.title terminalio Perform Terminal IO
.ident	/V1.0/

;
; Author:	Rodrick A. Eldridge
;		104 Computer Science
;		Iowa State University
;		Ames, Iowa 50011
;		(515) 294-5659
;
; Created:	April 1986
;
; Description:	This module contains a set of routines for performing
;		single character and line-oriented terminal I/O.
;
; Format:	external module terminal_io
;
;		external module read_ln
;		external module read -
;		  <char>
;		external module read_string -
;		  <descr>
;		external module read_again
;
;		external module write_ln
;		external module write -
;		  <char>
;		external module write_string -
;		  <descr>
;


global module terminal_io -
  psect=terminal_io

const
  $dscdef		; descriptor definitions
  $rabdef		; record access block definitons

  max_length		= 512

var
  input_fab:		$fab	fac=get,fnm=<SYS$INPUT>
  input_rab:		$rab	fab=input_fab,-
				ubf=input_buffer,-
				usz=max_length

  output_fab:		$fab	fac=put,fnm=<SYS$OUTPUT>
  output_rab:		$rab	fab=output_fab,-
				rbf=output_buffer,-
				rsz=max_length

  input_descr:		descr	.blkb max_length input_buffer  *
  output_descr:		descr	.blkb max_length output_buffer *

  input_position:	.word	0
  output_position:	.word	0

  open_flag:		.word	0
  cr_lf:		.byte	13,10

begin

; Initialize the terminal i/o routines

  $open		fab=input_fab
  $connect	rab=input_rab

  $open		fab=output_fab
  $connect	rab=output_rab

  movw   #max_length+1,input_position
  clrw   output_position

  movw   #1,open_flag

  return

end


global module read_ln -
  psect=terminal_io

begin

; read a string from the input device and position input pointer

  if <tstw open_flag> eql then
    terminal_io
  end

  $get   rab=input_rab				; read string

  moval  input_rab,r1
  movw   rab$w_rsz(r1),input_descr		; actual length read

  clrw   input_position

  return

end


global module read <char> -
  psect=terminal_io

begin

; read single character from the input device

  if <tstw open_flag> eql then
    terminal_io
  end

  if <cmpw input_position,input_descr> gtr then
    read_ln
  end

  movzwl input_position,r1
  movb   input_buffer[r1],@read.char(ap)
  incw   input_position

  return

end


global module read_string <descr> -
  psect=terminal_io -
  mask=<r6,r7>

begin

; read a string from the input device

  if <tstw open_flag> eql then
    terminal_io
  end

  $get   rab=input_rab				; read string

  moval  input_rab,r1
  movw   rab$w_rsz(r1),input_descr		; actual length read

  pushr  #^M<r0>
  movq   @read_string.descr(ap),r6		; r6=string length,r7=address
  movc5  #max_length,input_buffer,#^a/ /,r6,(r7)
  popr   #^M<r0>

  return

end


global module read_again -
  psect=terminal_io

begin

; Reset position input pointer

  if <tstw open_flag> eql then
    terminal_io
    read_ln
  end

  clrw   input_position

  return

end

    

global module write_ln -
  psect=terminal_io

begin

; write a carriage control and line feed to the output device and
; optionally, write a string to the output device

  if <tstw open_flag> eql then
    terminal_io
  end

  $rab_store	rab=output_rab,-
		rbf=cr_lf,-
		rsz=#2

  $put   rab=output_rab

  if <movzwl output_position,r6> neq then

    $rab_store	rab=output_rab,-
		rbf=output_buffer,-
		rsz=r6

    $put rab=output_rab				; write string

    clrw output_position

  end

  return

end


global module write <char> -
  psect=terminal_io

begin

; write a character to the output device

  if <tstw open_flag> eql then
    terminal_io
  end

  movzwl output_position,r1
  movb   @write.char(ap),output_buffer[r1]
  incw   output_position

  return

end


global module write_string <descr> -
  psect=terminal_io -
  mask=<r6,r7>

begin

; write a string to the output device

  if <tstw open_flag> eql then
    terminal_io
  end

  movq   @write_string.descr(ap),r6		; r6=string length, r7=buffer
  movc5  r6,(r7),#^a/ /,#max_length,output_buffer
  movw   r6,output_position

  write_ln

  return

end

.end