From b3b868ed50eccc8ff7318286aa7bcbfa162b1d14 Mon Sep 17 00:00:00 2001
From: rswier <rswier@acm.org>
Date: Wed, 16 Mar 2016 01:46:35 -0400
Subject: [PATCH] Ported B compiler b.c to b.b.

Ported B compiler b.c to b.b.  It is able to compile itself.  Hints are
in the comment block.
---
 src/other/b.b     | 785 ++++++++++++++++++++++++++++++++++++++++++++++
 src/other/hello.s |  85 ++---
 tools/a7out       |   8 +-
 tools/b.c         | 445 +++++++++++++-------------
 4 files changed, 1065 insertions(+), 258 deletions(-)
 create mode 100644 src/other/b.b

diff --git a/src/other/b.b b/src/other/b.b
new file mode 100644
index 0000000..57a7a27
--- /dev/null
+++ b/src/other/b.b
@@ -0,0 +1,785 @@
+/* b.b - B compiler for PDP-7 Unix
+
+   Coding style and organization based on lastc1120c.c
+  
+   (C) 2016 Robert Swierczek, GPL3
+  
+   To compile the compiler with b.c:
+      gcc -Wno-multichar b.c -o b
+      ./b b.b b.s
+      perl as7 --out b.out bl.s b.s bi.s
+
+   To compile hello.b:
+      perl a7out b.out hello.b hello.s
+      perl as7 --out h.out bl.s hello.s bi.s
+      perl a7out h.out
+   
+   To compile the compiler with itself:
+      perl a7out b.out b.b b2.s
+      perl as7 --out b2.out bl.s b2.s bi.s
+*/
+
+main() {
+  extrn symtab, eof, ns, nerror;
+
+  while (!eof) {
+    ns = symtab + 51;
+    extdef();
+    blkend();
+  }
+}
+
+lookup() {
+  extrn symtab, symbuf, eof, ns, nerror;
+  auto np, sp, rp;
+
+  rp = symtab;
+  while (rp < ns) {
+    np = rp + 2;
+    sp = symbuf;
+    while (*np==*sp) {
+      if (!*np)
+        return(rp);
+      np = np+1;
+      sp = sp+1;
+    }
+    while (*np)
+      np = np+1;
+    rp = np+1;
+  }
+  sp = symbuf;
+  if (ns >= symtab + 290) {
+    error('sf');
+    eof = 1;
+    return(rp);
+  }
+  *ns = 0;
+  ns[1] = 0;
+  ns = ns+2;
+  while (*ns = *sp) {
+    ns = ns+1;
+    sp = sp+1;
+  }
+  ns = ns+1;
+  return(rp);
+}
+
+symbol() {
+  extrn symbuf, ctab, peeksym, peekc, eof, line, csym, cval;
+  auto b, c, ct, sp;
+
+  if (peeksym>=0) {
+    c = peeksym;
+    peeksym = -1;
+    return(c);
+  }
+  if (peekc) {
+    c = peekc;
+    peekc = 0;
+  } else {
+    if (eof)
+      return(0);
+  else
+      c = read();
+  }
+loop:
+  ct = ctab[c];
+ 
+  if (ct==0) { /* eof */
+    eof = 1;
+    return(0);
+  }
+ 
+  if (ct==126) { /* white space */
+    if (c=='*n')
+      line = line+1;
+    c = read();
+    goto loop;
+  }
+
+  if (c=='=') {
+    return(subseq('=',80,60));
+  }
+  if (c=='<') {
+    return(subseq('=',63,62));
+  }
+  if (c=='>') {
+    return(subseq('=',65,64));
+  }
+  if (c=='!') {
+    return(subseq('=',34,61));
+  }
+  if (c=='$') {
+    if (subseq('(',0,1))
+      return(2);
+    if (subseq(')',0,1))
+      return(3);
+  }
+  if (c=='/') {
+    if (subseq('**',1,0))
+      return(43);
+com:
+    c = read();
+com1:
+    if (c==4) {
+      eof = 1;
+      error('**/'); /* eof */
+      return(0);
+    }
+    if (c=='*n')
+      line = line+1;
+    if (c!='**')
+      goto com;
+    c = read();
+    if (c!='/')
+      goto com1;
+    c = read();
+    goto loop;
+  }
+  if (ct==124) { /* number */
+    cval = 0;
+    if (c=='0')
+      b = 8;
+    else
+      b = 10;
+    while(c >= '0' & c <= '9') {
+      cval = cval*b + c -'0';
+      c = read();
+    }
+    peekc = c;
+    return(21);
+  }
+  if (c=='*'') { /* ' */
+    getcc();
+    return(21);
+  }
+  if (ct==123) { /* letter */
+    sp = symbuf;
+    while(ctab[c]==123 | ctab[c]==124) {
+      if (sp<symbuf+9) { *sp = c; sp = sp+1; }
+      c = read();
+    }
+    *sp = 0;
+    peekc = c;
+    csym = lookup();
+    if (csym[0]==1) {
+      cval = csym[1];
+      return(19); /* keyword */
+    }
+    return(20); /* name */
+  }
+  if (ct==127) { /* unknown */
+    error('sy');
+    c = read();
+    goto loop;
+  }
+  return(ctab[c]);
+}
+
+subseq(c,a,b) {
+  extrn peekc;
+
+  if (!peekc)
+    peekc = read();
+  if (peekc != c)
+    return(a);
+  peekc = 0;
+  return(b);
+}
+
+getcc() {
+  extrn cval;
