%%s 3/3/1024
%%d D 1.2 04-May-82 12:24:45 j 2 1
%%c Modified diff.w`diff.r`gscrip to fix a bug when generating `ed' script.
%%c `putint' was call with an insufficient number of arguments when generating
%%c delete commands.
%%s 0/0/0
%%d D 1.1 25-Mar-82 12:04:07 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
#-h- cdiff           1226  asc  25-mar-82 07:39:26  v1.1 (sw-tools v1.1)
   sym_pointer _
      Old_count (MAX_FILE_SIZE),
      New_count (MAX_FILE_SIZE),
      Old_xref (MAX_FILE_SIZE),
      New_xref (MAX_FILE_SIZE),
      Old_lno (MAX_UNIQUE_LINES),
      Bucket (HASH_TABLE_SIZE),
      Sym_store (MAX_UNIQUE_LINES2)
   linepointer _
      Text_loc (MAX_UNIQUE_LINES)

   common /c1/ Old_count      # separate common because of size limitations
   common /c2/ New_count      # on some machines...
   common /c3/ Old_xref
   common /c4/ New_xref
   common /c5/ Old_lno
   common /c6/ Bucket
   common /c7/ Sym_store
   common /c8/ Text_loc

   sym_pointer _
      Next_sym,
      Next_inx,
      New_size,
      Old_size
   filedes _
      Old_file,
      New_file,
      Text_file,
      Old_copy,
      New_copy
   linepointer _
      Old_copy_start,
      New_copy_start,
      Text_file_end
   integer _
      Option,
      Verbos
   character _
      Text_file_name (FILENAMESIZE),
      Old_copy_name (FILENAMESIZE),
      New_copy_name (FILENAMESIZE)

   common /difcom/ Next_sym, Next_inx, Old_file, New_file, Text_file,
      Old_copy_start, New_copy_start, Text_file_end,
      New_size, Old_size, Old_copy, New_copy, Option, Verbos,
      Text_file_name, Old_copy_name, New_copy_name
%%D 2
#-h- diff.r         23492  asc  25-mar-82 07:39:31  v1.1 (sw-tools v1.1)
%%E 2
%%I 2
#-h- diff.r         23488  asc  04-may-82 12:22:19  j (sventek j)
%%E 2
#-h- defns           2359  asc  25-mar-82 07:38:45  v1.1 (sw-tools v1.1)
# diff --- isolate differences between two files

ifdef(LARGE_ADDRESS_SPACE)
  define(MAX_UNIQUE_LINES,10000)
  define(HASH_TABLE_SIZE,6073)
  define(MAX_FILE_SIZE,10000)
elsedef
  define (MAX_UNIQUE_LINES,1000)   # no. of unique lines in all files
  define (HASH_TABLE_SIZE,1021)    # must be prime, as large as possible
  define (MAX_FILE_SIZE,1000)      # no. of lines in largest input file
enddef
define (MAX_UNIQUE_LINES2,arith(MAX_UNIQUE_LINES,*,2))
define (NULL_POINTER,0)

define (sym_pointer,integer)     # large enough to index MAX_UNIQUE_LINES2
define (hash_index,integer)      # large enough to index HASH_TABLE_SIZE
define (file_mark,linepointer)   # large enough to hold a file position

define (DIFFERENCES,1)           # -d => list differences
define (REVISION,2)              # -r => revision bar requests for 'fmt'
define (SCRIPT,3)                # -s => update script for 'ed'
define (COMPARISON,4)            # -c => simple line-by-line compare

define (ON,)
define (OFF,#)
define (DEBUG,OFF)               # turn debugging output on/off
define (TUNING,OFF)              # turn algorithm tuning output on/off


