5706 - example at different levels of syntax sugar

Thanks Mateusz Czapliński for the feedback:
  https://lobste.rs/s/xtxlec/mu_minimal_hobbyist_computing_stack#c_1mzq94

6 files changed, 740 insertions, 0 deletions

diff --git a/apps/factorial2.subx b/apps/factorial2.subx
new file mode 100644
index 00000000..af2f3eea
--- /dev/null
+++ b/apps/factorial2.subx
@@ -0,0 +1,115 @@
+## compute the factorial of 5, and return the result in the exit code
+#
+# To run:
+#   $ ./ntranslate init.linux 0*.subx apps/factorial.subx -o apps/factorial
+#   $ ./subx run apps/factorial
+# Expected result:
+#   $ echo $?
+#   120
+#
+# You can also run the automated test suite:
+#   $ ./subx run apps/factorial test
+# Expected output:
+#   ........
+# Every '.' indicates a passing test. Failing tests get a 'F'.
+
+== code
+
+Entry:  # run tests if necessary, compute `factorial(5)` if not
+    # . prologue
+    89/<- %ebp 4/r32/esp
+
+    # initialize heap
+    # . Heap = new-segment(Heap-size)
+    # . . push args
+    68/push Heap/imm32
+    68/push Heap-size/imm32
+    # . . call
+    e8/call new-segment/disp32
+    # . . discard args
+    81 0/subop/add %esp 8/imm32
+
+    # - if argc > 1 and argv[1] == "test", then return run_tests()
+    # if (argc <= 1) goto run-main
+    81 7/subop/compare *ebp 1/imm32
+    7e/jump-if-lesser-or-equal $run-main/disp8
+    # if (!kernel-string-equal?(argv[1], "test")) goto run-main
+    # . eax = kernel-string-equal?(argv[1], "test")
+    # . . push args
+    68/push "test"/imm32
+    ff 6/subop/push *(ebp+8)
+    # . . call
+    e8/call kernel-string-equal?/disp32
+    # . . discard args
+    81 0/subop/add %esp 8/imm32
+    # . if (eax == 0) goto run-main
+    3d/compare-eax-and 0/imm32
+    74/jump-if-equal $run-main/disp8
+    # run-tests()
+    e8/call run-tests/disp32
+    # syscall(exit, *Num-test-failures)
+    8b/-> *Num-test-failures 3/r32/ebx
+    eb/jump $main:end/disp8
+$run-main:
+    # - otherwise return factorial(5)
+    # eax = factorial(5)
+    # . . push args
+    68/push 5/imm32
+    # . . call
+    e8/call factorial/disp32
+    # . . discard args
+    81 0/subop/add %esp 4/imm32
+    # syscall(exit, eax)
+    89/<- %ebx 0/r32/eax
+$main:end:
+    b8/copy-to-eax 1/imm32/exit
+    cd/syscall 0x80/imm8
+
+factorial:  # n : int -> int/eax
+    # . prologue
+    55/push-ebp
+    89/<- %ebp 4/r32/esp
+    53/push-ebx
+    # if (n <= 1) return 1
+    b8/copy-to-eax 1/imm32
+    81 7/subop/compare *(ebp+8) 1/imm32
+    7e/jump-if-<= $factorial:end/disp8
+    # ebx = n-1
+    8b/-> *(ebp+8) 3/r32/ebx
+    4b/decrement-ebx
+    # eax = factorial(n-1)
+    # . . push args
+    53/push-ebx
+    # . . call
+    e8/call factorial/disp32
+    # . . discard args
+    81 0/subop/add %esp 4/imm32
+    # return n * factorial(n-1)
+    f7 4/subop/multiply-into-eax *(ebp+8)
+    # TODO: check for overflow
+$factorial:end:
+    # . epilogue
+    5b/pop-to-ebx
+    89/<- %esp 5/r32/ebp
+    5d/pop-to-ebp
+    c3/return
+
+test-factorial:
+    # factorial(5)
+    # . . push args
+    68/push 5/imm32
+    # . . call
+    e8/call factorial/disp32
+    # . . discard args
+    81 0/subop/add %esp 4/imm32
+    # check-ints-equal(eax, 120, msg)
+    # . . push args
+    68/push "F - test-factorial"/imm32
+    68/push 0x78/imm32/expected-120
+    50/push-eax
+    # . . call
+    e8/call check-ints-equal/disp32
+    # . . discard args
+    81 0/subop/add %esp 0xc/imm32
+    # end
+    c3/return
diff --git a/apps/factorial3.subx b/apps/factorial3.subx
new file mode 100644
index 00000000..6e9816c1
--- /dev/null
+++ b/apps/factorial3.subx
@@ -0,0 +1,77 @@
+## compute the factorial of 5, and return the result in the exit code
+#
+# To run:
+#   $ ./ntranslate init.linux 0*.subx apps/factorial.subx -o apps/factorial
+#   $ ./subx run apps/factorial
+# Expected result:
+#   $ echo $?
+#   120
+#
+# You can also run the automated test suite:
+#   $ ./subx run apps/factorial test
+# Expected output:
+#   ........
+# Every '.' indicates a passing test. Failing tests get a 'F'.
