1 //: Routines can be put in a 'waiting' state, from which it will be ready to
  2 //: run again when a specific memory location changes its value. This is Mu's
  3 //: basic technique for orchestrating the order in which different routines
  4 //: operate.
  5 
  6 :(scenario wait_for_location)
  7 def f1 [
  8   10:num <- copy 34
  9   start-running f2
 10   20:location <- copy 10/unsafe
 11   wait-for-reset-then-set 20:location
 12   # wait for f2 to run and reset location 1
 13   30:num <- copy 10:num
 14 ]
 15 def f2 [
 16   10:location <- copy 0/unsafe
 17 ]
 18 +schedule: f1
 19 +run: waiting for location 10 to reset
 20 +schedule: f2
 21 +schedule: waking up routine 1
 22 +schedule: f1
 23 +mem: storing 1 in location 30
 24 
 25 //: define the new state that all routines can be in
 26 
 27 :(before "End routine States")
 28 WAITING,
 29 :(before "End routine Fields")
 30 // only if state == WAITING
 31 int waiting_on_location;
 32 :(before "End routine Constructor")
 33 waiting_on_location = 0;
 34 
 35 :(before "End Mu Test Teardown")
 36 if (Passed && any_routines_waiting())
 37   raise << Current_scenario->name << ": deadlock!\n" << end();
 38 :(before "End Run Routine")
 39 if (any_routines_waiting()) {
 40   raise << "deadlock!\n" << end();
 41   dump_waiting_routines();
 42 }
 43 :(before "End Test Teardown")
 44 if (Passed && any_routines_with_error())
 45   raise << "some routines died with errors\n" << end();
 46 :(code)
 47 bool any_routines_waiting() {
 48   for (int i = 0;  i < SIZE(Routines);  ++i) {
 49   ¦ if (Routines.at(i)->state == WAITING)
 50   ¦ ¦ return true;
 51   }
 52   return false;
 53 }
 54 void dump_waiting_routines() {
 55   for (int i = 0;  i < SIZE(Routines);  ++i) {
 56   ¦ if (Routines.at(i)->state == WAITING)
 57   ¦ ¦ cerr << i << ": " << routine_label(Routines.at(i)) << '\n';
 58   }
 59 }
 60 
 61 :(scenario wait_for_location_can_deadlock)
 62 % Hide_errors = true;
 63 def main [
 64   10:num <- copy 1
 65   20:location <- copy 10/unsafe
 66   wait-for-reset-then-set 20:location
 67 ]
 68 +error: deadlock!
 69 
 70 //: Primitive recipe to put routines in that state.
 71 //: This primitive is also known elsewhere as compare-and-set (CAS). Used to
 72 //: build locks.
 73 
 74 :(before "End Primitive Recipe Declarations")
 75 WAIT_FOR_RESET_THEN_SET,
 76 :(before "End Primitive Recipe Numbers")
 77 put(Recipe_ordinal, "wait-for-reset-then-set", WAIT_FOR_RESET_THEN_SET);
 78 :(before "End Primitive Recipe Checks")
 79 case WAIT_FOR_RESET_THEN_SET: {
 80   if (SIZE(inst.ingredients) != 1) {
 81   ¦ raise << maybe(get(Recipe, r).name) << "'wait-for-reset-then-set' requires exactly one ingredient, but got '"pre { line-height: 125%; }
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<a href='https://github.com/akkartik/mu/blob/main/baremetal/life.mu'>https://github.com/akkartik/mu/blob/main/baremetal/life.mu</a>
<pre id='vimCodeElement'>
<span id="L1" class="LineNr">  1 </span><span class="muComment"># Conway's Game of Life</span>
<span id="L2" class="LineNr">  2 </span><span class="muComment">#</span>
<span id="L3" class="LineNr">  3 </span><span class="muComment"># To build:</span>
<span id="L4" class="LineNr">  4 </span><span class="muComment">#   $ ./translate_mu_baremetal baremetal/life.mu</span>
<span id="L5" class="LineNr">  5 </span><span class="muComment"># To run:</span>
<span id="L6" class="LineNr">  6 </span><span class="muComment">#   $ qemu-system-i386 disk.img</span>