 # definitions for long variable names
define(Old_count,ocount)
define(New_count,ncount)
define(Old_xref,oxref)
define(New_xref,nxref)
define(Old_lno,oldlno)
define(Sym_store,sstore)
define(Text_loc,tloc)
define(Next_sym,nsym)
define(Next_inx,ninx)
define(New_size,nsize)
define(Old_size,osize)
define(Old_file,ofile)
define(New_file,nfile)
define(Text_file,tfile)
define(Old_copy,ocopy)
define(New_copy,ncopy)
define(Text_file_end,tfend)
define(Old_copy_start,ocstrt)
define(New_copy_start,ncstrt)
define(Text_file_name,tfname)
define(Old_copy_name,ocname)
define(New_copy_name,ncname)

define(cleanup,clean)
define(gen_listing,glist)
define(gen_revision,grevis)
define(gen_script,gscrip)
define(initialize,init)
define(simple_compare,scompr)

define(mkuniq,scratf)
define(lower,fold)
define(blank_d,bld)
define(blank_i_blank,blibl)
define(blank_i_five_blanks,bli5bl)
define(n_bar,nbar)
define(c_i_blank,cibl)
define(c_i_five_blanks,ci5bl)
define(o_bar,obar)
define(c_d,cd)
define(five_blanks_bar,bl5bar)
define(start_revision_bar,brbar)
define(stop_revision_bar,erbar)
define(start_deletion_star,bdstar)
define(stop_deletion_star,edstar)
define(different,difrnt)
define(eof_on_old_file,eofold)
define(eof_on_new_file,eofnew)
#-h- diff             246  asc  25-mar-82 07:38:46  v1.1 (sw-tools v1.1)
   DRIVER (diff)

   include cdiff

   call initialize
   if (Option == COMPARISON)
      call simple_compare
   else {
      call load
      call pair
      call grow
      call label
      call report
      }
   call cleanup

   DRETURN
   end
#-h- clean            511  asc  25-mar-82 07:38:47  v1.1 (sw-tools v1.1)
# cleanup --- close input files, remove temporaries, and shut down

   subroutine cleanup

   integer junk
   integer remove

   include cdiff

   call close (Old_file)

   if (New_file != STDIN)
      call close (New_file)

   ifnotdef( CPM )
     call close(Old_copy)
   enddef
   junk = remove (Old_copy_name)

   ifnotdef( CPM )
     call close(New_copy)
   enddef
   junk = remove (New_copy_name)

   ifnotdef( CPM )
     call close(Text_file)
   enddef
   junk = remove (Text_file_name)

   return
   end
#-h- enter           1400  asc  25-mar-82 07:38:48  v1.1 (sw-tools v1.1)
# enter --- enter a line in the symbol table, return its index

   sym_pointer function enter (line)
   character line (ARB)

   include cdiff

   hash_index h
   hash_index hash

   sym_pointer i, p

   character text (MAXLINE)

   integer junk
   integer equal, getlin, note

   h = hash (line)
   p = Bucket (h)

   while (p != NULL_POINTER) {
      i = Sym_store (p + 1)      # grab index field of entry structure
      call seek (Text_loc (i), Text_file)
      junk = getlin (text, Text_file)
      if (equal (line, text) == YES)
         return (i)              # we got it; return its useful index
      p = Sym_store (p)          # try next item in the chain
      DEBUG call remark ("probing in lookup:.")
      DEBUG call remark ("ptr =.")
      DEBUG call putint (p, 0, ERROUT)
      DEBUG call putch ('@n', ERROUT)
      DEBUG call remark ("line =.")
      DEBUG call putlin (line, ERROUT)
      }

   if (Next_inx >= MAX_UNIQUE_LINES)
      call error ("too many unique lines; symbol table overflow.")
   i = Next_inx
   Next_inx = Next_inx + 1
   h = hash (line)
   Sym_store (Next_sym) = Bucket (h)   # link in new entry
   Sym_store (Next_sym + 1) = i
   Bucket (h) = Next_sym
   Next_sym = Next_sym + 2
   call seek (Text_file_end, Text_file)
   call ptrcpy(Text_file_end, Text_loc (i))
   call putlin (line, Text_file)
   junk = note(Text_file_end, Text_file)

   return (i)
   end
#-h- glist           3505  asc  25-mar-82 07:38:50  v1.1 (sw-tools v1.1)
# gen_listing --- generate a full listing of changes to a file