+
+== code
+
+Entry:  # run tests if necessary, compute `factorial(5)` if not
+    # . prologue
+    89/<- %ebp 4/r32/esp
+
+    # initialize heap
+    (new-segment Heap-size Heap)
+
+    # - if argc > 1 and argv[1] == "test", then return run_tests()
+    # if (argc <= 1) goto run-main
+    81 7/subop/compare *ebp 1/imm32
+    7e/jump-if-lesser-or-equal $run-main/disp8
+    # if (!kernel-string-equal?(argv[1], "test")) goto run-main
+    (kernel-string-equal? *(ebp+8) "test")  # => eax
+    # . if (eax == 0) goto run-main
+    3d/compare-eax-and 0/imm32
+    74/jump-if-equal $run-main/disp8
+    #
+    (run-tests)
+    # syscall(exit, *Num-test-failures)
+    8b/-> *Num-test-failures 3/r32/ebx
+    eb/jump $main:end/disp8
+$run-main:
+    # - otherwise
+    (factorial 5)  # => eax
+    # syscall(exit, eax)
+    89/<- %ebx 0/r32/eax
+$main:end:
+    b8/copy-to-eax 1/imm32/exit
+    cd/syscall 0x80/imm8
+
+factorial:  # n : int -> int/eax
+    # . prologue
+    55/push-ebp
+    89/<- %ebp 4/r32/esp
+    # save registers
+    53/push-ebx
+    # if (n <= 1) return 1
+    b8/copy-to-eax 1/imm32
+    81 7/subop/compare *(ebp+8) 1/imm32
+    7e/jump-if-<= $factorial:end/disp8
+    # ebx = n-1
+    8b/-> *(ebp+8) 3/r32/ebx
+    4b/decrement-ebx
+    #
+    (factorial %ebx)  # => eax
+    # return n * factorial(n-1)
+    f7 4/subop/multiply-into-eax *(ebp+8)
+    # TODO: check for overflow
+$factorial:end:
+    # restore registers
+    5b/pop-to-ebx
+    # . epilogue
+    89/<- %esp 5/r32/ebp
+    5d/pop-to-ebp
+    c3/return
+
+test-factorial:
+    (factorial 5)
+    (check-ints-equal %eax 0x78 "F - test-factorial")
+    c3/return
diff --git a/apps/factorial4.subx b/apps/factorial4.subx
new file mode 100644
index 00000000..202a6592
--- /dev/null
+++ b/apps/factorial4.subx
@@ -0,0 +1,83 @@
+## compute the factorial of 5, and return the result in the exit code
+#
+# To run:
+#   $ ./ntranslate init.linux 0*.subx apps/factorial.subx -o apps/factorial
+#   $ ./subx run apps/factorial
+# Expected result:
+#   $ echo $?
+#   120
+#
+# You can also run the automated test suite:
+#   $ ./subx run apps/factorial test
+# Expected output:
+#   ........
+# Every '.' indicates a passing test. Failing tests get a 'F'.
+
+== code
+
+Entry:  # run tests if necessary, compute `factorial(5)` if not
+    # . prologue
+    89/<- %ebp 4/r32/esp
+
+    # initialize heap
+    (new-segment 0x10000 Heap)
+
+    # - if argc > 1, then return run_tests()
+    {
+      # if (argc <= 1) break
+      81 7/subop/compare *ebp 1/imm32
+      7e/jump-if-lesser-or-equal break/disp8
+      # if (!kernel-string-equal?(argv[1], "test")) break
+      (kernel-string-equal? *(ebp+8) "test")  # => eax
+      3d/compare-eax-and 0/imm32
+      74/jump-if-equal break/disp8
+      #
+      (run-tests)
+      # eax = *Num-test-failures
+      8b/-> *Num-test-failures 3/r32/ebx
+    }
+    # if (argc <= 1) factorial(5)
+    {
+      # if (argc > 1) break
+      81 7/subop/compare *ebp 1/imm32
+      7f/jump-if-greater break/disp8
+      # eax = factorial(5)
+      (factorial 5)
+      # syscall(exit, eax)
+      89/<- %ebx 0/r32/eax
+    }
+
+    b8/copy-to-eax 1/imm32/exit
+    cd/syscall 0x80/imm8
+
+factorial:  # n : int -> int/eax
+    # . prologue
+    55/push-ebp
+    89/<- %ebp 4/r32/esp
+    # save registers
+    53/push-ebx
+    # if (n <= 1) return 1
+    81 7/subop/compare *(ebp+8) 1/imm32
+    {
+      7f/jump-if-greater break/disp8
+      b8/copy-to-eax 1/imm32
+    }
+    # if (n > 1) return n * factorial(n-1)
+    {
+      7e/jump-if-lesser-or-equal break/disp8
+      8b/-> *(ebp+8) 3/r32/ebx
+      4b/decrement-ebx
+      (factorial %ebx)  # => eax
+      f7 4/subop/multiply-into-eax *(ebp+8)
+    }
+    # restore registers
+    5b/pop-to-ebx
+    # . epilogue
+    89/<- %esp 5/r32/ebp
+    5d/pop-to-ebp
+    c3/return
+
+test-factorial:
+    (factorial 5)
+    (check-ints-equal %eax 0x78 "F - test-factorial")
+    c3/return
diff --git a/html/apps/factorial2.subx.html b/html/apps/factorial2.subx.html
new file mode 100644
index 00000000..5dd07391
--- /dev/null
+++ b/html/apps/factorial2.subx.html
@@ -0,0 +1,179 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
+<html>
+<head>
+<meta http-equiv="content-type" content="text/html; charset=UTF-8">
+<title>Mu - apps/factorial2.subx</title>
+<meta name="Generator" content="Vim/8.1">
+<meta name="plugin-version" content="vim8.1_v1">
+<meta name="syntax" content="none">
+<meta name="settings" content="number_lines,use_css,pre_wrap,no_foldcolumn,expand_tabs,line_ids,prevent_copy=">
+<meta name="colorscheme" content="minimal-light">
+<style type="text/css">
+<!--
+pre { white-space: pre-wrap; font-family: monospace; color: #000000; background-color: #c6c6c6; }
+body { font-size:12pt; font-family: monospace; color: #000000; background-color: #c6c6c6; }
+a { color:inherit; }
+* { font-size:12pt; font-size: 1em; }
+.subxComment { color: #005faf; }
+.subxS2Comment { color: #8a8a8a; }
+.subxFunction { color: #af5f00; text-decoration: underline; }
+.LineNr { }
+.subxS1Comment { color: #0000af; }
+.SpecialChar { color: #d70000; }
+.Constant { color: #008787; }
+.subxTest { color: #5f8700; }
+.subxH1Comment { color: #005faf; text-decoration: underline; }
+-->
+</style>
+
+<script type='text/javascript'>
+<!--
+
+/* function to open any folds containing a jumped-to line before jumping to it */
+function JumpToLine()
+{
+  var lineNum;
+  lineNum = window.location.hash;
+  lineNum = lineNum.substr(1); /* strip off '#' */
+
+  if (lineNum.indexOf('L') == -1) {
+    lineNum = 'L'+lineNum;
+  }
+  var lineElem = document.getElementById(lineNum);
+  /* Always jump to new location even if the line was hidden inside a fold, or
+   * we corrected the raw number to a line ID.
