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_start: INTM=#1      ; mask interrupts
  sp=#1000h                  ;初始化堆栈指针
  pmst=#1a0h             ;初始化堆栈指pmst，中断向量重定位道200h
  BSCR=#0800h     ; Set Wait States for Bank Switching
         ; STM #SWWSR_VAL, SWWSR ; Init S/W Wait State Register
         ;(commented out: power–up default value used)
 
  SWWSR=#2000h      ;7个等待状态
  TCR=#10h      ; Stop on–chip timer
  OVM=#1      ; overflow mode enabled
  SXM=#1       ; sign extension mode enabled
  IFR=#0ffffh      ; clear pending interrupts (if any)
  IMR=#0200h      ; select host to DSP interrupt
  INTM=#0      ; enable maskable interrupts
  
loop: xf=1                    ;turn off led
  nop
  nop
  nop
  nop
  dcall delay_1s
  nop
  nop
  nop
  nop
  xf=0                    ;turn on led
  nop
  nop
  nop
  nop
  dcall delay_1s
  nop
  nop
  nop
  nop
  dgoto loop
  nop
  nop

**************************************************************
****************delay 1s program*****************************
**************************************************************
delay_1s:
   push(ar6)
   push(ar7)
   ar6=#1000      
d_wait:  ar7=#1000
d_wait1: nop
   nop
   nop
   nop
   nop
   nop
   nop
   if (*ar7- != 0) dgoto d_wait1
   nop
   nop 
   if (*ar6- != 0) dgoto d_wait
   nop
   nop 
   ar7 = pop()
   ar6 = pop()
   dreturn
   nop
   nop  


**************************************************************************
* dsp interrupt service routine
**************************************************************************
DSP_ISR:
   ar5=#hostcommand; pointer to host command
   ar1=#flashaddr  ; pointer to flash addr
   ar2=#flashdata ; pointer to host data
   ar3=#dspstate ; pointer to dsp statue
   ar4=#dspresult ; pointer to flash data
**************************************************************************
* Bit test host command and process num1 and num2 accordingly
**************************************************************************
CHK_BIT0:
   TC = bit(*ar5,15-0) ; test bit0 of host command
   if (NTC) dgoto CHK_BIT1 ; if bit0=0 check bit1
   nop
   nop
   a=*ar1;
   ar5=a
   nop
   nop
   dcall _WRITEFlash ; program flash a word
   nop
   nop
   *ar3=#0001h
   dgoto EXIT
   nop
   nop
CHK_BIT1:
   TC = bit(*ar5,15-1) ; test bit0 of host command
   if (NTC) dgoto CHK_BIT2 ; if bit1=0 check bit2
   nop
   nop
   a=*ar1;
   nop
   nop
   ar2=a
   nop
   nop
   a=*ar2
   *ar4=a
   nop
   nop
   *ar3=#0001h
   dgoto EXIT
   nop
   nop
CHK_BIT2:
   TC = bit(*ar5,15-2) ; test bit0 of host command
   if (NTC) dgoto EXIT ; if bit2=0 then bad host command
   nop
   nop
   dcall _ERASEFlash ; erase the flash chip
   nop
   nop
   *ar3=#0001h
   dgoto EXIT
   nop
   nop


**************************************************************************
* DSP_ISR exit point
**************************************************************************
EXIT:  IFR=#0FFFFh ; clear interrupt flags
   dreturn_enable
   nop
   nop


  
*************************************************************
****program flash a word
************************************************************* 
_WRITEFlash: 
 push(ar0)
 ar0=#(05555H+OFFSET)
 nop
 nop
 *ar0= #0AAAAH     ; 周期1（解锁）
 nop
 nop
 ar0=#0AAAAH
 nop
 nop
 *ar0=#05555H     ; 周期2（解锁）
 nop
 nop
 ar0=#0d555H
 nop
 nop
 *ar0=#0A0A0H      ; 周期3（建立）
 nop
 nop
 a=*ar2
 nop
 nop
 *ar5=a      ; 周期4（编程）
 nop
 nop
 dcall Check_Toggle_Ready   ;检测编程是否正确，见Flash的操作检测
 nop
 nop
 ar0=pop()
 dreturn
 nop
 nop 


*******************************************************************
**********flash erash,whole chip
*******************************************************************
_ERASEFlash:   ;擦除宏 
 push(ar0)
 push(al)
 push(ah)
 push(ag)
 ar0=#0d555H
 *ar0=#0AAAAH; 周期1（解锁）
 nop
 nop
 nop
 nop
 ar0=#0AAAAH
 *ar0=#05555H; 周期2（解锁），应该对地址2aaa操作，但2aaa在5402中不可见，所以加一个偏移量8000h
 nop
 nop
 nop
 nop
 ar0=#0d555H
 *ar0=#08080H; 周期3（建立）
 nop
 nop
 nop
 nop
 ar0=#0d555H
 *ar0=#0AAAAH; 周期4（解锁）
 nop
 nop
 nop
 nop
 ar0=#0AAAAH
 *ar0=#05555H; 周期5（解锁）
 nop
 nop
 nop
 nop
 ar0=#0d555H
 *ar0=#01010H; 周期6（片擦除）
 nop
 nop
 nop
 nop
 ar0=#2000;;delay 1ms
 nop
 nop
erase_wait1:
 nop
 nop
 if (*ar0- != 0) dgoto erase_wait1
 nop
 nop
 a=#0;
 ar0=#8000h;
erase_wait2:;check data polling
 a=*ar0;
 nop
 nop
 a=a & #0080h
 nop
 nop
 if (aeq) dgoto erase_wait2
 nop
 nop
 ag=pop()
 ah=pop()
 al=pop()
 ar0=pop()
 dreturn
 nop
 nop
 
 
;======================================================================

Check_Toggle_Ready:
        
  
        a=*ar5        ; read a word form the chip
        nop
        nop
        a=a & #0040h   ; mask out the TOGGLE bit (DQ6)
        nop
        nop
CTR_Tog2:        
        b=*ar5         ; read the same word from the chip again
        nop
        nop
        b=b & #0040h         ; mask out the TOGGLE bit (DQ6)
        nop
        nop
        a=a-b             ; is DQ6 still toggling?
        nop
        nop
        if (aeq) dgoto CTR_Tog3 ; No, then the write operation is done
        nop
        nop
        a=b
        nop
        nop
        dgoto CTR_Tog2          ; YES, then continue checking...
        nop
        nop
CTR_Tog3:

        dreturn
        nop
        nop

 


;=======================================================================