   subroutine gen_listing

   include cdiff

   sym_pointer oi, ni

   integer junk
   integer getlin

   character line (MAXLINE)

   string n_bar "n|"
   string c_i_blank "ci "
   string c_i_five_blanks "ci     "
   string o_bar "o|"
   string c_d "cd"
   string five_blanks_bar "     |"
   string blank_d " d"
   string blank_i_blank " i "
   string blank_i_five_blanks " i     "

   oi = 2
   ni = 2

   repeat

      if (Old_count (oi) == 0 & New_count (ni) == 0) {
         if (Verbos == YES)
            call putch ('@n', STDOUT)
         while (Old_count (oi) == 0 & New_count (ni) == 0) {
            junk = getlin (line, Old_copy)
            if (Verbos == YES) {
               call putint (oi - 1, 7, STDOUT)
               call putint (ni - 1, 5, STDOUT)
               call putlin (line, STDOUT)
               }
            junk = getlin (line, New_copy)
            oi = oi + 1
            ni = ni + 1
            }
         }

      else if (Old_count (oi) != 1 & New_count (ni) == 1) {
         call putch ('@n', STDOUT)
         for (; New_count (ni) == 1; ni = ni + 1) {
            junk = getlin (line, New_copy)
            if (Verbos == YES) {
               call putlin (blank_i_five_blanks, STDOUT)
               call putint (ni - 1, 5, STDOUT)
               call putch ('|', STDOUT)
               }
            else {
               call putlin (blank_i_blank, STDOUT)
               call putint (ni - 1, 4, STDOUT)
               call putlin (n_bar, STDOUT)
               }
            call putlin (line, STDOUT)
            }
         }

      else if (Old_count (oi) == 1 & New_count (ni) != 1) {
         call putch ('@n', STDOUT)
         for (; Old_count (oi) == 1; oi = oi + 1) {
            junk = getlin (line, Old_copy)
            if (Verbos == YES) {
               call putlin (blank_d, STDOUT)
               call putint (oi - 1, 5, STDOUT)
               call putlin (five_blanks_bar, STDOUT)
               }
            else {
               call putlin (blank_d, STDOUT)
               call putint (oi - 1, 5, STDOUT)
               call putlin (o_bar, STDOUT)
               }
            call putlin (line, STDOUT)
            }
         }

      else if (Old_count (oi) == 1 & New_count (ni) == 1) {
         call putch ('@n', STDOUT)
         for (; Old_count (oi) == 1; oi = oi + 1) {
            junk = getlin (line, Old_copy)
            if (Verbos == YES) {
               call putlin (c_d, STDOUT)
               call putint (oi - 1, 5, STDOUT)
               call putlin (five_blanks_bar, STDOUT)
               }
            else {
               call putlin (c_d, STDOUT)
               call putint (oi - 1, 5, STDOUT)
               call putlin (o_bar, STDOUT)
               }
            call putlin (line, STDOUT)
            }
         call putch ('@n', STDOUT)
         for (; New_count (ni) == 1; ni = ni + 1) {
            junk = getlin (line, New_copy)
            if (Verbos == YES) {
               call putlin (c_i_five_blanks, STDOUT)
               call putint (ni - 1, 5, STDOUT)
               call putch ('|', STDOUT)
               }
            else {
               call putlin (c_i_blank, STDOUT)
               call putint (ni - 1, 4, STDOUT)
               call putlin (n_bar, STDOUT)
               }
            call putlin (line, STDOUT)
            }
         }

      else if (Old_count (oi) == 2 & New_count (ni) == 2)
         break

   return
   end
#-h- grevis          1824  asc  25-mar-82 07:38:55  v1.1 (sw-tools v1.1)
# gen_revision --- generate 'fmt' input text with revision bar requests

   subroutine gen_revision

   include cdiff

   sym_pointer oi, ni

   integer junk
   integer getlin

   character line (MAXLINE)

   string start_revision_bar  "[cc]mc |"
   string stop_revision_bar   "[cc]mc"
   string start_deletion_star "[cc]mc *"
   string stop_deletion_star  "[cc]mc"