+  auto c;
+
+  cval = 0;
+  if ((c = mapch('*'')) < 0) return;
+  cval = c;
+  if ((c = mapch('*'')) < 0) return;
+  cval = cval * 512 + c;
+  if ((c = mapch('*'')) >= 0)
+  error('cc');
+}
+
+mapch(c) {
+  extrn peekc;
+  auto a;
+
+  if((a=read())==c)
+    return(-1);
+ 
+  if (a=='*n' | a==0 | a==4) {
+    error('cc');
+    peekc = a;
+    return(-1);
+  }
+
+  if (a=='**') {
+    a=read();
+
+    if (a=='0')
+      return(0);
+
+    if (a=='e')
+      return(4);
+
+    if (a=='(')
+      return('{');
+
+    if (a==')')
+      return('}');
+
+    if (a=='t')
+      return('*t');
+
+    if (a=='r')
+      return('*r');
+
+    if (a=='n')
+      return('*n');
+  }
+  return(a);
+}
+
+expr(lev) {
+  extrn peeksym, csym, cval, isn;
+  auto o;
+
+  o = symbol();
+ 
+  if (o==21) { /* number */
+case21:
+    if ((cval & 017777)==cval) {
+      gen('c',cval); /* consop */
+      goto loop;
+    }
+    gen('n',5); /* litrl */
+    number(cval);
+    write('*n');
+    goto loop;
+  }
+
+  if (o==20) { /* name */
+    if (*csym==0) { /* not seen */
+      if((peeksym=symbol())==6) { /* ( */
+        *csym = 6; /* extrn */
+      } else {
+        *csym = 2; /* internal */
+        isn = isn+1;
+        csym[1] = isn;
+      }
+    }
+    if(*csym==5) /* auto */
+      gen('a',csym[1]);
+    else {
+      write('x ');
+      if (*csym==6) { /* extrn */
+        write('.');
+        name(csym+2);
+      } else { /* internal */
+        write('l');
+        number(csym[1]);
+      }
+      write('*n');
+    }
+    goto loop;
+  }
+ 
+  if (o==34) { /* ! */
+    expr(1);
+    gen('u',4); /* unot */
+    goto loop;
+  }
+
+  if (o==41) { /* - */
+    peeksym = symbol();
+    if (peeksym==21) { /* number */
+      peeksym = -1;
+      cval = -cval;
+      goto case21;
+    }
+    expr(1);
+    gen('u',2); /* umin */
+    goto loop;
+  }
+ 
+  if (o==47) { /* & */
+    expr(1);
+    gen('u',1); /* uadr */
+    goto loop;
+  }
+ 
+  if (o==42) { /* * */
+    expr(1);
+    gen('u',3); /* uind */
+    goto loop;
+  }
+ 
+  if (o==6) { /* ( */
+    peeksym = o;
+    pexpr();
+    goto loop;
+  }
+  error('ex');
+
+loop:
+  o = symbol();
+
+  if (lev>=14 & o==80) { /* = */
+    expr(14);
+    gen('b',1); /* asg */
+    goto loop;
+  }
+  if (lev>=10 & o==48) { /* | ^ */
+    expr(9);
+    gen('b',2); /* bor */
+    goto loop;
+  }
+  if (lev>=8 & o==47) { /* & */
+    expr(7);
+    gen('b',3); /* band */
+    goto loop;
+  }
+  if (lev>=7 & o>=60 & o<=61) { /* == != */
+    expr(6);
+    gen('b',o-56); /* beq bne */
+    goto loop;
+  }
+  if (lev>=6 & o>=62 & o<=65) { /* <= < >= > */
+    expr(5);
+    gen('b',o-56); /* ble blt bge bgt */
+    goto loop;
+  }
+  if (lev>=4 & o>=40 & o<=41) { /* + - */
+    expr(3);
+    gen('b',o-28); /* badd bmin */
+    goto loop;
+  }
+  if (lev>=3 & o>=42 & o<=43) { /* * / */
+    expr(2);
+    gen('b',o-27); /* bmul bdiv */
+    goto loop;
+  }
+  if (lev>=3 & o==44) { /* % */
+    expr(2);
+    gen('b',14); /* bmod */
+    goto loop;
+  }
+  if (o==4) { /* [ */
+    expr(15);
+    if (symbol() != 5)
+      error('[]');
+    gen('b',12); /* badd */
+    gen('u',3); /* uind */
+    goto loop;
+  }
+  if (o==6) { /* ( */
+    o = symbol();
+    if (o==7) /* ) */
+      gen('n',1); /* mcall */
+    else {
+      gen('n',2); /* mark */
+      peeksym = o;
+      while (o!=7) {
+        expr(15);
+        o = symbol();
+        if (o!=7 & o!=9) { /* ) , */
+          error('ex');
+          return;
+        }
+      }
+      gen('n',3); /* call */
+    }
+    goto loop;
+  }
+ 
+  peeksym = o;
+}
+
+pexpr()
+{
+  auto o, t;
+
+  if ((o=symbol())==6) { /* ( */
+    expr(15);
+    if ((o=symbol())==7) /* ) */
+      return;
+  }
+  error('()');
+}
+
+declare(kw) {
+  extrn csym, cval, nauto;
+  auto o;
+
+  while((o=symbol())==20) { /* name */
+    if (kw==6) { /* extrn */
+      *csym = 6;
+      o = symbol();
+    } else { /* auto/param */
+      *csym = 5; /* auto */
+      csym[1] = nauto;
