sdk/fidl/fuchsia.sysmem2/results.fidl

// Copyright 2020 The Fuchsia Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
library fuchsia.sysmem2;

using zx;

// The contents of this file are not final.  Incompatible changes are still
// being made to this file.  Do not rely on the contents of this file to provide
// backward compatibility (yet).
//
// TODO(fxbug.dev/34192): Sysmem should use llcpp and FIDL tables.  The definitions in
// this file are part of that transition, but the definitions here are not
// final.  For now, the definition here is only used internally to sysmem (not
// between processes), and therefore this definition can change for now.  Later
// after we're happy with this representation, we'll create
// fuchsia.sysmem2.BufferCollection.SetConstraints() which will accept
// constraints as defined here.

type VmoBuffer = resource table {
    /// The same VMO can be used by more than one CodecBuffer (only of the same
    /// buffer_lifetime_ordinal), but each vmo handle must be a separate handle.
    ///
    /// |vmo| can be un-set if a participant has no usage which requires a
    /// VMO handle.
    1: vmo zx.handle:VMO;

    /// Offset within the VMO of the first usable byte.  Must be < the VMO's
    /// size in bytes, and leave sufficient room for
    /// BufferMemorySettings.size_bytes before the end of the VMO.
    2: vmo_usable_start uint64;

    /// In some cases, we have a physically separate aux buffer that is a
    /// logical shadow of the main buffer.  The main use case so far is DRM L1
    /// where we can have a clear aux buffer that has meaningful bytes only for
    /// the portions of the input which are clear (not protected).  The
    /// protected portions will be set to a byte value that will prevent start
    /// code emulation (0xFF will work for most video formats).
    ///
    /// |aux_vmo| will be un-set if there are no aux buffers, or in the same
    /// cases that |vmo| can be un-set.
    3: aux_vmo zx.handle:VMO;
};

const MAX_COUNT_BUFFER_COLLECTION_INFO_BUFFERS uint32 = 128;

/// Information about a buffer collection and its buffers.
// TODO(fxbug.dev/32119): provide a way for clients to receive this table instead of the
// struct fuchsia.sysmem.BufferCollectionInfo_2.
type BufferCollectionInfo = resource table {
    /// These settings apply to all the buffers in the initial buffer allocation.
    /// This must be set.
    1: settings SingleBufferSettings;

    /// VMO handles (and vmo_usable_start offset) for each buffer in the
    /// collection.
    ///
    /// The size of this vector is the buffer_count (buffer_count is not sent
    /// separately).
    ///
    /// All buffer VMO handles have identical size and access rights.  The size
    /// is in settings.buffer_settings.size_bytes.
    ///
    /// The VMO access rights are determined based on the usages which the
    /// client specified when allocating the buffer collection.  For example,
    /// a client which expressed a read-only usage will receive VMOs without
    /// write rights.  In addition, the rights can be attenuated by the
    /// parameter to BufferCollectionToken.Duplicate() calls.
    ///
    /// This field will always have VmoBuffer(s) in it, even if the participant
    /// specifies usage whieh does not require VMO handles.  This permits such
    /// a participant to know the vmo_usable_start values, in case that's of any
    /// use to the participant.
    2: buffers vector<VmoBuffer>:MAX_COUNT_BUFFER_COLLECTION_INFO_BUFFERS;
};

/// These settings and constraints apply to all the buffers in the collection.
type SingleBufferSettings = table {
    1: buffer_settings BufferMemorySettings;

    /// Buffers holding data that is not uncompressed image data will not have
    /// this field set.  Buffers holding data that is uncompressed image data
    /// _may_ have this field set.
    ///
    /// At least for now, changing the PixelFormat requires re-allocating
    /// buffers.
    ///
    /// If un-set, there are no image format constraints.
    2: image_format_constraints ImageFormatConstraints;
};

/// These are memory-related settings for all buffers of a buffer collection.
type BufferMemorySettings = table {
    1: size_bytes uint32;
    2: is_physically_contiguous bool;
    3: is_secure bool;
    4: coherency_domain CoherencyDomain;
    /// The specific heap from which buffers are allocated.
    /// See above in this file for heap identifier values.
    5: heap HeapType;
};