   oi = 2
   ni = 2

   repeat

      if (Old_count (oi) == 0 & New_count (ni) == 0) {
         oi = oi + 1
         ni = ni + 1
         junk = getlin (line, New_copy)
         call putlin (line, STDOUT)
         }

      else if (Old_count (oi) != 1 & New_count (ni) == 1) {
         call putlin (start_revision_bar, STDOUT)
         call putch ('@n', STDOUT)
         for (; New_count (ni) == 1; ni = ni + 1) {
            junk = getlin (line, New_copy)
            call putlin (line, STDOUT)
            }
         call putlin (stop_revision_bar, STDOUT)
         call putch ('@n', STDOUT)
         }

      else if (Old_count (oi) == 1 & New_count (ni) != 1) {
         call putlin (start_deletion_star, STDOUT)
         call putch ('@n', STDOUT)
         call putlin (stop_deletion_star, STDOUT)
         call putch ('@n', STDOUT)
         for (; Old_count (oi) == 1; oi = oi + 1)
            ;
         }

      else if (Old_count (oi) == 1 & New_count (ni) == 1) {
         for (; Old_count (oi) == 1; oi = oi + 1)
            ;
         call putlin (start_revision_bar, STDOUT)
         call putch ('@n', STDOUT)
         for (; New_count (ni) == 1; ni = ni + 1) {
            junk = getlin (line, New_copy)
            call putlin (line, STDOUT)
            }
         call putlin (stop_revision_bar, STDOUT)
         call putch ('@n', STDOUT)
         }

      else if (Old_count (oi) == 2 & New_count (ni) == 2)
         break

   return
   end
%%D 2
#-h- gscrip          2263  asc  25-mar-82 07:38:57  v1.1 (sw-tools v1.1)
%%E 2
%%I 2
#-h- gscrip          2266  asc  04-may-82 12:11:45  j (sventek j)
%%E 2
# gen_script --- produce editor script to convert old file into new

   subroutine gen_script

   include cdiff

   sym_pointer oi, ni, offset, length

   integer junk
   integer getlin

   character line (MAXLINE)

   oi = 2
   ni = 2
   offset = 0

   repeat

      if (Old_count (oi) == 0 & New_count (ni) == 0) {
         oi = oi + 1
         ni = ni + 1
         junk = getlin (line, New_copy)
         }

      else if (Old_count (oi) != 1 & New_count (ni) == 1) {
         call putint (oi - 2 + offset, 0, STDOUT)
         call putch ('a', STDOUT)
         call putch ('@n', STDOUT)
         length = 0
         for (; New_count (ni) == 1; ni = ni + 1) {
            length = length + 1
            junk = getlin (line, New_copy)
            call putlin (line, STDOUT)
            }
         call putch ('.', STDOUT)
         call putch ('@n', STDOUT)
         offset = offset + length
         }

      else if (Old_count (oi) == 1 & New_count (ni) != 1) {
         length = 0
         for (; Old_count (oi) == 1; oi = oi + 1)
            length = length + 1
         call putint (oi - 1 - length + offset, 0, STDOUT)
         call putch (',', STDOUT)
%%D 2
         call putint (oi - 2 + offset, STDOUT)
%%E 2
%%I 2
         call putint (oi - 2 + offset, 0, STDOUT)
%%E 2
         call putch ('d', STDOUT)
         call putch ('@n', STDOUT)
         offset = offset - length
         }

      else if (Old_count (oi) == 1 & New_count (ni) == 1) {
         length = 0
         for (; Old_count (oi) == 1; oi = oi + 1)
            length = length + 1
         call putint (oi - 1 - length + offset, 0, STDOUT)
         call putch (',', STDOUT)
         call putint (oi - 2 + offset, 0, STDOUT)
         call putch ('c', STDOUT)
         call putch ('@n', STDOUT)
         offset = offset - length
         length = 0
         for (; New_count (ni) == 1; ni = ni + 1) {
            length = length + 1
            junk = getlin (line, New_copy)
            call putlin (line, STDOUT)
            }
         call putch ('.', STDOUT)
         call putch ('@n', STDOUT)
         offset = offset + length
         }