+      o = symbol();
+      if (kw==5 & o==21) { /* auto & number */
+        gen('y',nauto); /* aryop */
+        nauto = nauto + cval;
+        o = symbol();
+      }
+      nauto = nauto+1;
+    }
+    if (o!=9) /* , */
+      goto done;
+  }
+done:
+  if(o==1 & kw!=8 | o==7 & kw==8) /* auto/extrn ;  param ')' */
+    return;
+syntax:
+  error('[]'); /* declaration syntax */
+}
+
+extdef() {
+  extrn peeksym, csym, cval, nauto;
+  auto o, c;
+
+  o = symbol();
+  if(o==0 | o==1) /* eof ; */
+    return;
+
+  if(o!=20) /* name */
+    goto syntax;
+
+  csym[0] = 6; /* extrn */
+  write('.');
+  name(csym + 2);
+  write(':');
+  o=symbol();
+ 
+  if (o==2 | o==6) { /* $( ( */
+    write('.+');
+    write('1*n');
+    nauto = 2;
+    if (o==6) { /* ( */
+      declare(8); /* param */
+      if ((o=symbol())!=2) /* $( */
+        goto syntax;
+    }
+    while((o=symbol())==19 & cval<10) /* auto extrn */
+      declare(cval);
+    peeksym = o;
+    gen('s',nauto); /* setop */
+    stmtlist();
+    gen('n',7); /* retrn */
+    return;
+  }
+
+  if (o==41) { /* - */
+    if (symbol()!=21) /* number */
+      goto syntax;
+    number(-cval);
+    write('*n');
+    return;
+  }
+
+  if (o==21) { /* number */
+    number(cval);
+    write('*n');
+    return;
+  }
+
+  if (o==1) { /* ; */
+    write('0*n');
+    return;
+  }
+
+  if (o==4) { /* [ */
+    c = 0;
+    if ((o=symbol())==21) { /* number */
+      c = cval;
+      o = symbol();
+    }
+    if (o!=5) /* ] */
+      goto syntax;
+    write('.+');
+    write('1*n');
+    if ((o=symbol())==1) /* ; */
+      goto done;
+    while (o==21 | o==41) { /* number - */
+      if (o==41) { /* - */
+        if (symbol()!=21)
+          goto syntax;
+        cval = -cval;
+      }
+      number(cval);
+      write('*n');
+      c = c-1;
+      if ((o=symbol())==1) /* ; */
+        goto done;
+      if (o!=9) /* , */
+        goto syntax;
+      else
+        o = symbol();
+    }
+    goto syntax;
+done:
+    if (c>0) {
+      write('.=');
+      write('.+');
+      number(c);
+      write('*n');
+    }
+    return;
+  }
+
+  if (o==0) /* eof */
+    return;
+
+syntax:
+  error('xx');
+  stmt();
+}
+
+stmtlist() {
+  extrn peeksym, eof;
+  auto o;
+
+  while (!eof) {
+    if ((o = symbol())==3) /* $) */
+      return;
+    peeksym = o;
+    stmt();
+  }
+  error('$)'); /* missing $) */
+}
+
+stmt() {
+  extrn peeksym, peekc, csym, cval, isn, nauto;
+  auto o, o1, o2;
+
+next:
+  o = symbol();
+ 
+  if (o==0) /* eof */
+  {
+    error('fe'); /* Unexpected eof */
+    return;
+  }
+ 
+  if (o==1 | o==3) /* ; $) */
+    return;
+ 
+  if (o==2) { /* $( */
+    stmtlist();
+    return;
+  }
+
+  if (o==19) { /* keyword */
+
+    if (cval==10) { /* goto */
+      expr(15);
+      gen('n',6); /* goto */
+      goto semi;
+    }
+
+    if (cval==11) { /* return */
+      if((peeksym=symbol())==6) /* ( */
+        pexpr();
+      gen('n',7); /* retrn */
+      goto semi;
+    }
+
+    if (cval==12) { /* if */
+      pexpr();
+      isn = isn+1;
+      o1 = isn;
+      jumpc(o1);
+      stmt();
+      o = symbol();
+      if (o==19 & cval==14) { /* else */
+        isn = isn+1;
+        o2 = isn;
+        jump(o2);
+        label(o1);
+        stmt();
+        label(o2);
+        return;
+      }
+      peeksym = o;
+      label(o1);
+      return;
+    }
+
+    if (cval==13) { /* while */
+      isn = isn+1;
+      o1 = isn;
+      label(o1);
+      pexpr();
+      isn = isn+1;
+      o2 = isn;
+      jumpc(o2);
+      stmt();
+      jump(o1);
+      label(o2);
+      return;
+    }
+
+    error('sx');
+    goto syntax;
+  }
+
+  if (o==20 & peekc==':') { /* name : */
+    peekc = 0;
+    if (!*csym) {
+      *csym = 2; /* param */
+      isn = isn+1;
+      csym[1] = isn;
+    } else if (*csym != 2) {
+      error('rd');
+      goto next;
+    }
+    label(csym[1]);
+    goto next;
+  }
+
+  peeksym = o;
+  expr(15);
+  gen('s',nauto); /* setop */
+
+semi:
+  o = symbol();
+  if (o==1) /* ; */
