putchar.asm

ADUC842 C程序集,包括ADC,DAC,PLL,PWM,WDT等程序．

;File: putchar.a51
;Author: Eckart Hartmann Date:17/10/2003
;Development progress: Urt834.df
;
;_putchar=========Output a character to UART.
;C Function prototype: char _putchar(char cTx);
;Description of Function: Sends a character via UART.
;User interface: UART must be initialised with _UrtCfg() before calling 
;		_putchar. Put character to send in parameter1.
;		Call _putchar.
;		_putchar waits if UART busy then adds the required parity
;		and sends the new character via the UART.
 ; Robustness: CD bits bits must be correct when communicating - variable
;		cUrtVar (bits 4 to 6) contains the required CD value.
;		Can be controlled by XON/XOFF protocol.
;Side effects: Overwrites a, cy, p, r1 RI and TI.
;		Uses two stack levels. 
;
NAME	PUTCHAR
$NOMOD51
 $IC(..kei842.inc) ; Parameter passing registers for Keil .
 $IC(..kei842.dat) ; SFR definition for Keil .
;
extrn DATA (cUrtVar)
public	_putchar

?PR?_putchar?PUTCHAR SEGMENT CODE

	RSEG  ?PR?_putchar?PUTCHAR
	USING	0

_putchar:
	mov  	a,cP1l		;if(ch=='\n')
	xrl  	a,#0AH
	jnz  	pncr		; {
	mov	ip1h,#0dh	; r6 = '\r';
	lcall	xoap		; xoap(); }
pncr:	mov	a,cP1l		;r6 = ch;
	mov	ip1h,a
	lcall	xoap		;xoap();
	ret	
;
xoap:	jnb  	RI,putcTi	; if(RI) {
	mov  	a,SBUF		;  if(SBUF==XOFF)
	cjne 	a,#013h,putcTi	;   {
putcX:				;   do {
	clr  	RI		;    RI = 0;
putcRi:	jnb  	RI,putcRi	;    while(!RI);
				;    }
	mov  	a,SBUF		;   while(SBUF!=XON)
	cjne 	a,#011h,putcX
	clr  	RI		;   RI = 0;
				;  }}
putcTi:	jnb  	TI,putcTi	; while(!TI);  
	clr  	TI		; TI = 0;
	setb	TB8		; // As default.
	mov	a,iP1h		; c = parity(iP1h);
	mov	c,p
	mov	r1,#cUrtVar	;if(noparity);
	mov	a,@r1
	jnb	ACC.3,putcR	;else
	anl	a,#0ch		; {
	mov	TB8,c		; TB8 = c;
	cjne	a,#8,putcR	; if(parity=='o')
	cpl	TB8		;  TB8 = !TB8; }
putcR:	mov  	SBUF,iP1h	;SBUF = iP1h;
	ret
;
;Function End==========================================================Function End
	end