%%s 153/43/64
%%d D 1.2 19-Jul-82 12:12:50 j 2 1
%%c Generally overhauled os to cause the overprints to be performed in as few
%%c additional lines as possible.  All tabs are expanded into stops every 8
%%c columns, and carriage returns are interpreted as well as backspaces.
%%s 0/0/0
%%d D 1.1 25-Mar-82 12:10:24 v1.1 1 0
%%c Version 1.1 is the Spring 1982 Distribution of the LBL/Hughes release
%%c of the Software Tools Virtual Operating System software and documentation.
%%T
%%I 1
%%D 2
#-h- os.r            1768  asc  25-mar-82 08:15:24  v1.1 (sw-tools v1.1)
#-h- defns            213  asc  25-mar-82 08:15:14  v1.1 (sw-tools v1.1)
%%E 2
%%I 2
#-h- os.r            4223  asc  19-jul-82 12:11:09  j (sventek j)
#-h- defns            269  asc  19-jul-82 12:02:40  j (sventek j)
%%E 2
 ## definitions for overstrike tool
 # put on a file named 'defns'
 # Used only by overstrike
 
 define(NOSKIP,'+')		#suppress carriage-return/line feed
 define(SKIP,' ')
 define(NEWPAGE,'1')		# top of page on ^L
%%D 2
#-h- main             612  asc  25-mar-82 08:15:14  v1.1 (sw-tools v1.1)
%%E 2
%%I 2
 define(NLINES,6)		# line plus max of 5 overprint lines
#-h- main             620  asc  19-jul-82 12:02:40  j (sventek j)
%%E 2
 ## os - convert backspaces into multiple lines
 DRIVER(os)
 
 character buf(MAXLINE)
 integer getarg, open, assign
 integer i
 
 call query("usage:  os [file] ...")
 call filnfo(STDOUT, buf, i)
 if (assign(buf, STDOUT, PRINT) == ERR)
    call error("Cannot reset standard output to PRINT carriage control.")
 for (i=1; ; i=i+1)
	{
	if (getarg(i,buf,MAXLINE) == EOF)
		{
		if (i != 1)
			break
		int = STDIN
		}
	else if (buf(1) == '-' & buf(2) == EOS)
		int = STDIN
	else
		{
		int = open(buf,READ)
		if (int == ERR)
			call cant(buf)
		}
%%D 2
	call overs (int)
%%E 2
%%I 2
	call overs (int, STDOUT)
%%E 2
	if (int != STDIN)
		call close(int)
	}
 DRETURN
 end
%%D 2
#-h- overs            724  asc  25-mar-82 08:15:15  v1.1 (sw-tools v1.1)
 ## overs - convert backspaces into multiple lines from file -int-
 subroutine overs(int)
 character getch
 character c
 integer col, newcol, int
 
 col = 1
 repeat
	{
	newcol = col
	while (getch(c,int) == BACKSPACE)	#eat up backspaces
		newcol = max(newcol-1, 1)
	if (newcol < col)			#start overstrike line
		{
		call putc('@n')
		call putc(NOSKIP)
		for (col=1; col<newcol; col=col+1)
			call putc(' ')
		}
	else if (col == 1 & c == FF)		# top of page
		{
		call putc(NEWPAGE)
		col = col + 1
		next
		}
	else if (col == 1 & c != EOF)		#start normal line
		call putc(SKIP)
						#else middle of line
	if (c == EOF)
		break
	call putc(c)				#normal character
	if (c == '@n')
		col = 1
	else
		col = col + 1
	}
 return
 end
%%E 2
%%I 2
#-h- overs            906  asc  19-jul-82 12:02:41  j (sventek j)
## overs - convert backspaces and <CR>'s into multiple lines from file ifd
## to file ofd
subroutine overs(ifd, ofd)

filedes ifd, ofd
character buf(MAXLINE), outbuf(MAXLINE, NLINES)
integer col, i
integer getlin

