/***************************************************************************
 * Copyright (c) 2024 Microsoft Corporation 
 * 
 * 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.
 * 
 * SPDX-License-Identifier: MIT
 **************************************************************************/


/**************************************************************************/
/**************************************************************************/
/**                                                                       */
/** ThreadX Component                                                     */
/**                                                                       */
/**   Thread                                                              */
/**                                                                       */
/**************************************************************************/
/**************************************************************************/
#ifdef TX_INCLUDE_USER_DEFINE_FILE
#include "tx_user.h"
#endif

    .syntax unified
#if defined(THUMB_MODE)
    .thumb
#else
    .arm
#endif

#ifdef TX_ENABLE_FIQ_SUPPORT
DISABLE_INTS    =       0xC0                    // Disable IRQ/FIQ interrupts
#else
DISABLE_INTS    =       0x80                    // Disable IRQ interrupts
#endif
MODE_MASK       =       0x1F                    // Mode mask
FIQ_MODE_BITS   =       0x11                    // FIQ mode bits

    .text
    .align 2
/**************************************************************************/
/*                                                                        */
/*  FUNCTION                                               RELEASE        */
/*                                                                        */
/*    _tx_thread_fiq_nesting_end                           ARMv7-A        */
/*                                                           6.4.0        */
/*  AUTHOR                                                                */
/*                                                                        */
/*    William E. Lamie, Microsoft Corporation                             */
/*                                                                        */
/*  DESCRIPTION                                                           */
/*                                                                        */
/*    This function is called by the application from FIQ mode after      */
/*    _tx_thread_fiq_nesting_start has been called and switches the FIQ   */
/*    processing from system mode back to FIQ mode prior to the ISR       */
/*    calling _tx_thread_fiq_context_restore.  Note that this function    */
/*    assumes the system stack pointer is in the same position after      */
/*    nesting start function was called.                                  */
/*                                                                        */
/*    This function assumes that the system mode stack pointer was setup  */
/*    during low-level initialization (tx_initialize_low_level.s).        */
/*                                                                        */
/*    This function returns with FIQ interrupts disabled.                 */
/*                                                                        */
/*  INPUT                                                                 */
/*                                                                        */
/*    None                                                                */
/*                                                                        */
/*  OUTPUT                                                                */
/*                                                                        */
/*    None                                                                */
/*                                                                        */
/*  CALLS                                                                 */
/*                                                                        */
/*    None                                                                */
/*                                                                        */
/*  CALLED BY                                                             */
/*                                                                        */
/*    ISRs                                                                */
/*                                                                        */
/*  RELEASE HISTORY                                                       */
/*                                                                        */
/*    DATE              NAME                      DESCRIPTION             */
/*                                                                        */
/*  09-30-2020     William E. Lamie         Initial Version 6.1           */
/*  04-25-2022     Zhen Kong                Updated comments,             */
/*                                            resulting in version 6.1.11 */
/*  10-31-2023     Tiejun Zhou              Modified comment(s), added    */
/*                                            #include tx_user.h,         */
/*                                            resulting in version 6.3.0  */
/*  12-31-2023     Yajun Xia                Modified comment(s),          */
/*                                            Added thumb mode support,   */
/*                                            resulting in version 6.4.0  */
/*                                                                        */
/**************************************************************************/
#if defined(THUMB_MODE)
    .thumb_func
#endif
    .global  _tx_thread_fiq_nesting_end
    .type    _tx_thread_fiq_nesting_end,function
_tx_thread_fiq_nesting_end:
    MOV     r3,lr                               // Save ISR return address
    MRS     r0, CPSR                            // Pickup the CPSR
    ORR     r0, r0, #DISABLE_INTS               // Build disable interrupt value
    MSR     CPSR_c, r0                          // Disable interrupts
    LDMIA   sp!, {r1, lr}                       // Pickup saved lr (and r1 throw-away for
                                                //   8-byte alignment logic)
    BIC     r0, r0, #MODE_MASK                  // Clear mode bits
    ORR     r0, r0, #FIQ_MODE_BITS              // Build IRQ mode CPSR
    MSR     CPSR_c, r0                          // Reenter IRQ mode

    BX      r3                                  // Return to caller
