#include "Monitor.h"

#include "Thread.h"

extern "C" void __stdcall force_yield(Thread* t);

Monitor::Monitor(Scheduler* scheduler, DWORD thread_id) :

scheduler_(scheduler), thread_(OpenThread(THREAD_GET_CONTEXT | THREAD_SET_CONTEXT, FALSE, thread_id))

{

}

Monitor::~Monitor()

{

enable_ = false;

WaitForSingleObject(thread_, INFINITE);

CloseHandle(thread_);

}

void Monitor::Start()

{

enable_ = true;

union

{

LPTHREAD_START_ROUTINE r;

decltype(&Monitor::MonitorThread) p;

} u;

u.p = &Monitor::MonitorThread;

CloseHandle(CreateThread(nullptr, 0, u.r, this, 0, nullptr));

}

void __stdcall Monitor::MonitorThread()

{

std::uint32_t count = 0;

while (enable_)

{

Sleep(100);

if (scheduler_->status == ThreadStatus::READY && scheduler_->switch_count_ == count)

{

SuspendThread(thread_);

if (scheduler_->status == ThreadStatus::READY && scheduler_->switch_count_ == count)

{

auto current = scheduler_->next;

CONTEXT context = { CONTEXT_CONTROL };

GetThreadContext(thread_, &context);

auto esp = (std::uint32_t*)context.Esp;

*--esp = (std::uint32_t)current;

*--esp = context.Eip;

context.Esp = (DWORD)esp;

context.Eip = (DWORD)&force_yield;

context.ContextFlags = CONTEXT_CONTROL;

SetThreadContext(thread_, &context);

}

ResumeThread(thread_);

}

count = scheduler_->switch_count_;

}

}