From 43355dec6f61b14a00ccf197bdb219632d073746 Mon Sep 17 00:00:00 2001
From: Jeff Parsons <Jeff@pcjs.org>
Date: Tue, 31 May 2016 09:59:19 -0700
Subject: [PATCH] Support for message buffering (PC8080 only; needs to be added
 to PCx86, too)

---
 modules/pc8080/lib/debugger.js | 16 ++++++++++++++++
 modules/pc8080/lib/messages.js |  5 +++--
 modules/pc8080/lib/video.js    | 21 ++++++++++++++++++---
 3 files changed, 37 insertions(+), 5 deletions(-)

diff --git a/modules/pc8080/lib/debugger.js b/modules/pc8080/lib/debugger.js
index a2fdbb4ff..18d6e86e6 100644
--- a/modules/pc8080/lib/debugger.js
+++ b/modules/pc8080/lib/debugger.js
@@ -696,7 +696,11 @@ if (DEBUGGER) {
         /*
          * Now we turn to message actions rather than message types; for example, setting "halt"
          * on or off doesn't enable "halt" messages, but rather halts the CPU on any message above.
+         *
+         * Similarly, "m buffer on" turns on message buffering, defering the display of all messages
+         * until "m buffer off" is issued.
          */
+        "buffer":   Messages.BUFFER,
         "halt":     Messages.HALT
     };
 
@@ -1302,6 +1306,7 @@ if (DEBUGGER) {
         this.dbg = this;
         this.bitsMessage = this.bitsWarning = Messages.WARN;
         this.sMessagePrev = null;
+        this.aMessageBuffer = [];
         /*
          * Internally, we use "key" instead of "keys", since the latter is a method on JavasScript objects,
          * but externally, we allow the user to specify "keys"; "kbd" is also allowed as shorthand for "keyboard".
@@ -1548,6 +1553,11 @@ if (DEBUGGER) {
             sMessage += " at " + this.toHexAddr(this.newAddr(this.cpu.getPC()));
         }
 
+        if (this.bitsMessage & Messages.BUFFER) {
+            this.aMessageBuffer.push(sMessage);
+            return;
+        }
+
         if (this.sMessagePrev && sMessage == this.sMessagePrev) return;
         this.sMessagePrev = sMessage;
 
@@ -3921,6 +3931,12 @@ if (DEBUGGER) {
                 else if (asArgs[2] == "off") {
                     this.bitsMessage &= ~bitsMessage;
                     fCriteria = false;
+                    if (bitsMessage == Messages.BUFFER) {
+                        for (var i = 0; i < this.aMessageBuffer.length; i++) {
+                            this.println(this.aMessageBuffer[i]);
+                        }
+                        this.aMessageBuffer = [];
+                    }
                 }
             }
         }
diff --git a/modules/pc8080/lib/messages.js b/modules/pc8080/lib/messages.js
index accd8f265..dc131b3fa 100644
--- a/modules/pc8080/lib/messages.js
+++ b/modules/pc8080/lib/messages.js
@@ -45,8 +45,9 @@ var Messages = {
     SERIAL:     0x00800000,
     SPEAKER:    0x02000000,
     COMPUTER:   0x04000000,
-    LOG:        0x20000000,
-    WARN:       0x40000000,
+    LOG:        0x10000000,
+    WARN:       0x20000000,
+    BUFFER:     0x40000000,
     HALT:       0x80000000|0
 };
 
diff --git a/modules/pc8080/lib/video.js b/modules/pc8080/lib/video.js
index 345b0c7a3..0bbda415e 100644
--- a/modules/pc8080/lib/video.js
+++ b/modules/pc8080/lib/video.js
@@ -206,6 +206,8 @@ function Video(parmsVideo, canvas, context, textarea, container)
             }
         }
     }
+
+    if (DEBUG) this.nCyclesPrev = 0;
 }
 
 Component.subclass(Video);
@@ -484,6 +486,9 @@ Video.prototype.setPixel = function(imageBuffer, x, y, bPixel)
  */
 Video.prototype.updateScreen = function(n)
 {
+    var fClean;
+    var fUpdate = true;
+
     if (n >= 0) {
         if (!(n & 1)) {
             /*
@@ -497,17 +502,27 @@ Video.prototype.updateScreen = function(n)
              * update the bottom half of the frame buffer after acknowledging this interrupt.
              */
             this.cpu.requestINTR(2);
-            return;
+            fUpdate = false;
         }
 
         /*
          * Since this is not a forced update, if our cell cache is valid AND the buffer is clean, then do nothing.
          */
-        if (this.fCellCacheValid && this.bus.cleanMemory(this.addrBuffer, this.sizeBuffer)) {
-            return;
+        if (fUpdate && this.fCellCacheValid) {
+            if ((fClean = this.bus.cleanMemory(this.addrBuffer, this.sizeBuffer))) {
+                fUpdate = false;
+            }
         }
     }
 
+    if (DEBUG) {
+        var nCycles = this.cpu.getCycles();
+        var nCyclesDelta = nCycles - this.nCyclesPrev;
+        this.nCyclesPrev = nCycles;
+        this.printMessage("updateScreen(" + n + "): clean=" + fClean + ", update=" + fUpdate + ", cycles=" + nCycles + ", delta=" + nCyclesDelta);
+    }
+    if (!fUpdate) return;
+
     var addr = this.addrBuffer;
     var addrLimit = addr + this.sizeBuffer;