while (getlin(buf, ifd) != EOF)
  {
  call initbl(outbuf)			# initialize matrix
  if (buf(1) == FF)			# formfeed
    {
    outbuf(1,1) = '1'			# top of page
    call scopy(buf, 2, buf, 1)		# eliminate FF
    }
  else
    outbuf(1,1) = ' '			# just skip to next line
  call exptab(buf)			# expand tabs into blanks
  col = 0
  for (i = 1; buf(i) != '@n'; i = i + 1)# for each character
    if (buf(i) == '@r')			# carriage return
      col = 0
    else if (buf(i) == '@b')		# backspace
      {
      col = col - 1
      col = max(col, 0)			# in case of error
      }
    else
      {
      col = col + 1
      call packit(buf(i), outbuf, col)
      }
  call dumpbl(outbuf, ofd)
  }

return
end
#-h- leng             223  asc  19-jul-82 12:02:42  j (sventek j)
# function to return length of row i in matrix outbuf
integer function leng(outbuf, i)

character outbuf(MAXLINE, NLINES)
integer i, j

for (j = MAXLINE; j > 1; j = j - 1)
  if (outbuf(j,i) != ' ')
    break

return(j)
end
#-h- prnt             240  asc  19-jul-82 12:02:43  j (sventek j)
# subroutine to print row i of matrix on unit fd
subroutine prnt(outbuf, i, n, fd)

character outbuf(MAXLINE, NLINES)
integer i, n, j
filedes fd

for (j = 1; j <= n; j = j + 1)
  call putch(outbuf(j,i), fd)
call putch('@n', fd)

return
end
#-h- dumpbl           330  asc  19-jul-82 12:02:43  j (sventek j)
# subroutine to dump non-empty lines in matrix
subroutine dumpbl(outbuf, fd)

character outbuf(MAXLINE, NLINES)
integer n, i
integer leng
filedes fd

n = leng(outbuf, 1)
call prnt(outbuf, 1, n, fd)
for (i = 2; i <= NLINES; i = i + 1)
  {
  n = leng(outbuf, i)
  if (n <= 1)
    break
  call prnt(outbuf, i, n, fd)
  }

return
end
#-h- packit           374  asc  19-jul-82 12:02:44  j (sventek j)
# subroutine to pack character into column col in next available row in matrix
subroutine packit(c, outbuf, col)

character c, outbuf(MAXLINE, NLINES)
integer col, i, j

j = col + 1				# all columns are offset by one
for (i = 1; i <= NLINES; i = i + 1)	# find a row which is empty
  if (outbuf(j,i) == ' ')		# found one
    {
    outbuf(j,i) = c
    break
    }

return
end
#-h- initbl           265  asc  19-jul-82 12:02:45  j (sventek j)
# initialize matrix of lines
subroutine initbl(outbuf)

character outbuf(MAXLINE, NLINES)
integer i, j

for (i = 1; i <= NLINES; i = i + 1)
  {
  outbuf(1,i) = '+'			# overprint character
  for (j = 2; j <= MAXLINE; j = j + 1)
    outbuf(j,i) = ' '
  }

return
end
#-h- exptab           402  asc  19-jul-82 12:04:38  j (sventek j)
# subroutine to expand tabs to stops every eight columns
subroutine exptab(buf)

character buf(MAXLINE), temp(MAXLINE)
integer i, j

for ([i=1; j=1]; buf(i) != EOS; i = i + 1)
  if (buf(i) == '@t')
    {
    repeat
      {
      temp(j) = ' '
      j = j + 1
      }
    until (mod(j,8) == 1)
    }
  else
    {
    temp(j) = buf(i)
    j = j + 1
    }
temp(j) = EOS
call strcpy(temp, buf)

return
end
%%E 2
#-h- os.fmt           660  asc  25-mar-82 08:15:25  v1.1 (sw-tools v1.1)
.so ~bin/manhdr
.hd Os (1) 16-Jan-79
convert backspaces into multiple lines for "printers"
.sy
os [file] ...
.ds
os (overstrike) looks for backspaces in the files specified and 
generates a sequence of print lines with carriage control codes
to reproduce the effect of the backspaces.
 
If no files are given, or the filename '-' appears, input is
taken from the standard input.
.fl
.sa
lpr - queue file to line printer
.br
ul - process overstrikes for "terminals"
.di
A message is printed if an input file cannot be opened; further
processing is terminated.
.au
Original from Kernighan & Plauger's 'Software Tools', with modifications
by Debbie Scherrer.
.bu
%%E 1