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/*
* Win32 coroutine initialization code
*
* Copyright (c) 2011 Kevin Wolf <kwolf@redhat.com>
*
* Permission is hereby granted, free of charge, to any person obtaining a copy
* of this software and associated documentation files (the "Software"), to deal
* in the Software without restriction, including without limitation the rights
* to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
* copies of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be included in
* all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
* THE SOFTWARE.
*/
#include "qemu/osdep.h"
#include "qemu/coroutine_int.h"
typedef struct
{
Coroutine base;
LPVOID fiber;
CoroutineAction action;
} CoroutineWin32;
static __thread CoroutineWin32 leader;
static __thread Coroutine *current;
/* This function is marked noinline to prevent GCC from inlining it
* into coroutine_trampoline(). If we allow it to do that then it
* hoists the code to get the address of the TLS variable "current"
* out of the while() loop. This is an invalid transformation because
* the SwitchToFiber() call may be called when running thread A but
* return in thread B, and so we might be in a different thread
* context each time round the loop.
*/
CoroutineAction __attribute__((noinline))
qemu_coroutine_switch(Coroutine *from_, Coroutine *to_,
CoroutineAction action)
{
CoroutineWin32 *from = DO_UPCAST(CoroutineWin32, base, from_);
CoroutineWin32 *to = DO_UPCAST(CoroutineWin32, base, to_);
current = to_;
to->action = action;
SwitchToFiber(to->fiber);
return from->action;
}
static void CALLBACK coroutine_trampoline(void *co_)
{
Coroutine *co = co_;
while (true) {
co->entry(co->entry_arg);
qemu_coroutine_switch(co, co->caller, COROUTINE_TERMINATE);
}
}
Coroutine *qemu_coroutine_new(void)
{
const size_t stack_size = COROUTINE_STACK_SIZE;
CoroutineWin32 *co;
co = g_malloc0(sizeof(*co));
co->fiber = CreateFiber(stack_size, coroutine_trampoline, &co->base);
return &co->base;
}
void qemu_coroutine_delete(Coroutine *co_)
{
CoroutineWin32 *co = DO_UPCAST(CoroutineWin32, base, co_);
DeleteFiber(co->fiber);
g_free(co);
}
Coroutine *qemu_coroutine_self(void)
{
if (!current) {
current = &leader.base;
leader.fiber = ConvertThreadToFiber(NULL);
}
return current;
}
bool qemu_in_coroutine(void)
{
return current && current->caller;
}
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