      else if (Old_count (oi) == 2 & New_count (ni) == 2)
         break

   call putch ('w', STDOUT)
   call putch ('@n', STDOUT)
   # DON'T output a 'q' command -- prevents concatentation of scripts
   return
   end
#-h- grow             751  asc  25-mar-82 07:38:58  v1.1 (sw-tools v1.1)
# grow --- grow unchanged blocks around unique line pairs

   subroutine grow

   include cdiff

   sym_pointer i, nx

   for (i = 1; i < New_size; i = i + 1) {
      nx = New_xref (i)
      if (nx > 0)       # is this line paired with an old line?
         if (New_xref (i + 1) < 0
          & New_xref (i + 1) == Old_xref (nx + 1)) {
            Old_xref (nx + 1) = i + 1
            New_xref (i + 1) = nx + 1
            }
      }

   for (i = New_size; i > 1; i = i - 1) {
      nx = New_xref (i)
      if (nx > 0)       # is this line paired?
         if (New_xref (i - 1) < 0
          & New_xref (i - 1) == Old_xref (nx - 1)) {
            Old_xref (nx - 1) = i - 1
            New_xref (i - 1) = nx - 1
            }
      }

   return
   end
#-h- hash             267  asc  25-mar-82 07:38:58  v1.1 (sw-tools v1.1)
# hash --- hash a line into a hash_index

   hash_index function hash (line)
   character line (ARB)

   integer i

   hash = 0
   for (i = 1; line (i) != EOS; i = i + 1)
      hash = hash + line (i)
   hash = mod (iabs (hash), HASH_TABLE_SIZE) + 1

   return
   end
#-h- init            2403  asc  25-mar-82 07:38:59  v1.1 (sw-tools v1.1)
# initialize --- set up everything needed for a file comparison

   subroutine initialize

   include cdiff

   filedes open, create

   integer argno, i, junk
   integer equal, getarg, note

   character arg (FILENAMESIZE)

   string tf1 "df1"      # text of unique lines
   string tf2 "df2"      # copy of "old" file
   string tf3 "df3"      # copy of "new" file
 
   call query ("usage:  diff [-{c|d|r|s|v}] old_file [new_file].")

   Option = DIFFERENCES    # the default
   Verbos = NO

   argno = 1      # where we expect to find file names
   if (getarg (1, arg, FILENAMESIZE) != EOF)
   if (arg (1) == '-') {
      call lower (arg)
      for (i = 2; arg (i) != EOS; i = i + 1)
         if (arg (i) == 'c')
            Option = COMPARISON
         else if (arg (i) == 'd')
            Option = DIFFERENCES
         else if (arg (i) == 'r')
            Option = REVISION
         else if (arg (i) == 's')
            Option = SCRIPT
         else if (arg (i) == 'v')
            Verbos = YES
         else
            call usage
      argno = 2
      }

   if (getarg (argno, arg, FILENAMESIZE) == EOF) {   # no files, use STDIN
      # Old_file = STDIN1
      # New_file = STDIN2
      call usage     # GT implementation has multiple standard ports...
      }
   else {
      Old_file = open (arg, READ)
      if (Old_file == ERR)
         call cant (arg)
      argno = argno + 1
      if (getarg (argno, arg, FILENAMESIZE) == EOF)
         New_file = STDIN     # STDIN1, to be precise
      else {
         New_file = open (arg, READ)
         if (New_file == ERR)
            call cant (arg)
         argno = argno + 1
         call close(STDIN)	# save a unit
         }
      }

   if (getarg (argno, arg, FILENAMESIZE) != EOF)
      call usage

   Next_inx = 1
   Next_sym = 1
   call mkuniq (tf1, Text_file_name)
   Text_file = create (Text_file_name, READWRITE)
   if (Text_file == ERR)
      call error ("can't open temporary file.")
   junk = note(Text_file_end, Text_file)

   call mkuniq (tf2, Old_copy_name)
   Old_copy = create (Old_copy_name, READWRITE)
   if (Old_copy == ERR)
      call error ("can't open temporary file.")
   junk = note(Old_copy_start, Old_copy)