+   */
+  if (lineElem) {
+    lineElem.scrollIntoView(true);
+  }
+  return true;
+}
+if ('onhashchange' in window) {
+  window.onhashchange = JumpToLine;
+}
+
+-->
+</script>
+</head>
+<body onload='JumpToLine();'>
+<a href='https://github.com/akkartik/mu/blob/master/apps/factorial2.subx'>https://github.com/akkartik/mu/blob/master/apps/factorial2.subx</a>
+<pre id='vimCodeElement'>
+<span id="L1" class="LineNr">  1 </span><span class="subxComment">## compute the factorial of 5, and return the result in the exit code</span>
+<span id="L2" class="LineNr">  2 </span><span class="subxComment">#</span>
+<span id="L3" class="LineNr">  3 </span><span class="subxComment"># To run:</span>
+<span id="L4" class="LineNr">  4 </span><span class="subxComment">#   $ ./ntranslate init.linux 0*.subx apps/factorial.subx -o apps/factorial</span>
+<span id="L5" class="LineNr">  5 </span><span class="subxComment">#   $ ./subx run apps/factorial</span>
+<span id="L6" class="LineNr">  6 </span><span class="subxComment"># Expected result:</span>
+<span id="L7" class="LineNr">  7 </span><span class="subxComment">#   $ echo $?</span>
+<span id="L8" class="LineNr">  8 </span><span class="subxComment">#   120</span>
+<span id="L9" class="LineNr">  9 </span><span class="subxComment">#</span>
+<span id="L10" class="LineNr"> 10 </span><span class="subxComment"># You can also run the automated test suite:</span>
+<span id="L11" class="LineNr"> 11 </span><span class="subxComment">#   $ ./subx run apps/factorial test</span>
+<span id="L12" class="LineNr"> 12 </span><span class="subxComment"># Expected output:</span>
+<span id="L13" class="LineNr"> 13 </span><span class="subxComment">#   ........</span>
+<span id="L14" class="LineNr"> 14 </span><span class="subxComment"># Every '.' indicates a passing test. Failing tests get a 'F'.</span>
+<span id="L15" class="LineNr"> 15 </span>
+<span id="L16" class="LineNr"> 16 </span>== code
+<span id="L17" class="LineNr"> 17 </span>
+<span id="L18" class="LineNr"> 18 </span><span class="SpecialChar">Entry</span>:  <span class="subxComment"># run tests if necessary, compute `factorial(5)` if not</span>
+<span id="L19" class="LineNr"> 19 </span>    <span class="subxS1Comment"># . prologue</span>
+<span id="L20" class="LineNr"> 20 </span>    89/&lt;- %ebp 4/r32/esp
+<span id="L21" class="LineNr"> 21 </span>
+<span id="L22" class="LineNr"> 22 </span>    <span class="subxComment"># initialize heap</span>
+<span id="L23" class="LineNr"> 23 </span>    <span class="subxS1Comment"># . Heap = new-segment(Heap-size)</span>
+<span id="L24" class="LineNr"> 24 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L25" class="LineNr"> 25 </span>    68/push <span class="SpecialChar"><a href='../069allocate.subx.html#L22'>Heap</a></span>/imm32
+<span id="L26" class="LineNr"> 26 </span>    68/push <span class="SpecialChar"><a href='../069allocate.subx.html#L29'>Heap-size</a></span>/imm32
+<span id="L27" class="LineNr"> 27 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L28" class="LineNr"> 28 </span>    e8/call <a href='../053new-segment.subx.html#L41'>new-segment</a>/disp32
+<span id="L29" class="LineNr"> 29 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L30" class="LineNr"> 30 </span>    81 0/subop/add %esp 8/imm32
+<span id="L31" class="LineNr"> 31 </span>
+<span id="L32" class="LineNr"> 32 </span>    <span class="subxH1Comment"># - if argc &gt; 1 and argv[1] == &quot;test&quot;, then return run_tests()</span>
+<span id="L33" class="LineNr"> 33 </span>    <span class="subxComment"># if (argc &lt;= 1) goto run-main</span>
+<span id="L34" class="LineNr"> 34 </span>    81 7/subop/compare *ebp 1/imm32
+<span id="L35" class="LineNr"> 35 </span>    7e/jump-if-lesser-or-equal $run-main/disp8
+<span id="L36" class="LineNr"> 36 </span>    <span class="subxComment"># if (!kernel-string-equal?(argv[1], &quot;test&quot;)) goto run-main</span>
+<span id="L37" class="LineNr"> 37 </span>    <span class="subxS1Comment"># . eax = kernel-string-equal?(argv[1], &quot;test&quot;)</span>
+<span id="L38" class="LineNr"> 38 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L39" class="LineNr"> 39 </span>    68/push <span class="Constant">&quot;test&quot;</span>/imm32
+<span id="L40" class="LineNr"> 40 </span>    ff 6/subop/push *(ebp+8)
+<span id="L41" class="LineNr"> 41 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L42" class="LineNr"> 42 </span>    e8/call <a href='../052kernel-string-equal.subx.html#L31'>kernel-string-equal?</a>/disp32
+<span id="L43" class="LineNr"> 43 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L44" class="LineNr"> 44 </span>    81 0/subop/add %esp 8/imm32
+<span id="L45" class="LineNr"> 45 </span>    <span class="subxS1Comment"># . if (eax == 0) goto run-main</span>
+<span id="L46" class="LineNr"> 46 </span>    3d/compare-eax-and 0/imm32
+<span id="L47" class="LineNr"> 47 </span>    74/jump-if-equal $run-main/disp8
+<span id="L48" class="LineNr"> 48 </span>    <span class="subxComment"># run-tests()</span>