+    return;
+
+syntax:
+  error('sz');
+  goto next;
+}
+
+blkend() {
+  extrn isn, nisn;
+
+  while (nisn < isn) {
+    nisn = nisn+1;
+    write('l');
+    number(nisn);
+    write(':');
+    write('ll');
+    number(nisn);
+    write('*n');
+  }
+}
+
+gen(o,n) {
+  write(o);
+  write(' ');
+  number(n);
+  write('*n');
+}
+
+jumpc(n) {
+  write('f '); /* ifop */
+  write('l');
+  number(n);
+  write('*n');
+}
+
+jump(n) {
+  write('t '); /* traop */
+  write('ll');
+  number(n);
+  write('*n');
+}
+
+label(n) {
+  write('ll');
+  number(n);
+  write(':');
+}
+
+printn(n) {
+  if (n > 9) {
+    printn(n / 10);
+    n = n % 10;
+  }
+  write(n + '0');
+}
+
+number(x) {
+  if (x < 0) {
+    write('-');
+    x = -x;
+  }
+  printn(x);
+}
+
+name(s) {
+  while (*s) {
+    write(*s);
+    s = s+1;
+  }
+}
+
+error(code)
+{
+  extrn line, eof, csym, nerror, fout;
+  auto f;
+
+  if (eof | nerror==20) {
+    eof = 1;
+    return;
+  }
+  nerror = nerror+1;
+  flush();
+  f = fout;
+  fout = 1;
+  write(code);
+  write(' ');
+  if (code=='rd' | code=='un') {
+    name(csym + 2);
+    write(' ');
+  }
+  printn(line);
+  write('*n');
+  flush();
+  fout = f;
+}
+
+/* storage */
+
+symtab[300] /* class value name */
+  1, 5,'a','u','t','o', 0 ,
+  1, 6,'e','x','t','r','n', 0 ,
+  1,10,'g','o','t','o', 0 ,
+  1,11,'r','e','t','u','r','n', 0 ,
+  1,12,'i','f', 0 ,
+  1,13,'w','h','i','l','e', 0 ,
+  1,14,'e','l','s','e', 0 ;
+
+ctab[]
+    0,127,127,127,  0,127,127,127,  /* NUL SOH STX ETX EOT ENQ ACK BEL */
+  127,126,126,127,127,127,127,127,  /* BS  TAB LF  VT  FF  CR  SO  SI  */
+  127,127,127,127,127,127,127,127,  /* DLE DC1 DC2 DC3 DC4 NAK SYN ETB */
+  127,127,127,127,127,127,127,127,  /* CAN EM  SUB ESC FS  GS  RS  US  */
+  126, 34,122,127,127, 44, 47,121,  /* SPC  !   "   #   $   %   &   '  */
+    6,  7, 42, 40,  9, 41,127, 43,  /*  (   )   *   +   ,   -   .   /  */
+  124,124,124,124,124,124,124,124,  /*  0   1   2   3   4   5   6   7  */
+  124,124,  8,  1, 63, 80, 65, 90,  /*  8   9   :   ;   <   =   >   ?  */
+  127,123,123,123,123,123,123,123,  /*  @   A   B   C   D   E   F   G  */
+  123,123,123,123,123,123,123,123,  /*  H   I   J   K   L   M   N   O  */
+  123,123,123,123,123,123,123,123,  /*  P   Q   R   S   T   U   V   W  */
+  123,123,123,  4,127,  5, 48,127,  /*  X   Y   Z   [   \   ]   ^   _  */
+  127,123,123,123,123,123,123,123,  /*  `   a   b   c   d   e   f   g  */
+  123,123,123,123,123,123,123,123,  /*  h   i   j   k   l   m   n   o  */
+  123,123,123,123,123,123,123,123,  /*  p   q   r   s   t   u   v   w  */
+  123,123,123,  2, 48,  3,127,127;  /*  x   y   z   {   |   }   ~  DEL */
+
+symbuf[10];
+peeksym -1;
+peekc;
+eof;
+line 1;
+csym;
+ns;
+cval;
+isn;
+nisn;
+nerror;
+nauto;
diff --git a/src/other/hello.s b/src/other/hello.s
index e552760..0a417e1 100644
--- a/src/other/hello.s
+++ b/src/other/hello.s
@@ -1,40 +1,45 @@
-.main: .+1
- s 2
- x .write
- n 2    " etcop mark
- n 5    " etcop litrl
- 36965
- n 3    " etcop call
- x .write
- n 2    " etcop mark
- n 5    " etcop litrl
- 55404
- n 3    " etcop call
- x .write
- n 2    " etcop mark
- n 5    " etcop litrl
- 56876
- n 3    " etcop call
- x .write
- n 2    " etcop mark
- n 5    " etcop litrl
- 16471
- n 3    " etcop call
- x .write
- n 2    " etcop mark
- n 5    " etcop litrl
- 56946
- n 3    " etcop call
- x .write
- n 2    " etcop mark
- n 5    " etcop litrl
- 55396
- n 3    " etcop call
- x .write
- n 2    " etcop mark
- n 5    " etcop litrl
- 16906
- n 3    " etcop call
- x .flush
- n 1    " etcop mcall
- n 7    " etcop retrn
+.main:.+1
+s 2
+x .write
+n 2
+n 5
+36965
+n 3
+s 2
+x .write
+n 2
+n 5
+55404
+n 3
+s 2
+x .write
+n 2
+n 5
+56876
+n 3
+s 2
+x .write
+n 2
+n 5
+16471
+n 3
+s 2
+x .write
+n 2
+n 5
+56946
+n 3
+s 2
+x .write
+n 2
+n 5
+55396
+n 3
+s 2
+x .write
+n 2
+n 5
+16906
+n 3
+s 2
+n 7
diff --git a/tools/a7out b/tools/a7out
index 0e33615..eeb81c7 100755
--- a/tools/a7out
+++ b/tools/a7out
@@ -545,7 +545,8 @@ sub eae {
 
