Atmosphere/libraries/libstratosphere/source/sf/cmif/sf_cmif_inline_context.cpp

/*
 * Copyright (c) 2018-2020 Atmosphère-NX
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms and conditions of the GNU General Public License,
 * version 2, as published by the Free Software Foundation.
 *
 * This program is distributed in the hope it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License for
 * more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <stratosphere.hpp>

namespace ams::sf {

    namespace cmif {

        namespace {

            ALWAYS_INLINE std::atomic<uintptr_t> *GetAtomicSfInlineContext(os::ThreadType *thread) {
            static_assert(sizeof(thread->atomic_sf_inline_context) >= sizeof(std::atomic<uintptr_t>));
                return reinterpret_cast<std::atomic<uintptr_t> *>(std::addressof(thread->atomic_sf_inline_context));
            }

            ALWAYS_INLINE std::atomic<uintptr_t> *GetAtomicSfInlineContext() {
                return GetAtomicSfInlineContext(os::GetCurrentThread());
            }

            ALWAYS_INLINE void OnSetInlineContext(os::ThreadType *thread) {
                /* Ensure that libnx receives the priority value. */
                ::fsSetPriority(static_cast<::FsPriority>(::ams::sf::GetFsInlineContext(thread)));
            }

        }

        InlineContext GetInlineContext() {
            /* Get current thread. */
            os::ThreadType * const cur_thread = os::GetCurrentThread();

            /* Get the context. */
            uintptr_t thread_context = GetAtomicSfInlineContext()->load();

            /* Copy it out. */
            InlineContext ctx;
            static_assert(sizeof(ctx) <= sizeof(thread_context));
            std::memcpy(std::addressof(ctx), std::addressof(thread_context), sizeof(ctx));
            return ctx;
        }

        InlineContext SetInlineContext(InlineContext ctx) {
            /* Get current thread. */
            os::ThreadType * const cur_thread = os::GetCurrentThread();
            ON_SCOPE_EXIT { OnSetInlineContext(cur_thread); };

            /* Create the new context. */
            static_assert(sizeof(ctx) <= sizeof(uintptr_t));
            uintptr_t new_context_value = 0;
            std::memcpy(std::addressof(new_context_value), std::addressof(ctx), sizeof(ctx));

            /* Get the old context. */
            uintptr_t old_context_value = GetAtomicSfInlineContext()->exchange(new_context_value);

            /* Convert and copy it out. */
            InlineContext old_ctx;
            std::memcpy(std::addressof(old_ctx), std::addressof(old_context_value), sizeof(old_ctx));
            return old_ctx;
        }

    }

    namespace {

        ALWAYS_INLINE std::atomic<u8> *GetAtomicFsInlineContext(os::ThreadType *thread) {
            static_assert(sizeof(thread->atomic_sf_inline_context) >= sizeof(std::atomic<u8>));
            return reinterpret_cast<std::atomic<u8> *>(std::addressof(thread->atomic_sf_inline_context));
        }

    }

    u8 GetFsInlineContext(os::ThreadType *thread) {
        return GetAtomicFsInlineContext(thread)->load();
    }

    u8 SetFsInlineContext(os::ThreadType *thread, u8 ctx) {
        ON_SCOPE_EXIT { cmif::OnSetInlineContext(thread); };

        return GetAtomicFsInlineContext(thread)->exchange(ctx);
    }

}