<span id="L7" class="LineNr">  7 </span>
<span id="L8" class="LineNr">  8 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='life.mu.html#L8'>state</a></span> _grid: (addr array boolean), x: int, y: int<span class="PreProc"> -&gt; </span>_/<span class="Constant">eax</span>: boolean <span class="Delimiter">{</span>
<span id="L9" class="LineNr">  9 </span>  <span class="muComment"># clip at the edge</span>
<span id="L10" class="LineNr"> 10 </span>  compare x, <span class="Constant">0</span>
<span id="L11" class="LineNr"> 11 </span>  <span class="Delimiter">{</span>
<span id="L12" class="LineNr"> 12 </span>    <span class="PreProc">break-if-&gt;=</span>
<span id="L13" class="LineNr"> 13 </span>    <span class="PreProc">return</span> <span class="Constant">0</span>/false
<span id="L14" class="LineNr"> 14 </span>  <span class="Delimiter">}</span>
<span id="L15" class="LineNr"> 15 </span>  compare y, <span class="Constant">0</span>
<span id="L16" class="LineNr"> 16 </span>  <span class="Delimiter">{</span>
<span id="L17" class="LineNr"> 17 </span>    <span class="PreProc">break-if-&gt;=</span>
<span id="L18" class="LineNr"> 18 </span>    <span class="PreProc">return</span> <span class="Constant">0</span>/false
<span id="L19" class="LineNr"> 19 </span>  <span class="Delimiter">}</span>
<span id="L20" class="LineNr"> 20 </span>  compare x, <span class="Constant">0x100</span>/width
<span id="L21" class="LineNr"> 21 </span>  <span class="Delimiter">{</span>
<span id="L22" class="LineNr"> 22 </span>    <span class="PreProc">break-if-&lt;</span>
<span id="L23" class="LineNr"> 23 </span>    <span class="PreProc">return</span> <span class="Constant">0</span>/false
<span id="L24" class="LineNr"> 24 </span>  <span class="Delimiter">}</span>
<span id="L25" class="LineNr"> 25 </span>  compare y, <span class="Constant">0xc0</span>/height
<span id="L26" class="LineNr"> 26 </span>  <span class="Delimiter">{</span>
<span id="L27" class="LineNr"> 27 </span>    <span class="PreProc">break-if-&lt;</span>
<span id="L28" class="LineNr"> 28 </span>    <span class="PreProc">return</span> <span class="Constant">0</span>/false
<span id="L29" class="LineNr"> 29 </span>  <span class="Delimiter">}</span>
<span id="L30" class="LineNr"> 30 </span>  <span class="PreProc">var</span> idx/<span class="Constant">eax</span>: int <span class="SpecialChar">&lt;-</span> copy y
<span id="L31" class="LineNr"> 31 </span>  idx <span class="SpecialChar">&lt;-</span> shift-left <span class="Constant">8</span>/log2width
<span id="L32" class="LineNr"> 32 </span>  idx <span class="SpecialChar">&lt;-</span> add x
<span id="L33" class="LineNr"> 33 </span>  <span class="PreProc">var</span> grid/<span class="Constant">esi</span>: (addr array boolean) <span class="SpecialChar">&lt;-</span> copy _grid
<span id="L34" class="LineNr"> 34 </span>  <span class="PreProc">var</span> result/<span class="Constant">eax</span>: (addr boolean) <span class="SpecialChar">&lt;-</span> index grid, idx
<span id="L35" class="LineNr"> 35 </span>  <span class="PreProc">return</span> *result
<span id="L36" class="LineNr"> 36 </span><span class="Delimiter">}</span>
<span id="L37" class="LineNr"> 37 </span>
<span id="L38" class="LineNr"> 38 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='life.mu.html#L38'>set-state</a></span> _grid: (addr array boolean), x: int, y: int, val: boolean <span class="Delimiter">{</span>
<span id="L39" class="LineNr"> 39 </span>  <span class="muComment"># don't bother checking bounds</span>
