object. The primary use
     * is to force immediate cleanup of resources when it is believed the GC
     * may not respond quickly enough.
     *
     * @param handle Opaque handle to the server-side object to be destroyed
     */
    @callflow(next={"*"})
    objDestroy(ObjectBase obj);

    /**
     * Creates a Sampler.
     *
     * @param magFilter Magnification value for the filter
     * @param minFilter Minification value for the filter
     * @param wrapS S wrapping mode for the sampler
     * @param wrapT T wrapping mode for the sampler
     * @param wrapR R wrapping mode for the sampler
     * @param aniso Anisotropy setting for the sampler
     * @return sampler Created Sampler
     */
    @callflow(next={"*"})
    samplerCreate(SamplerValue magFilter, SamplerValue minFilter,
                  SamplerValue wrapS, SamplerValue wrapT, SamplerValue wrapR,
                  float aniso)
       generates (Sampler sampler);

    /**
     * Binds an Allocation to a global pointer in the Script.
     *
     * @param script Script to be bound to
     * @param allocation Allocation to be bound
     * @param slot Slot of a global variable
     */
    @callflow(next={"*"})
    scriptBindAllocation(Script script, Allocation allocation, uint32_t slot);

    /**
     * TODO: is this necessary?
     *
     * Sets the timezone of a Script.
     *
     * @param script Script to be altered
     * @param timeZone Time Zone value as text
     */
    @callflow(next={"*"})
    scriptSetTimeZone(Script script, string timeZone);

    /**
     * TODO: can scriptInvoke be combined with scriptInvokeV?
     *
     * Launches an invokable function.
     *
     * @param vs Script to be invoked
     * @param slot Slot of invokable function
     */
    @callflow(next={"*"})
    scriptInvoke(Script vs, uint32_t slot);

    /**
     * Invokes a Script with values.
     *
     * @param vs Script to be invoked
     * @param slot Slot
     * @param data Data buffer of packed arguments
     */
    @callflow(next={"*"})
    scriptInvokeV(Script vs, uint32_t slot, vec<uint8_t> data);

    /**
     * TODO: add documentation for params
     * TODO: Should we rename "ScriptCall" to "LaunchOptions"?
     *
     * Launches a ForEach kernel.
     *
     * @param vs Script
     * @param slot Slot of ForEach Kernel
     * @param vains Collection of input Allocations or null
     * @param vaout Output Allocation or null
     * @param params Collection of parameters
     * @param sc Pointer to a ScriptCall, nullptr if unused
     */
    @callflow(next={"*"})
    scriptForEach(Script vs, uint32_t slot, vec<Allocation> vains,
                  Allocation vaout, vec<uint8_t> params, Ptr sc);

    /**
     * Launches a Reduction kernel.
     *
     * @param vs Script
     * @param slot Slot of Reduction Kernel
     * @param vains Collection of input Allocations
     * @param vaout Output Allocation
     * @param sc Pointer to a ScriptCall, nullptr if unused
     */
    @callflow(next={"*"})
    scriptReduce(Script vs, uint32_t slot, vec<Allocation> vains,
                 Allocation vaout, Ptr sc);

    /**
     * Sets a Script's integer variable to a value.
     *
     * @param vs RenderScript Script
     * @param slot Slot number of variable to be updated
     * @param value Value to be pushed to variable
     */
    @callflow(next={"*"})
    scriptSetVarI(Script vs, uint32_t slot, int32_t value);

    /**
     * Sets a Script's Object variable to a value
     *
     * @param vs RenderScript Script
     * @param slot Slot number of variable to be updated
     * @param obj ObjectBase
     */
    @callflow(next={"*"})
    scriptSetVarObj( Script vs,  uint32_t slot, ObjectBase obj);

    /**
     * Sets a Script's long variable to a value.
     *
     * @param vs RenderScript Script
     * @param slot Slot number of variable to be updated
     * @param value Value to be pushed to variable
     */
    @callflow(next={"*"})
    scriptSetVarJ(Script vs, uint32_t slot, int64_t value);

    /**
     * Sets a Script's float variable to a value.
     *
     * @param vs RenderScript Script
     * @param slot Slot number of variable to be updated
     * @param value Value to be pushed to variable
     */
    @callflow(next={"*"})
    scriptSetVarF(Script vs, uint32_t slot, float value);

    /**
     * Sets a Script's double variable to a value.
     *
     * @param vs RenderScript Script
     * @param slot Slot number of variable to be updated
     * @param value Value to be pushed to variable
     */
    @callflow(next={"*"})
    scriptSetVarD(Script vs, uint32_t slot, double value);

    /**
     * Sets a Script's struct variable to a value.
     *
     * @param vs RenderScript Script
     * @param slot Slot number of variable to be updated
     * @param data Data to be pushed to variable
     */
    @callflow(next={"*"})
    scriptSetVarV(Script vs, uint32_t slot, vec<uint8_t> data);

    /**
     * TODO: Why do we have typed setters but only untyped getter?
     *
     * Retrieves the value from a global variable in a script.
     *
     * @param vs RenderScript Script
     * @param slot Slot number of variable to be read
     * @param len Size of data to be filled
     * @return data Data to be updated
     */
    @callflow(next={"*"})
    scriptGetVarV(Script vs, uint32_t slot, Size len)
       generates (vec<uint8_t> data);

    /**
     * TODO: Is this a value to be replicated for each member of the array? Or
     * is there a representation for each separate member?
     *
     * Sets the value of a global array of structs, given the Element and
     * dimension.
     *
     * @param vs RenderScript Script
     * @param slot Slot number of variable to be updated
     * @param data Data
     * @param ve Element
     * @param dims Collection of dimensions
     */
    @callflow(next={"*"})
    scriptSetVarVE(Script vs, uint32_t slot, vec<uint8_t> data, Element ve,
                   vec<uint32_t> dims);

    /**
     * TODO: is cacheDir redundant with createCache() function? Can we remove
     * it?
     * TODO: define resName more clearly
     *
     * Creates a RenderScript C99 kernel script.
     *
     * @param resName Resource name of the bitcode
     * @param cacheDir Cache directory name
     * @param text The kernel's bitcode as a uint8_t vector
     * @return script Created Script
     */
    @callflow(next={"*"})
    scriptCCreate(string resName, string cacheDir, vec<uint8_t> text)
       generates (Script script);

    /**
     * Creates a RenderScript Intrinsic script.
     *
     * @param id Intrinsic Script identifier
     * @param elem Element
     * @return script Created Script
     */
    @callflow(next={"*"})
    scriptIntrinsicCreate(ScriptIntrinsicID id, Element elem)
               generates (Script script);

};