+<span id="L49" class="LineNr"> 49 </span>    e8/call run-tests/disp32
+<span id="L50" class="LineNr"> 50 </span>    <span class="subxComment"># syscall(exit, *Num-test-failures)</span>
+<span id="L51" class="LineNr"> 51 </span>    8b/-&gt; *<span class="SpecialChar"><a href='../051test.subx.html#L90'>Num-test-failures</a></span> 3/r32/ebx
+<span id="L52" class="LineNr"> 52 </span>    eb/jump $main:end/disp8
+<span id="L53" class="LineNr"> 53 </span><span class="Constant">$run-main</span>:
+<span id="L54" class="LineNr"> 54 </span>    <span class="subxH1Comment"># - otherwise return factorial(5)</span>
+<span id="L55" class="LineNr"> 55 </span>    <span class="subxComment"># eax = factorial(5)</span>
+<span id="L56" class="LineNr"> 56 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L57" class="LineNr"> 57 </span>    68/push 5/imm32
+<span id="L58" class="LineNr"> 58 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L59" class="LineNr"> 59 </span>    e8/call <a href='factorial2.subx.html#L68'>factorial</a>/disp32
+<span id="L60" class="LineNr"> 60 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L61" class="LineNr"> 61 </span>    81 0/subop/add %esp 4/imm32
+<span id="L62" class="LineNr"> 62 </span>    <span class="subxComment"># syscall(exit, eax)</span>
+<span id="L63" class="LineNr"> 63 </span>    89/&lt;- %ebx 0/r32/eax
+<span id="L64" class="LineNr"> 64 </span><span class="Constant">$main:end</span>:
+<span id="L65" class="LineNr"> 65 </span>    b8/copy-to-eax 1/imm32/exit
+<span id="L66" class="LineNr"> 66 </span>    cd/syscall 0x80/imm8
+<span id="L67" class="LineNr"> 67 </span>
+<span id="L68" class="LineNr"> 68 </span><span class="subxFunction">factorial</span>:  <span class="subxComment"># n : int -&gt; int/eax</span>
+<span id="L69" class="LineNr"> 69 </span>    <span class="subxS1Comment"># . prologue</span>
+<span id="L70" class="LineNr"> 70 </span>    55/push-ebp
+<span id="L71" class="LineNr"> 71 </span>    89/&lt;- %ebp 4/r32/esp
+<span id="L72" class="LineNr"> 72 </span>    53/push-ebx
+<span id="L73" class="LineNr"> 73 </span>    <span class="subxComment"># if (n &lt;= 1) return 1</span>
+<span id="L74" class="LineNr"> 74 </span>    b8/copy-to-eax 1/imm32
+<span id="L75" class="LineNr"> 75 </span>    81 7/subop/compare *(ebp+8) 1/imm32
+<span id="L76" class="LineNr"> 76 </span>    7e/jump-if-&lt;= $factorial:end/disp8
+<span id="L77" class="LineNr"> 77 </span>    <span class="subxComment"># ebx = n-1</span>
+<span id="L78" class="LineNr"> 78 </span>    8b/-&gt; *(ebp+8) 3/r32/ebx
+<span id="L79" class="LineNr"> 79 </span>    4b/decrement-ebx
+<span id="L80" class="LineNr"> 80 </span>    <span class="subxComment"># eax = factorial(n-1)</span>
+<span id="L81" class="LineNr"> 81 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L82" class="LineNr"> 82 </span>    53/push-ebx
+<span id="L83" class="LineNr"> 83 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L84" class="LineNr"> 84 </span>    e8/call <a href='factorial2.subx.html#L68'>factorial</a>/disp32
+<span id="L85" class="LineNr"> 85 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L86" class="LineNr"> 86 </span>    81 0/subop/add %esp 4/imm32
+<span id="L87" class="LineNr"> 87 </span>    <span class="subxComment"># return n * factorial(n-1)</span>
+<span id="L88" class="LineNr"> 88 </span>    f7 4/subop/multiply-into-eax *(ebp+8)
+<span id="L89" class="LineNr"> 89 </span>    <span class="subxComment"># TODO: check for overflow</span>
+<span id="L90" class="LineNr"> 90 </span><span class="Constant">$factorial:end</span>:
+<span id="L91" class="LineNr"> 91 </span>    <span class="subxS1Comment"># . epilogue</span>
+<span id="L92" class="LineNr"> 92 </span>    5b/pop-to-ebx
+<span id="L93" class="LineNr"> 93 </span>    89/&lt;- %esp 5/r32/ebp
+<span id="L94" class="LineNr"> 94 </span>    5d/pop-to-ebp
+<span id="L95" class="LineNr"> 95 </span>    c3/return
+<span id="L96" class="LineNr"> 96 </span>
+<span id="L97" class="LineNr"> 97 </span><span class="subxTest">test-factorial</span>:
+<span id="L98" class="LineNr"> 98 </span>    <span class="subxComment"># factorial(5)</span>
+<span id="L99" class="LineNr"> 99 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L100" class="LineNr">100 </span>    68/push 5/imm32
+<span id="L101" class="LineNr">101 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L102" class="LineNr">102 </span>    e8/call <a href='factorial2.subx.html#L68'>factorial</a>/disp32
+<span id="L103" class="LineNr">103 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L104" class="LineNr">104 </span>    81 0/subop/add %esp 4/imm32
+<span id="L105" class="LineNr">105 </span>    <span class="subxComment"># check-ints-equal(eax, 120, msg)</span>
+<span id="L106" class="LineNr">106 </span>    <span class="subxS2Comment"># . . push args</span>
+<span id="L107" class="LineNr">107 </span>    68/push <span class="Constant">&quot;F - test-factorial&quot;</span>/imm32
