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/chmod.s

@@ -1,77 +1,83 @@
-" chmode
+" chmod: chmod mode file [file file ...]
+"
+" mode is an octal number
 
-   lac 017777 i
+   lac 017777 i		" Have we got any arguments?
    sad d4
-   jmp error
-
+     jmp error		" No, give an error
    lac 017777
-   tad d4
-   dac 8
-   tad d1
-   dac name
-   dzm octal
-   dzm nchar
-   -8
-   dac c1
+   tad d4		" Skip past argc
+   dac 8		" and save the ptr to the octal value at location 8
+   tad d1		" Why only 1 here?
+   dac name		" Save the filename pointer
+   dzm octal		" Zero the octal value and
+   dzm nchar		" the number of characters
+   -8			" Set c1 to -8 so we can increment up to zero
+   dac c1		" and thus count the number of chars in the argument
+
 1:
-   lac nchar
-   dzm nchar
-   sza
-   jmp 2f
-   lac 8 i
-   lmq
-   and o177
-   dac nchar
-   lacq
-   lrss 9
+   lac nchar		" Get any left-over character from the last loop
+   dzm nchar		" and set nchar to empty now
+   sza			" It was already empty, so get a new word
+     jmp 2f		" Not empty, it has the second ASCII value, goto 2f
+   lac 8 i		" Read the next word with two chars in it
+   lmq			" Copy it to MQ
+   and o177		" Trim off all but the second ASCII value
+   dac nchar		" Save it into nchar
+   lacq			" Bring it back from MQ
+   lrss 9		" and shift down the first ASCII value
+
 2:
-   sad o40
-   jmp 3f
-   tad om60
-   lmq
-   lac octal
-   cll; als 3
-   omq
-   dac octal
+   sad o40		" If the character is a space
+     jmp 3f		" don't try to make it part of the octal value
+   tad om60		" Not a space, subtract 060 i.e. '0'
+   lmq			" Move it into MQ
+   lac octal		" Load the octal value up to here
+   cll; als 3		" Shift it left 3 bits
+   omq			" OR in the digit from MQ
+   dac octal		" and save back in the octal value
+
 3:
-   isz c1
-   jmp 1b
+   isz c1		" Is that the last character?
+     jmp 1b		" No, go back and get another one
 
 loop:
-   lac 017777 i
+   lac 017777 i			" How many arguments left?
    sad d8
-   sys exit
-   tad dm4
-   dac 017777 i
-   lac name
+     sys exit			" None, exit
+   tad dm4			" Subtract 4 to indicate one less argument
+   dac 017777 i			" and save for next time
+   lac name			" Also move to the next filename
    tad d4
    dac name
-   lac octal
-   sys chmode; name:0
+   lac octal			" Set AC to have the new file mode
+   sys chmod; name:0		" and change the file's mode
    sma
-   jmp loop
-   lac name
-   dac 1f
-   lac d1
-   sys write; 1:0; 4
+     jmp loop			" Loop if no error
+   lac name			" We got back -1, error
+   dac 1f			" Write out the filename on stdout
+   lac d1			" followed by the " ?\n" string
+   sys write; 1:0; 4		" and loop back
    lac d1
    sys write; 1f; 2
    jmp loop
+
 1:
-   040;077012
+   040;077012			" String literal " ?\n"
+
 error:
-   lac d1
+   lac d1			" Write " "\n" to stdout and exit
    sys write; 1b+1; 1
    sys exit
 
-om60: -060
-o40: 040
-d1: 1
+d1: 1				" Numeric constants
+d4: 4
 d8: 8
 dm4: -4
-d4: 4
+o40: 040
 o177: 0177
+om60: -060
 
-nchar: .=.+1
+nchar: .=.+1			" Number of characters in the value entered
 c1: .=.+1
-octal: .=.+1
+octal: .=.+1			" The resulting octal value