<span id="L40" class="LineNr"> 40 </span>  <span class="PreProc">var</span> idx/<span class="Constant">eax</span>: int <span class="SpecialChar">&lt;-</span> copy y
<span id="L41" class="LineNr"> 41 </span>  idx <span class="SpecialChar">&lt;-</span> shift-left <span class="Constant">8</span>/log2width
<span id="L42" class="LineNr"> 42 </span>  idx <span class="SpecialChar">&lt;-</span> add x
<span id="L43" class="LineNr"> 43 </span>  <span class="PreProc">var</span> grid/<span class="Constant">esi</span>: (addr array boolean) <span class="SpecialChar">&lt;-</span> copy _grid
<span id="L44" class="LineNr"> 44 </span>  <span class="PreProc">var</span> result/<span class="Constant">eax</span>: (addr boolean) <span class="SpecialChar">&lt;-</span> index grid, idx
<span id="L45" class="LineNr"> 45 </span>  <span class="PreProc">var</span> src/<span class="Constant">ecx</span>: boolean <span class="SpecialChar">&lt;-</span> copy val
<span id="L46" class="LineNr"> 46 </span>  copy-to *result, src
<span id="L47" class="LineNr"> 47 </span><span class="Delimiter">}</span>
<span id="L48" class="LineNr"> 48 </span>
<span id="L49" class="LineNr"> 49 </span><span class="PreProc">fn</span> <span class="muFunction"><a href='life.mu.html#L49'>num-live-neighbors</a></span> grid: (addr array boolean), x: int, y: int<span class="PreProc"> -&gt; </span>_/<span class="Constant">eax</span>: int <span class="Delimiter">{</span>
<span id="L50" class="LineNr"> 50 </span>  <span class="PreProc">var</span> result/<span class="Constant">edi</span>: int <span class="SpecialChar">&lt;-</span> copy <span class="Constant">0</span>
<span id="L51" class="LineNr"> 51 </span>  <span class="muComment"># row above: zig</span>
<span id="L52" class="LineNr"> 52 </span>  decrement y
<span id="L53" class="LineNr"> 53 </span>  decrement x
<span id="L54" class="LineNr"> 54 </span>  <span class="PreProc">var</span> s/<span class="Constant">eax</span>: boolean <span class="SpecialChar">&lt;-</span> <a href='life.mu.html#L8'>state</a> grid, x, y
<span id="L55" class="LineNr"> 55 </span>  <span class="Delimiter">{</span>
<span id="L56" class="LineNr"> 56 </span>    compare s, <span class="Constant">0</span>/false
<span id="L57" class="LineNr"> 57 </span>    <span class="PreProc">break-if-=</span>
<span id="L58" class="LineNr"> 58 </span>    result <span class="SpecialChar">&lt;-</span> increment
<span id="L59" class="LineNr"> 59 </span>  <span class="Delimiter">}</span>
<span id="L60" class="LineNr"> 60 </span>  increment x
<span id="L61" class="LineNr"> 61 </span>  s <span class="SpecialChar">&lt;-</span> <a href='life.mu.html#L8'>state</a> grid, x, y
<span id="L62" class="LineNr"> 62 </span>  <span class="Delimiter">{</span>
<span id="L63" class="LineNr"> 63 </span>    compare s, <span class="Constant">0</span>/false
<span id="L64" class="LineNr"> 64 </span>    <span class="PreProc">break-if-=</span>
<span id="L65" class="LineNr"> 65 </span>    result <span class="SpecialChar">&lt;-</span> increment
<span id="L66" class="LineNr"> 66 </span>  <span class="Delimiter">}</span>
<span id="L67" class="LineNr"> 67 </span>  increment x
<span id="L68" class="LineNr"> 68 </span>  s <span class="SpecialChar">&lt;-</span> <a href='life.mu.html#L8'>state</a> grid, x, y
<span id="L69" class="LineNr"> 69 </span>  <span class="Delimiter">{</span>
<span id="L70" class="LineNr"> 70 </span>    compare s, <span class="Constant">0</span>/false
<span id="L71" class="LineNr"> 71 </span>    <span class="PreProc">break-if-=</span>