         # Save the AC's sign into LINK
         my $newlink = ( $AC << 1 ) & LINKMASK;
-        $AC = ( ( $LINK | $AC ) >> $step ) & MAXINT;
+#        $AC = ( ( $LINK | $AC ) >> $step ) & MAXINT;
+        $AC = ( ( ($newlink * -1) | $AC ) >> $step ) & MAXINT;   # XXX Not sure if this is correct!?!?!
         $LINK = $newlink;
         $PC++;
         return;
@@ -1301,8 +1302,8 @@ sub word2ascii {
     my $c1     = ( $word >> 9 ) & 0177;
     my $c2     = $word & 0177;
     my $result = "";
-    $result .= (($c1 >= 32) && ($c1 <= 126)) ? chr($c1) : ' ';
-    $result .= (($c2 >= 32) && ($c2 <= 126)) ? chr($c2) : ' ';
+    if (($c1 >= 1) && ($c1 <= 126)) { $result .= chr($c1); }
+    if (($c2 >= 1) && ($c2 <= 126)) { $result .= chr($c2); }
     return ($result);
 }
 
@@ -1313,6 +1314,7 @@ sub mem2arg {
     my $addr   = shift;
     my $result = "";
 
+    $addr &= MAXADDR;
     foreach ( 1 .. 4 ) {
 
         # Stop if the address leave the 8K word address space
diff --git a/tools/b.c b/tools/b.c
index bebc123..bc340b4 100644
--- a/tools/b.c
+++ b/tools/b.c
@@ -1,16 +1,16 @@
-// b.c - B compiler for PDP-7 Unix
-//
-// Implemented in a subset of the C language compatible with B.
-// Coding style and organization based on lastc1120c.c
-//
-// (C) 2016 Robert Swierczek, GPL3
-//
+/* b.c - B compiler for PDP-7 Unix
 
-// Just enough working to compile hello.b:
-//    gcc -m32 -Wno-multichar b.c -o b
-//    ./b hello.b hello.s
-//    perl as7 --out a.out bl.s hello.s bi.s
-//    perl a7out a.out
+   Implemented in a subset of the C language compatible with B.
+   Coding style and organization based on lastc1120c.c
+ 
+   (C) 2016 Robert Swierczek, GPL3
+ 
+   To compile hello.b:
+      gcc -Wno-multichar b.c -o b
+      ./b hello.b hello.s
+      perl as7 --out a.out bl.s hello.s bi.s
+      perl a7out a.out
+*/
 
 #ifdef _WIN32
 #include <io.h>
@@ -21,66 +21,51 @@
 #include <stdlib.h>
 #include <memory.h>
 #include <fcntl.h>
-#define eof xeof
 
-int fin = 0;
+/* runtime */
+int fin;
 int fout = 1;
 
-int symtab[500] = { /* class value name */
-  1, 5,'a','u','t','o', 0 ,
-  1, 6,'e','x','t','r','n', 0 ,
-  1,10,'g','o','t','o', 0 ,
-  1,11,'r','e','t','u','r','n', 0 ,
-  1,12,'i','f', 0 ,
-  1,13,'w','h','i','l','e', 0 ,
-  1,14,'e','l','s','e', 0 ,
-};
+xread() {
+  char buf[1];
+  if (read(fin, buf, 1) <= 0)
+  return 4;
+  return buf[0];
+}
 
-int ctab[] = {
-    0,127,127,127,  0,127,127,127, /* NUL SOH STX ETX EOT ENQ ACK BEL */
-  127,126,126,127,127,127,127,127, /* BS  TAB LF  VT  FF  CR  SO  SI  */
-  127,127,127,127,127,127,127,127, /* DLE DC1 DC2 DC3 DC4 NAK SYN ETB */
-  127,127,127,127,127,127,127,127, /* CAN EM  SUB ESC FS  GS  RS  US  */
-  126, 34,122,127,127, 44, 47,121, /* SPC  !   "   #   $   %   &   '  */
-    6,  7, 42, 40,  9, 41,127, 43, /*  (   )   *   +   ,   -   .   /  */
-  124,124,124,124,124,124,124,124, /*  0   1   2   3   4   5   6   7  */
-  124,124,  8,  1, 63, 80, 65, 90, /*  8   9   :   ;   <   =   >   ?  */
-  127,123,123,123,123,123,123,123, /*  @   A   B   C   D   E   F   G  */
-  123,123,123,123,123,123,123,123, /*  H   I   J   K   L   M   N   O  */
-  123,123,123,123,123,123,123,123, /*  P   Q   R   S   T   U   V   W  */
-  123,123,123,  4,127,  5, 48,127, /*  X   Y   Z   [   \   ]   ^   _  */
-  127,123,123,123,123,123,123,123, /*  `   a   b   c   d   e   f   g  */
-  123,123,123,123,123,123,123,123, /*  h   i   j   k   l   m   n   o  */
-  123,123,123,123,123,123,123,123, /*  p   q   r   s   t   u   v   w  */
-  123,123,123,  2, 48,  3,127,127, /*  x   y   z   {   |   }   ~  DEL */
-};
+xwrite(c) {
+  char buf[2];
+  if (c & 0xff00) {
+    buf[0] = (c >> 8) & 0xff;
+    buf[1] = c & 0xff;
+    write(fout, buf, 2);
+  } else {
+    buf[0] = c & 0xff;
+    write(fout, buf, 1);
+  }
+}
 
-/* storage */
+xflush() {
+}
+#define eof xeof
+#define read xread
+#define write xwrite
+#define flush xflush
 
-int symbuf[10];
-int peeksym = -1;
-int peekc = 0;
-int eof = 0;
-int line = 1;
-int *csym = 0;
-int *ns;
-int cval = 0;
-int isn = 0;
-int nisn = 0;
-int nerror = 0;
-int nauto = 0;
+main(int argc, char **argv) {
+  extern symtab[], eof, *ns, nerror;
+  extern fin, fout;
 
-int main(int argc, char **argv) {
   if (argc > 1) {
     if (argc > 2) {
       if ((fout = creat(argv[2], 0777))<0) {
         error('fo');
-        exit(1);
+        return;
       }
     }
     if ((fin = open(argv[1],0))<0) {
       error('fi');
-      exit(1);
+      return;
     }
   }
 
@@ -89,50 +74,46 @@ int main(int argc, char **argv) {
     extdef();
     blkend();
   }
-  xflush();
- 
-  exit(nerror);
 }
 
 int *lookup() {
-  int *np, *sp, *rp;
+  extern symtab[], symbuf[], eof, *ns, nerror;
+  auto *np, *sp, *rp;
+
   rp = symtab;
   while (rp < ns) {
     np = rp + 2;
     sp = symbuf;
     while (*np==*sp) {
       if (!*np)
-        return rp;
-      np = np + 1;
-      sp = sp + 1;
+        return(rp);
+      np = np+1;
+      sp = sp+1;
     }
     while (*np)
-      np = np + 1;
-    rp = np + 1;
+      np = np+1;
+    rp = np+1;
   }
   sp = symbuf;
-  if (ns >= symtab + 490) {
-    error("sf");
-    exit(1);
+  if (ns >= symtab + 290) {
+    error('sf');
+    eof = 1;
+    return(rp);
   }
   *ns = 0;
   ns[1] = 0;
-  ns = ns + 2;  
+  ns = ns+2;
   while (*ns = *sp) {
-    ns = ns + 1;
-    sp = sp + 1;
+    ns = ns+1;
+    sp = sp+1;
   }
-  ns = ns + 1;
-  return rp;
+  ns = ns+1;
+  return(rp);
 }
 
