Category : C Source Code
Archive   : MIKECOMM.ZIP
Filename : RTS.ASM

 
Output of file : RTS.ASM contained in archive : MIKECOMM.ZIP

title RTS SET/RESET
include subfx.h

; Mike Dumdei, 6 Holly Lane, Texarkana TX 75503

;******************************************************************************
; ASYNC_RTS -- Sets or clears 'request to send' based on passed flag. Returns
; R_NOPORT if port invalid else returns R_OK.
;******************************************************************************
begseg COMM_TEXT
publicproc _async_rts
push bp
mov bp,sp
push si ;stack frame setup
call __ck_port_arg ;ck if valid, load pointers
jz rts_exit ;bad arg if ZR flag set
mov dx,COM_BASE
add dx,4 ;xFC)modem control register
in al,dx
cmp Flag,OFF
jne rts_on
and al,n B_RTS ;clear RTS bit
jmp s snd_MCRbyte ;exits through DTR proc
rts_on:
or al,B_RTS ;set RTS bit
snd_MCRbyte:
out dx,al ;send new mask to UART
xor ax,ax ;returning R_OK
rts_exit:
pop si
pop bp
ret ;restore regs and exit
_async_rts endp

endseg COMM_TEXT
end



  3 Responses to “Category : C Source Code
Archive   : MIKECOMM.ZIP
Filename : RTS.ASM

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