methods to reset font rom to default

assets/disk0/fontredef.js

@@ -1,4 +1,10 @@
-sys.poke(-1299460, 4)
+if ("reset" == (exec_args[1] || "").toLowerCase()) {
+    sys.poke(-1299460, 20)
+    sys.poke(-1299460, 21)
+    return 0
+}
+
+sys.poke(-1299460, 16)
 
 let off = -1300607 - (14*0x4F)
 let char = [0,42,85,62,65,85,65,81,93,65,62,0,0,0]
@@ -22,7 +28,7 @@ for (let k = 0; k < 14*128; k += 14) {
 }
 
 
-sys.poke(-1299460, 6)
+sys.poke(-1299460, 18)
 
 for (let y=0; y < 16; y++) {
     for (let x = 0; x < 16; x++) {

src/net/torvald/tsvm/peripheral/GraphicsAdapter.kt

@@ -69,7 +69,8 @@ open class GraphicsAdapter(val vm: VM, val config: AdapterConfig, val sgr: Super
         val channel = it % 4
         rgba.shr((3 - channel) * 8).and(255) / 255f
     }
-    protected var chrrom = Pixmap(Gdx2DPixmap(Gdx.files.internal("./assets/"+config.chrRomPath).read(), Gdx2DPixmap.GDX2D_FORMAT_ALPHA))
+    protected fun getOriginalChrrom() = Pixmap(Gdx2DPixmap(Gdx.files.internal("./assets/"+config.chrRomPath).read(), Gdx2DPixmap.GDX2D_FORMAT_ALPHA))
+    protected var chrrom: Pixmap = getOriginalChrrom()
     protected var chrrom0 = Texture(1,1,Pixmap.Format.RGBA8888)
     protected val faketex: Texture
 
@@ -298,8 +299,9 @@ open class GraphicsAdapter(val vm: VM, val config: AdapterConfig, val sgr: Super
                 framebuffer.setColor(0f,0f,0f,arg1 / 255f)
                 framebuffer.fill()
             }
-            4, 5 -> readFontRom(opcode - 4)
-            6, 7 -> writeFontRom(opcode - 6)
+            16, 17 -> readFontRom(opcode - 16)
+            18, 19 -> writeFontRom(opcode - 18)
+            20, 21 -> resetFontRom(opcode - 20)
         }
     }
 
@@ -368,6 +370,23 @@ open class GraphicsAdapter(val vm: VM, val config: AdapterConfig, val sgr: Super
 
     }
 
+    /**
+     * @param mode 0-Low, 1-High
+     */
+    open fun resetFontRom(mode: Int) {
+        val pixmap = getOriginalChrrom()
+        val data = ByteArray(chrrom0.width * chrrom0.height / 2)
+        val dataOffset = mode * chrrom0.width * chrrom0.height / 2
+        pixmap.pixels.position(dataOffset)
+        pixmap.pixels.get(data)
+
+        chrrom.pixels.position(dataOffset)
+        chrrom.pixels.put(data)
+        chrrom.pixels.position(0)
+
+        pixmap.dispose()
+    }
+
 
     override fun resetTtyStatus() {
         ttyFore = TTY_FORE_DEFAULT

terranmon.txt

@@ -157,10 +157,13 @@ From the start of the memory space:
         1: reset palette to default
         2: fill framebuffer with given colour (arg1)
         3: do '1' then do '2'
-        4: copy Low Font ROM (char 0–127) to mapping area
-        5: copy High Font ROM (char 128–255) to mapping area
-        6: write contents of the font ROM mapping area to the Low Font ROM
-        7: write contents of the font ROM mapping area to the High Font ROM
+
+        16: copy Low Font ROM (char 0–127) to mapping area
+        17: copy High Font ROM (char 128–255) to mapping area
+        18: write contents of the font ROM mapping area to the Low Font ROM
+        19: write contents of the font ROM mapping area to the High Font ROM
+        20: reset Low Font ROM to default
+        21: reset High Font ROM to default
 12 bytes
     argument for "command" (arg1: Byte, arg2: Byte)
     write to this address FIRST and then write to "command" to execute the command