 symbol() {
-//  extern peeksym, peekc, eof, xread, subseq, error, line;
-//  extern *csym, symbuf[], namsiz, lookup[], ctab, cval;
-//  auto b, c, ct;
-// char symbuf[], sp[], ctab[];
-  int b, c, ct;
-  int *sp;
+  extern symbuf[], ctab[], peeksym, peekc, eof, line, *csym, cval;
+  auto b, c, ct, *sp;
 
   if (peeksym>=0) {
     c = peeksym;
@@ -146,20 +127,20 @@ symbol() {
     if (eof)
       return(0);
   else
-      c = xread();
+      c = read();
   }
 loop:
   ct = ctab[c];
  
   if (ct==0) { /* eof */
-    eof++;
+    eof = 1;
     return(0);
   }
  
   if (ct==126) { /* white space */
     if (c=='\n')
-      line = line + 1;
-    c = xread();
+      line = line+1;
+    c = read();
     goto loop;
   }
 
@@ -185,21 +166,21 @@ loop:
     if (subseq('*',1,0))
       return(43);
 com:
-    c = xread();
+    c = read();
 com1:
     if (c==4) {
-      eof++;
+      eof = 1;
       error('*/'); /* eof */
       return(0);
     }
     if (c=='\n')
-      line++;
+      line = line+1;
     if (c!='*')
       goto com;
-    c = xread();
+    c = read();
     if (c!='/')
       goto com1;
-    c = xread();
+    c = read();
     goto loop;
   }
   if (ct==124) { /* number */
@@ -208,9 +189,9 @@ com1:
       b = 8;
     else
       b = 10;
-    while(c >= '0' && c <= '9') {
+    while(c >= '0' & c <= '9') {
       cval = cval*b + c -'0';
-      c = xread();
+      c = read();
     }
     peekc = c;
     return(21);
@@ -222,13 +203,13 @@ com1:
   if (ct==123) { /* letter */
     sp = symbuf;
     while(ctab[c]==123 | ctab[c]==124) {
-      if (sp<symbuf+9) *sp++ = c;
-      c = xread();
+      if (sp<symbuf+9) { *sp = c; sp = sp+1; }
+      c = read();
     }
     *sp = 0;
     peekc = c;
     csym = lookup();
-    if (csym[0]==1) { 
+    if (csym[0]==1) {
       cval = csym[1];
       return(19); /* keyword */
     }
@@ -236,17 +217,17 @@ com1:
   }
   if (ct==127) { /* unknown */
     error('sy');
-    c = xread();
+    c = read();
     goto loop;
   }
   return(ctab[c]);
 }
 
 subseq(c,a,b) {
-  extern peekc; //    extern xread, peekc;
- 
+  extern peekc;
+
   if (!peekc)
-    peekc = xread();
+    peekc = read();
   if (peekc != c)
     return(a);
   peekc = 0;
@@ -267,10 +248,10 @@ getcc() {
 }
 
 mapch(c) {
-  extern peekc, line;
+  extern peekc;
   auto a;
 
-  if((a=xread())==c)
+  if((a=read())==c)
     return(-1);
  
   if (a=='\n' | a==0 | a==4) {
@@ -280,10 +261,10 @@ mapch(c) {
   }
 
   if (a=='*') {
-    a=xread();
+    a=read();
 
     if (a=='0')
-      return('\0');
+      return(0);
 
     if (a=='e')
       return(4);
@@ -306,40 +287,46 @@ mapch(c) {
   return(a);
 }
 
-void expr(int lev) {
-  int o;
+expr(lev) {
+  extern peeksym, *csym, cval, isn;
+  auto o;
 
   o = symbol();
  
   if (o==21) { /* number */
 case21:
+    if ((cval & 017777)==cval) {
+      gen('c',cval); /* consop */
+      goto loop;
+    }
     gen('n',5); /* litrl */
     number(cval);
-    xwrite('\n');
+    write('\n');
     goto loop;
   }
-   
+
   if (o==20) { /* name */
     if (*csym==0) { /* not seen */
       if((peeksym=symbol())==6) { /* ( */
         *csym = 6; /* extrn */
       } else {
         *csym = 2; /* internal */
-        csym[1] = ++isn;
+        isn = isn+1;
+        csym[1] = isn;
       }
     }
     if(*csym==5) /* auto */
       gen('a',csym[1]);
     else {
-      xwrite('x ');
+      write('x ');
       if (*csym==6) { /* extrn */
-        xwrite('.');
+        write('.');
         name(csym+2);
       } else { /* internal */
-        xwrite('l');
+        write('l');
         number(csym[1]);
-      }    
-      xwrite('\n');
+      }
+      write('\n');
     }
     goto loop;
   }
@@ -408,22 +395,22 @@ loop:
     expr(5);
     gen('b',o-56); /* ble blt bge bgt */
     goto loop;
-  }  
+  }
   if (lev>=4 & o>=40 & o<=41) { /* + - */
     expr(3);
     gen('b',o-28); /* badd bmin */
     goto loop;
-  }  
+  }
   if (lev>=3 & o>=42 & o<=43) { /* * / */
     expr(2);
     gen('b',o-27); /* bmul bdiv */
     goto loop;
-  }  
+  }
   if (lev>=3 & o==44) { /* % */
     expr(2);
     gen('b',14); /* bmod */
     goto loop;
-  }  
+  }
   if (o==4) { /* [ */
     expr(15);
     if (symbol() != 5)
@@ -442,7 +429,7 @@ loop:
       while (o!=7) {
         expr(15);
         o = symbol();
-        if (o!=7 && o!=9) { /* ) , */
+        if (o!=7 & o!=9) { /* ) , */
           error('ex');
           return;
         }
@@ -468,40 +455,36 @@ pexpr()
 }
 
