st-hooks.h

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//
// Created by styyx on 09/03/2026.
//
 
#pragma once
#include <xbyak/xbyak.h>
 
namespace StyyxUtil
{
namespace HookUtils
{
template <class T>
void WriteCall5(const REL::ID a_relID, const uint32_t a_offset)
{
    static REL::Relocation<uintptr_t> targ{a_relID, a_offset};
    auto& trampoline = SKSE::GetTrampoline();
    T::func          = trampoline.write_call<5>(targ.address(), T::Call);
}
template <class O, uint32_t table, uint32_t index, class T>
void WriteVFunc()
{
    static REL::Relocation<uintptr_t> vtbl{O::VTABLE[table]};
    T::func = vtbl.write_vfunc(index, T::Call);
}
 
template <typename Ret, typename... Args>
static Ret GenericCall(REL::ID a_id, uint32_t a_offset, Args... args)
{
    using func_t = Ret (*)(Args...);
    static REL::Relocation<func_t> target{a_id, a_offset};
    return target(std::forward<Args>(args)...);
}
// copied from
// https://github.com/powerof3/PapyrusExtenderSSE/blob/0fbb355b634f2edcfd72bd364884e3ee5caadfc9/include/PCH.h#L140-L167
// MIT License
template <class T, std::size_t BYTES>
void hook_function_prologue(std::uintptr_t a_src)
{
    struct Patch : Xbyak::CodeGenerator
    {
        Patch(std::uintptr_t a_originalFuncAddr, std::size_t a_originalByteLength)
        {
            // Hook returns here. Execute the restored bytes and jump back to the
            // original function.
            for (size_t i = 0; i < a_originalByteLength; ++i)
            {
                db(*reinterpret_cast<std::uint8_t*>(a_originalFuncAddr + i));
            }
            jmp(ptr[rip]);
            dq(a_originalFuncAddr + a_originalByteLength);
        }
    };
 
    Patch p(a_src, BYTES);
    p.ready();
 
    auto& trampoline = SKSE::GetTrampoline();
    trampoline.write_branch<5>(a_src, T::thunk);
 
    auto alloc = trampoline.allocate(p.getSize());
    std::memcpy(alloc, p.getCode(), p.getSize());
 
    T::func = reinterpret_cast<std::uintptr_t>(alloc);
}
} // namespace HookUtils
} // namespace StyyxUtil