From 83f2218e2750e3b419507c9f0496d48508de2dae Mon Sep 17 00:00:00 2001
From: Jeff Parsons <Jeff@pcjs.org>
Date: Fri, 8 May 2015 12:58:53 -0700
Subject: [PATCH] More debugger paging improvements

---
 modules/pcjs/bin/romtests.json |  2 +-
 modules/pcjs/lib/debugger.js   | 14 ++++++++------
 modules/pcjs/lib/x86cpu.js     | 19 ++++++++++++-------
 tests/pc/80386/tests.nasm      |  4 +++-
 4 files changed, 24 insertions(+), 15 deletions(-)

diff --git a/modules/pcjs/bin/romtests.json b/modules/pcjs/bin/romtests.json
index a40b43ce4..168d9ef63 100644
--- a/modules/pcjs/bin/romtests.json
+++ b/modules/pcjs/bin/romtests.json
@@ -78,7 +78,7 @@
   "debugger": {
     "id": "pc386.debugger",
     "name": "",
-    "commands": "",
+    "commands": "bp F000:825F;g",
     "messages": ""
   }
 }
diff --git a/modules/pcjs/lib/debugger.js b/modules/pcjs/lib/debugger.js
index 653493f86..c5e8de92c 100644
--- a/modules/pcjs/lib/debugger.js
+++ b/modules/pcjs/lib/debugger.js
@@ -2688,12 +2688,14 @@ if (DEBUGGER) {
         if (nState >= 0 && this.aaOpcodeCounts.length) {
             this.cInstructions++;
             var bOpcode = this.cpu.probeAddr(addr);
-            this.aaOpcodeCounts[bOpcode][1]++;
-            var a = this.aOpcodeHistory[this.iOpcodeHistory];
-            a[0] = this.cpu.getIP();
-            a[1] = this.cpu.getCS();
-            a[2] = addr;
-            if (++this.iOpcodeHistory == this.aOpcodeHistory.length) this.iOpcodeHistory = 0;
+            if (bOpcode != null) {
+                this.aaOpcodeCounts[bOpcode][1]++;
+                var a = this.aOpcodeHistory[this.iOpcodeHistory];
+                a[0] = this.cpu.getIP();
+                a[1] = this.cpu.getCS();
+                a[2] = addr;
+                if (++this.iOpcodeHistory == this.aOpcodeHistory.length) this.iOpcodeHistory = 0;
+            }
         }
         return false;
     };
diff --git a/modules/pcjs/lib/x86cpu.js b/modules/pcjs/lib/x86cpu.js
index 8a20013bc..ef563a359 100644
--- a/modules/pcjs/lib/x86cpu.js
+++ b/modules/pcjs/lib/x86cpu.js
@@ -737,9 +737,10 @@ X86CPU.prototype.enablePageBlocks = function()
  * @this {X86CPU}
  * @param {number} addr is a linear address
  * @param {boolean} fWrite (true if called for a write, false if for a read)
+ * @param {boolean} [fSuppress] (true if any faults, remapping, etc should be suppressed)
  * @return {Memory|null}
  */
-X86CPU.prototype.mapPageBlock = function(addr, fWrite)
+X86CPU.prototype.mapPageBlock = function(addr, fWrite, fSuppress)
 {
     var offPDE = (addr & X86.LADDR.PDE.MASK) >>> X86.LADDR.PDE.SHIFT;
     var addrPDE = this.regCR3 + offPDE;
@@ -752,12 +753,12 @@ X86CPU.prototype.mapPageBlock = function(addr, fWrite)
     var pde = blockPDE.readLong(offPDE);
 
     if (!(pde & X86.PTE.PRESENT)) {
-        X86.fnPageFault.call(this, addr, false, fWrite);
+        if (!fSuppress) X86.fnPageFault.call(this, addr, false, fWrite);
         return null;
     }
 
     if (!(pde & X86.PTE.USER) && this.segCS.cpl == 3) {
-        X86.fnPageFault.call(this, addr, true, fWrite);
+        if (!fSuppress) X86.fnPageFault.call(this, addr, true, fWrite);
         return null;
     }
 
@@ -771,13 +772,13 @@ X86CPU.prototype.mapPageBlock = function(addr, fWrite)
     var blockPTE = this.aBusBlocks[(addrPTE & this.busMask) >>> this.blockShift];
     var pte = blockPTE.readLong(offPTE);
 
-    if (!(pte & X86.PTE.PRESENT)) {
-        X86.fnPageFault.call(this, addr, false, fWrite);
+    if (!(pte & X86.PTE.PRESENT) && !fSuppress) {
+        if (!fSuppress) X86.fnPageFault.call(this, addr, false, fWrite);
         return null;
     }
 
     if (!(pte & X86.PTE.USER) && this.segCS.cpl == 3) {
-        X86.fnPageFault.call(this, addr, true, fWrite);
+        if (!fSuppress) X86.fnPageFault.call(this, addr, true, fWrite);
         return null;
     }
 
@@ -786,6 +787,7 @@ X86CPU.prototype.mapPageBlock = function(addr, fWrite)
      * TODO: Since we're immediately shifting addrPhys by blockShift, we could also skip adding the addr's offset.
      */
     var blockPhys = this.aBusBlocks[(addrPhys & this.busMask) >>> this.blockShift];
+    if (fSuppress) return blockPhys;
 
     /*
      * So we have the block containing the physical memory corresponding to the given linear address.
@@ -2717,7 +2719,10 @@ X86CPU.prototype.setBinding = function(sHTMLType, sBinding, control)
 X86CPU.prototype.probeAddr = function(addr)
 {
     var block = this.aMemBlocks[(addr & this.memMask) >>> this.blockShift];
-    if (block.type == Memory.TYPE.UNPAGED) return null;
+    if (block.type == Memory.TYPE.UNPAGED) {
+        block = this.mapPageBlock(addr, false, true);
+        if (!block) return null;
+    }
     return block.readByteDirect(addr & this.blockLimit, addr);
 };
 
diff --git a/tests/pc/80386/tests.nasm b/tests/pc/80386/tests.nasm
index 7f398a52b..03a290849 100644
--- a/tests/pc/80386/tests.nasm
+++ b/tests/pc/80386/tests.nasm
@@ -39,6 +39,8 @@
 
 	bits	16
 
+PAGING equ 1
+
 ;
 ; If we built our data structures in RAM, we might use the first page of RAM (0x0000-0x0fff) like so:
 ;
@@ -264,7 +266,7 @@ initPT:	stosd
 goProt:	o32 lgdt [cs:addrGDT]
 	mov	cr3,esi
 	mov	eax,cr0
-    %ifdef PAGING
+    %if PAGING
 	or	eax,CR0_MSW_PE | CR0_PG
     %else
 	or	eax,CR0_MSW_PE