system/fidl/fuchsia-sysmem/collections.fidl

// Copyright 2018 The Chromium 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.sysmem;

// An interface for accessing a collection of buffers which were allocated
// together as a group by an |Allocator| on behalf of one of its clients.
//
// Individual buffers within the collection are identified by their zero-based
// index.  All of the buffers have the same characteristics.
interface BufferCollection {
    // Gets information about the buffer collection, including its handles.
    1: GetInfo() -> (BufferCollectionInfo info);
};

// Information about a buffer collection and its buffers.
// TODO(ZX-2260): change struct to table
struct BufferCollectionInfo {
    // The number of buffers in the collection.
    uint32 bufferCount;

    // Describes how the contents of buffers are represented.
    // All buffers within the collection have the same format.
    BufferFormat format;

    // VMO handles for each buffer in the collection.
    // This vector is only present when the buffers are backed by VMOs.
    //
    // If present, the count of this vector equals |numBuffers|.
    // All buffer VMO handles have identical size and access rights.
    // 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.
    vector<handle<vmo>>:64 vmos;

    // The size of each VMO provided.
    // This property is only present when the buffers are backed by VMOs.
    uint64 vmoSize = 0;
};