   call mkuniq (tf3, New_copy_name)
   New_copy = create (New_copy_name, READWRITE)
   if (New_copy == ERR)
      call error ("can't open temporary file.")
   junk = note(New_copy_start, New_copy)

   return
   end
#-h- label           1871  asc  25-mar-82 07:39:00  v1.1 (sw-tools v1.1)
# label --- label lines as "inserted," "deleted," or "unchanged"

   subroutine label

   include cdiff

   sym_pointer oi, ni, ox, nx

DEBUG call remark ("input new xref:.")
DEBUG do ni = 1, New_size; {
DEBUG    call putch (' ', ERROUT)
DEBUG    call putint (New_xref (ni), 0, ERROUT)
DEBUG    }
DEBUG call putch ('@n', ERROUT)
DEBUG call remark ("input old xref:.")
DEBUG do oi = 1, Old_size; {
DEBUG    call putch (' ', ERROUT)
DEBUG    call putint (Old_xref (oi), 0, ERROUT)
DEBUG    }
DEBUG call putch ('@n', ERROUT)

   oi = 2
   ni = 2

   repeat {

      ox = Old_xref (oi)
      nx = New_xref (ni)

      if (oi >= Old_size & ni >= New_size)
         break

      else if (oi < Old_size & ox < 0) { # deletion from old file
         Old_count (oi) = 1
         oi = oi + 1
         }

      else if (ni < New_size & nx < 0) { # insertion in new file
         New_count (ni) = 1
         ni = ni + 1
         }

      else if (ox == ni & nx == oi) {    # unchanged line
         Old_count (oi) = 0
         oi = oi + 1
         New_count (ni) = 0
         ni = ni + 1
         }

      else if (oi <= Old_size & ni <= New_size) {  # out-of-order block
         New_count (ni) = 1
         ni = ni + 1
         Old_count (nx) = 1
         Old_count (oi) = 1
         oi = oi + 1
         New_count (ox) = 1
         }

      else {
         call remark ("oi, ox, ni, nx:.")
         call putint (oi, 10, ERROUT)
         call putint (ox, 10, ERROUT)
         call putint (ni, 10, ERROUT)
         call putint (nx, 10, ERROUT)
         call putch ('@n', ERROUT)
         call error ("in label:  can't happen.")
         }

      }

   Old_count (1) = 2             # mark the null lines specially,
   Old_count (Old_size) = 2      #    so people won't have to deal
   New_count (1) = 2             #    with file sizes
   New_count (New_size) = 2

   return
   end
#-h- load            2085  asc  25-mar-82 07:39:02  v1.1 (sw-tools v1.1)
# load --- load symbol table, set up cross-reference structures

   subroutine load

   include cdiff

   sym_pointer lno, i
   sym_pointer enter

   hash_index h

   character line (MAXLINE)

   integer getlin, length

TUNING sym_pointer p
TUNING integer used, chain_len, max_chain_len, min_chain_len

   do h = 1, HASH_TABLE_SIZE
      Bucket (h) = NULL_POINTER

   do lno = 1, MAX_UNIQUE_LINES; {
      Old_count (lno) = 0
      New_count (lno) = 0
      }

  # Load the "old" file:
   for (lno = 2; getlin (line, Old_file) != EOF; lno = lno + 1) {
      if (lno > MAX_FILE_SIZE)
         call error ("old file too large to handle.")
      call putlin (line, Old_copy)
      i = enter (line)
      Old_count (i) = Old_count (i) + 1
      Old_lno (i) = lno
      Old_xref (lno) = -i
      }
   Old_size = lno    # includes null line at end

  # Load the "new" file:
   for (lno = 2; getlin (line, New_file) != EOF; lno = lno + 1) {
      if (lno > MAX_FILE_SIZE)
         call error ("new file too large to handle.")
      call putlin (line, New_copy)
      i = enter (line)
      New_count (i) = New_count (i) + 1
      New_xref (lno) = -i
      }
   New_size = lno    # also allows for null line at end

