tools/as7: added syscalls chmod and chown, added auto-increment

locations, fixed a bug in character input, added several EAE
instructions. We now have cp.s, chmod.s and chown.s working.

src/cmd/cp.s

@@ -1,81 +1,89 @@
-" cp
+" cp: cp file1 file2 [file3 file4 [file5 file6] ...]
+"
+" Copies in pairs: file1 to file2, file3 to file4 etc.
+
+   lac 017777			" Skip past argc and save
+   tad d1			" argv[0] (our name) into name2
+   dac name2			" We will skip past it later
 
-   lac 017777
-   tad d1
-   dac name2
 loop:
-   lac 017777 i
+   lac 017777 i			" Any arguments left?
    sad d4
-   sys exit
-   sad d8
-   jmp unbal
-   tad dm8
-   dac 017777 i
-   lac name2
+     sys exit			" 4 words = no args left, exit
+   sad d8			" Do we have 2 args?
+     jmp unbal			" No, an unbalanced set of arguments
+   tad dm8			" Subtract 8 (two args) from the argc
+   dac 017777 i			" and save it
+   lac name2			
    tad d4
-   dac name1
+   dac name1			" Skipping pairs of filenames? not sure
    tad d4
    dac name2
-   sys open; name1: 0; 0
+   sys open; name1: 0; 0	" Open the input file
    spa
-   jmp error
-   lac o17
-   sys creat; name2: 0
+     jmp error			" File open error
+   lac o17			" Why load 15 (017) into AC?
+   sys creat; name2: 0		" Create the output file
    spa
-   jmp error
-   dzm nin
+     jmp error			" File create error
+   dzm nin			" Set the number of input words to zero
 
 1:
-   lac bufp
-   tad nin
-   dac 0f
+   lac bufp			" Set up the base of the upcoming read
+   tad nin			" to be the buffer + nin so we skip
+   dac 0f			" the existing words in the buffer
    -1
-   tad nin
-   cma
-   tad d1024
+   tad nin			" Calculate 1024 - nin, i.e. the number
+   cma				" of empty words yet to be filled in the
+   tad d1024			" buffer, and use it as the read count
    dac 0f+1
-   lac d2
+   lac d2			" Read from fd 2: hard-wired in fd!
    sys read; 0:..;..
    sna
-   jmp 2f
-   tad nin
-   dac nin
+     jmp 2f			" No words were read in, go to 2f
+   tad nin			" Add the number of words read in
+   dac nin			" to the existing number of words
    sad d1024
-   jmp 2f
-   jmp 1b
+     jmp 2f			" We do have 1,024 words, go to 2f
+   jmp 1b			" Loop back if we don't have 1,024 words
+
 2:
-   lac nin
-   dac 2f
-   lac d3
-   sys write; buf; 2: 0
-   dzm nin
-   lac 2b
-   sad d1024
-   jmp 1b
-   lac d2
-   sys close
+   lac nin			" Load the number of words in the input buffer
+   dac 2f			" Save in the write word count argument
+   lac d3			" Write to fd 3: hard-wired out fd!
+   sys write; buf; 2:0
+   dzm nin			" Set nin back to zero
+   lac 2b			" Get the write count (updated by sys write)
+   sad d1024			" Did we write the buffer out?
+     jmp 1b			" Yes, we wrote 1,024 words, so loop back
+				" to read another buffer's worth
+   lac d2		
+   sys close			" Close fd 2 and fd 3
    lac d3
    sys close
-   jmp loop
-error:
-   lac name1
+   jmp loop			" Loop back to deal with the next arguments
+
+error:				" File error, print out the name1 on
+   lac name1			" standard output, fd 1 followed by " ?\n"
    dac 1f
-   lac d1
-   sys write; 1: 0; 4
+   lac d1			
+   sys write; 1:0; 4
    lac d1
    sys write; mes; 1
-   lac name2
+   lac name2			" Then do the same with name 2
    dac 1f
    lac d1
    sys write; 1: 0; 4
    lac d1
    sys write; mes; 2
-   jmp loop
+   jmp loop			" Loop back to deal with the next arguments
+
 mes:
-   040000;077012
-unbal:
-   lac name2
-   tad d4
+   040000;077012		" String literal: " ?\n"
+
+unbal:				" We had an unbalanced set of arguments
+   lac name2			" so print out the name after name2
+   tad d4			" on standard output followed by " ?\n"
    dac 1f
    lac d1
    sys write; 1: 0; 4
@@ -83,15 +91,14 @@ unbal:
    sys write; mes; 2
    sys exit
 
-d1: 1
+d1: 1				" Numeric constants
+d2: 2
+d3: 3
 d4: 4
 d8: 8
 o17: 017
 dm8: -8
-d3: 3
 d1024: 1024
-nin: 0
-bufp: buf
-d2: 2
-
-buf:
+nin: 0				" Number of words in the input buffer
+bufp: buf			" Pointer to the buffer
+buf: .=.+1024			" Buffer of 1,024 words