<span id="L72" class="LineNr"> 72 </span>    result <span class="SpecialChar">&lt;-</span> increment
<span id="L73" class="LineNr"> 73 </span>  <span class="Delimiter">}</span>
<span id="L74" class="LineNr"> 74 </span>  <span class="muComment"># curr row: zag</span>
<span id="L75" class="LineNr"> 75 </span>  increment y
<span id="L76" class="LineNr"> 76 </span>  s <span class="SpecialChar">&lt;-</span> <a href='life.mu.html#L8'>state</a> grid, x, y
<span id="L77" class="LineNr"> 77 </span>  <span class="Delimiter">{</span>
<span id="L78" class="LineNr"> 78 </span>    compare s, <span class="Constant">0</span>/false
<span id="L79" class="LineNr"> 79 </span>    <span class="PreProc">break-if-=</span>
<span id="L80" class="LineNr"> 80 </span>    result <span class="SpecialChar">&lt;-</span> increment
<span id="L81" class="LineNr"> 81 </span>  <span class="Delimiter">}</span>
<span id="L82" class="LineNr"> 82 </span>  subtract-from x, <span class="Constant">2</span>
<span id="L83" class="LineNr"> 83 </span>  s <span class="SpecialChar">&lt;-</span> <a href='life.mu.html#L8'>state</a> grid, x, y
<span id="L84" class="LineNr"> 84 </span>  <span class="Delimiter">{</span>
<span id="L85" class="LineNr"> 85 </span>    compare s, <span class="Constant">0</span>/false
<span id="L86" class="LineNr"> 86 </span>    <span class="PreProc">break-if-=</span>
<span id="L87" class="LineNr"> 87 </span>    result <span class="SpecialChar">&lt;-</span> increment
<span id="L88" class="LineNr"> 88 </span>  <span class="Delimiter">}</span>
<span id="L89" class="LineNr"> 89 </span>  <span class="muComment"># row below: zig</span>
<span id="L90" class="LineNr"> 90 </span>  increment y
<span id="L91" class="LineNr"> 91 </span>  s <span class="SpecialChar">&lt;-</span> <a href='life.mu.html#L8'>state</a> grid, x, y
<span id="L92" class="LineNr"> 92 </span>  <span class="Delimiter">{</span>
<span id="L93" class="LineNr"> 93 </span>    compare s, <span class="Constant">0</span>/false
<span id="L94" class="LineNr"> 94 </span>    <span class="PreProc">break-if-=</span>
<span id="L95" class="LineNr"> 95 </span>    result <span class="SpecialChar">&lt;-</span> increment
<span id="L96" class="LineNr"> 96 </span>  <span class="Delimiter">}</span>
<span id="L97" class="LineNr"> 97 </span>  increment x
<span id="L98" class="LineNr"> 98 </span>  s <span class="SpecialChar">&lt;-</span> <a href='life.mu.html#L8'>state</a> grid, x, y
<span id="L99" class="LineNr"> 99 </span>  <span class="Delimiter">{</span>
<span id="L100" class="LineNr">100 </span>    compare s, <span class="Constant">0</span>/false
<span id="L101" class="LineNr">101 </span>    <span class="PreProc">break-if-=</span>
<span id="L102" class="LineNr">102 </span>    result <span class="SpecialChar">&lt;-</span> increment
<span id="L103" class="LineNr">103 </span>  <span class="Delimiter">}</span>
<span id="L104" class="LineNr">104 </span>  increment x
<span id="L105" class="LineNr">105 </span>  s <span class="SpecialChar">&lt;-</span> <a href='life.mu.html#L8'>state</a> grid, x, y
<span id="L106" class="LineNr">106 </span>  <span class="Delimiter">{</span>
<span id="L107" class="LineNr">107 </span>    compare s, <span class="Constant">0</span>/false
<span id="L108" class="LineNr">108 </span>    <span class="PreProc">break-if-=</span>
<span id="L109" class="LineNr">109 </span>    result <span class="SpecialChar">&lt;-</span> increment
<span id="L110" class="LineNr">110 </span>  <span class="Delimiter">}</span>
<span id<