sh.s: more stuff working

src/other/sh.s

@@ -3,6 +3,8 @@
 " started by p budne 3/4/2016
 " with code from cat.s, init.s, and looking at the v1 (pdp-11) shell
 
+" XXX cat.s seems to write error output on fd 8
+
 start:
 " XXX take command line argument (script file to open), suppress prompt??
 " NOTE!!! v0 init.s doesn't set up the argv at the top of memory,
@@ -21,30 +23,31 @@ interactive:
 newline:
    lac d1; sys write; prompt; 1	" output prompt
 newcom:
-   dzm argc			" clear arg count
    dzm char			" clear saved char
    dzm infile			" clear input redirect file name
    dzm outfile			" clear output redirect file name
-   dzm argv0			" clear out argv0 for chdir comparison
-   dzm argv0+1
-   dzm argv0+2
-   lac argcptr
-   dac argptr
    lac iopt			" reset output pointer
    dac opt
    dac nextarg
 
+" reset high memory
+   dzm argc			" clear arg count
+   lac argcptr
+   dac argptr
+   dzm argv0			" clear out argv0 for chdir comparison
+   dzm argv0+1
+   dzm argv0+2
+
 newarg:
    -8				" save 8 chars
    dac bcount
    dzm redirect
 
    lac opt			" save start for print (TEMP)
-   dac 8f
    dac nextarg
 
    jms blank			" skip whitespace
-   sad o12			" newline?
+   jms delim			" newline?
     jmp eol			"  yes
    sad lt			" input redirect?
     jmp redirin
@@ -56,23 +59,21 @@ redirin:			" saw <
    dac redirect			" flag redirect
    lac infilep
    dac opt
-   dac 8f			" TEMP
    jmp newchar			" v1 behavior? no whitespace eater
 
 redirout:			" saw >
    dac redirect			" flag redirect
    lac outfilep
    dac opt
-   dac 8f			" TEMP
+   " v1 behavior? no whitespace eater!
-   " v1 behavior? no whitespace eater
    " fall
 
 newchar:
    jms getc
    sad o40			" space?
     jmp ws			"  yes
-   sad o12
+   jms delim
-    jmp ws
+    jmp eoname
 3: jms putc			" save
    isz bcount			" loop unless full
     jmp newchar
@@ -83,20 +84,20 @@ discard:
    dac char
    sad o4
     jmp eof
-   sad o12
+   jms delim			" end of line?
     jmp eoname
    sad o40
     jmp eoname
    jmp discard
 
-" here with EOF in command
+" here with EOF in command: process command?
 eof:
    sys exit			" quit, for now?
 
 " name ended (short) with whitespace or newline
 " pad out last name to 8 with spaces
 ws:
-   dac char
+   dac char			" save terminator
 1: lac o40
    jms putc			" no: copy into argv
    isz bcount			" loop until full
@@ -104,9 +105,10 @@ ws:
 
 " saw end of name
 eoname:
+   dac char
    lac redirect
    sza
-    jmp 1f			" last name was a redirect file, skip increment
+    jmp 2f			" last name was a redirect file, skip increment
 
    lac argc			" increment argc
    tad d4
@@ -115,19 +117,13 @@ eoname:
    tad d4			" advance nextarg
    dac nextarg
 
-1f:
+2:
    dzm redirect			" clear redirect flag
-" TEMP output each name on a line:
-   lac d1; sys write; gt; 1
-   lac d1; sys write; 8:0; 4
-   lac d1; sys write; nl; 1
-
    lac nextarg
    dac opt
-   dac 8b		" TEMP
 
    lac char
-   sad o12
+   jms delim
     jmp eol
 
    -maxargs
@@ -135,41 +131,42 @@ eoname:
    sza
     jmp newarg
 
-" too many args, (complain?) eat rest of line 
+" too many args, (complain?).  for now eat rest of line 
 4: jms getc
-   sad o12
+   jms delim
     skp
      jmp 4b
+   lac d1; sys write; toomany; ltoomany
+   jmp newline
 
 " here at end of line
 eol:
-   cla			" get anything?
+   sad delimchar		" save eol character
-   sad argc
+   lac argc			" check for empty command line
-    jmp newline		" no, go back for another
+   sna				" get anything?
+    jmp 2f			" no, go back for another
 