+<span id="L108" class="LineNr">108 </span>    68/push 0x78/imm32/expected-120
+<span id="L109" class="LineNr">109 </span>    50/push-eax
+<span id="L110" class="LineNr">110 </span>    <span class="subxS2Comment"># . . call</span>
+<span id="L111" class="LineNr">111 </span>    e8/call <a href='../051test.subx.html#L24'>check-ints-equal</a>/disp32
+<span id="L112" class="LineNr">112 </span>    <span class="subxS2Comment"># . . discard args</span>
+<span id="L113" class="LineNr">113 </span>    81 0/subop/add %esp 0xc/imm32
+<span id="L114" class="LineNr">114 </span>    <span class="subxComment"># end</span>
+<span id="L115" class="LineNr">115 </span>    c3/return
+</pre>
+</body>
+</html>
+<!-- vim: set foldmethod=manual : -->
diff --git a/html/apps/factorial3.subx.html b/html/apps/factorial3.subx.html
new file mode 100644
index 00000000..1a9566d5
--- /dev/null
+++ b/html/apps/factorial3.subx.html
@@ -0,0 +1,140 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
+<html>
+<head>
+<meta http-equiv="content-type" content="text/html; charset=UTF-8">
+<title>Mu - apps/factorial3.subx</title>
+<meta name="Generator" content="Vim/8.1">
+<meta name="plugin-version" content="vim8.1_v1">
+<meta name="syntax" content="none">
+<meta name="settings" content="number_lines,use_css,pre_wrap,no_foldcolumn,expand_tabs,line_ids,prevent_copy=">
+<meta name="colorscheme" content="minimal-light">
+<style type="text/css">
+<!--
+pre { white-space: pre-wrap; font-family: monospace; color: #000000; background-color: #c6c6c6; }
+body { font-size:12pt; font-family: monospace; color: #000000; background-color: #c6c6c6; }
+a { color:inherit; }
+* { font-size:12pt; font-size: 1em; }
+.subxComment { color: #005faf; }
+.subxFunction { color: #af5f00; text-decoration: underline; }
+.LineNr { }
+.subxS1Comment { color: #0000af; }
+.SpecialChar { color: #d70000; }
+.Constant { color: #008787; }
+.subxTest { color: #5f8700; }
+.subxH1Comment { color: #005faf; text-decoration: underline; }
+-->
+</style>
+
+<script type='text/javascript'>
+<!--
+
+/* function to open any folds containing a jumped-to line before jumping to it */
+function JumpToLine()
+{
+  var lineNum;
+  lineNum = window.location.hash;
+  lineNum = lineNum.substr(1); /* strip off '#' */
+
+  if (lineNum.indexOf('L') == -1) {
+    lineNum = 'L'+lineNum;
+  }
+  var lineElem = document.getElementById(lineNum);
+  /* Always jump to new location even if the line was hidden inside a fold, or
+   * we corrected the raw number to a line ID.
+   */
+  if (lineElem) {
+    lineElem.scrollIntoView(true);
+  }
+  return true;
+}
+if ('onhashchange' in window) {
+  window.onhashchange = JumpToLine;
+}
+
+-->
+</script>
+</head>
+<body onload='JumpToLine();'>
+<a href='https://github.com/akkartik/mu/blob/master/apps/factorial3.subx'>https://github.com/akkartik/mu/blob/master/apps/factorial3.subx</a>
+<pre id='vimCodeElement'>
+<span id="L1" class="LineNr"> 1 </span><span class="subxComment">## compute the factorial of 5, and return the result in the exit code</span>
+<span id="L2" class="LineNr"> 2 </span><span class="subxComment">#</span>
+<span id="L3" class="LineNr"> 3 </span><span class="subxComment"># To run:</span>
+<span id="L4" class="LineNr"> 4 </span><span class="subxComment">#   $ ./ntranslate init.linux 0*.subx apps/factorial.subx -o apps/factorial</span>
+<span id="L5" class="LineNr"> 5 </span><span class="subxComment">#   $ ./subx run apps/factorial</span>
+<span id="L6" class="LineNr"> 6 </span><span class="subxComment"># Expected result:</span>
+<span id="L7" class="LineNr"> 7 </span><span class="subxComment">#   $ echo $?</span>
+<span id="L8" class="LineNr"> 8 </span><span class="subxComment">#   120</span>
+<span id="L9" class="LineNr"> 9 </span><span class="subxComment">#</span>
+<span id="L10" class="LineNr">10 </span><span class="subxComment"># You can also run the automated test suite:</span>
+<span id="L11" class="LineNr">11 </span><span class="subxComment">#   $ ./subx run apps/factorial test</span>
+<span id="L12" class="LineNr">12 </span><span class="subxComment"># Expected output:</span>
+<span id="L13" class="LineNr">13 </span><span class="subxComment">#   ........</span>
+<span id="L14" class="LineNr">14 </span><span class="subxComment"># Every '.' indicates a passing test. Failing tests get a 'F'.</span>
+<span id="L15" class="LineNr">15 </span>
+<span id="L16" class="LineNr">16 </span>== code
+<span id="L17" class="LineNr">17 </span>
+<span id="L18" class="LineNr">18 </span><span class="SpecialChar">Entry</span>:  <span class="subxComment"># run tests if necessary, compute `factorial(5)` if not</span>
+<span id="L19" class="LineNr">19 </span>    <span class="subxS1Comment"># . prologue</span>
+<span id="L20" class="LineNr">20 </span>    89/&lt;- %ebp 4/r32/esp
+<span id="L21" class="LineNr">21 </span>
+<span id="L22" class="LineNr">22 </span>    <span class="subxComment"># initialize heap</span>