 declare(kw) {
-//  extern csym[], symbol, paraml[], parame[];
-//  extern error, cval, peeksym, exit;
-//  int t[], n, o;
-  int o;
+  extern *csym, cval, nauto;
+  auto o;
 
   while((o=symbol())==20) { /* name */
     if (kw==6) { /* extrn */
       *csym = 6;
-      o = symbol();      
+      o = symbol();
     } else { /* auto/param */
       *csym = 5; /* auto */
       csym[1] = nauto;
-      o = symbol();      
+      o = symbol();
       if (kw==5 & o==21) { /* auto & number */
         gen('y',nauto); /* aryop */
         nauto = nauto + cval;
         o = symbol();
       }
-      nauto++;
+      nauto = nauto+1;
     }
     if (o!=9) /* , */
       goto done;
   }
 done:
-  if(o==1 & kw!=8 | o==7 & kw==8) /* auto/extrn ;   param ')' */
+  if(o==1 & kw!=8 | o==7 & kw==8) /* auto/extrn ;  param ')' */
     return;
 syntax:
   error('[]'); /* declaration syntax */
 }
 
 extdef() {
-//  extern eof, cval;
-//  extern symbol, block, printf, pname, csym[];
-//  extern error;
+  extern peeksym, *csym, cval, nauto;
   auto o, c;
 
   o = symbol();
@@ -512,40 +495,48 @@ extdef() {
     goto syntax;
 
   csym[0] = 6; /* extrn */
-  xwrite('.');
+  write('.');
   name(csym + 2);
-  xwrite(': ');
+  write(':');
   o=symbol();
  
   if (o==2 | o==6) { /* $( ( */
-    xwrite('.+');
-    xwrite('1\n');
+    write('.+');
+    write('1\n');
     nauto = 2;
     if (o==6) { /* ( */
       declare(8); /* param */
       if ((o=symbol())!=2) /* $( */
         goto syntax;
     }
-    while((o=symbol())==19 && cval<10) /* auto extrn */
+    while((o=symbol())==19 & cval<10) /* auto extrn */
       declare(cval);
     peeksym = o;
     gen('s',nauto); /* setop */
-    stmtlist();        
-    gen('n',7); /* retrn */  
+    stmtlist();
+    gen('n',7); /* retrn */
+    return;
+  }
+
+  if (o==41) { /* - */
+    if (symbol()!=21) /* number */
+      goto syntax;
+    number(-cval);
+    write('\n');
     return;
   }
 
   if (o==21) { /* number */
     number(cval);
-    xwrite('\n');
+    write('\n');
     return;
   }
-  
+
   if (o==1) { /* ; */
-    xwrite('0\n');
+    write('0\n');
     return;
   }
-  
+
   if (o==4) { /* [ */
     c = 0;
     if ((o=symbol())==21) { /* number */
@@ -554,14 +545,19 @@ extdef() {
     }
     if (o!=5) /* ] */
       goto syntax;
-    xwrite('.+');
-    xwrite('1\n');
+    write('.+');
+    write('1\n');
     if ((o=symbol())==1) /* ; */
       goto done;
-    while (o==21) { /* number */
+    while (o==21 | o==41) { /* number - */
+      if (o==41) { /* - */
+        if (symbol()!=21)
+          goto syntax;
+        cval = -cval;
+      }
       number(cval);
-      xwrite('\n');
-      c--;
+      write('\n');
+      c = c-1;
       if ((o=symbol())==1) /* ; */
         goto done;
       if (o!=9) /* , */
@@ -572,13 +568,13 @@ extdef() {
     goto syntax;
 done:
     if (c>0) {
-      xwrite('.=');
-      xwrite('.+');
+      write('.=');
+      write('.+');
       number(c);
-      xwrite('\n');
+      write('\n');
     }
     return;
-  }    
+  }
 
   if (o==0) /* eof */
     return;
@@ -589,7 +585,9 @@ syntax:
 }
 
 stmtlist() {
-  int o;
+  extern peeksym, eof;
+  auto o;
+
   while (!eof) {
     if ((o = symbol())==3) /* $) */
       return;
@@ -600,14 +598,8 @@ stmtlist() {
 }
 
 stmt() {
-//  extern symbol, error, blkhed, eof, peeksym;
-//  extern blkend, csym[], rcexpr, block[], tree[], regtab[];
-//  extern jumpc, jump, label, contlab, brklab, cval;
-//  extern swp[], isn, pswitch, peekc, slabel;
-//  extern efftab[], declare, deflab, swtab[], swsiz, branch;
-
-//  int o, o1, o2, np[];
-  int o, o1, o2;
+  extern peeksym, peekc, *csym, cval, isn, nauto;
+  auto o, o1, o2;
 
 next:
   o = symbol();
@@ -618,7 +610,7 @@ next:
     return;
   }
  
-  if (o==1 || o==3) /* ; $) */
+  if (o==1 | o==3) /* ; $) */
     return;
  
   if (o==2) { /* $( */
@@ -633,23 +625,23 @@ next:
       gen('n',6); /* goto */
       goto semi;
     }
-   
+
     if (cval==11) { /* return */
       if((peeksym=symbol())==6) /* ( */
         pexpr();
       gen('n',7); /* retrn */
       goto semi;
     }
-   
+
     if (cval==12) { /* if */
       pexpr();
-      isn++;
+      isn = isn+1;
       o1 = isn;
       jumpc(o1);
       stmt();
       o = symbol();
       if (o==19 & cval==14) { /* else */
-        isn++;
+        isn = isn+1;
         o2 = isn;
         jump(o2);
         label(o1);
@@ -663,11 +655,11 @@ next:
     }
 
