dp_read_video.a51

这是TCP/IP协议组播的实现代码

#include <REG400.H>
;汇编代码
; 在代码段中定义段
?PR?dp_read_video?LOWLVL SEGMENT CODE

; 输出函数名
PUBLIC dp_read_video
;这个函数可被连接器放置在任何地方
RSEG ?PR?dp_read_video?LOWLVL
;*****************************************************************
; Function: _dpread
; Description: 等待定时器0溢出向外部器件表明P1中的数据是有效的如果定时器尚
; 未溢出被写入XDATA的指定地址中
; Parameters: R7 – 存放要等待的时标数
; R4|R5 – 存放要写入的XDATA区地址
; Returns: 读数成功返回1,时间到返回0
; Side Effects: none.
;*****************************************************************
dp_read_video:

	mov dpx,#0x21  ; 取地址并放入DPTR ; load source address
	mov dph,#0x00
	mov dpl,#0x00 

	mov dpx1,#0x04  ; 取地址并放入DPTR ; load destination address
	mov dph1,#0x00
	mov dpl1,#0x00

	mov R0,#0x02e    ; the number of moved data (0x080 *0x010 = 2048 bytes)
       
	mov dps,#0x30        ; auto-toggle mode,auto-increment enable,increment DPTR0  

read_loop_v:  
           
	movx a, @dptr       ; read from dataport1
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport2
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport3
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport4
	movx @dptr,a        ; write to  RAM
     
	movx a, @dptr       ; read from dataport5
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport6 	 
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport7
 	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport8
	movx @dptr,a        ; write to  RAM

	movx a, @dptr       ; read from dataport9
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport10
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport11
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport12
	movx @dptr,a        ; write to  RAM
     
	movx a, @dptr       ; read from dataport13
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport14 	 
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport15
 	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport16
	movx @dptr,a        ; write to  RAM

	movx a, @dptr       ; read from dataport17
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport18
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport19
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport20
	movx @dptr,a        ; write to  RAM
     
	movx a, @dptr       ; read from dataport21
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport22 	 
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport23
 	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport24
	movx @dptr,a        ; write to  RAM

	movx a, @dptr       ; read from dataport25
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport26
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport27
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport28
	movx @dptr,a        ; write to  RAM
     
	movx a, @dptr       ; read from dataport29
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport30 	 
	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport31
 	movx @dptr,a        ; write to  RAM
	
	movx a, @dptr       ; read from dataport32
	movx @dptr,a        ; write to  RAM

	djnz R0,read_loop_v        
	mov dps,#0x00    ; resume the value of dps

	RET
	END