+<span id="L23" class="LineNr">23 </span>    (<a href='../053new-segment.subx.html#L41'>new-segment</a> <span class="SpecialChar"><a href='../069allocate.subx.html#L29'>Heap-size</a></span> <span class="SpecialChar"><a href='../069allocate.subx.html#L22'>Heap</a></span>)
+<span id="L24" class="LineNr">24 </span>
+<span id="L25" class="LineNr">25 </span>    <span class="subxH1Comment"># - if argc &gt; 1 and argv[1] == &quot;test&quot;, then return run_tests()</span>
+<span id="L26" class="LineNr">26 </span>    <span class="subxComment"># if (argc &lt;= 1) goto run-main</span>
+<span id="L27" class="LineNr">27 </span>    81 7/subop/compare *ebp 1/imm32
+<span id="L28" class="LineNr">28 </span>    7e/jump-if-lesser-or-equal $run-main/disp8
+<span id="L29" class="LineNr">29 </span>    <span class="subxComment"># if (!kernel-string-equal?(argv[1], &quot;test&quot;)) goto run-main</span>
+<span id="L30" class="LineNr">30 </span>    (<a href='../052kernel-string-equal.subx.html#L31'>kernel-string-equal?</a> *(ebp+8) <span class="Constant">&quot;test&quot;</span>)  <span class="subxComment"># =&gt; eax</span>
+<span id="L31" class="LineNr">31 </span>    <span class="subxS1Comment"># . if (eax == 0) goto run-main</span>
+<span id="L32" class="LineNr">32 </span>    3d/compare-eax-and 0/imm32
+<span id="L33" class="LineNr">33 </span>    74/jump-if-equal $run-main/disp8
+<span id="L34" class="LineNr">34 </span>    <span class="subxComment">#</span>
+<span id="L35" class="LineNr">35 </span>    (run-tests)
+<span id="L36" class="LineNr">36 </span>    <span class="subxComment"># syscall(exit, *Num-test-failures)</span>
+<span id="L37" class="LineNr">37 </span>    8b/-&gt; *<span class="SpecialChar"><a href='../051test.subx.html#L90'>Num-test-failures</a></span> 3/r32/ebx
+<span id="L38" class="LineNr">38 </span>    eb/jump $main:end/disp8
+<span id="L39" class="LineNr">39 </span><span class="Constant">$run-main</span>:
+<span id="L40" class="LineNr">40 </span>    <span class="subxH1Comment"># - otherwise</span>
+<span id="L41" class="LineNr">41 </span>    (<a href='factorial3.subx.html#L48'>factorial</a> 5)  <span class="subxComment"># =&gt; eax</span>
+<span id="L42" class="LineNr">42 </span>    <span class="subxComment"># syscall(exit, eax)</span>
+<span id="L43" class="LineNr">43 </span>    89/&lt;- %ebx 0/r32/eax
+<span id="L44" class="LineNr">44 </span><span class="Constant">$main:end</span>:
+<span id="L45" class="LineNr">45 </span>    b8/copy-to-eax 1/imm32/exit
+<span id="L46" class="LineNr">46 </span>    cd/syscall 0x80/imm8
+<span id="L47" class="LineNr">47 </span>
+<span id="L48" class="LineNr">48 </span><span class="subxFunction">factorial</span>:  <span class="subxComment"># n : int -&gt; int/eax</span>
+<span id="L49" class="LineNr">49 </span>    <span class="subxS1Comment"># . prologue</span>
+<span id="L50" class="LineNr">50 </span>    55/push-ebp
+<span id="L51" class="LineNr">51 </span>    89/&lt;- %ebp 4/r32/esp
+<span id="L52" class="LineNr">52 </span>    <span class="subxComment"># save registers</span>
+<span id="L53" class="LineNr">53 </span>    53/push-ebx
+<span id="L54" class="LineNr">54 </span>    <span class="subxComment"># if (n &lt;= 1) return 1</span>
+<span id="L55" class="LineNr">55 </span>    b8/copy-to-eax 1/imm32
+<span id="L56" class="LineNr">56 </span>    81 7/subop/compare *(ebp+8) 1/imm32
+<span id="L57" class="LineNr">57 </span>    7e/jump-if-&lt;= $factorial:end/disp8
+<span id="L58" class="LineNr">58 </span>    <span class="subxComment"># ebx = n-1</span>
+<span id="L59" class="LineNr">59 </span>    8b/-&gt; *(ebp+8) 3/r32/ebx
+<span id="L60" class="LineNr">60 </span>    4b/decrement-ebx
+<span id="L61" class="LineNr">61 </span>    <span class="subxComment">#</span>
+<span id="L62" class="LineNr">62 </span>    (<a href='factorial3.subx.html#L48'>factorial</a> %ebx)  <span class="subxComment"># =&gt; eax</span>
+<span id="L63" class="LineNr">63 </span>    <span class="subxComment"># return n * factorial(n-1)</span>
+<span id="L64" class="LineNr">64 </span>    f7 4/subop/multiply-into-eax *(ebp+8)
+<span id="L65" class="LineNr">65 </span>    <span class="subxComment"># TODO: check for overflow</span>
+<span id="L66" class="LineNr">66 </span><span class="Constant">$factorial:end</span>:
+<span id="L67" class="LineNr">67 </span>    <span class="subxComment"># restore registers</span>
+<span id="L68" class="LineNr">68 </span>    5b/pop-to-ebx
+<span id="L69" class="LineNr">69 </span>    <span class="subxS1Comment"># . epilogue</span>
+<span id="L70" class="LineNr">70 </span>    89/&lt;- %esp 5/r32/ebp
+<span id="L71" class="LineNr">71 </span>    5d/pop-to-ebp
+<span id="L72" class="LineNr">72 </span>    c3/return
+<span id="L73" class="LineNr">73 </span>
+<span id="L74" class="LineNr">74 </span><span class="subxTest">test-factorial</span>:
+<span id="L75" class="LineNr">75 </span>    (<a href='factorial3.subx.html#L48'>factorial</a> 5)
