ARM Macro Assembler    Page 1 


    1 00000000         ;*******************************************************
                       ************************************
    2 00000000         ;OS_CPU_A.s
    3 00000000         
    4 00000000         
    5 00000000         
    6 00000000                 PRESERVE8
    7 00000000                 AREA             OS_CPU_A, CODE, READONLY
    8 00000000                 CODE32
    9 00000000         
   10 00000000         ; 定義于ucos_ii.h中的外部變量
   11 00000000         ;OS_EXT  OS_TCB           *OSTCBCur;                    
                           /* Pointer to currently running TCB         */
   12 00000000         ;OS_EXT  OS_TCB           *OSTCBHighRdy;                
                           /* Pointer to highest priority TCB R-to-R   */
   13 00000000         ;OS_EXT  INT8U             OSPrioCur;                   
                           /* Priority of current task                 */
   14 00000000         ;OS_EXT  INT8U             OSPrioHighRdy;               
                           /* Priority of highest priority task        */
   15 00000000         ;OS_EXT  BOOLEAN           OSRunning;                   
                           /* Flag indicating that kernel is running   */
   16 00000000         
   17 00000000                 IMPORT           OSTCBCur
   18 00000000                 IMPORT           OSTCBHighRdy
   19 00000000         
   20 00000000                 IMPORT           OSPrioCur
   21 00000000                 IMPORT           OSPrioHighRdy
   22 00000000         
   23 00000000                 IMPORT           OSRunning
   24 00000000         
   25 00000000         ;*******************************************************
                       ************************************
   26 00000000                 EXPORT           OSStartHighRdy
   27 00000000         ;功能:       
   28 00000000         ;1)SP=OSTCBHighRdy->OSTCBStkPtr
   29 00000000         ;2)OSTCBCur->OSTCBHighRdy
   30 00000000         ;3)將當(dāng)前優(yōu)先級(jí)最高的任務(wù)切換到運(yùn)行態(tài),本任務(wù)只在系統(tǒng)開始
                       運(yùn)行前運(yùn)行一次!該函數(shù)不會(huì)返回到
   31 00000000         ;  調(diào)用者OSStart().
   32 00000000         
   33 00000000         OSStartHighRdy
   34 00000000 E59F40C8        LDR              r4,=OSRunning ;起始狀態(tài)時(shí)OSRunn
                                                            ing顯然為0
   35 00000004 E3A05001        MOV              r5,#1
   36 00000008 E5C45000        STRB             r5,[r4]     ;直接置1,標(biāo)志系統(tǒng)進(jìn)
                                                            入運(yùn)行狀態(tài)
   37 0000000C         
   38 0000000C                 IMPORT           OSTaskSwHook
   39 0000000C EBFFFFFE        BL               OSTaskSwHook
   40 00000010         
   41 00000010 E59F40BC        LDR              r4, =OSTCBCur ; 當(dāng)前任務(wù)TCB地址
                                                            
   42 00000014 E59F50BC        LDR              r5, =OSTCBHighRdy ; 最高優(yōu)先級(jí)