Preserve state across hot code reload!!

asm/asm.fnl

@@ -115,7 +115,7 @@
   ;   takes the form [:op args]
   ; pdat - a parsed dat; takes the form {:type type :addr addr ...}
   (local dat-parser {})
-  (fn new-block [last-symbol] {:type :block :pdats [] :symbols {} :globals {} : last-symbol})
+  (fn new-block [last-symbol] {:type :block :pdats [] :preserved {} :symbols {} :globals {} : last-symbol})
 
   (fn parse-dats [block dats]
     (each [_ dat (ipairs dats)]
@@ -139,7 +139,10 @@
             (table.insert block.pdats pdat)
             (when pdat.globals
               (each [name _ (pairs pdat.globals)]
-                (tset block.globals name (length block.pdats))))))))
+                (tset block.globals name (length block.pdats))))
+            (when pdat.preserved
+              (each [name pdat-preserved (pairs pdat.preserved)]
+                (tset block.preserved name pdat-preserved)))))))
     block)
 
   (fn dat-parser.op [op]
@@ -166,6 +169,13 @@
     nil)
 
   (fn dat-parser.align [pad] {:type :pad :align (. pad 2)})
+  (fn dat-parser.hot-preserve [[_ label & dats] block]
+    (let [preserve-block (new-block)]
+      (tset block.preserved label preserve-block)
+      (tset preserve-block.globals label true)
+      (parse-dats preserve-block [label])
+      (parse-dats preserve-block dats)
+      preserve-block))
 
   (local pdat-processor {
     :op {}
@@ -338,6 +348,17 @@
        (self.dbgfile:close)
        (set self.dbgfile nil))
      self)
+   :read-hotswap
+   (fn [self machine]
+     (let [hotswap {}]
+       (each [_ block (pairs self.org-to-block)]
+         (each [label pdat (pairs block.preserved)]
+           (tset hotswap label (machine:read pdat.addr pdat.size))))
+       hotswap))
+   :write-hotswap
+   (fn [self machine hotswap]
+     (each [label bytes (pairs hotswap)]
+       (machine:write (self:lookup-addr label) bytes)))
    :upload
    (fn [self machine]
      (if machine.upload (machine:upload self)

asm/vm.fnl

@@ -385,8 +385,9 @@
 
   (fn vm.var [self name init]
     (self.code:append name [:jsr :$dovar]
+      [:hot-preserve (.. :G-HOT-PRESERVE- name)
                      (if (= (type init) :table) init
-          [:dw init])))
+                       [:dw init])]))
 
   (vm:def :$doconst ; usage: [jsr :$doconst] followed by two bytes
     (vm:reserve)

game/defs.fnl

@@ -132,7 +132,7 @@
     [:jmp (if (= (or map.moveword "") "") :move-noop map.moveword)]
     [:jmp (if (= (or map.loadword "") "") :next map.loadword)]))
 
-(vm.code:append :map-ptr [:db 0] :map-page [:db 0])
+(vm.code:append :map-ptr [:db 0] [:hot-preserve :map-page [:db 0]])
 (vm:word :map :lit :map-ptr :get)
 (vm:word :entity-count :map 240 :+ :bget)
 (vm:word :map-player-yx-ptr 241 :+)

game/init.fnl

@@ -45,7 +45,7 @@
   [:vm :hires
     :lit :map1 :load-level
     (vm:forever
-      (vm:hotswap-sync :lit :map1 :load-level)
+      (vm:hotswap-sync :full-redraw)
       :interactive-eval-checkpoint
       :handle-key
     )

link/mame.fnl

@@ -87,6 +87,20 @@
   (when self.monitor (self.monitor:shutdown-session))
   (when (nrepl:connected?) (nrepl:disconnect))
   (set self.breakpoints {}))
+(fn Machine.read [self addr len]
+  (-> (self:coro-eval
+        (.. "(let [bencode (require :bencode)
+                   addr " addr "
+                   len " len "
+                   mem (. manager.machine.devices ::maincpu :spaces :program)]
+               (var bytes \"\")
+               (print :reading len :from addr)
+               (for [i 1 len]
+                 (set bytes (.. bytes (string.char (mem:read_u8 (+ addr i -1))))))
+               bytes)"))
+      ; result is piped through fennelview; have to eval it to turn it back into bytes
+      ; would be nice if io.write worked
+      (fennel.eval)))
 (fn Machine.write [self addr bytes]
   (if (> (bytes:len) 0x1000)
         (do (self:write addr (bytes:sub 1 0x1000))
@@ -103,11 +117,11 @@
   (self:eval "(manager.machine:soft_reset)")
   (self:eval (string.format "(emu.keypost \"CALL-151\\n %xG\\n\")" (prg:lookup-addr prg.start-symbol))))
 (fn Machine.reboot [self] (self:eval "(manager.machine:hard_reset)"))
-(fn Machine.coro-eval [self code]
+(fn Machine.coro-eval [self code ?handlers]
   (var result nil)
   (local append-to-result #(set result (.. (or result "") $2)))
   (self:eval code
-    (self:coro-handlers (coroutine.running) {:value append-to-result :out append-to-result}))
+    (self:coro-handlers (coroutine.running) {:value append-to-result :out append-to-result} ?handlers))
   (coroutine.yield)
   (or result "<no result>"))
 (fn Machine.dbgcmd [self cmd ?handlers]
@@ -130,10 +144,14 @@
 (fn Machine.hotswap [self prg-old prg-new]
   (local addr (prg-old:lookup-addr :debug-stub))
   (self:set-bp addr
-    (fn [] (self:clear-bp addr)
+    #(util.in-coro (fn []
+       (self:clear-bp addr)
+       (local hotswap (prg-old:read-hotswap self))
        (prg-new:upload self)
+       (prg-new:write-hotswap self hotswap)
        (self:jump (prg-new:lookup-addr :on-hotswap))
-           (self:continue))))
+       (self:continue)))))
+
 (fn Machine.overlay [self prg-overlay]
   (self:step)
   (prg-overlay:upload self)

link/nrepl-session.fnl

@@ -19,7 +19,7 @@
 (fn Session.shutdown-session [self]
   (set self.queue [])
   (set self.in-progress false)
-  (set self.sesion nil))
+  (set self.session nil))
 
 (fn Session.cleanup-handlers [self]
   {:status/done #(self:done-msg)
@@ -63,9 +63,11 @@
 (fn Session.eval [self code ?handlers]
   (self:send {:op :eval : code} ?handlers))
 
+(fn Session.input-handler [self input]
+  {:status/need-input #(self:send-oob {:op :stdin :stdin input})})
+
 (fn Session.eval-input [self code input ?handlers]
   (self:send {:op :eval : code}
-    (lume.merge (or ?handlers {})
-      {:status/need-input #(self:send-oob {:op :stdin :stdin input})})))
+    (lume.merge (or ?handlers {}) (self:input-handler input))))
 
 Session