-   lac argv0		" check for built-in "chdir" command
+" check for built-in "chdir" command
-   sad chdir
+   lac argv0
+   sad chdirstr
     skp
-     jmp forkexec
+     jmp 1f
    lac argv0+1
-   sad chdir+1
+   sad chdirstr+1
     skp
-     jmp forkexec
+     jmp 1f
    lac argv0+2
-   sad chdir+2
+   sad chdirstr+2
     jmp changedir
 
-forkexec:
+1:
-" temp just exec in place
+" comment these out to test "exec"
-"  sys fork
+   sys fork
-"   jmp parent
+    jmp parent
-
-   dac pid			" here in child: save parent pid for smes
 
+" here in child
    lac d2; sys close		" close fd 2
-
+   sys unlink; exectemp		" remove temp file
-" XXX open executable BEFORE I/O redirection, so we can output error!!!!
-   sys unlink; exectemp
 
 " try to link binary from "system" directory to "exectemp" file
 "   sys link; system; argv0; exectemp
@@ -180,13 +177,8 @@ forkexec:
 "     jmp error
 "   sys unlink; exectemp
 "   jmp 1f
+"notsys:			" not found in "system"
 
-   lac d1; sys write; star; 1
-   lac d1; sys write; star; 1
-   lac d1; sys write; argv0; 4
-   lac d1; sys write; nl; 1
-
-notsys:			" not found in "system"
    sys open; argv0; 0		" try cwd
    spa
      jmp cmderr
@@ -207,16 +199,15 @@ notsys:			" not found in "system"
    spa
      jmp outerror
 
-
+" here to "exec" file open on fd 2, adapted from init.s
-" here to "exec" file open on fd 2, adapted from init.s:
 exec:
    law boot-1			" Get source addr
    dac 8			" set up index 8 (pre-increments)
-   law bootloc-1	" Copy the code at the boot label into high memory
+   law bootloc-1		" Copy "boot" code into high memory
    dac 9			" set up index 9 (pre-increments)
 1: lac 8 i
    dac 9 i
-   isz bootcount
+   isz bootcount		" can only do this once!
      jmp 1b
    jmp bootloc			" and then jump to the code
 
@@ -236,39 +227,67 @@ bootcount: -bootlen	" isz loop count for bootstrap copy
 inerror:			" error opening input redirection
   lac infilep
   jmp error
-outerror:		" error opening output redirection (stdout closed!)
+outerror:			" error opening new stdout (stdout closed!)
   lac outfilep
   skp
 cmderr:				" error opening command
    lac argv0p
-error:			" here for error in child: filename pointer in AC
+error:				" error in child: filename pointer in AC
   dac 1f			" save filename to complain about
-  lac d1; sys write; qmsp; 1
   lac d1; sys write; 1: 0; 4
-  lac d1; sys write; nl; 1
+  lac d1; sys write; qmnl; 1
   lac d2; sys close
   sys exit
 
-" end code from init.s
+" chdir command: executed in shell process
-" ================
+changedir:
+" XXX check if argc == 4 (no directories) and complain??
+   lac argv0p
+   skp
+1:  lac 0f			" increment argvp
+   tad d4
+   sad 0f
+   -4				" decrement argc
+   tad argc
+   dac argc
+   sna				" done?
+    jmp 2f			"  yes: join parent code
+   sys chdir; 0:0
+   sma				" error?
+    jmp 1b			"  no: look for another directory
+
+" chdir call failed
+   lac 0b
+   dac 0f
+   lac d1; sys write; 0:0; 4
+   lac d1; sys write; qmnl; 1
+   jmp 2f			" join parent code
 
