From f86fc47790ee8facc6be87eaea760108eacd0837 Mon Sep 17 00:00:00 2001
From: Mark Pizzolato <mark@infocomm.com>
Date: Wed, 13 Jul 2016 14:58:11 -0700
Subject: [PATCH] PDP1: Fix PTP and PTR ASCII Mode from Bob Supnik

ASCII mode for the paper tape reader and punch didn't <quite> work.

In ASCII mode, the <simulator> must create the leader and trailer. The
leader was already there. There shouldn't be nulls in an ASCII file. The
whole point is to be able to prepare and look at input and output files
with a normal text editor.

So this version should work right. It "autogens" trailer more or less
forever. It doesn't really need to return a STOP code on EOF, but users
would probably forget to put form feed at the end, so it doesn't hurt.
---
 PDP1/pdp1_stddev.c | 18 +++++++++++-------
 1 file changed, 11 insertions(+), 7 deletions(-)

diff --git a/PDP1/pdp1_stddev.c b/PDP1/pdp1_stddev.c
index c317e58f..c0374b7e 100644
--- a/PDP1/pdp1_stddev.c
+++ b/PDP1/pdp1_stddev.c
@@ -177,8 +177,8 @@ REG ptr_reg[] = {
 MTAB ptr_mod[] = {
     { MTAB_XTD|MTAB_VDV, 0, "SBSLVL", "SBSLVL",
       &dev_set_sbs, &dev_show_sbs, (void *) &ptr_sbs },
-    { UNIT_ASCII, UNIT_ASCII, "ASCII", NULL },
-    { UNIT_ASCII, 0,          "FIODEC", NULL },
+    { UNIT_ASCII, UNIT_ASCII, "ASCII", "ASCII", NULL },
+    { UNIT_ASCII, 0,          "FIODEC", "FIODEC", NULL },
     { 0 }
     };
 
@@ -215,8 +215,8 @@ REG ptp_reg[] = {
 MTAB ptp_mod[] = {
     { MTAB_XTD|MTAB_VDV, 0, "SBSLVL", "SBSLVL",
       &dev_set_sbs, &dev_show_sbs, (void *) &ptp_sbs },
-    { UNIT_ASCII, UNIT_ASCII, "ASCII", NULL },
-    { UNIT_ASCII, 0,          "FIODEC", NULL },
+    { UNIT_ASCII, UNIT_ASCII, "ASCII", "ASCII", NULL },
+    { UNIT_ASCII, 0,          "FIODEC", "FIODEC", NULL },
     { 0 }
     };
 
@@ -405,8 +405,10 @@ if (ptr_hold & CW) {                                    /* char waiting? */
     }
 else {
     for (;;) {                                          /* until valid char */
-        if ((c = getc (uptr->fileref)) == EOF)          /* get next char, EOF? */
+        if ((c = getc (uptr->fileref)) == EOF) {        /* get next char, EOF? */
+            ptr_leader = PTR_LEADER;                    /* set up for trailer */
             return FIODEC_STOP;                         /* return STOP */
+            }
         uptr->pos = uptr->pos + 1;                      /* count char */
         c = c & 0177;                                   /* cut to 7b */
         if (c == '\n')                                  /* NL -> CR */
@@ -531,11 +533,13 @@ if ((uptr->flags & UNIT_ATT) == 0)                      /* not attached? */
     return IORETURN (ptp_stopioe, SCPE_UNATT);
 if ((uptr->flags & UNIT_ASCII) != 0) {                  /* ASCII mode? */
     int32 c1 = uptr->buf & 077;
-    if (c1 == FIODEC_UC) {
+    if (uptr->buf == 0)                                 /* ignore nulls */
+        return SCPE_OK;
+    if (c1 == FIODEC_UC) {                              /* UC? absorb */
         ptp_uc = UC;
         return SCPE_OK;
         }
-    else if (c1 == FIODEC_LC) {
+    else if (c1 == FIODEC_LC) {                         /* LC? absorb */
         ptp_uc = 0;
         return SCPE_OK;
         }