rxhex.a51

msc1201 编程4

$NOMOD51
$include (reg1210.inc)
PUBLIC	rx_hex_echo, _ascii2bin, rx_hex_word_echo, rx_hex_double_echo
EXTRN code (rx_byte, rx_byte_echo)

RxHex  SEGMENT  CODE
	RSEG  RxHex
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
;Convert R7 from ascii to bin 
;Used acc and Cy
_ascii2bin:
	mov	a,r7
	clr	c
	subb	a,#'A'	; -65
	jbc	cy,a2b_under10
	add	a,#0ah	; A~F
	sjmp	a2b_end
a2b_under10:
	add	a,#17	;0~9
a2b_end:
	mov	r7,a
	ret
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; unsigned int rx_hex_word_echo(void)
; Receive 4 ascii (/w echo), return bin val in R7:R6
; Warning: R7:R6 convention for stack, 
;          but wrong for Keil C int
; Used acc, and 2 stack
rx_hex_word_echo:
	call	rx_hex_double_echo
	push	reg6
	mov	reg6,reg7
	pop	reg7
	ret	
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; unsigned int rx_hex_word_echo(void)
; Receive 4 ascii (/w echo), return bin val in R6:R7
rx_hex_double_echo:
	call	rx_hex_echo
	mov	REG6,REG7
;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
; Receive 2 ascii (/w echo), return bin val in R7
; Used acc, and a stack
rx_hex_echo:
	; get hi nibble
	call	rx_byte_echo		;rx a byte in R7
	acall	_ascii2bin	;convert R7 to bin
	push	reg7		;hi nib in stk
	; get lo nibble
	call	rx_byte_echo		;rx a byte in R7
	acall	_ascii2bin	;convert R7 to bin
	pop	acc		;get hi nib from stk
	swap	a		;position hi nib
	orl	reg7,a		;combine hinib with low nib
	ret

	end