Common.h

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#ifndef ARCH_x86_COMMON_H
#define ARCH_x86_COMMON_H
 
#include "CothreadPrivate.h"
#include "CothreadImpl.h"
 
#include <array>
#include <cstddef>
 
#if defined(_MSC_VER) && !__INTEL_COMPILER
#define FASTCALL_TAG __fastcall
#else
#define FASTCALL_TAG __attribute__((fastcall))
#endif
 
namespace libcommunism::internal {
class x86 final: public CothreadImpl {
    friend CothreadImpl *libcommunism::AllocKernelThreadWrapper();
 
    private:
        struct CallInfo {
            Entry entry;
        };
 
    public:
        x86(const Entry &entry, const size_t stackSize = 0);
        x86(const Entry &entry, std::span<uintptr_t> stack);
        x86(std::span<uintptr_t> stack) : CothreadImpl(stack) {}
        ~x86();
 
        void switchTo(CothreadImpl *from) override;
 
    private:
        static void ValidateStackSize(const size_t size);
        static void* AllocStack(const size_t bytes);
        static void DeallocStack(void* stack);
        static void CothreadReturned();
        static void FASTCALL_TAG DereferenceCallInfo(CallInfo *info);
        static void Prepare(x86 *thread, const Entry &entry);
 
        static void FASTCALL_TAG Switch(x86 *from, x86 *to);
 
        static void JumpToEntry();
 
    public:
        static const size_t kNumSavedRegisters{4};
 
        static constexpr const size_t kMainStackSize{64};
 
        static constexpr const size_t kStackAlignment{16};
 
        static constexpr const size_t kDefaultStackSize{0x40000};
 
    private:
        static thread_local std::array<uintptr_t, kMainStackSize> gMainStack;
 
        bool ownsStack{false};
        void *stackTop{nullptr};
};
}
 
#endif