+<span id="L76" class="LineNr">76 </span>    (<a href='../051test.subx.html#L24'>check-ints-equal</a> %eax 0x78 <span class="Constant">&quot;F - test-factorial&quot;</span>)
+<span id="L77" class="LineNr">77 </span>    c3/return
+</pre>
+</body>
+</html>
+<!-- vim: set foldmethod=manual : -->
diff --git a/html/apps/factorial4.subx.html b/html/apps/factorial4.subx.html
new file mode 100644
index 00000000..d8cdec7d
--- /dev/null
+++ b/html/apps/factorial4.subx.html
@@ -0,0 +1,146 @@
+<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01//EN" "http://www.w3.org/TR/html4/strict.dtd">
+<html>
+<head>
+<meta http-equiv="content-type" content="text/html; charset=UTF-8">
+<title>Mu - apps/factorial4.subx</title>
+<meta name="Generator" content="Vim/8.1">
+<meta name="plugin-version" content="vim8.1_v1">
+<meta name="syntax" content="none">
+<meta name="settings" content="number_lines,use_css,pre_wrap,no_foldcolumn,expand_tabs,line_ids,prevent_copy=">
+<meta name="colorscheme" content="minimal-light">
+<style type="text/css">
+<!--
+pre { white-space: pre-wrap; font-family: monospace; color: #000000; background-color: #c6c6c6; }
+body { font-size:12pt; font-family: monospace; color: #000000; background-color: #c6c6c6; }
+a { color:inherit; }
+* { font-size:12pt; font-size: 1em; }
+.subxComment { color: #005faf; }
+.subxFunction { color: #af5f00; text-decoration: underline; }
+.LineNr { }
+.subxS1Comment { color: #0000af; }
+.SpecialChar { color: #d70000; }
+.Constant { color: #008787; }
+.subxTest { color: #5f8700; }
+.subxH1Comment { color: #005faf; text-decoration: underline; }
+-->
+</style>
+
+<script type='text/javascript'>
+<!--
+
+/* function to open any folds containing a jumped-to line before jumping to it */
+function JumpToLine()
+{
+  var lineNum;
+  lineNum = window.location.hash;
+  lineNum = lineNum.substr(1); /* strip off '#' */
+
+  if (lineNum.indexOf('L') == -1) {
+    lineNum = 'L'+lineNum;
+  }
+  var lineElem = document.getElementById(lineNum);
+  /* Always jump to new location even if the line was hidden inside a fold, or
+   * we corrected the raw number to a line ID.
+   */
+  if (lineElem) {
+    lineElem.scrollIntoView(true);
+  }
+  return true;
+}
+if ('onhashchange' in window) {
+  window.onhashchange = JumpToLine;
+}
+
+-->
+</script>
+</head>
+<body onload='JumpToLine();'>
+<a href='https://github.com/akkartik/mu/blob/master/apps/factorial4.subx'>https://github.com/akkartik/mu/blob/master/apps/factorial4.subx</a>
+<pre id='vimCodeElement'>
+<span id="L1" class="LineNr"> 1 </span><span class="subxComment">## compute the factorial of 5, and return the result in the exit code</span>
+<span id="L2" class="LineNr"> 2 </span><span class="subxComment">#</span>
+<span id="L3" class="LineNr"> 3 </span><span class="subxComment"># To run:</span>
+<span id="L4" class="LineNr"> 4 </span><span class="subxComment">#   $ ./ntranslate init.linux 0*.subx apps/factorial.subx -o apps/factorial</span>
+<span id="L5" class="LineNr"> 5 </span><span class="subxComment">#   $ ./subx run apps/factorial</span>
+<span id="L6" class="LineNr"> 6 </span><span class="subxComment"># Expected result:</span>
+<span id="L7" class="LineNr"> 7 </span><span class="subxComment">#   $ echo $?</span>
+<span id="L8" class="LineNr"> 8 </span><span class="subxComment">#   120</span>
+<span id="L9" class="LineNr"> 9 </span><span class="subxComment">#</span>
+<span id="L10" class="LineNr">10 </span><span class="subxComment"># You can also run the automated test suite:</span>
+<span id="L11" class="LineNr">11 </span><span class="subxComment">#   $ ./subx run apps/factorial test</span>
+<span id="L12" class="LineNr">12 </span><span class="subxComment"># Expected output:</span>
+<span id="L13" class="LineNr">13 </span><span class="subxComment">#   ........</span>
+<span id="L14" class="LineNr">14 </span><span class="subxComment"># Every '.' indicates a passing test. Failing tests get a 'F'.</span>
+<span id="L15" class="LineNr">15 </span>
+<span id="L16" class="LineNr">16 </span>== code
+<span id="L17" class="LineNr">17 </span>
+<span id="L18" class="LineNr">18 </span><span class="SpecialChar">Entry</span>:  <span class="subxComment"># run tests if necessary, compute `factorial(5)` if not</span>
+<span id="L19" class="LineNr">19 </span>    <span class="subxS1Comment"># . prologue</span>
+<span id="L20" class="LineNr">20 </span>    89/&lt;- %ebp 4/r32/esp
+<span id="L21" class="LineNr">21 </span>
+<span id="L22" class="LineNr">22 </span>    <span class="subxComment"># initialize heap</span>
+<span id="L23" class="LineNr">23 </span>    (<a href='../053new-segment.subx.html#L41'>new-segment</a> 0x10000 <span class="SpecialChar"><a href='../069allocate.subx.html#L22'>Heap</a></span>)
+<span id="L24" class="LineNr">24 </span>
+<span id="L25" class="LineNr">25 </span>    <span class="subxH1Comment"># - if argc &gt; 1, then return run_tests()</span>
+<span id="L26" class="LineNr">26 </span>    {
