/***************************************************************************
 * Copyright (C) 2026 Eclipse ThreadX contributors
 *
 * This program and the accompanying materials are made available under the
 * terms of the MIT License which is available at
 * https://opensource.org/licenses/MIT.
 *
 * AI Disclosure: This file was largely AI-generated by Codex (gpt 5.4).
 * The AI-generated portions may be considered public domain (CC0-1.0)
 * and not subject to the project's licence. The human contributor has
 * reviewed and verified that the code is correct.
 *
 * SPDX-License-Identifier: MIT and CC0-1.0
 **************************************************************************/

// Some portions generated by Codex (gpt 5.4).
// Some portions generated by GitHub Copilot (claude-sonnet-4.6).

#define TX_SOURCE_CODE
#define TX_THREAD_SMP_SOURCE_CODE

#include "tx_api.h"
#include "tx_thread.h"
#include "tx_timer.h"

VOID  _tx_thread_context_save(VOID)
{
TX_THREAD   *thread_ptr;
UINT        interrupt_posture;

    interrupt_posture =  _tx_thread_smp_protect();
    if (interrupt_posture != TX_FALSE)
    {
        _tx_win32_system_error++;
    }

    _tx_win32_debug_entry_insert("CONTEXT_SAVE", __FILE__, __LINE__);

    thread_ptr =  _tx_thread_current_ptr[0];

    if ((thread_ptr != TX_NULL) && (_tx_thread_system_state[0] == 0UL))
    {
        if (thread_ptr -> tx_thread_win32_mutex_access == TX_FALSE)
        {
            if (_tx_thread_preempt_disable == 0U)
            {
                /* Thread is not in a preempt-disabled section; suspend it normally so
                 * context_restore can preempt it if a higher-priority thread is ready. */
                _tx_win32_thread_suspend(thread_ptr -> tx_thread_win32_thread_handle);
                _tx_win32_debug_entry_insert("CONTEXT_SAVE-suspend_thread", __FILE__, __LINE__);
            }
            else
            {
                /* Thread holds the SMP preemption lock (_tx_thread_preempt_disable != 0).
                 * Issuing SuspendThread/ResumeThread here would cost ~100 µs for zero
                 * benefit: context_restore will skip preemption anyway because
                 * _tx_thread_preempt_disable is still non-zero when it runs (the ISR
                 * cannot lower the count below its value at ISR entry while it holds the
                 * Win32 critical section).  Flag the thread so context_restore knows not
                 * to issue a matching ResumeThread.
                 *
                 * MISRA C 2012 Rule 10.3 deviation: suspension_type is a UINT field used
                 * as a small state tag; value 3 is a port-local extension of the existing
                 * 0/1/2 enumeration. */
                thread_ptr -> tx_thread_win32_suspension_type =  3U;
            }
        }
        else
        {
            /* Thread is spinning on the Win32 critical section (mutex_access TRUE).
             * It is blocked waiting to acquire the CS and cannot execute any protected
             * ThreadX code, so SuspendThread is unnecessary.  Tag the thread with
             * suspension_type 4 so context_restore handles it correctly:
             *   - no-preemption path: just clear the flag (no ResumeThread).
             *   - preemption path: call SuspendThread retrospectively and proceed.
             *
             * MISRA C 2012 Rule 10.3 deviation: value 4 is a port-local extension. */
            thread_ptr -> tx_thread_win32_suspension_type =  4U;
        }
    }

    _tx_thread_system_state[0]++;
}