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Fri, 19 Apr 2024 15:58:22 +0000 From: Andreas Rheinhardt To: ffmpeg-devel@ffmpeg.org Date: Fri, 19 Apr 2024 17:58:10 +0200 Message-ID: X-Mailer: git-send-email 2.40.1 X-TMN: [QGBnJhxorLYtCws2F8fVKe8TSzkMx/ucuX5Mh96Txjs=] X-ClientProxiedBy: ZR2P278CA0088.CHEP278.PROD.OUTLOOK.COM (2603:10a6:910:65::19) To AS8P250MB0744.EURP250.PROD.OUTLOOK.COM (2603:10a6:20b:541::14) X-Microsoft-Original-Message-ID: <20240419155814.1104217-1-andreas.rheinhardt@outlook.com> MIME-Version: 1.0 X-MS-Exchange-MessageSentRepresentingType: 1 X-MS-PublicTrafficType: Email X-MS-TrafficTypeDiagnostic: AS8P250MB0744:EE_|PR3P250MB0098:EE_ X-MS-Office365-Filtering-Correlation-Id: 2db4c8ab-b33d-4883-5cc2-08dc608989f3 X-Microsoft-Antispam: BCL:0; X-Microsoft-Antispam-Message-Info: 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 X-MS-Exchange-AntiSpam-MessageData-ChunkCount: 1 X-MS-Exchange-AntiSpam-MessageData-0: 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 X-OriginatorOrg: outlook.com X-MS-Exchange-CrossTenant-Network-Message-Id: 2db4c8ab-b33d-4883-5cc2-08dc608989f3 X-MS-Exchange-CrossTenant-AuthSource: AS8P250MB0744.EURP250.PROD.OUTLOOK.COM X-MS-Exchange-CrossTenant-AuthAs: Internal X-MS-Exchange-CrossTenant-OriginalArrivalTime: 19 Apr 2024 15:58:22.3173 (UTC) X-MS-Exchange-CrossTenant-FromEntityHeader: Hosted X-MS-Exchange-CrossTenant-Id: 84df9e7f-e9f6-40af-b435-aaaaaaaaaaaa X-MS-Exchange-CrossTenant-RMS-PersistedConsumerOrg: 00000000-0000-0000-0000-000000000000 X-MS-Exchange-Transport-CrossTenantHeadersStamped: PR3P250MB0098 Subject: [FFmpeg-devel] [PATCH 1/5] avcodec/progressframe: Explain how unnamed union can simplify accesses X-BeenThere: ffmpeg-devel@ffmpeg.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: FFmpeg development discussions and patches List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: FFmpeg development discussions and patches Cc: Andreas Rheinhardt Errors-To: ffmpeg-devel-bounces@ffmpeg.org Sender: "ffmpeg-devel" X-TUID: JlWt0cJ6hrLs This relies on the common initial seqence guarantee (and on C11 support for unnamed members). Signed-off-by: Andreas Rheinhardt --- Alternatively, we could rely on type punning via unions and even use union { AVFrame *const f; ProgressFrame pf; }; libavcodec/progressframe.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/libavcodec/progressframe.h b/libavcodec/progressframe.h index dc841f30d2..428a461659 100644 --- a/libavcodec/progressframe.h +++ b/libavcodec/progressframe.h @@ -58,6 +58,18 @@ struct AVCodecContext; +/** + * The ProgressFrame structure. + * Hint: It is guaranteed that the AVFrame pointer is at the start + * of ProgressFrame. This allows to use an unnamed + * union { + * struct { + * AVFrame *f; + * }; + * ProgressFrame pf; + * }; + * to simplify accessing the embedded AVFrame. + */ typedef struct ProgressFrame { struct AVFrame *f; struct ProgressInternal *progress;