     if (cval==13) { /* while */
-      isn++;
+      isn = isn+1;
       o1 = isn;
       label(o1);
       pexpr();
-      isn++;
+      isn = isn+1;
       o2 = isn;
       jumpc(o2);
       stmt();
@@ -684,7 +676,7 @@ next:
     peekc = 0;
     if (!*csym) {
       *csym = 2; /* param */
-      ++isn;
+      isn = isn+1;
       csym[1] = isn;
     } else if (*csym != 2) {
       error('rd');
@@ -709,42 +701,44 @@ syntax:
 }
 
 blkend() {
+  extern isn, nisn;
+
   while (nisn < isn) {
-    ++nisn;
-    xwrite('l');
+    nisn = nisn+1;
+    write('l');
     number(nisn);
-    xwrite(': ');
-    xwrite('ll');
+    write(':');
+    write('ll');
     number(nisn);
-    xwrite('\n');    
+    write('\n');
   }
 }
 
 gen(o,n) {
-  xwrite(o);
-  xwrite(' ');
+  write(o);
+  write(' ');
   number(n);
-  xwrite('\n');
+  write('\n');
 }
 
 jumpc(n) {
-  xwrite('f '); /* ifop */
-  xwrite('l');
+  write('f '); /* ifop */
+  write('l');
   number(n);
-  xwrite('\n');
+  write('\n');
 }
 
 jump(n) {
-  xwrite('t '); /* traop */
-  xwrite('ll');
+  write('t '); /* traop */
+  write('ll');
   number(n);
-  xwrite('\n');
+  write('\n');
 }
 
 label(n) {
-  xwrite('ll');
+  write('ll');
   number(n);
-  xwrite(':\n');
+  write(':');
 }
 
 printn(n) {
@@ -752,12 +746,12 @@ printn(n) {
     printn(n / 10);
     n = n % 10;
   }
-  xwrite(n + '0');
+  write(n + '0');
 }
 
 number(x) {
   if (x < 0) {
-    xwrite('-');
+    write('-');
     x = -x;
   }
   printn(x);
@@ -765,53 +759,74 @@ number(x) {
 
 name(int *s) {
   while (*s) {
-    xwrite(*s);
-    s = s + 1;
+    write(*s);
+    s = s+1;
   }
 }
 
 error(code)
 {
-  extern line;
-  int f;
+  extern line, eof, *csym, nerror, fout;
+  auto f;
  
-  nerror++;
-  xflush();
+  if (eof | nerror==20) {
+    eof = 1;
+    return;
+  }
+  nerror = nerror+1;
+  flush();
   f = fout;
   fout = 1;
-  xwrite(code);
-  xwrite(' ');
+  write(code);
+  write(' ');
   if (code=='rd' | code=='un') {
     name(csym + 2);
-    xwrite(' ');
+    write(' ');
   }
   printn(line);
-  xwrite('\n');
-  if (nerror==20)
-    exit(20);
+  write('\n');
+  flush();
   fout = f;
 }
 
-// runtime:
+/* storage */
 
-xread() {
-  char buf[1];
-  if (read(fin, buf, 1) <= 0)
-  return 4;
-  return buf[0];
-}
+int symtab[300] = { /* class value name */
+  1, 5,'a','u','t','o', 0 ,
+  1, 6,'e','x','t','r','n', 0 ,
+  1,10,'g','o','t','o', 0 ,
+  1,11,'r','e','t','u','r','n', 0 ,
+  1,12,'i','f', 0 ,
+  1,13,'w','h','i','l','e', 0 ,
+  1,14,'e','l','s','e', 0 };
 
-xwrite(int c) {
-  char buf[2];
-  if (c & 0xff00) {
-    buf[0] = (c >> 8) & 0xff;
-    buf[1] = c & 0xff;
-    write(fout, buf, 2);
-  } else {
-    buf[0] = c & 0xff;
-    write(fout, buf, 1);
-  }
-}
+int ctab[] = {
+    0,127,127,127,  0,127,127,127,  /* NUL SOH STX ETX EOT ENQ ACK BEL */
+  127,126,126,127,127,127,127,127,  /* BS  TAB LF  VT  FF  CR  SO  SI  */
+  127,127,127,127,127,127,127,127,  /* DLE DC1 DC2 DC3 DC4 NAK SYN ETB */
+  127,127,127,127,127,127,127,127,  /* CAN EM  SUB ESC FS  GS  RS  US  */
+  126, 34,122,127,127, 44, 47,121,  /* SPC  !   "   #   $   %   &   '  */
+    6,  7, 42, 40,  9, 41,127, 43,  /*  (   )   *   +   ,   -   .   /  */
+  124,124,124,124,124,124,124,124,  /*  0   1   2   3   4   5   6   7  */
+  124,124,  8,  1, 63, 80, 65, 90,  /*  8   9   :   ;   <   =   >   ?  */
+  127,123,123,123,123,123,123,123,  /*  @   A   B   C   D   E   F   G  */
+  123,123,123,123,123,123,123,123,  /*  H   I   J   K   L   M   N   O  */
+  123,123,123,123,123,123,123,123,  /*  P   Q   R   S   T   U   V   W  */
+  123,123,123,  4,127,  5, 48,127,  /*  X   Y   Z   [   \   ]   ^   _  */
+  127,123,123,123,123,123,123,123,  /*  `   a   b   c   d   e   f   g  */
+  123,123,123,123,123,123,123,123,  /*  h   i   j   k   l   m   n   o  */
+  123,123,123,123,123,123,123,123,  /*  p   q   r   s   t   u   v   w  */
+  123,123,123,  2, 48,  3,127,127}; /*  x   y   z   {   |   }   ~  DEL */
 
-xflush() {
-}
\ No newline at end of file
+int symbuf[10];
+int peeksym = -1;
+int peekc;
+int eof;
+int line = 1;
+int *csym;
+int *ns;
+int cval;
+int isn;
+int nisn;
+int nerror;
+int nauto;