From: Neil Smith <neil.git@njae.me.uk>
Date: Fri, 16 Jun 2017 07:39:57 +0000 (+0100)
Subject: Working on Brainfuck solutions
X-Git-Url: https://git.njae.me.uk/?a=commitdiff_plain;h=e87288e9e5b3903773574b9244822c618a107e6e;p=ou-summer-of-code-2017.git

Working on Brainfuck solutions
---

diff --git a/02-lifts/part1-brainfuck.ipynb b/02-lifts/part1-brainfuck.ipynb
index bc880de..608180d 100644
--- a/02-lifts/part1-brainfuck.ipynb
+++ b/02-lifts/part1-brainfuck.ipynb
@@ -292,7 +292,7 @@
   },
   {
    "cell_type": "code",
-   "execution_count": 197,
+   "execution_count": 200,
    "metadata": {},
    "outputs": [
     {
@@ -301,7 +301,7 @@
        "([94, 94, 24, 0, 3, 0], 255, 5)"
       ]
      },
-     "execution_count": 197,
+     "execution_count": 200,
      "metadata": {},
      "output_type": "execute_result"
     }
diff --git a/02-lifts/part2-brainfuck.ipynb b/02-lifts/part2-brainfuck.ipynb
index d43ab27..0452e3b 100644
--- a/02-lifts/part2-brainfuck.ipynb
+++ b/02-lifts/part2-brainfuck.ipynb
@@ -121,20 +121,29 @@
     "set cell 3 to 118-94=24\n",
     "copy cell 1 into cell 0, using cell 4\n",
     "\n",
+    "cell 5 for ???? currently at an exit: 1 if at an exit, 0 otherwise\n",
+    "\n",
     "set cell 6 to 0 (current level)\n",
-    "set cell 7 to 0 (highest exit)\n",
-    "reserve cell 8 for scratch\n",
+    "set cell 7 to  for non-negative flag: 0 for +ive, 1 for -ive, 0 for zero.\n",
+    "set cell 8 to 0 (highest exit)\n",
+    "cell 9 for input\n",
+    "cell 10 for whether input has been dealt with: 0 for yes, 1 for no\n",
+    "reserve cell 11 and higher for scratch\n",
     "\n",
     "read character into cell 9\n",
     "while cell 9 != 0\n",
     "  subtract cell 0 from cell 9\n",
     "  if cell 9 == 0 we're at an exit\n",
-    "     if cell 6 is higher then cell 7\n",
-    "       copy cell 6 into cell 7\n",
+    "     if cell 7 != 0\n",
+    "       if cell 6 is higher then cell 7\n",
+    "         copy cell 6 into cell 7\n",
     "  else\n",
     "    subtract cell 2 from cell 9\n",
     "    if cell 9 == 0 we're going up\n",
     "      increment cell 6\n",
+    "      if cell 6 is zero\n",
+    "        if cell 7 != 0\n",
+    "          decrement cell 7\n",
     "    else\n",
     "      decrement cell 6\n",
     "      \n",
@@ -145,6 +154,48 @@
     "```\n",
     "\n",
     "```\n",
+    "read character into cell 9\n",
+    "set cell 10 to 1\n",
+    "while cell 9 != 0\n",
+    "  subtract cell 0 from cell 9\n",
+    "  while cell 9 == 0 we're not at an exit\n",
+    "    subtract cell 1 from cell 9\n",
+    "    set cell 10 to 0\n",
+    "    while cell 9 == 0 we're going up\n",
+    "      increment cell 6\n",
+    "      increment cell 6\n",
+    "      while cell 6 is zero\n",
+    "        set cell 7 to zero    \n",
+    "    decrement cell 6\n",
+    "  while cell 10 != 0 (at an exit)\n",
+    "    while cell 7 != 0 (above ground level)\n",
+    "      copy cell 8 to cell 11 using cell 13 (highest)\n",
+    "      copy cell 6 to cell 12 using cell 13 (current)\n",
+    "      set cell 14 to 0\n",
+    "      while cell 11 != 0\n",
+    "        increment cell 14\n",
+    "        while cell 12 != 0\n",
+    "          decrement cell 12\n",
+    "          set cell 14 to 0, keep pointer at 14 (this exits the inner loop)\n",
+    "        decrement cell 11\n",
+    "      add cell 12 to cell 8\n",
+    "      set cell 7 to 0\n",
+    "    set cell 10 to 0\n",
+    "          \n",
+    "    \n",
+    "  \n",
+    "  \n",
+    "     if cell 7 != 0\n",
+    "       if cell 6 is higher then cell 7\n",
+    "         copy cell 6 into cell 7\n",
+    "  else\n",
+    "      \n",
+    "  copy cell 1 into cell 0 using cell 4\n",
+    "  read character into cell 6\n",
+    "```\n",
+    "\n",
+    "```\n",
+    "Need a flag to say if below ground level, and only update the highest exit level if positive\n",
     "Hold highest exit in unary, as seq 10, 9, 8... 1, 0.\n",
     "When get a new exit, set level in leftmost cell, rebuild the sequence.\n",
     "If when you get to the end, there's a non-zero cell to the right, it wasn't longest.\n",