Xycom XVME-400 Manual page 43

XVME-400/40I /490/491 Manual
October, 1989
********************************************************************************
*
*
This routine will receive a byte of data in polled mode.
*
*
On entry:
*
A3 contains the address of the command
register of the SCC channel used for
receiving.
On exit:
D3.B contains the byte which was received.
*********************************************************************************
RPOLA
M0VE M.L DO/D 1 /A 1 ,-(SP)
RXPOLL M0VE.B (A3),DO
BTST
BEQ.S
RXCHA M0VE.B 2(A3),D3
RXIT MOVEM.L (SP)+,D0/D 1 /A 1
RTS
END
#O,DO
RXPOLL
3-15
* Save registers
* Read the contents of RR0
* Is a character available?
* No, then try again
* Get the character
* Restore registers