 " here in parent, child pid in AC
 parent:
-"  sys smes		" hangs until child exits
+"	https://www.bell-labs.com/usr/dmr/www/hist.html
-   jmp newline
+"	The message facility was used as follows: the parent shell, after
-
+"	creating a process to execute a command, sent a message to the new
-" chdir command:
+"	process by smes; when the command terminated (assuming it did not
-changedir:
+"	try to read any messages) the shell's blocked smes call returned an
-" XXX check argc > 1!!!
+"	error indication that the target process did not exist. Thus the
-   lac d1; sys write; gt; 1
+"	shell's smes became, in effect, the equivalent of wait.
-   lac d1; sys write; gt; 1
+   dac pid
-   lac d1; sys write; gt; 1
+   lac delimchar
-   lac d1; sys write; argv0+4; 4
+   sad o46			" ampersand?
-" XXX loop for multiple components!!!
+    jmp newcom			"  yes: go back without wait
-   jmp newline
+   lac pid
+   sys smes			" hang until child exits
+2: lac delimchar
+   sad o73			" semi?
+    jmp newcom			"  yes: look for another command w/o prompt
+   jmp newline			" no: output prompt
 
 " ================
 " subroutines
+
+" eat spaces
+" v1 routine name:
 blank: 0
 1: jms getc
    sad o40
@@ -276,25 +295,29 @@ blank: 0
    jmp blank i
 
 " give skip return if AC *NOT* a command delimiter
+" v1 routine name:
 delim: 0
-   sad o12
+   sad o12			" newline
     jmp delim i
-   isz delim
+   sad o46			" ampersand
+    jmp delim i
+   sad o73			" semi
+    jmp delim i
+   isz delim			" ran the gauntlet: skip home
    jmp delim i
 
-" ****************************************************************
 " from cat.s
 getc: 0
-   lac ipt			" Load the pointer to the next word in the buffer
+   lac ipt			" Load pointer to next word in the buffer
    sad eipt
-     jmp 1f			" We've reached the end of the buffer, so read more
+     jmp 1f			" end of the buffer, so read more
    dac 2f			" Save the pointer
-   add o400000			" Flip the msb and save into ipt
+   add o400000			" flip MSB, increment pointer on overflow
    dac ipt
    ral				" Move the msb into the link register
    lac 2f i			" Load the word from the buffer
-   szl				" Skip if this is the second character in the word
+   szl				" Skip if second character in word
-     lrss 9			" It's the first char, shift down the top character
+     lrss 9			"  first char: shift down the top character
    and o177			" Keep the lowest 7 bits
    sna
      jmp getc+1			" Skip a NUL characters and read another one
@@ -341,37 +364,38 @@ eipt: 0				" Pointer to end of data read in input buffer
 iipt: ibuf
 ibuf: .=.+64
 
-
-" end from cat.s
-" ****************************************************************
 " literals
 d1: 1
 d2: 2
 o4:d4: 4
-o12:nl: 012	" newline
+o12: 012			" newline
 o17: 017
-o40:sp: 040	" space
+o40: 040			" space
-o74:lt: 074
+o46: 046			" ampersand
-o76:gt: 076
+o73: 046			" semi
-o177: 0177			" ASCII mask
+o74:lt: 074			" <
-o400000: 0400000		" Msb toggle bit
+o76:gt: 076			" >
+o177: 0177			" 7-bit (ASCII) mask
+o400000: 0400000		" MSB
 
 hash: <#> " superuser prompt
-qmsp: <? > "			" question mark, space
+qmnl: <? 012			" question mark, newline
-				" (traditional DDT error label was "dt"
+
-				" for "dink, tab")
 system:
    <sy>;<st>;<em>; 040040
 
 exectemp:
-   <ex>;<ec>;<te><mp>		" temporary link for file being exec'ed
+   <ex>;<ec>;<te>;<mp>		" temporary link for file being exec'ed
 
-chdir:
+chdirstr:
    <ch>;<di>;<r 040
 
 " TEMP FOR DEBUG:
 star: <*> "
 
+toomany: <to>;<o> ;<ma>;<ny>;< a>;<rg>;<s 012
+ltoomany=.-toomany
+
 " ################ variables
 
 prompt: <@> " v1 prompt
@@ -379,6 +403,7 @@ pid: 0				" "other" pid
 char: 0				" white space char
 redirect: 0			" last file was a redirect (lt or gt)
 bcount: 0			" byte counter for current filename
+delimchar: 0			" character that terminated line
 
 iopt:argv0p: argv0		" initial value for nextarg, opt
 nextarg: 0			" next slot in argv to fill