TUNING call print (STDOUT2, "Old_size = *i, New_size = *i*n"s,
TUNING    Old_size, New_size)
TUNING call print (STDOUT2, "*i unique lines*n"s, Next_inx - 1)
TUNING used = 0
TUNING max_chain_len = 0
TUNING min_chain_len = MAX_UNIQUE_LINES
TUNING do h = 1, HASH_TABLE_SIZE; {
TUNING    p = Bucket (h)
TUNING    if (p != NULL_POINTER)
TUNING       used += 1
TUNING    chain_len = 0
TUNING    while (p != NULL_POINTER) {
TUNING       chain_len += 1
TUNING       p = Sym_store (p)
TUNING       }
TUNING    max_chain_len = max0 (chain_len, max_chain_len)
TUNING    min_chain_len = min0 (chain_len, min_chain_len)
TUNING    }
TUNING call print (STDOUT2, "chain lengths:  min = *i, avg = *i, max = *i*n"s,
TUNING    min_chain_len, (Next_inx - 1) / used, max_chain_len)
TUNING call print (STDOUT2, "hash buckets *i% full*n"s,
TUNING    (100 * used) / HASH_TABLE_SIZE)

   return
   end
#-h- pair             536  asc  25-mar-82 07:39:03  v1.1 (sw-tools v1.1)
# pair --- pair up unique lines in both files

   subroutine pair

   include cdiff

   sym_pointer i, j, k

   for (i = 2; i < New_size; i = i + 1) {
      j = -New_xref (i)
      if (Old_count (j) == 1 & New_count (j) == 1) { # unique pair
         New_xref (i) = Old_lno (j)
         k = Old_lno (j)
         Old_xref (k) = i
         }
      }

   New_xref (1) = 1                 # match null lines at BOF
   Old_xref (1) = 1
   New_xref (New_size) = Old_size   # ... and at EOF
   Old_xref (Old_size) = New_size

   return
   end
#-h- report           714  asc  25-mar-82 07:39:04  v1.1 (sw-tools v1.1)
# report --- report differences between files in desired format

   subroutine report

   include cdiff

DEBUG sym_pointer i

DEBUG call print (ERROUT, "New mark: "s)
DEBUG do i = 1, New_size
DEBUG    call print (ERROUT, "  *i"s, New_count (i))
DEBUG call print (ERROUT, "*nOld mark: "s)
DEBUG do i = 1, Old_size
DEBUG    call print (ERROUT, "  *i"s, Old_count (i))
DEBUG call putch ('@n', ERROUT)

   call seek (Old_copy_start, Old_copy)
   call seek (New_copy_start, New_copy)

   if (Option == DIFFERENCES)
      call gen_listing
   else if (Option == REVISION)
      call gen_revision
   else if (Option == SCRIPT)
      call gen_script
   else
      call error ("in report:  can't happen.")

   return
   end
#-h- scompr          1450  asc  25-mar-82 07:39:04  v1.1 (sw-tools v1.1)
# simple_compare --- do a line-by-line comparison of the input files

   subroutine simple_compare

   include cdiff

   character line1 (MAXLINE), line2 (MAXLINE)

   integer lineno, m1, m2
   integer equal, getlin

   string different "different"
   string eof_on_old_file "eof on old file"
   string eof_on_new_file "eof on new file"

   lineno = 0
   repeat {
      m1 = getlin (line1, Old_file)
      m2 = getlin (line2, New_file)
      if (m1 == EOF | m2 == EOF)
         break
      lineno = lineno + 1
      if (equal (line1, line2) == NO)
         if (Verbos == YES) {
            call putch ('@n', STDOUT)
            call putint (lineno, 5, STDOUT)
            call putch ('@n', STDOUT)
            call putlin (line1, STDOUT)
            call putlin (line2, STDOUT)
            }
         else {
            call putlin (different, STDOUT)
            call putch ('@n', STDOUT)
            return
            }
      }

   if (m1 == EOF & m2 != EOF)
      if (Verbos == YES) {
         call putlin (eof_on_old_file, STDOUT)
         call putch ('@n', STDOUT)
         }
      else {
         call putlin (different, STDOUT)
         call putch ('@n', STDOUT)
         }
   if (m1 != EOF & m2 == EOF)
      if (Verbos == YES) {
         call putlin (eof_on_new_file, STDOUT)
         call putch ('@n', STDOUT)
         }
      else {
         call putlin (different, STDOUT)
         call putch ('@n', STDOUT)
         }

   return
   end
#-h- usage            139  asc  25-mar-82 07:39:05  v1.1 (sw-tools v1.1)
# usage --- print usage message, then die

   subroutine usage

   call error ("usage:  diff [-{c|d|r|s|v}] old_file [new_file].")