+<span id="L27" class="LineNr">27 </span>      <span class="subxComment"># if (argc &lt;= 1) break</span>
+<span id="L28" class="LineNr">28 </span>      81 7/subop/compare *ebp 1/imm32
+<span id="L29" class="LineNr">29 </span>      7e/jump-if-lesser-or-equal <span class="Constant">break</span>/disp8
+<span id="L30" class="LineNr">30 </span>      <span class="subxComment"># if (!kernel-string-equal?(argv[1], &quot;test&quot;)) break</span>
+<span id="L31" class="LineNr">31 </span>      (<a href='../052kernel-string-equal.subx.html#L31'>kernel-string-equal?</a> *(ebp+8) <span class="Constant">&quot;test&quot;</span>)  <span class="subxComment"># =&gt; eax</span>
+<span id="L32" class="LineNr">32 </span>      3d/compare-eax-and 0/imm32
+<span id="L33" class="LineNr">33 </span>      74/jump-if-equal <span class="Constant">break</span>/disp8
+<span id="L34" class="LineNr">34 </span>      <span class="subxComment">#</span>
+<span id="L35" class="LineNr">35 </span>      (run-tests)
+<span id="L36" class="LineNr">36 </span>      <span class="subxComment"># eax = *Num-test-failures</span>
+<span id="L37" class="LineNr">37 </span>      8b/-&gt; *<span class="SpecialChar"><a href='../051test.subx.html#L90'>Num-test-failures</a></span> 3/r32/ebx
+<span id="L38" class="LineNr">38 </span>    }
+<span id="L39" class="LineNr">39 </span>    <span class="subxComment"># if (argc &lt;= 1) factorial(5)</span>
+<span id="L40" class="LineNr">40 </span>    {
+<span id="L41" class="LineNr">41 </span>      <span class="subxComment"># if (argc &gt; 1) break</span>
+<span id="L42" class="LineNr">42 </span>      81 7/subop/compare *ebp 1/imm32
+<span id="L43" class="LineNr">43 </span>      7f/jump-if-greater <span class="Constant">break</span>/disp8
+<span id="L44" class="LineNr">44 </span>      <span class="subxComment"># eax = factorial(5)</span>
+<span id="L45" class="LineNr">45 </span>      (<a href='factorial4.subx.html#L53'>factorial</a> 5)
+<span id="L46" class="LineNr">46 </span>      <span class="subxComment"># syscall(exit, eax)</span>
+<span id="L47" class="LineNr">47 </span>      89/&lt;- %ebx 0/r32/eax
+<span id="L48" class="LineNr">48 </span>    }
+<span id="L49" class="LineNr">49 </span>
+<span id="L50" class="LineNr">50 </span>    b8/copy-to-eax 1/imm32/exit
+<span id="L51" class="LineNr">51 </span>    cd/syscall 0x80/imm8
+<span id="L52" class="LineNr">52 </span>
+<span id="L53" class="LineNr">53 </span><span class="subxFunction">factorial</span>:  <span class="subxComment"># n : int -&gt; int/eax</span>
+<span id="L54" class="LineNr">54 </span>    <span class="subxS1Comment"># . prologue</span>
+<span id="L55" class="LineNr">55 </span>    55/push-ebp
+<span id="L56" class="LineNr">56 </span>    89/&lt;- %ebp 4/r32/esp
+<span id="L57" class="LineNr">57 </span>    <span class="subxComment"># save registers</span>
+<span id="L58" class="LineNr">58 </span>    53/push-ebx
+<span id="L59" class="LineNr">59 </span>    <span class="subxComment"># if (n &lt;= 1) return 1</span>
+<span id="L60" class="LineNr">60 </span>    81 7/subop/compare *(ebp+8) 1/imm32
+<span id="L61" class="LineNr">61 </span>    {
+<span id="L62" class="LineNr">62 </span>      7f/jump-if-greater <span class="Constant">break</span>/disp8
+<span id="L63" class="LineNr">63 </span>      b8/copy-to-eax 1/imm32
+<span id="L64" class="LineNr">64 </span>    }
+<span id="L65" class="LineNr">65 </span>    <span class="subxComment"># if (n &gt; 1) return n * factorial(n-1)</span>
+<span id="L66" class="LineNr">66 </span>    {
+<span id="L67" class="LineNr">67 </span>      7e/jump-if-lesser-or-equal <span class="Constant">break</span>/disp8
+<span id="L68" class="LineNr">68 </span>      8b/-&gt; *(ebp+8) 3/r32/ebx
+<span id="L69" class="LineNr">69 </span>      4b/decrement-ebx
+<span id="L70" class="LineNr">70 </span>      (<a href='factorial4.subx.html#L53'>factorial</a> %ebx)  <span class="subxComment"># =&gt; eax</span>
+<span id="L71" class="LineNr">71 </span>      f7 4/subop/multiply-into-eax *(ebp+8)
+<span id="L72" class="LineNr">72 </span>    }
+<span id="L73" class="LineNr">73 </span>    <span class="subxComment"># restore registers</span>
+<span id="L74" class="LineNr">74 </span>    5b/pop-to-ebx
+<span id="L75" class="LineNr">75 </span>    <span class="subxS1Comment"># . epilogue</span>
+<span id="L76" class="LineNr">76 </span>    89/&lt;- %esp 5/r32/ebp
+<span id="L77" class="LineNr">77 </span>    5d/pop-to-ebp
+<span id="L78" class="LineNr">78 </span>    c3/return
+<span id="L79" class="LineNr">79 </span>
+<span id="L80" class="LineNr">80 </span><span class="subxTest">test-factorial</span>:
+<span id="L81" class="LineNr">81 </span>    (<a href='factorial4.subx.html#L53'>factorial</a> 5)
+<span id="L82" class="LineNr">82 </span>    (<a href='../051test.subx.html#L24'>check-ints-equal</a> %eax 0x78 <span class="Constant">&quot;F - test-factorial&quot;</span>)
+<span id="L83" class="LineNr">83 </span>    c3/return
+</pre>
+</body>
+</html>
+<!-- vim: set foldmethod=manual : -->