tx_tsr.68

threadx嵌入式实时操作系统源代码

/**************************************************************************/ 
/*                                                                        */ 
/*            Copyright (c) 1996-2000 by Express Logic Inc.               */ 
/*                                                                        */ 
/*  This software is copyrighted by and is the sole property of Express   */ 
/*  Logic, Inc.  All rights, title, ownership, or other interests         */ 
/*  in the software remain the property of Express Logic, Inc.  This      */ 
/*  software may only be used in accordance with the corresponding        */ 
/*  license agreement.  Any unauthorized use, duplication, transmission,  */ 
/*  distribution, or disclosure of this software is expressly forbidden.  */ 
/*                                                                        */
/*  This Copyright notice may not be removed or modified without prior    */ 
/*  written consent of Express Logic, Inc.                                */ 
/*                                                                        */ 
/*  Express Logic, Inc. reserves the right to modify this software        */ 
/*  without notice.                                                       */ 
/*                                                                        */ 
/*  Express Logic, Inc.                                                   */
/*  11440 West Bernardo Court               [e-mail]         */
/*  Suite 366                               http://www.expresslogic.com   */
/*  San Diego, CA  92127                                                  */
/*                                                                        */
/**************************************************************************/


/**************************************************************************/
/**************************************************************************/
/**                                                                       */ 
/** ThreadX Component                                                     */ 
/**                                                                       */
/**   Thread Control (THR)                                                */
/**                                                                       */
/**************************************************************************/
/**************************************************************************/

/* #define    TX_SOURCE_CODE  */


/* Include necessary system files.  */

/*  #include   "tx_api.h"
    #include   "tx_thr.h"
    #include   "tx_tim.h"  */


    XREF    _tx_thread_current_ptr
    XREF    _tx_thread_system_stack_ptr
    XREF    _tx_timer_time_slice
    XREF    _tx_thread_schedule


    SECT    .text,x
    ALIGN   4
/**************************************************************************/ 
/*                                                                        */ 
/*  FUNCTION                                               RELEASE        */ 
/*                                                                        */ 
/*    _tx_thread_system_return                        68332/Green Hills   */ 
/*                                                           3.0a         */ 
/*  AUTHOR                                                                */ 
/*                                                                        */ 
/*    William E. Lamie, Express Logic, Inc.                               */ 
/*                                                                        */ 
/*  DESCRIPTION                                                           */ 
/*                                                                        */ 
/*    This function is target processor specific.  It is used to transfer */ 
/*    control from a thread back to the system.  Only a minimal context   */ 
/*    is saved since the compiler assumes temp registers are going to get */ 
/*    slicked by a function call anyway.                                  */ 
/*                                                                        */ 
/*  INPUT                                                                 */ 
/*                                                                        */ 
/*    None                                                                */ 
/*                                                                        */ 
/*  OUTPUT                                                                */ 
/*                                                                        */ 
/*    None                                                                */ 
/*                                                                        */ 
/*  CALLS                                                                 */ 
/*                                                                        */ 
/*    _tx_thread_schedule                   Thread scheduling loop        */ 
/*                                                                        */ 
/*  CALLED BY                                                             */ 
/*                                                                        */ 
/*    ThreadX components                                                  */ 
/*                                                                        */ 
/*  RELEASE HISTORY                                                       */ 
/*                                                                        */ 
/*    DATE              NAME                      DESCRIPTION             */ 
/*                                                                        */ 
/*  09-07-1999     William E. Lamie         Initial Version 3.0           */ 
/*  12-02-1999     William E. Lamie         Modified comment(s) and added */ 
/*											  code to keep the thread's   */ 
/*											  stack long word aligned,    */ 
/*                                            resulting in version 3.0a.  */ 
/*                                                                        */ 
/**************************************************************************/ 
/* VOID   _tx_thread_system_return(VOID)
{  */
    XDEF    _tx_thread_system_return
_tx_thread_system_return:

    /* Save minimal context on the stack.  */

    adda    #-2,%A7							; Adjust stack for long word alignment
    move.w  %SR,-(%A7)                      ; Save thread's status register
    movem.l	%D2-%D7/%A2-%A6,-(%A7)          ; Save preserved registers on the
                                        /*  ;   thread's stack  */
    move.w  #0,-(%A7)                       ; Push the stack frame type on the
                                        /*  ;   thread's stack  */
	
   /* Lockout interrupts.  */

    ori.w   #$0700,%SR                      ; Lockout interrupt for serious 
                                        /*  ;   business  */

    /* Save current stack and switch to system stack.  */
    /* _tx_thread_current_ptr -> tx_stack_ptr =  a7;
    a7 = _tx_thread_system_stack_ptr;  */

    movea.l _tx_thread_current_ptr,%A0      ; Point to thread's control block
    move.l  %A7,8(%A0)                      ; Save thread's stack pointer
    movea.l _tx_thread_system_stack_ptr,%A7 ; Switch to system stack

    /* Determine if the time-slice is active.  */
    /* if (_tx_timer_time_slice)
    {  */
    tst.l   _tx_timer_time_slice            ; Is a time-slice present?
    beq     __tx_thread_dont_reset_ts       ; No, don't reset the time-slice

	/* Setup a new time-slice for the thread and clear the current time-slice.  */
	/* _tx_thread_current_ptr -> tx_time_slice =  
					_tx_thread_current_ptr -> tx_new_time_slice;
	_tx_timer_time_slice =  0;  */

    move.l  28(%A0),%D0                     ; Pickup the fresh time-slice
    move.l  %D0,24(%A0)                     ; Setup the time-slice for next execution
    clr.l   _tx_timer_time_slice            ; Disable the time-slice

    /* }  */
__tx_thread_dont_reset_ts:

    /* Clear the current thread pointer.  */
    /* _tx_thread_current_ptr =  TX_NULL;  */

    clr.l   _tx_thread_current_ptr          ; Set current thread pointer to NULL

    jmp     _tx_thread_schedule             ; Return to thread scheduler
/* }  */
    END