pg_port.c

一个移植到凌阳单片机spce061a上面的实时操作系统

///////////////////////////////////////////////////////////////
//
//
//   PGOS : A Portable,Configable Embedded System Kernel
//
//           Sunplus unSP(TM) Specific code
//
//   This is an open source project under GPL lincence  
//
//        Version 0.9.0 ---- Development Snopshot
//
//   File name : pg_port.c : Portable code on unSP(TM) architecture   
//   History :
//
//          2005-07-24  First build by X.K. @ PGOS Team
//          2005-08-22  Rewrite for unSP(TM) by X.K.   
//          
/////////////////////////////////////////////////////////////////
#include "pgos.h"

VOID BREAK() __attribute__((ISR)) ;

extern BYTE task_cur_id ;
extern BYTE task_cur_prio ;
extern BYTE task_nxt_id ;
extern BYTE task_nxt_prio ;
pgTASK*  task_nxt ;
pgTASK*  task_prv ;
extern pgTASKLIST*  task_list_head ;

#if  PG_TASK_BASIC_SUPPORT == 1
REGSZ*  pgos_tk_initstk( REGSZ* stk,VOID ( *task )() )
{
    /*------------------------------
    The init task stack looks like this :
    SR
    BP
    R4
    R3
    R2
    R1
    Entry Point of TASK
    -------------------------------*/
    
    /*-------------------------------
      GCC compiler uses a pointer to
      save the true address of a fun
      entry point.so we must get the 
      true value here.
    -------------------------------*/   
    *stk -- = *( ( WORD* )( task + 1 ) );
    *stk -- = 0x0000 ;  // For the segment register
    *stk -- = 0x0001 ;
    *stk -- = 0x0002 ;
    *stk -- = 0x0003 ;
    *stk -- = 0x0004 ;
	*stk -- = ( ( 'B' << 8 ) | 'P' ) ; 
	
    return ( REGSZ* ) stk ;
}

#endif  // PG_TASK_BASIC_SUPPORT

VOID pgos_sys_runhigh()
{
   __asm("
         r2 = [_task_nxt]
         r1 = [r2]
         sp = r1
         pop bp,r1 from [sp]
         //pop r1,r4 from [sp]
         reti
   ");
}

VOID BREAK()
{
   __asm("
         r2 = [_task_prv]
         [r2] = sp
         
         r1 = [_task_nxt]
         r1 = [r1]
         sp = r1
         pop bp,r1 from [sp]
         //pop r1,r4 from [sp]
         reti
   ") ;
}