nes: update presets, vram browser

presets/nes/nesdefs.asm

@@ -109,11 +109,11 @@ NES_MIRR_QUAD	= 8
 ;;;;; NES_VECTORS - CPU vectors at end of address space
 
 	MAC NES_VECTORS
-	seg Vectors
-	org $fffa
-       	.word NMIHandler	;$fffa vblank nmi
-	.word Start		;$fffc reset
-	.word NMIHandler	;$fffe irq / brk (not used)
+	seg Vectors		; segment "Vectors"
+	org $fffa		; start at address $fffa
+       	.word NMIHandler	; $fffa vblank nmi
+	.word Start		; $fffc reset
+	.word NMIHandler	; $fffe irq / brk
 	ENDM
 
 ;;;;; PPU_SETADDR <address> - set 16-bit PPU address

presets/nes/nesppu.asm

@@ -2,22 +2,22 @@
 ;;;;; SUBROUTINES
 
 ClearRAM: subroutine
-	lda #0
-        tax
+	lda #0		; A = 0
+        tax		; X = 0
 .clearRAM
-	sta $0,x
-        cpx #$fe	; don't clear last 2 bytes of stack
-        bcs .skipStack
-	sta $100,x
+	sta $0,x	; clear $0-$ff
+        cpx #$fe	; last 2 bytes of stack?
+        bcs .skipStack	; don't clear it
+	sta $100,x	; clear $100-$1fd
 .skipStack
-        ; skip $200-$2FF, used for OAM display list
-	sta $300,x
-	sta $400,x
-	sta $500,x
-	sta $600,x
-	sta $700,x
-        inx
-        bne .clearRAM
+	sta $200,x	; clear $200-$2ff
+	sta $300,x	; clear $300-$3ff
+	sta $400,x	; clear $400-$4ff
+	sta $500,x	; clear $500-$5ff
+	sta $600,x	; clear $600-$6ff
+	sta $700,x	; clear $700-$7ff
+        inx		; X = X + 1
+        bne .clearRAM	; loop 256 times
         rts
 
 ; wait for VSYNC to start

presets/nes/vrambuf.h

@@ -8,17 +8,11 @@
 #define VBUFSIZE 128
 
 // update buffer starts at $100 (stack page)
-#define updbuf ((byte* const)0x100)
+#define updbuf ((byte*)0x100)
 
 // index to end of buffer
 extern byte updptr;
 
-// macro to add a multibyte header
-#define VRAMBUF_PUT(addr,len,flags)\
-  VRAMBUF_ADD(((addr) >> 8) | (flags));\
-  VRAMBUF_ADD(addr);\
-  VRAMBUF_ADD(len);
-
 // macro to set a single byte in buffer
 #define VRAMBUF_SET(b)\
   __A__ = (b);\
@@ -30,6 +24,9 @@ extern byte updptr;
   VRAMBUF_SET(b)\
   asm("inc %v", updptr);
 
+//#define VRAMBUF_SET(b) updbuf[updptr] = (b);
+//#define VRAMBUF_ADD(b) VRAMBUF_SET(b); ++updptr
+
 // add EOF marker to buffer (but don't increment pointer)
 void cendbuf(void);
 

src/baseplatform.ts

@@ -73,6 +73,7 @@ export interface Platform {
   inspect?(ident:string) : string;
   disassemble?(addr:number, readfn:(addr:number)=>number) : DisasmLine;
   readAddress?(addr:number) : number;
+  readVRAMAddress?(addr:number) : number;
   setFrameRate?(fps:number) : void;
   getFrameRate?() : number;
 

src/platform/nes.ts

@@ -233,6 +233,9 @@ const _JSNESPlatform = function(mainElement) {
   getRasterScanline() : number {
     return nes.ppu.scanline;
   }
+  readVRAMAddress(addr : number) : number {
+    return nes.ppu.vramMem[addr & 0x7fff];
+  }
 
   getCPUState() {
     var c = nes.cpu.toJSON();

src/ui.ts

@@ -210,6 +210,11 @@ function refreshWindowList() {
       return new Views.MemoryView();
     });
   }
+  if (platform.readVRAMAddress) {
+    addWindowItem("#memvram", "VRAM Browser", function() {
+      return new Views.VRAMMemoryView();
+    });
+  }
   if (current_project.segments) {
     addWindowItem("#memmap", "Memory Map", function() {
       return new Views.MemoryMapView();

src/views.ts

@@ -659,7 +659,7 @@ export class MemoryView implements ProjectView {
     for (var i=0; i<n1; i++) s += '   ';
     if (n1 > 8) s += ' ';
     for (var i=n1; i<n2; i++) {
-      var read = platform.readAddress(offset+i);
+      var read = this.readAddress(offset+i);
       if (i==8) s += ' ';
       s += ' ' + (read!==null?hex(read,2):'??');
     }
@@ -667,6 +667,10 @@ export class MemoryView implements ProjectView {
     if (sym) s += '  ' + sym;
     return s;
   }
+  
+  readAddress(n : number) {
+    return platform.readAddress(n);
+  }
 
   getDumpLineAt(line : number) {
     var d = this.dumplines[line];
@@ -726,6 +730,18 @@ export class MemoryView implements ProjectView {
   }
 }
 
+export class VRAMMemoryView extends MemoryView {
+  readAddress(n : number) {
+    return platform.readVRAMAddress(n);
+  }
+  getMemorySegment(a:number) : string {
+    return 'video';
+  }
+  getDumpLines() {
+    return null;
+  }
+}
+
 ///
 
 export class BinaryFileView implements ProjectView {