   end
#-h- diff.fmt        3460  asc  25-mar-82 07:39:39  v1.1 (sw-tools v1.1)
.so ~bin/manhdr
.hd Diff (1) 20-Mar-80
isolate differences between files
.sy
diff [-{c|d|r|s|v}] old_file [new_file]
.ds
'Diff' compares the contents of two files
and reports on the differences between them.
The default behavior is to describe the insert, delete, and change
operations that must be performed on `old_file' to convert its
contents into those of `new_file'.
.sp
The second file name argument is optional.
If omitted, the standard input is read for the text of the `new_file'.
.sp
The options currently available are:
.in +10
.rm -5
.sp
.ti -5
-c   Perform a simple line-by-line comparison.
'Diff' will compare successive lines of the input files;
if any corresponding lines differ,
or if one file is shorter than the other,
'diff' prints the message
"different" and exits.
If the files are the same, 'diff' produces no output.
When the "-v" option (see below) is specified,
'diff' prints the lines that differ along with their line
number in the input file, and notifies the user if
one file is shorter than the other.
.sp
.ti -5
-d   List the "differences" between the two files, by highlighting
the insertions, deletions, and changes that will convert `old_file'
into `new_file'.  This is the default option.
If the "verbose" option "-v" (see below) is specified, unchanged
text will also be listed.
.sp
.ti -5
-r   Insert text formatter requests to mark the `new_file'
with revision bars and deletion asterisks.
This option is particularly useful for maintenance of large documents,
like Software Tools reference manuals.
(At present, only GT's version of 'format' can produce revision bars.)
.sp
.ti -5
-s   Output a "script" of commands for the text editor 'ed' that will
convert `old_file' into `new_file'.
This is handy for preparing updates to large programs or data files,
since generally the volume of changes required will be much smaller
than the new text in its entirety.
.sp
.ti -5
-v   Make output "verbose."
This option applies to the "-c" and "-d" options discussed above.
If not selected, 'diff' produces "concise" output;
if selected, 'diff' produces more verbiage.
.sp
.in -10
'Diff' is based on the algorithm found in
Heckel, P., "A Technique for Isolating Differences Between Files",
.ul
Comm. ACM
21, 4 (April 1978), 264-268.
.ex
To print the differences between two files on your terminal:
.in -5
.sp
diff -cv file maybe_the_same_file
.br
.in +5
does a simple line-by-line comparison on the two files, 
printing lines which differ.
(Expects no missing or extra lines.)
Same as 'cmp file1 file2'.
.in -5
.sp
diff -s old_version new_version | ed - old_version
.br
.in +5
make an ed script which changes 'old_version' into 'new_version'
.in -5
.sp
diff -r old_manual.fmt new_manual.fmt | format
.br
.in +5
to mark changes in a document.
Useful only if your version of 'format' has this capability.
.in -5
.sp
diff -s old new >>update_old_to_new
.br
.in +5
to keep a list of changes made to an original source file
.in -5
.fi
.sp
.ne 2
.di
"<file>:  can't open" if either `new_file' or `old_file' is not readable.
.sp
"Usage: diff . . ." for illegal options.
.ne 4
.au
Allen Akin and friends, Georgia Institute of Technology
.ne 2
.bu
The algorithm used has one quirk: a line or a block of lines which
is not unique within a file will be labeled as an insertion (deletion)
if its immediately adjacent neighbors both above and below are labeled
as insertions (deletions).
.sp
Fails on very large files (> 10000 lines on VMS).
%%E 1