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+// Copyright 2011 Google Inc. All Rights Reserved.
+//
+// Use of this source code is governed by a BSD-style license
+// that can be found in the COPYING file in the root of the source
+// tree. An additional intellectual property rights grant can be found
+// in the file PATENTS. All contributing project authors may
+// be found in the AUTHORS file in the root of the source tree.
+// -----------------------------------------------------------------------------
+//
+// Multi-threaded worker
+//
+// Author: Skal (pascal.massimino@gmail.com)
+
+#ifndef WEBP_UTILS_THREAD_H_
+#define WEBP_UTILS_THREAD_H_
+
+#ifdef HAVE_CONFIG_H
+#include "../webp/config.h"
+#endif
+
+#include "../webp/types.h"
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+// State of the worker thread object
+typedef enum {
+ NOT_OK = 0, // object is unusable
+ OK, // ready to work
+ WORK // busy finishing the current task
+} WebPWorkerStatus;
+
+// Function to be called by the worker thread. Takes two opaque pointers as
+// arguments (data1 and data2), and should return false in case of error.
+typedef int (*WebPWorkerHook)(void*, void*);
+
+// Platform-dependent implementation details for the worker.
+typedef struct WebPWorkerImpl WebPWorkerImpl;
+
+// Synchronization object used to launch job in the worker thread
+typedef struct {
+ WebPWorkerImpl* impl_;
+ WebPWorkerStatus status_;
+ WebPWorkerHook hook; // hook to call
+ void* data1; // first argument passed to 'hook'
+ void* data2; // second argument passed to 'hook'
+ int had_error; // return value of the last call to 'hook'
+} WebPWorker;
+
+// The interface for all thread-worker related functions. All these functions
+// must be implemented.
+typedef struct {
+ // Must be called first, before any other method.
+ void (*Init)(WebPWorker* const worker);
+ // Must be called to initialize the object and spawn the thread. Re-entrant.
+ // Will potentially launch the thread. Returns false in case of error.
+ int (*Reset)(WebPWorker* const worker);
+ // Makes sure the previous work is finished. Returns true if worker->had_error
+ // was not set and no error condition was triggered by the working thread.
+ int (*Sync)(WebPWorker* const worker);
+ // Triggers the thread to call hook() with data1 and data2 arguments. These
+ // hook/data1/data2 values can be changed at any time before calling this
+ // function, but not be changed afterward until the next call to Sync().
+ void (*Launch)(WebPWorker* const worker);
+ // This function is similar to Launch() except that it calls the
+ // hook directly instead of using a thread. Convenient to bypass the thread
+ // mechanism while still using the WebPWorker structs. Sync() must
+ // still be called afterward (for error reporting).
+ void (*Execute)(WebPWorker* const worker);
+ // Kill the thread and terminate the object. To use the object again, one
+ // must call Reset() again.
+ void (*End)(WebPWorker* const worker);
+} WebPWorkerInterface;
+
+// Install a new set of threading functions, overriding the defaults. This
+// should be done before any workers are started, i.e., before any encoding or
+// decoding takes place. The contents of the interface struct are copied, it
+// is safe to free the corresponding memory after this call. This function is
+// not thread-safe. Return false in case of invalid pointer or methods.
+WEBP_EXTERN(int) WebPSetWorkerInterface(
+ const WebPWorkerInterface* const winterface);
+
+// Retrieve the currently set thread worker interface.
+WEBP_EXTERN(const WebPWorkerInterface*) WebPGetWorkerInterface(void);
+
+//------------------------------------------------------------------------------
+
+#ifdef __cplusplus
+} // extern "C"
+#endif
+
+#endif /* WEBP_UTILS_THREAD_H_ */